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SCHEME OF WORK 1ST TERM

WEEK 1: BIOLOGY AND LIVING THINGS

WEEK 2: CLASSIFICATION OF LIVING THINGS

WEEK 3: ORGANIZATION OF LIFE

WEEK 4: HUMAN REPRODUCTIVE ANATOMY AND PHYSIOLOGY

WEEK 5: PUBERTY

WEEK 6: ENERGY

WEEK 7: NUTRITION

WEEK 8: EVIDENCES OF PHOTOSYNTHESIS

WEEK 9: MINERAL REQUIREMENTS OF PLANT

WEEK 10: ANIMAL NUTRITION

WEEK 11 - 12: REVISION


NEW
WEEK TOPIC
1 Introduction to Biology; Recognizing living things: (a) Characteristics of living things
(b) Differences between plants and animals (c) Levels of organization of life.

2 Classification of living things : (a) Kingdom Monera (b) Kingdom Protista (c) Kingdom Fungi

3 Classification of living things: Kingdom Plantae (b) Kingdom Animalia.

4 The Cell : (a) Cell as a living unit of an organism (b) Forms in which cells exist

5 The Cell : (a) Cell structure (i) The cell theory (ii) Cell structure and functions of cell
components (iii) Differences and similarities between plant and animal cells.

6 Cell and its environment : (a) Diffusion (b) Osmosis (i) Diffusion of water through a selective
permeable membrane (iv) osmometer with living material (c) Biological significance of these
processes.

7 Some Properties and functions of the cell : (a) Micro and macro nutrients (b) Cellular
respiration (c) Nutrition (d) Excretion.

8 Some Properties and functions of the cell: (c) Growth (d) cell reactions to its environment
(e) Movement (f) Reproduction.

9 Tissues and supporting systems : (a) Skeleton and Supporting systems in animals
(i) Biological significance (ii) Forms (b) Types of skeleton (c) Vertebrate skeletons (d) Bones
of the vertebral column (e) Functions of the skeleton in animals.

10 Tissues and supporting systems: (a) Different types of supporting tissues in plants
(b) Functions of supporting tissues in plants.

11 Revision

REFERENCE TEXTS
1. Modern Biology for SSS by Sarojini T. Ramalingam; African First Publishers PLC
2. New System Biology for SSS by Lam Peng Kwan et al; African First Publishers PLC
3. Nelson Functional Biology for SSS by Kola soyibo et al;
4. New Biology for SSS by R.H. Stone et al; Longman
5. Biology for SSS by STAN; HEBN Publishers Plc
6. Comprehensive certificate Biology for SSS by Ambuno Sunday et al; University Press Plc
7. Practical Biology

TOPIC: 1. INTRODUCTION TO BIOLOGY: BIOLOGY AS AN INQUIRY IN SCIENCE
CONTENT: 1. Meaning of (a) Science and (b) Biology
2. Scientific method
3. Experimental pattern
Sub – Topic 1: MEANING OF (a) SCIENCE AND (b) BIOLOGY
Science can be defined as a systematic process of making inquiry about the living and non-living things in our environment. Science is both an organized body of knowledge and a process of finding out knowledge.
Biology is the branch of science that studies living things. The word ‘biology’ is derived from two Greek words: ‘bios’ which means life, and ‘logos’ which means study. Biology therefore means the study of life or of living things.
Biology has several branches, these include Botany (study of plants), Zoology (study of animals), Morphology (study of the external features of living things), Anatomy (study of internal structure of living things), Physiology (Study of how living things function), Ecology (study of the relationships between living things and their environment), Genetics (Study of how living things inherit characters from their parents), etc.
The prime purpose of science is research, i.e. finding out about things, so biology involves finding out or making inquiry about living things, their interaction with themselves and with nature.
EVALUATION
1. Define the terms (a) Science (b) Biology
2. State five branches of biology.
3. Of what use is (a) science (b) biology to man?

Sub – Topic 2: METHOD OF SCIENCE
The method of science involves systematically making inquiries about something under study. It begins with observation (that is, looking at something carefully with a view to finding an answer to a question). This involves using all the senses i.e. sight, hearing, touch, feeling, pressure, taste, etc. and instruments (e.g. ruler, microscope, magnifying lens, weighing balance, telescopes, barometer, etc.) where necessary.
Observation is followed by a hypothesis i.e. a sensible, reasonable guess which is capable of being tested or verified.
The hypothesis is tested by an experiment. Experiments usually involve measurements/counting, as such they have to be carried out as accurately as possible. Scientific experiments have a control. The control experiment is identical with the experiment proper, but the factor to be tested is omitted. This gives the investigator a higher degree of confidence in his result and conclusion.
Results from an experiment are put together and an inference/generalization ( or conclusion) is made.
Other scientists may repeat the same experiment and if similar results are obtained then the generalization is accepted as a theory.
When a theory has been tested extensively, worldwide and found to be consistently true, it becomes a law e.g. the law of gravity

EVALUATION
1. State and explain the processes involved in making inquiries in science?
2. In your own words, what are the proper attitudes which should characterize a scientist?

Sub – Topic 3: EXPERIMENTAL PATTERN
Experiments are designed to eliminate all forms of bias so as to avoid making false conclusions. To achieve this, only the factor being tested is varied, all other factors that may affect the result are kept constant. These experiments are known as controlled experiments.
While experimenting, a biologist uses processes of science such as counting, measuring, classifying, organizing data, communicating, recording and interpreting data.
In recording an experiment/ giving the account of a scientific investigation, the following pattern is used:
i. Date of experiment
ii. Aim/purpose of experiment
iii. Apparatus/materials required
iv. Procedure/method used (including control and precautions)
v. Observations
vi. Inference (deduction from what is already known)
vii. Conclusion.

In biology, experiments are carried out on living things. It may not be possible to get a sample of test population with identical organisms. This problem can be reduced by using large test samples and also repeating the experiment many times.
EVALUATION
3. Enumerate the steps specified in giving account of a scientific investigation.
4. How is bias taken care of in a biological investigation?

SUGGESTED PRACTICAL
Is water necessary for the germination of seeds?

TOPIC: 2. RECOGNIZING LIVING THINGS
CONTENT: 1. Living and non- living things; Characteristics of living things.
2. Differences between plants and animals.
3. Levels of organization of life; complexity of organization, its advantages and
disadvantages
Sub – Topic 1: LIVING AND NON LIVING THINGS

Everything in the world can be classified as either a living thing or non-living thing. Living things include plants and animals (things that have life) e.g. Man, Monkey, Earthworm, Flies, Mango, Fresh okra plant, Hibiscus etc. Non-living things do not have life e.g. Stone, Water, Air, Table, etc.

CHARACTERISTICS OF LIVING THINGS
Some features have been found in every living thing ever studied by Biologists, these are;
Living things consist mainly of water and compounds carbon.
They are made up of one or more units called cells
They carry out seven basic life processes namely;
Movement – This is defined as the ability of an organism to change its position. It may be a total change in position of the body as in the case of animals that move their whole body from one place to another or a limited change in position as in the case of plants which can only move parts of their body (e.g. in bending). Living things move in order to look for food, shelter, mates (reproduction) and to escape from danger. Generally, most animals can walk, swim, or fly from one place to another but plants can only move parts of themselves in response to external stimuli. Movement from place to place is also referred to as Locomotion.

Nutrition - This is the ability of an organism to feed. The reason for feeding is to enable living things to live and carry out life processes like growth, respiration and reproduction. Plants manufacture their own food through the process of photosynthesis (autotrophic nutrition). Animals cannot manufacture their own food but depend directly or indirectly on plants for food (heterotrophic nutrition).

Respiration – This involves the taking in of oxygen in order to burn down (oxidize) food substances to release energy which is used to carry out all life processes. Carbondioxide is given off in the process.

Excretion – This is the removal of metabolic waste products from the body. Many chemical activities go on in an organism and produce waste. These waste products are substances which the organism does not need and which may poison it if allowed to build up in the body. The waste products of metabolism include carbondioxide, water, urea, e. t. c.

Irritability or Sensitivity – This is the ability of an organism to perceive and respond to stimuli (changes in the surrounding). Living things exhibits sensitivity in order to survive in their environment. The response is often by some form of movement. Stimuli include heat, light, pain, sounds, chemical substances, e.t.c.

Growth – This is defined as permanent increase in size and mass of an organism especially while young. Organisms also replace and repair worn or damaged parts of the body throughout life. The food eaten provides the basis of growth.

Reproduction – This is the ability of a living organism to produce young ones or offsprings. This ensures continuity of life. Reproduction occurs in two forms.
Asexual reproduction – This involves only one organism producing offsprings from itself.
Sexual reproduction – This involves two organisms coming together to produce offspring(s).

Apart from these seven basic life processes another characteristic of living things is that they all die. All living things have a definite and limited period of existence, and they pass through five basic stages of existence;
Birth → Growth → Maturity → Decline (old age) → Death.

EVALUATION
1. Make a list of five living things and five non-living things.
2. Briefly discuss the characteristics of living things.

Sub - Topic 2: DIFFERENCES BETWEEN PLANTS AND ANIMALS
PLANTS ANIMALS
Green plants carry out photosynthesis Animals cannot carry out photosynthesis; they depend on plants for their food.

Plants do not move from one place to another and do not have organs of movement. Animals move from one place to another and have organs of movement. They exhibit locomotion.

Growth is indefinite (continues throughout life) and apical. Growth is definite and occurs uniformly in every part of the body. It stops when they become adults.

Plants do not have specialized organs for excretion, respiration and coordination. Animals have specific organs for excretion, respiration and coordination.

Plants are slow in response to stimuli Animals are fast in their response to stimuli

Excess carbohydrates are stored as starch
Excess carbohydrates are stored in form of glycogen
They have many branches They do not have any branches


Some organisms exist which posses characteristics of both plants and animals an example is Euglena viridis. Euglena viridis is a microscopic unicellular organism, which lives in water.
The characteristics of Euglena which make it an animal are;
i. Possession of flagellum used for movement.
ii. Possession of gullet for passage of food and which acts as a reservoir.
iii. Presence of eye spot which enables it respond to light.
iv. Possession of contractile vacuole used for excretion.
v. Possession of pellicle which makes its body flexible.
vi. It can feed on other organisms (holozoic nutrition) in the absence of sunlight.

The plant characteristics of Euglena are;
i. Possession of chloroplast which enables it to carry out photosynthesis.
ii. Possession of pyrenoid where starch is stored
iii. It can produce its own food (holophytic or autotrophic nutrition)

EVALUATION
1. State five differences between plants and animals
2. Mention two characteristics of Euglena that makes it (a) a plant (b) an animal

Sub – Topic 3: LEVELS OF ORGANISATION OF LIFE
The bodies of living things are highly organized. This organization occurs in levels, with the simplest structure occurring at the lowest levels (single cells) which interact to build up more complex structures (multicellular organisms).
The basic levels of organization of life in organisms are; cells, tissues, organs and systems.
Cell: This is the smallest unit of living organism. It is the first and simplest level of organization of life. Plants and animals are made up of cells. One celled organisms are called unicellular organisms. They include Amoeba, Plasmodium, Euglena, Paramecium, etc. Organisms made up of many cells are called multicellular organisms e.g man, mango, trees etc. The single celled organism can carry out all life processes on its own.

Tissues: This is a group of similar cells which come together to perform a particular function. A tissue consist of two or more different types of cells aggregating together to perform a specific function e.g. the mesophyl layer in leaves, xylem tissue in stems, muscles, blood (a liquid tissue) etc. Organisms which exist at the tissue level include the hydra, jelly fish, sponge etc.

Organ: Is a group of similar tissues which come together to perform a specific function. Examples in plants are flowers, roots, leaves, seeds, a rhizome, a corm, an onion bulb, a tuber, etc. Examples in animals are the skin, stomach, heart, brain, liver, eyes, ears, kidney, etc.

System: This is a group of functionally related organs which work together to perform specific functions. Examples in plants include the shoot system and root system. Examples in animals include the digestive, nervous, excretory and circulatory systems. Examples in plants are the transport system, shoot and root system.

Complex multicellular organisms: The climax of organization in higher living things is the aggregation of systems to form an organism. Complex multicellular organisms are composed of several organ systems which work harmoniously for the benefit of the organism. All animals from Platyhelminthes to Mammals, and all vascular plants are organized on this level.

Complexity of Organization In Higher Animals
As organisms acquire more layers of cells, they become complex in structure, thus there is an increase in complexity from unicellular to multicellular organism.

Advantages of Complexity
i. It leads to cellular differentiation, thus groups of similar cells are differentiated to form tissues which carry out similar functions
ii. It leads to internal structural specialization in which the tissues become specialized to carry out specific functions.
iii. There is mutual interdependence between component cells i.e division of labour among the cells.
iv. Complexity makes higher organisms to be more efficient in carrying out life processes.
v. Complexity leads to increase in size of organisms.
vi. It makes it possible for organisms to become more resistant to adverse condition within the environment.

Disadvantages of Complexity
i. The cells lose their independence and become increasingly dependent on one another’s activities.
ii. Difficulties in acquisition of materials (such as oxygen and food materials) and removal of waste products by the millions of cells making up a multicellular organism
iii. Slower rate of diffusion of oxygen or respiratory gas to individual cells.
iv. Slower rate of expulsion of waste products from cells.
v. Decrease in ability to regenerate
vi. Difficulties in reproduction.



EVALUATION
1. Mention and explain the levels of organization of life.
2. State three advantages and disadvantages each, of complexity

WEEKEND ASSIGNMENT

OBJECTIVE TEST
1. Biology is the study of ……….
(a) existing things (b) living things (c) living and non- living things (d) non-living things
2. One difference between plants and animals is the ability to
(a) respire (b) reproduce (c) photosynthesize (d) respond
3. Which of the following is not an organ?
(a) Bone (b) Heart (c) Kidney (d) Leaf
4. A collection of cells of the same origin, performing a specific function is called ………..
(a) organ (b) organism (c) system (d) tissue
5. The correct sequence of levels of organization is:
(a) Cells→ Organs→ Tissue→ Systems
(b) Cells→ Tissue→ Organs → Systems
(c) Systems→ Tissues→ Organs → Cells
(d) Tissues→ Cells→ Systems → Organs

ESSAY QUESTIONS
1. Is a virus a living thing or a non-living thing? Give reasons for your answers.
2. Describe one organism at the tissue level of organization (e.g. Hydra)

TOPIC: CLASSIFICATION OF LIVING THINGS
CONTENT: (a) Classification/Taxonomy of living things
(b) Binomial system of nomenclature
(c) Classification and evolution

Sub- Topic 1: CLASSIFICATION (TAXONOMY) OF LIVING THINGS
To classify means to arrange or organize things into groups. Classification of living things involves placing living things that have certain important features in common into specific groups which distinguish them from other groups.
The largest group of organisms is the kingdom. The kingdom has the largest variety of organisms.
The kingdoms are further split into a large number of smaller groups called ‘phyla’ (singular phylum) for animals and ‘division’ for plants. All members of a phylum or division have certain features in common. Each phylum or division is broken down into classes. Classes are split into orders. Orders are split into families. Families are split into genera (singular genus) and genera into species.








The seven groups used in classification of living things in order of hierarchy are;

Kingdom
↓
Phylum (Animal) or
Division (Plant)
↓
Class
↓
Order
↓
Family
↓
Genus
↓
Species

The species is the basic (i.e. smallest) unit in biological classification. A species is a group of individuals which can interbreed to produce fertile offspring. Example, all human beings belong to one species and all monkeys belong to a different species, thus human beings and monkeys cannot interbreed.

Classification Human Dog Lion
Kingdom Animalia Animalia Animalia
Phylum Chordata Chordata Chordata
Class Mammalia Mammalia Mammalia
Order Primate Carnivora Carnivora
Family Hominidae Canidae Felidae
Genus Homo Canis Panthera
Species sapiens familiaris leo

EVALUATION
1. What is taxonomy?
2. Make a list of the hierarchy of groups used in classification of living things.

Sub- Topic 2: BINOMIAL SYSTEM OF NOMENCLATURE

A Swiss Scientist, Carl Von Linne (1707 – 1778) (Latin – Carolus Linnaeus) introduced the present system of classification of living things. He also introduced the binomial system of nomenclature in which an organism is given two names. The first name is the generic name and always begins with a capital letter while the second name is the specific name (species) and begins with a small letter. The generic name is common to all the species in a genus e.g. Equus cabellus (horse), Equus asinus (the donkey), Equus burchelli (common Zebra) are different species of the same genus.

Examples of Scientific names of some organisms

i) Man - Homo sapiens
ii) Housefly - Musca domestica
iii) Maize - Zea mays
iv) Orange - Citrus sinensis
v) Pawpaw - Carica papaya


EVALUATION
1. Who introduced the binomial system of nomenclature?
2. Write the scientific names of the following: (a) Rice plant (b) Domestic cat (c) Monkey




Sub – Topic 3: CLASSIFICATION AND EVOLUTION
As a result of advances in the field of science a five-kingdom system introduced by R.H Whittaker (1969) has been adopted by some biologists. Most biologist however, prefer to divide living things into prokaryotids (bacteria and blue-green algae) and eukaryotids (all other organisms) based on the complexity of cell structure and cell chemistry.

Prokaryotids – Monera: bacteria, blue-green algae
Eukaryotids – Protista: protozoa, unicellular algae
Fungi: yeasts inclusive
Plantae: multicellular plants and multicellular algae
Animalia: multicellular animals

The five kingdom classification is as follows;
(i) kingdom Monera,
(ii) kingdom Protista (Protoctista),
(iii) kingdom Fungi,
(iv) kingdom Plantae and
(v) Kingdom animalia.

Viruses
These are not cells. They are particles made up of DNA (deoxyribonucleic acid) or RNA (ribonucleic acid) surrounded by a protein coat. The genetic material is composed of a few genes that code for the proteins that form the coat and other proteins that help it reproduce.
They are very harmful parasites that enter the cells of another organism (host) in order to multiply.
They do not respond to antibiotics and are constantly changing into new strains.

A. Kingdom Monera
i. They are unicellular
ii. The cells are prokaryotic with no organized nucleus and no nuclear membrane, just a loop of DNA within the cytoplasm.
iii. They do not have complex chromosomes
iv. Cells have no mitochondria, endoplasmic reticulum and no chloroplasts.
v. Cell wall does not contain cellulose but polysaccharides and amino acids
vi. No sexual reproduction.
vii. They may be autotrophic or heterotrophic
Examples include bacteria and blue-green algae.




Helicobacter pylori Anatomy of a simple bacterium




B. Kingdom Protista
i. The organisms are eukaryotic and unicellular.
ii. Some are heterotrophic, some are autotrophic and some are both
iii. Reproduction is usually asexual by mitosis but some have sexual reproduction by fusion of gametes.
iv. Movement may be by cilia, flagella or may be amoeboid
v. The kingdom is divided into the following phyla;
(a). Phylum protozoa: Examples are Amoeba, Paramecium, Zooflagellates, Plasmodium, Trypanosoma
(b). Phylum Euglenophyta: Example Euglena
(c). Phylum Chrysophyta: Example diatoms
(d).Phylum Pyrrophyta: Example dinoflagellates




Paramecium Amoeba engulfing a paramecium

C. Kingdom Fungi
i. Some are unicelleluar e.g yeast, many are multicellular e.g rhizopus, mushroom and toadstools .
ii. The body of a fungi is composed of threads/filaments each called a hypha.
iii. All the hyphae of a single organism are collectively called a mycelium.
iv. There are many nuclei in a cell.
v. All fungi are heterotrophic – They lack chlorophyll. Some are saprophytic, some are parasitic and some are symbiotic.
vi. Fungi together with bacteria are the principal decomposers in the biosphere
vii. Fungi reproduce by asexual or sexual methods.



Fly Agaric Mushroom
The brightly colored fly agaric mushroom is a deadly poisonous mushroom. Containing ibotenic acid and a number of other organic poisons, the fly agaric can cause severe damage to the central nervous system, blood vessels, kidneys, liver, and muscles. Symptoms, which may not become apparent for 8 to 12 hours or longer, include nausea, vomiting, and severe diarrhea and can lead to coma and death.

Structure of Mushroom

EVALUATION
1. List the five kingdoms of classification of living things.
2. Give two characteristics each of organisms in each group mentioned above.

WEEKEND ASSIGNMENT

OBJECTIVE TEST
1. Which of the following groups embraces the rest? (a) Class (b) Kingdom (c) Phylum (d) Species
2. Which of the following indicates that Euglena is a plant?
(a) Conspicuous eye spot (b) limited movement (c) presence of gullet (d) presence of starch grains
3. Which of the following is not true of rhizopus or mucor? (a) It bears spores in sporangia
(b) It manufactures its own food (c) It has non-septate hyphae
(d) It undergoes asexual reproduction
4. Bacteria cells differ from eukaryotic cells by having (a) cell membrane (b) cell wall
(c) nuclear material (d) nuclear membrane
5. Fungi and bacteria help to (a) decompose materials (b) eliminate waste (c) produce food
(d) produce new species


ESSAY QUESTIONS
1. State two differences between prokaryotic and eukaryotic cells
2. Make a large well labeled diagram of a mushroom.

CLASSIFICATION OF LIVING THINGS:
CONTENT: (a) Kingdom Plantae
(b) Kingdom Animalia.
Sub – Topic 1: KINGDOM PLANTAE
-They are mainly non-motile
-They are all autotrophic

(1) Division Thallophyta (Algae): e.g. pondweeds, seaweeds, diatoms
- They are nearly all aquatic
- Some are unicellular e.g. Chlamydomonas and diatoms some are filamentous e.g. spirogyra while some have flat body called a thallus e.g. seaweeds.
- The body is simple in structure. They have no true roots, stems, leaves or specialized conducting systems.
- All have chlorophyll and they photosynthesis. However, some have other pigments which mask the green colour of chlorophyll e.g. seaweeds may be brown, red, and green in colour.


Euglena Spirogyra


(2) Division Embryophyta
(a). Bryophyta e.g. mosses and liverworts.
- The cells are differentiated into tissues.
- They lack true roots stems and leaves, but have structures resembling them e.g. a typical moss has a stalk, small leaves which are one or two cells thick and thread-like rhizoids. There are no specialized conducting tissues.
- They are terrestrial and most live in deep and shady places.
- They need moisture for fertilization.
- They exhibit asexual reproduction by spores in which there is alteration of generation.

(b). Tracheophyta-(vascular plants)
(i). Pteridophyta: e.g. ferns
- Are more complex in structure than Bryophytes.
- They have proper roots, stems and leaves and a well-developed conducting system (i.e they are vascular green plants).
- They are non-flowering and non-seed producing plants.
- A large number of spores develop on the under surface of the leaves (or ponds) which are dispersed by wind.
- They need moisture for fertilization.
- Nearly all ferns are terrestrial, growing in damp and shady places. Many tropical ferns grow as epiphytes on palms and other trees.
- Most are herbs but a few are small trees.



Fern



(ii).Spermatophyta: e.g. all seed-bearing plants.
- They are multicellular, seed producing plants.
- They have true roots, stems and leaves.
- They have well developed vascular tissues.
- They reproduce sexually and do not need water for fertilization.
- They are mainly terrestrial plants.
There are two main sub-divisions namely,
(a) Sub-division Gymnospermae: All cone-bearing plants e.g. cycads, conifers and pines.
- They produce seeds in cones (naked seeds).
- They do not form flowers and fruits.
- All are woody plants and most are trees.
(b) Sub-division Angiospermae: All flowering plants.
- The seeds are produced in special structures called flowers.
- Fertilized seeds are enclosed in fruits
- They are nearly all terrestrial.
Angiosperms can be further divided into two classes according to the number of seed leaves (cotyledons). These are:
Dicotyledonous plants (seed have two seed leaves) e.g. Cowpea, groundnut, etc.
Monocotyledonous plants (seeds have one seed leaf) e.g. maize, millet, wheat, etc.



Conifer Pine

Sub – Topic 2: KINGDOM ANIMALIA

Classification of Animals
Types of Invertebrates
Invertebrate Phylum Characteristics Examples
Placozoa Microscopic marine animal. Flattened body composed of two outer layers of flagellated cells enclosing loose cells. Reproduces asexually and possibly sexually. Single species identified as Trichoplax adherens.
Porifera Simple, multicellular animals with tissues but no distinct organs. Commonly known as sponges, they typically attach to rocks, shells, or coral. Most sponges have an irregular shape supported by a skeleton composed of calcareous crystals, silicon spicules, or spongin fibers. Most sponges have an internal water canal system that moves water through the body, providing a constant supply of food particles and oxygen to all cells and removing wastes. Sponges reproduce sexually. They regenerate lost or injured body parts. Sponges
Cnidaria Aquatic radially symmetrical animals with tentacles encircling the mouth at one end of the body. Cnidarians appear in two forms during their life cycle, the sessile, cylindrical polyp and the free-swimming medusa that looks like a jellyfish. Most feed on zooplankton, although some eat larger invertebrates. Cnidarians use tentacles to capture prey, immobilizing the prey with stinging cells called nematocysts. Cnidarians reproduce both asexually (by budding) and sexually. Some species are hermaphroditic, with both eggs and sperm produced in each individual. Most regenerate lost or injured body parts. Coral, hydra, jellyfish, Portuguese man-of-war, sea anemone
Ctenophora Jellyfish-like marine animals distinguished by eight rows of cilia that propel the body in swimming. They feed on other invertebrates using two retractable sticky tentacles to capture prey. All ctenophores are hermaphroditic and reproduce sexually. Many are luminescent. Sea walnuts, comb jellies
Platyhelminthes Structurally simple worms with no anus or circulatory system. Known as flatworms, their flattened bodies enable internal tissues to be near the skin surface, permitting gas and nutrient exchange with the environment. A muscular layer just beneath the skin layer aids in locomotion. Flatworms are hermaphrodites and reproduce sexually. They typically have a life cycle involving a parasitic larval stage. Many types of flatworms are parasites of vertebrates. Flatworms, flukes, tapeworms
Mesozoa Minute parasitic animals of invertebrates, particularly squids and octopuses. These worms have a simple, elongated, ciliated body. They reproduce sexually and have a complex life cycle involving more than one larval form. Rhopalura granosa
Nemertea or Rhynchocoela Animals characterized by a proboscis, a long, muscular tube used in capturing invertebrate food. Nemerteans have elongated, flattened bodies and they lack an internal body cavity. They have a mouth opening for food ingestion and an anal opening for wastes. The blood of some nermerteans contains oxygen-carrying hemoglobin. Nemerteans reproduce sexually. Nemertine worms, ribbon worms
Gastrotricha Microscopic multicellular animals that inhabit both freshwater and marine water. An external layer, the cuticle, encasing these animals contains cilia that aid in locomotion. Adhesive tubes found on the sides or at the posterior end aid in surface attachment. Freshwater species have a forked tail. These animals feed on dead or living bacteria, diatoms, or small protozoa. Marine species are hermaphroditic, while most fresh water species are female, reproducing by parthenogenesis. Turbanella cornuta, Chaetonotus anomalus
Rotifera or Rotatoria Microscopic aquatic animals characterized by a corona, a wheel-shaped organ on the head used in feeding and swimming. The rapid beating of the cilia on the corona draws nutrient-containing water into the mouth. A protective cuticle covers the elongated, cylindrical body. Reproduction is sexual during brief periods of the year and throughout the rest of the year females reproduce via parthenogenesis. Synchaeta oblonga, Phylodina roseola
Kinorhyncha or Echinodera Tiny worms with spiny bodies. An outer protective cuticle is segmented and articulated. Found in the muddy bottoms of coastal waters, they feed on microorganisms and organic particles by means of a sucking pharynx. Reproduction is sexual. Echinoderes, Condyloderes
Nematoda Commonly known as roundworms, these animals are one of the most diverse and geographically widespread invertebrate phyla. Free-living roundworms inhabit freshwater and marine habitats, as well as soil. Parasitic roundworms prey on both plants and animals, causing widespread agricultural damage and disease. Roundworms have long, cylindrical bodies with a mouth surrounded by lips and sensory papillae or bristles. Fluid in the body cavity distributes nutrients and oxygen-roundworms do not have special respiratory or circulatory systems. Roundworms prey on other invertebrates as well as diatoms, algae, and fungi. They reproduce sexually and larvae undergo at least four molts before reaching their adult size and shape. Ascarids, vinegar eels, cyst nematodes, heartworms, hookworms
Nematomorpha Long, threadlike worms found in soil or freshwater, commonly known as horsehair worms. They have no distinct head. Larvae are parasitic on terrestrial arthropods, usually insects. Adults do not feed but depend entirely on nutrients obtained during the parasitic larval stage. Reproduction is sexual. Nectoneme, gordian worms
Acanthocephala Worms characterized by the presence of retractable spiny hooks that attach to the intestinal walls of aquatic and terrestrial vertebrates. Lacking a digestive tract, these worms absorb nutrients through their body wall. Reproduction is sexual and the life cycle includes larval forms that are parasites of crustaceans or insects. Spiny-headed worms
Gnathostomulida Elongated, ciliated worms that live in marine sand. These animals have a mouth structure with a combed plate and toothed jaws. Bacteria and fungi are scraped into the mouth by the comb and passed into the gut by snapping movements of the jaws. Hermaphroditic, these animals reproduce sexually. Jaw worms
Mollusca Diverse animals found in water and on land. Most mollusks have a hard shell that protects a soft body, although in some mollusks the hard shell is missing or hardly visible. A feeding organ called a radula contains rows of teeth used to scrape food into the mouth. Enzymes in salivary glands partially digest food before it reaches the intestines. Reproduction is sexual and some mollusks have a larval form. Chitons, oysters, snails, clams, squid
Annelida Segmented worms with a muscular body wall used for burrowing. External hairs called setae aid in traction during burrowing. An internal coelom is divided into compartments by walls known as septum. The digestive system stretches from the mouth to the anus, differentiated into regions, each with a different function. Reproduction is sexual. Lugworms, earthworms,
leeches
Pogonophora Deep-sea worms that live in chitinous tubes attached to the ocean floor. Their long, slender body has a beard of tentacles at the head end. There is no mouth or digestive system and these animals absorb all nourishment through the body surface. They reproduce sexually. Bead worms
Vestimentifera Giant deep-sea worms that live in chitinous tubes attached to the ocean floor. They derive nutrition using a specialized organ called a trophosome to digest sulfide-oxidizing bacteria. Llamellibrachs
Sipuncula Marine worms with a saclike body and a long proboscis. These worms withdraw their narrow head into the fatter posterior portion. The head
end bears tentacles used in burrowing and gathering food particles. Lacking a cardiovascular system, they use internal fluid to transfer oxygen and food to body tissues. They reproduce sexually and some have a larval form. Peanut worms
Echiura Plump marine worms that take shelter in sand burrows or rock crevices. They use a mucous net or a scoop-shaped proboscis to capture food particles. Reproduction is sexual. Spoon worms
Priapulida Cucumber-shaped, marine worms with spiny heads. During movement the barrel-shaped proboscis withdraws into the trunk of the worm. Reproduction is sexual. Priapulus
Tardigrada Microscopic animals with four pairs of stubby legs that live in marine and freshwater sediments and on the surface of mosses and lichens. They use sharp stylets protruding from their mouths to suck food from plant cells. These animals have a remarkable ability to withstand extreme dryness and low temperatures. Reproduction is sexual. Water bears
Pentastomida or Linguatulida Parasitic worms that live in the lungs of snakes, crocodiles, and some mammals and birds, feeding on blood and tissue. The head bears four leglike claws and a snoutlike mouth. The body is covered by a cuticle that is molted during larval development. They reproduce sexually. Tongue worms
Phoronida Cylindrical, marine worms that live in a chitinous tube embedded in sand or attached to rocks, shells, or other objects in shallow water. Protruding out of the tube is the animal's lophophore, a structure of ciliated tentacles arranged in a horseshoe shape, that is used for feeding. They have a U-shaped digestive tract. Adults are sedentary and larvae are free-swimming. Reproduction is asexual in at least one species, but most species reproduce sexually. Horseshoe worms
Arthropoda Largest and most diverse invertebrate phylum characterized by animals with jointed limbs, a segmented body, and an exoskeleton made of chitin. Arthropods are abundant and successful in almost all habitats. The exoskeleton is divided into plates that enhance flexibility and movement. Periodic molting of the exoskeleton permits growth. Arthropods have a complex brain and nervous system. Many arthropods have a compound eye made up of numerous light-sensitive parts. Reproduction is sexual. Ants, beetles, butterflies, lobsters, shrimp, crabs, scorpions, spiders, ticks
Ectoprocta or Bryozoa Small, mostly marine animals that resemble simplified horseshoe worms, with a lophophore surrounding the mouth. They live in colonies, attaching to the sea bottom or seaweed. Bryozoans are hermaphroditic and reproduce asexually (by budding) and sexually. Moss animals
Entoprocta or Kamptozoa Small, mostly marine animals with a globular body mounted on a stalk. A lophophore surrounds both the mouth and anus. Entoprocts live in colonies. They reproduce both asexually and sexually. Urnatella, Pedicellina
Brachiopoda Marine animals that resemble clams except that their shells form on the top and bottom of the animal, while clam shells form on the left and right of the animal. The shell attaches to the ocean bottom, rocks, or other objects by means of a cordlike stalk. Brachiopods reproduce sexually. Lamp shells
Echinodermata Marine animals distinguished by their radial symmetry in which the body can be divided into five parts arranged around a central axis. They have internal skeletons composed of calcareous ossicles with projecting spines that give the body surface a bumpy appearance. They use body appendages called processes for feeding and locomotion. Reproduction is sexual and some have a larval form. Sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers
Cycliophora Discovered in 1995, these parasites live in the mouthparts of certain lobsters. They have a characteristic saclike body with a bell-shaped mouth structure called a buccal funnel. Only one species has been identified, and it displays alternation of generations, with both asexual and sexual components of the life cycle. Single species identified as Symbion pandora
Loricifera Marine sediment dwellers with a protective structure called a lorica, consisting of plates that surround the animal's trunk. The mouth and head retract into the lorica for protection. Reproduction is sexual and little is known about the life cycle, although a larval form has been identified. Nanaloricus mysticus
Onychophora Terrestrial, caterpillar-like animals found only in the tropics and southern hemisphere. The soft body is covered by a flexible cuticle that periodically molts. The head region contains a pair of antennae and clawlike mandibles. They have from 14 to 43 pairs of legs, depending upon the species and gender. Reproduction is sexual. Velvet worms
Chaetognatha Torpedo-shaped marine animals with fins that enable them to swim with rapid, dartlike movements as well as gliding and floating motions. Movable hooks on their heads are used to capture prey. These animals are hermaphrodites and reproduction is sexual. Arrow worms
Hemichordata Simple, wormlike marine animals with a primitive notochord and a system of gills. They use a distinctive proboscis to capture food and also to aid in locomotion. Reproduction is sexual and some have a larval form that resembles the larvae of echinoderms. Acorn worms

Types of Vertebrates
Vertebrate Type Characteristics Examples
Jawless fishes Cold-blooded animals that live in water. These fishes have no bone structure and their sole support is from a simple cartilaginous rod known as the notochord. Unlike other vertebrates, these fishes do not have opposing jaws. They have round, sucker-like mouths and use tongues with embedded teeth that scrape tissue from prey. Jawless fishes have primitive breathing openings that provide oxygen to the blood. They reproduce by laying eggs. Hagfish, lamprey
Cartilaginous fishes Cold-blooded animals that live in water. Their notochord is surrounded by rings of cartilage known as vertebrae. The remainder of the skeleton is also cartilaginous rather than bony. They have breathing organs called gills that provide oxygen to the blood. Cartilaginous fishes have powerful jaws for grasping prey. Reproduction varies depending upon the species. Some fish produce live young, while others lay eggs outside of the female body. Sharks, skates, rays, chimaeras
Bony fishes Cold-blooded animals that live in water. Their skeleton is made of bone, and most bony fishes also have an internal bladder that aids in buoyancy. The anatomy of these fishes varies greatly, but typically includes fins, scales, a two-chambered heart, and gills. Bony fishes reproduce by laying eggs. In some species the eggs develop inside the female, who then give birth to live young. Sturgeon, herring, salmon, perch, cod, coelacanth
Amphibians Cold-blooded animals that live some part of their life on land but usually must breed and develop from egg to larvae to adult in water. Most amphibian larvae use gills to breathe underwater. These gills are then replaced in adults by lungs for breathing air. Their permeable skin acts as an additional breathing organ by permitting oxygen exchange. Their skin also permits water to pass in and out, requiring amphibians to stay nearby a water source so that their bodies do not dry out. Amphibians were the first animals with backbones to adapt to life on land. Frogs and toads, salamanders, newts, caecilians
Reptiles Cold-blooded animals with an outer covering of scales or bony plates that prevents their bodies from drying out when not near water. Reptiles reproduce by laying eggs protected by shells or by giving birth to live young. They do not have a larval stage. Mostly land-dwellers, they breathe air using lungs. Snakes, crocodiles, alligators, lizards, turtles, tortoises
Birds Warm-blooded animals whose body is covered with feathers. Birds have wings that in most cases help them fly. A number of adaptations make flight easier, including a lightweight skeleton in which many major bones are hollow and a furculum, or wishbone, that absorbs the shock of wing motion during flight. Birds reproduce by laying eggs protected by shells. Penguin, flamingo, eagle, turkey, thrush, parrot
Mammals Warm-blooded animals, the females of which have milk-secreting organs that they use to feed their young. Mammals have highly developed brains, giving them an intelligence unmatched by any other group of animals. Most mammals reproduce by giving birth to live young. They are the only animals with hair, and they have specialized teeth that make it possible to eat a wide variety of plants and animals for food. Platypus, kangaroo, bat, lion, wolf, mouse, seal, antelope, cow, dolphin, whale, lemur, monkey, ape, human
Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.

EVALUATION
1. List the groups in the division embryophyta.
2. Give two characteristics each, of organisms in each group mentioned above.

WEEKEND ASSIGNMENT

OBJECTIVE TEST

1. Another name for vascular plant is…….. (a) Angiosperm (b) Gymnosperm (c) Pteridophyte
(d) Tracheophyte
2. Amoeba moves by means of …..(a) cilia (b) flagella (c) pseudopodia (d) seta
3. The dominant phase in the life cycle of the bryophyte is (a) gametangium (b) gametophyte
(c) prothallus (d) sporophyte
4. Which of these is not a cold blooded animal? (a) Fish (b) Lizard (c) Rat (d) Toad
5. Which of these is the odd one out? (a) Bat (b) Rat (c) Tilapia (d) Whale


ESSAY QUESTIONS
1. State the two groups of the animal kingdom and their respective phyla.
2. Enumerate the general characteristics of vertebrates and list the classes.
3. Make a well labeled diagram of the ventral view of an earthworm.

TOPIC: THE CELL
CONTENT: (a) Cell as a living unit of an organism
(b) Forms in which cells exist

Sub – Topic 1: CELL AS A LIVING UNIT
The cell is defined as the simplest, the smallest and basic unit of life. It is the structural and functional unit of a living organism. The cell can carry out all life activities such as feeding, respiration, movement etc.

Classification of Living Things Based on The Number of Cells
All living things are classified into two major groups depending on the number of cells they possess. These groups are:
A. Unicellular or Acellular organism: Organisms which consist of only one cell e.g. Amoeba, Paramecium, Chlamydomonas and Euglena.
B. Multicellular Organisms: Organisms which consist of two or more cells, e.g. Hydra, Flowering plants, Fish, Bird, Man etc.

EVALUATION
1. Define the term ‘cell’
2. Mention the two groups in which organisms can be placed based on the number of their cells.

Sub – Topic 2: FORMS IN WHICH LIVING CELLS EXIST
Living cells exist basically in four forms;
1. As single and free living organisms: These are organisms which possess only one cell and are able to live freely on their own. The single cell carries out all life processes such as feeding. Euglena, etc. Parts of the cell may be specialized to carry out a particular process, for example Paramecium.
Paramecium is a fresh-water protozoan. It lives in ponds and puddles and feeds mainly
on bacteria. It is often described as having a slipper shape and is about 0.25mm long. It has a
stiff outer-covering called the pellicle which gives it a fixed shape. Its cytoplasm is divided into
a clear outer layer called the ectoplasm and a granular inner layer called the endoplasm.
The endoplasm contains several food vacuoles, two contractile vacuoles and two nuclei.
The larger one called the meganucleus and the smaller one the micronucleus. It moves (swims)
in the water by means of cilia. The cilia are tiny projections of the ectoplasm through the
pellicle. The oral groove and gullet are specialized for feeding, while the contractile vacuole
is specialized for water regulation.

2. As a colony: A colony consists of many similar cells which are joined together. E.g. Volvox, Pandorina, etc. Diagram of volvox

3. As a filament: This consists of many similar or identical cells joined end to end to form unbranched filaments. e.g. spirogyra, zygnema, oscillatoria and oedogonium.
Each cell in a colony or filament behaves as an individual. Each carries out life
processes independently of its neighbours.

4. As a part of a living multicellular organism: In multicellular organism cells which perform the same function are grouped together to form a tissue, e.g. tissues of the ileum wall, the retina, and the blood (a tissues which perform a specific function form an organ and a group of organism working together to perform a specific task form a system.

EVALUATION
1. Mention the various forms in which a cell can exist.
2. Make a well labeled diagram of spirogyra.

TOPIC: THE CELL
CONTENT: (a) Cell Structure, (i) The Cell Theory (ii) Cell Structure and Functions of Cell Components (iii) Differences and Similarities between Plant and Animal cells.
From the general point of view, cell is considered as an idea. The dictionary explains the meaning as ‘a small room in a prison for one or more persons’ or as ‘a small number of people.’ When one commits a crime, such a person is put in a police cell while investigation is going on.
However, in Biology the term cell is a vital subject matter and has a special definition. It is defined as the smallest, structural and functional unit of life having a nucleus at the centre and bounded by a cell membrane.
They are two types of cells: Plant and Animal cells. See diagram below



Plant Cell
Plant cells contain a variety of membrane-bound structures called organelles. These include a nucleus that carries genetic material; mitochondria that generate energy; ribosomes and rough endoplasmic reticulum that manufacture proteins; smooth endoplasmic reticulum that manufactures lipids used for making membranes and storing energy; and a thin lipid membrane that surrounds the cell. Plant cells also contain chloroplasts that capture energy from sunlight and a single fluid-filled vacuole that stores compounds and helps in plant growth. Plant cells are surrounded by a rigid cell wall that protects the cell and maintains its shape.




Animal Cell
An animal cell typically contains several types of membrane-bound organs, or organelles. The nucleus directs activities of the cell and carries genetic information from generation to generation. The mitochondria generate energy for the cell. Proteins are manufactured by ribosomes, which are bound to the rough endoplasmic reticulum or float free in the cytoplasm. The Golgi apparatus modifies, packages, and distributes proteins while lysosomes store enzymes for digesting food. The entire cell is wrapped in a lipid membrane that selectively permits materials to pass in and out of the cytoplasm.
EVALUATION:
1. Define the term cell.
2. Sketch a well labelled diagram of plant and animal cells
THE CELL THEORY
The man who first discovered and described cell in living things is called Robert Hooke in 1665, he also invented the microscope, but the cell theory was proposed by another man called Mathias Schleiden, a German Botanist 1838, and Theodor Schwann, a German Zoologist, these two men postulated the theory known as cell theory in 1839. Another man who made contribution to cell theory is known as Felix Dujardin. What was his contribution and when?
The cell theory states that:
1. Cell is the structural unit of all living things;
2. Cell is the functional unit of all living things;
3. Cell originates from a pre-existing cell; and
4. Cell contains hereditary materials.





Another name for cell components are cell organelles e.g of an organelle is the nucleus of a cell as shown below.

Mitochondria
Mitochondria, minute sausage-shaped structures found in the hyaloplasm (clear cytoplasm) of the cell, are responsible for energy production. Mitochondria contain enzymes that help convert food material into adenosine triphosphate (ATP), which can be used directly by the cell as an energy source. Mitochondria tend to be concentrated near cellular structures that require large inputs of energy, such as the flagellum, which is responsible for movement in sperm cells and single-celled plants and animals.








Nucleus of a Cell
The characteristic feature of a eukaryotic organism is the presence of a nucleus within the organism’s cells. The nucleus—visible here as a darkly stained area—encloses a cell’s hereditary material. It is separated from the cytoplasm of the cell by a double-layered membrane called the nuclear envelope.
STRUCTURE DESCRIPTION AND FUNCTION OF CELL COMPONENTS
1. Cell wall
Description: Non-living, made of cellulose, permeable to water and substance
Functions: Provides rigidity to the cell and gives it a definite shape.
2.Cell membrane
Description: Living and differentially permeable to water and substance.
Function: Allows selective movement of materials in and out of the cell.
3.Cytoplasm:
Description: Semi-fluid mass enclosed within the cell membrane and contain many organelles.
Functions: The largest and liquid part of the cell in which metabolic reactions occur.
4. Nucleus
Description: Enclosed by a nuclear membrane, and contains chromatin and nucleolus.
Functions: It stores and carries hereditary information from generation to generation. It also translates genetic information into the kind of protein characteristic of the cell. It controls the cell’s life processes
5. Vacuoles
Description: This is the fluid filled spaces in the cytoplasm.
Functions: Help in maintaining turgidity in the plant cell.
6. Mitochondria
Description: It is a double membrane system, found in all cells. It contains the enzymes for cellular respiration.
Functions: it carries out metabolism for all life processes. Kreb’s cycle and electron transfer system take place in the mitochondria.
EVALUATION
1. State the cell theory.
2. Who is the first founder of the cell?
3. List four men who contributed to the discovery of the cell
4. Describe the nucleus and its functions.
GENERAL EVALUATION
1. One of these men did not contribute to the discovery of the cell (a) Leo Newman (b) Felix Dujardin (c) Mathias Schleiden (d) Theodore Schwaan (e) Robert Hooke.
2. The organelle or cell component that functions for respiration is --------- (a) cell wall (b) cell membrane (c) mitochondria (d) nucleus (e) ribosome.
ESSAY TEST
Describe and state the functions of the following cell components or organelles: 1.Endoplasmic reticulum, 2. Ribosome, 3.Centrioles, and 4.Chloroplasts.
WEEKEND ASSIGNMENT
Read Exam Focus Biology for WASSCE AND SSCE by A. Egunyomi et-al (Pages 4-6)
PRE-READING ASSIGNMENT
Read and Study about cell in your Biology text book.
WEEKEND ACTIVITY
1. State Five (5) differences between plant and animal cell.
2. Outline four similarities between plant and animal cell.
REFERENCE TEXTS:
A. Egunyomi et-al. (2011) Exam Focus Biology for WASSCE and SSCE. UNIVERSITY PRESS PLC IBADAN.
F.O.C Ndu et-al (2013). Senior Secondary Biology 1, Third edition. BHS Book Printing Shd, Bhd. Kuala Lumpur. Malaysia.

TOPIC: Cell and its Environment: DATE-----------------------
CONTENT: (a) Diffusion (b) Osmosis (i) Diffusion of water through a selective permeable membrane, (ii) Haemolysis (iii) Plasmolysis (iv) Osmometer with living material.
The topic ‘Cell and its Environment’ refers to the activities of the cell in a given environment or the functions of the cell given a particular condition. Some conditions can be harmful to the cell while others are helpful for proper functioning of the cell. This is why we discuss the cell and its environment.
diffusion
Diffusion can take place in liquid and gases, but diffusion is faster in gases than in liquid, because air and gases as a medium has more spaces to be filled.
Diffusion can be defined as the process by which molecules of substances, such as liquid and gases move randomly from a region of higher concentration to a region of lower concentration until they are evenly distributed.
It is also a process by which fine particles (molecules) flow in and out of cells of living things, and it can occur in non-living things or membrane.
SUGGESTED PRACTICALS
Stand at the corner of the classroom, and spray a perfume, after a while the scent of the perfume will circulate the whole class and every student will testify to the perception. This is diffusion in gas.
You can also demonstrate diffusion of solid material in liquid medium using potassium tetraoxomanganate (vii) crystals. i.e. KMnO4
Materials: Distilled water, Beakers, Spatula, and KMnO4.
RATE OF DIFFUSION
The rate of diffusion is the time taken by molecules of a diffusing substance to be uniformly distributed in any given area of the diffusing medium.
Some factors may affect (inhibit or facilitate) the rate of diffusion:
1. State of matter of diffusing molecules
2. Size of diffusing molecules
3. Differences in concentration of diffusing molecules and the medium (conc. gradient).
4. Temperature of diffusing medium.
IMPOTANCE OF DIFFUSION
In a Biological system, diffusion is essential in the following:
i. Gaseous exchange in lungs during external respiration.
ii. The movement of carbon iv oxide and Oxygen during photosynthesis and respiration in plants.
iii. Movement of digestive food from the intestine into the blood circulatory system.
iv. Movement of nutrients, and other metabolic products from the mother through the placenta to the foetus.
v. The upward movement of mineral salts and nutrients from the soil through the roots to other parts of the plant.

EVALUATION
1. Define the term diffusion.
2. What is rate of diffusion?
3. State three importance of diffusion.



Diffusion
Diffusion is the natural tendency of molecules to flow from higher concentrations to lower concentrations. When the barrier between two substances is removed (as shown here), the molecules will diffuse throughout the entire container. While the number of molecules in the container is the same as it was before the barrier was removed, the substances are now at lower concentrations. The rate of diffusion depends on the weight of the molecules—heavy molecules diffuse more slowly than light molecules.


OSMOSIS
Osmosis is the movement of water molecules from a dilute solution into a more concentrated solution through a semi-permeable membrane. Living organisms has the cell as the semi-permeable membrane. Since the water molecules are small, the cell is somewhat limited in the amount of direct control it can impose on their passage across the membrane. In osmosis, the stronger solution is called hypertonic solution, while the weaker solution is called hypotonic solution. In osmosis, water molecule move from hypotonic to hypertonic solution, but when the concentrations are equal, the solution is said to be isotonic.
APPLICATION OF OSMOSIS IN ANIMALS
They include:
1. Reabsorption of water in kidney tubules,
2. Entry of water into the cytoplasm of unicellular animals, e.g. Amoeba and Paramecium,
3. Movement of water in and out of living animal cells,
4. Absorption of water in the large intestine.
APPLICATION OF OSMOSIS IN PLANTS
They include:
1. Absorption of water from the soil by the root hairs,
2. The movement of water in and out of living plant cell,
3. The movement of water from the root hairs to the cells of the cortex, and
4. Opening and closing of the stomata by the guard cells in the leaf.
DEMONSTRATION OF OSMOSIS
1. Using a living membrane or tissue such as yam, pawpaw etc.
2. By Osmometer; Osmometer can be constructed using a thistle funnel covered with cellophane. The cellophane is semi-permeable. The thistle funnel is filled with a strong sugar solution to a certain level. It is then lowered into the beaker containing water. After about 30 minutes, it could be seen that the level of the solution in the thistle funnel has increased due to passage of water through the cellophane membrane. This indicates that cellophane membrane is a semi-permeable membrane allowing only molecules of water to pass through, but preventing the passage of sugar molecules. This is the demonstration of osmosis using a non-living membrane.
OSMOTIC PRESSURE
This is the pressure that develops by a solution that permits uptake of water by osmosis. The osmotic pressure that a solution is capable of developing depends on the number or concentration of its solute molecules. The stronger the solution, the greater the osmotic pressure.





Osmosis
The experiment shown above demonstrates the process of osmosis. Water flows through a semipermeable membrane into a sugar solution, diluting the solution. The sugar molecules cannot pass through the membrane, so the water outside remains pure.
IMPORTANCE OF OSMOSIS
1. Osmosis regulates the concentrations of salt and water of the blood and other body fluid in animals.
2. It maintains the cell shape through turgidity and plasmolysis if need be.
3. It enables the absorption of water molecules from the soil solution to the plants through the root hair.
4. Movement of water molecules within the plant from the root to the leaves.
EVALUATION
1. Define the term osmosis.
2. Write two application of osmosis each in plant and animals.
3. What is osmotic pressure?
4. Enumerate three importance of osmosis.

GENERAL EVALUATION
OBJECTIVE TEST:
1. One of these is not a factor that affects diffusion. (a) State of the matter (b) pressure of the substance (c) Size of molecules (d) Temperature (e) Concentration gradient.
2. When two solutions has equal concentration, it is said to be -------------- (a) isometric solution (b) hypertonic (c) hypotonic (d) isotonic (e) isobarism.
ESSAY QUESTIONS
1. Explain the term Haemolysis.
2. Write short note on plasmolysis.
3. Explain what happens when a red blood cell is placed on water. (b) What if it is placed on salt solution?
4. What is turgor pressure?


WEEKEND ASSIGNMENT
Read Nelson Functional Biology for Senior Secondary Schools (pages 42-49)
PRE-READING ASSIGNMENT
Study about cell and its environment in Biology text book.
WEEKEND ACTIVITIES
Carry out an experiment to demonstrate osmosis using living membrane.
REFERENCE TEXTS
A.Egunyomi et-al. (2011) Exam Focus Biology for WASSCE and SSCE. UNIVERSITY PRESS PLC IBADAN.
Kola Soyibo et-al (2012). Nelson Functional Biology for Senior Secondary schools. Revised edition. Nelson Publisher Limited. Ibadan.

TOPIC: SOME PROPERTIES AND FUNCTIONS OF THE CELL.
CONTENT: (a) Micro and Macro Nutrient, (b) Cellular respiration, (c) Nutrition, (d) Excretion.
Micro elements are also known as minor or Trace elements or Micronutrients. These are elements required by plants in very tiny or very little amount. Although they are needed in trace amount, it leads to some deficiency when not available at all.
Some micronutrients include; Boron (B), Cobalt (Co), Copper (Cu), Manganese (Mn), Silicon (Si), Zinc (Zn), Chlorine (Cl).
On other hand, Macro or Major or Macronutrients refer to elements that are required by plant in large amount. Examples are the seven major elements which include Nitrogen (N), Potassium (K), Calcium (Ca), Magnesium (Mg), Iron (Fe), Phosphorus (P), Sulphur (S).
MICRO-NUTRIENTS
Elememts Uses/Importance to Plants Effects of Deficiency
Boron (B) Transport of Calcium and sugar Shoot goes brown
Cobalt (Co) For action of some enzymes Poor growth
Copper (Cu) For respiratory enzymes Poor growth
Manganese(Mn) Activation of some enzymes Shoots die back
Silicon (Si) Cell wall formation, particularly in grasses May affect growth
Zinc (Zn) Activation of some enzymes Poor leaf formation
Chlorine (Cl) For Oxygen release during photosynthesis and for growth and development Plant wilts and chlorophyll necrosis and reduce growth.

MACRO-NUTRIENTS
Nitrogen (N) Formation of amino acids, protein and nucleic acids. Hormone synthesis. Poor growth, underdeveloped
Potassium (K) Formation of amino acids, protein and cell membranes, crop maturation. Death of plant, yellow leaf at edges.
Calcium (Ca) Development of the cell wall at the growing points. Activate some enzymes Poor growth, particularly of the root.
Magnesium (Mg) Part of the chlorophyll molecule Leaves go yellow.
Iron (Fe) Needed for the synthesis of chlorophyll molecule Leaves go yellow.
Phosphorus (P) Formation of energy storage compound Poor growth leaves go dark green.
Sulphur (S) Needed for protein formation Leaves go yellow, stunted growth.


EVALUATION
1. Define the terms micro and macronutrients
2. List Four (4) each of micro and micro nutrients
3. Write two (2) importance each of macro and micro nutrients
4. Outline two (2) each of the effects of deficiency of micro and macro nutrients.
CELLULAR RESPIRATION
Respiration is the enzymatic breakdown of organic food substances, like glucose, through a series of chemical reactions in the cell to release energy and produce carbon (iv) oxide and water as by-products. Respiration occurs in all living cells.
Now, the energy released during respiration is used by the organism for such activities as synthesis of proteins, lipids and protoplasm; germination; cell division and enlargement leading to growth; movement; transmission of nerve impulses; active transport and maintenance of body temperature. There is variation in the amount of energy used by different organisms depending on their activities. A very active organism like Tiger uses much more energy than a sluggish one, like Chameleon.
TYPES OF RESPIRATION
You already know that we have external and internal respiration, while external deals with breathing in and out i.e. inhalation and exhalation, the internal which takes place in the cell hence, cellular respiration is divided into two basic parts:
1. Anaerobic Respiration and
2. Aerobic Respiration
Anaerobic respiration is that type which involve the use of very little or no Oxygen, while Aerobic Respiration is that type which involves the use of large amount of Oxygen.


CHEMICAL PROCESS IN CELLULAR RESPIRATION
The reactions that occur in cellular or tissue respiration are usually represented by the following equation:
C6H12O6 + 6O2 6CO2 + 6H2O + Energy
Glucose Oxygen Carbon iv oxide Water
The equation represents only a summary of the raw materials and the end products of tissue respiration. The complex pathway of cellular respiration is shown below:
Tissue respiration is divided into two main parts. The first is the glycolysis, the stepwise series of reactions which leads to the breakdown of glucose to pyruvic acid. The process occurs in the cytoplasm in the cells. It consists of step- wise reactions, each brought about by specific enzymes. Glycolysis is common to, and occurs in the same general manner in all organisms. In animal cell,
Equation for lactic acid formation: C6H12O6 2C3H6O3 + Energy
In plant cell, the products of anaerobic respiration are ethanol and carbon iv oxide. Formation of alcohol is represented by the equation: C6H12O6 2C2H5OH + 2CO2 + Energy



Converting Food to Usable Energy
Cellular respiration is a complex series of chemical reactions that harvests the energy trapped in the bonds of glucose sugar molecules and converts it into a chemical form that can be stored for later use. Humans and other animals obtain glucose sugar molecules from food, such as the fruits and grains shown here, while plants create glucose sugars in the process of photosynthesis. Essential to the survival of most organisms on Earth, cellular respiration yields the energy that makes our bodies function properly.

As for glycolysis, or anaerobic glycolysis or fermentation, Oxygen is not required because the process is anaerobic. This series of reaction convert glycogen in animal and starch in plant to glucose. The glucose is then converted by ten steps to pyruvic acid as below:
Diagram
AEROBIC RESPIRATIO
Aerobic respiration is a breaking down process known as catabolism, an aspect of metabolism. It is represented by the Kreb’s Cycle. Diagram required. In Kreb’s Cycle, for one molecule of pyruvic acid 15 molecules of ATP are produced. Since a molecule of glucose produce 2 molecules of pyruvic acid, therefore 30 molecules of ATP are produced from the the 2 molecules of pyruvic acid. Hence, a molecule of glucose produceds a total of 38 molecules of ATP during a complete aerobic respiratory process. The oxidation of glucose can thus be summarised with the following equation:
C6H12O6 + 6O2 6CO2 + 6H2O + Energy
Glucose Oxygen Carbon iv oxide Water

EVALUATION
1. Explain the terms; Aerobic and anaerobi respiration.
2. Discuss with a digram the glycolytic pathway and Kreb’s cycle.
3. State the following equations: respiration, lactic acid, and fermentation.
Another aspect of metabolism is the Anabolism which is a building up process. An example is an aspect of plant nutrition commonly known as photosynthesis.
PLANT AND ANIMAL NUTRITION
Nutrition can be defined as the totality of the processes by which a living thing obtains, and uses food. We have two types of nutrition; plant and animal nutrition.
PLANT NUTRITION
In plant nutrition, we have photosynthesis and chemosynthesis. The later is a process through which non-green plants use either parasitic or saprophytic modes of nutrition to obtain their food. It can occur in colourless autotrophic bacteria.
Photosynthesis is the process by which green plants make use of raw materials such as carbon (iv) oxide and water to produce sugar and Oxygen in presence of sun light or solar energy and chlorophyll.
EQUATION FOR PHOTOSYNTHESIS
6CO2 + 6H2O C6H12O6 + 6O2
Light Reaction
(i) Light energy is captured by chlorophyll
(ii) The energy splits water into hydrogen (H+) and hydroxyl (OH-) ions. The process is called photolysis of water and it is the first step in photosynthesis.
4H2O 4H+ + 4(OH-) + ATP
(a) The hydroxyl part is reconverted to water and Oxygen is given off as a by-product.
4(OH) 2H2O + O2
(b) The compound (NADH) coenzyme is reduced by hydrogen ion and ATP is formed.
With the energy provided by ATP, the reduced compound (NADH) brings about the assimilation of carbon (iv) oxide through series of small steps , each controlled by a specific enzyme to form sugar or starch.
CO2 + 2H2 CH2O + H2O
The overall reaction is below:
CO2 + 2H2O CH2O + H2O + O2

Significance of Photosynthesis
1. All living things are supported by the by-products of photosynthesis. For example all animals and non-green plants obtain their energy from green plants.
2. It brings about the purification of the atmosphere by removing excess carbon (iv) oxide (carbon iv oxide)
Materials Necessary for Photosynthesis
These materials are divided into two basic parts: (1) External conditions and (2) Internal conditions.
External condition:
1. Water
2. Light
3. Carbon (iv) oxide.
Internal condition:
1. Mineral salts
2. Chlorophyll
3. Enzymes.
Some Factors Affecting Photosynthesis:
They include;
 Temperature,
 Light intensity,
 Carbon (iv) oxide,
 Amount of soil water/ moisture
EVALUATION
1. What is nutrition?
2. Define photosynthesis.
3. Explain what happens in light and dark reaction stages of photosynthesis using equations.
4. List materials necessary for photosynthesis in the order of external and internal conditions.
5. Outline some factors that affects photosynthesis.
EXCRETION
Definition: Excretion is defined as the process by which living things eliminate waste products or toxic substances from their body through their excretory organs.







Excretory System of some organisms
ORGANISM EXCRETORY SYSTEM
Some unicellular organism Contractile Vacuole
Flatworms Flame cells
Annelids (e.g. earthworm) Nephridia
Insects Malpighian tubules
Vertebrates Kidneys, lungs, skin, and liver.
Plants Stomata and Linticels
EXCRETORY ORGAN AND SUBSTANCES THEY EXCRETE IN VERTEBRATES
IN ANIMAL
Lungs: Carbon (iv) oxide, and water vapour.
Skin: Sweats, Salts and nitrogenous waste.
Kidney: Urea, excess water, excess salts, ammonium compounds, and acids.
Liver: Bile Pigments.
IN PLANTS
Stomata: Oxygen, Carbon (iv) oxide and water vapour.
Bark: Tannins, resins and latex.
Leaves: Crystals of calcium oxalate, calcium carbonate and anthocyanin pigments which give red, blue, and violet colours to many flowers.
Lenticels: Oxygen, Carbon (IV) oxide and vapour.
EVALUATION
1. Define the term excretion
2. List some organs of excretion and the organism concerned.
3. Outline some waste products in animals and plants and organs responsible.
GENERAL EVALUATION:
1. One of these is a micronutrient (a) cobalt (b) nitrogen (c) potassium (d) magnesium (e) calcium.
2. The compound (NADH) coenzyme is reduced by ------------ (a) hydrogen compound (b) hydrogen ion (c) carboxylic acid (d) hydroxyl ion (e) hydroxyl group.
3. The kidney excretes all these except----- (a) acids (b) excess water (c) excess salts (d) Oxygen (e) ammonium compound.
ESSAY TEST
1. Outline seven micro and macro nutrients for healthy growth of plants
2. Sketch an annotated diagram of photosynthetic leaf structure.
WEEKEND ASSIGNMENT
Read Senior Secondary Biology 1 by F.O.C NDU (pages 47-56),
PRE- READING ASSIGNMENT
Read about some properties and functions of the cell, and write a short note on macro/microelements.
WEEKEND ACTIVITIES
Sketch the glycolytic pathway and the kreb’s cycle in your note book (Well labelled)
REFERENCE TEXT
Senior Secondary Biology 1 by F.O.C.Ndu et-al
Exam Focus Biology for WASSCE and SSCE by a. Egunyomi et-al.
Concise Biology for Senior Secondary School by B.N Okoro.

TOPIC: SOME PROPERTIES AND FUNCTIONS OF THE CELL
CONTENT: 1. Growth
2. Cell Reactions to its Environment
3. Movement
4. Reproduction
Sub-Topic 1: GROWTH
Meaning of Growth
Growth is defined as an irreversible increase in size and mass due to formation of new protoplasm in the cell. Whenever the anabolic processes proceed at a faster rate than the catabolic process, there will be a supply of new substances to cause growth.
The three distinct processes that contribute to growth are cell division, cell enlargement and cell differentiation. In cell division, the nucleus and then the cytoplasm of the parent cell divide to form two daughter cells, then into four and so on bringing about an increase in the number of cells.
The daughter cells then increase in mass and size (i.e. enlarge) and eventually develop into a special type of cell (i.e. differentiate) by changing its shape and structure to carry out a particular function. The kind of cell it becomes depends on its position in the body of the organism. It may develop into a nerve cell in the brain, a muscle cell in the heart or a ciliated lining cell in the trachea.
Diagram of root tip showing apical meristem


Root Tip Showing Apical Meristem
This lengthwise section of the tip of a plant root shows the apical meristem, which, with its rapidly dividing cells, is responsible for primary growth. Apical meristem can also be found at the tips of stems.
Basis of Growth
Cell division (mitosis) is the basis for growth in all multicelluar organisms. Mitosis is the cell division which occurs in the body cell (somatic cells) during which a parent cell divides to produce two daughter cells having the same number of chromosomes as itself.
Mitosis does not occur in all the cells of growing region of the organisms e.g. the root tips or shoot apices and cambium that undergo mitosis. These growing regions are described as meristems.
Cell division by mitosis occurs in four successive phases of continuous sequence namely prophase, metaphase, anaphase and telophase. Between the end of one mitosis and the commencement of a new mitotic division is a period described as interphase or pre-mitotic phase.
Interphase is not a resting time, but a period during which the young daughter cells accumulate and synthesize new body materials, thus preparing itself for the next division.
Diagram showing the growth of embryo


Spemann's Experiments
The experiments of Hans Spemann in the early 1900s demonstrated the role of certain cytoplasmic signalling substances in the amphibian embryo. (Left): By cleaving the fertilized egg unnaturally, Spemann showed that an area called the gray crescent is essential to embryonic development. (Right): By the two-cell-layer (blastula) stage, the cells in the embryo have already been “mapped” to the structures they will form in the complete embryo. Spemann showed that if the embryo were cleaved at this point, only the section containing the dorsal lip of the blastopore (once the gray crescent area) would continue to develop.
The daughter cells synthesize new structures from the raw materials that they absorb from their surroundings. This process is called assimilation and results into cell enlargement. Cell differentiation also occurs as the cell develops into specialized cells.
An organism may be said to achieve growth when there is an increase in its dry weight, size or number of cells.
Factors Affecting Growth
These factors may be divided into external and internal factors. The external factors include the following:
1. Nutrient availability: Body substances are synthesized from available nutrient materials and energy.
2. Accumulation of toxic byproducts of metabolism may inhibit growth.
3. Temperature: All biological processes including growth are accelerated as temperature rises from a minimum value at which no growth occur to a certain point beyond which retardation occurs.
4. Light is essential for the growth of photosynthetic plants because it supplies the energy by which all new tissues are synthesised.
5. PH: the Ph of the fluid in contact with a cell has a profound effect on all its activities. Some species grow best in a given PH range.
6. The main internal factors controlling growth are hormones and enzymes.



Rodents
Rodents represent nearly 40 percent of all mammal species. Over 1700 species of rodents, including (top from left) porcupines, beavers, chinchillas, pacas, (bottom from left) flying squirrels, mice, muskrats, and capybaras, can be found in nearly every terrestrial and arboreal habitat. The success of this group is due in part to its adaptability to new food sources and habitats and its relatively brief reproductive cycle.
Michael Leach/Oxford Scientific Films;Aldo Brando Leon/Oxford Scientific Films;Dorling Kindersley;Shattil and Rozinski/Oxford
SUGGESTED PRACTICAL
Activity 1: Identification of fastest growth regions in plant. Nelson Functional Biology for SSS by Kola Soyibo etal page 74
2. Experiment to find out the effect of light on the growth of seedlings. (Modern Biology for SSS by Sarojini page 241
Regulation of Growth by Hormones
The auxins in plants influence cell division (e.g. cytokinins), cell elongation (e.g. gibberellins), regeneration of tissues at cut surfaces, growth of ovaries into fruits, development of buds and roots, and the growth of abscission layer in leaves. The thyroid glands of vertebrates produce thyroxin at a concentration that promotes normal growth. In the absence of thyroxin growth does not occur. Other hormones that exert influence on growth are produced by the pituitary gland and sex hormones.
EVALUATION:
• Define growth
• List three processes that contribute to growth
• Define mitosis and list the four main phases of mitosis
• Name five external factors and two internal factors that affect growth
• Name two plant hormones and state their influence on plant growth
2. CELL’S REACTIONS TO ITS ENVIRONMENT
The protoplasm of plant and animal cells is irritable. It can detect and respond to the changes in their environment. Any change in conditions which is enough to produce a change in the activities of an organism or its part is called a stimulus.
Types of Responses
The three responses of the cell to its environment are tactic, nastic and tropic responses.
a. Tactic responses (Taxism): It is a response made by a whole organism or its freely locomotive part in response to an external stimulus. Types of tactic responses are:
• Phototactic (Phototaxis): response to variation and intensity of light e.g. in free swimming Euglena, Chlamydomonas etc.
• Chemotactic (Chemotaxis): response to the presence of chemical substances e.g. chemotactic movement of Amoeba away from an acidic environment.
• Aerotactic (Aerotaxis): response to the source of oxygen
• Osmotactic (Osmotaxis): response to variation in osmotic concentration
b. Nastic responses (Nastism): This is a response made by a fixed plant in response to a non-directional or diffuse stimulus. Various types of nastic responses include the following:
• Nyctinastic (Nyctinastism): response to changing day and night conditions as exhibited by some flowers and leaves due to changing conditions of temperature and light intensity. Nyctinastic movement is a combination of two factors- temperature and light i.e. thermonastic and photonastic respectively e.g. leaflets of leguminous plants such as acacia, groundnut and clover.
• Haptonastic (Haptonastism): response due to contact e.g. movement of leaves of insectivorous plants such as venus flytrap.
• Hydronastic (Hydronastism): response to humidity changes
• Chemonastic: response to presence of specific chemical substances.
c. Tropic Responses (Tropism): This is a response made by a fixed plant part to a stimulus. The direction of movement is determined by the direction from which the stimulus originates. Various types of tropic responses include the following:
1. Phototropism: growth movement in response to the stimulus of light e.g. growth of plant stems. Shoot is positively phototropic while the root is negatively phototropic.
2. Geotropism: a growth response to the stimulus of gravity e.g. geotropic response of root and shoot. Root is positively geotropic while shoot is negatively geotropic.
3. Hydrotropism: a growth response to the stimulus of water e.g. root of plants grow towards a water source.
4. Chemotropism: response to concentration of chemical substances.
5. Haptotropism (Thigmotropism): a response to the stimulus of touch e.g. tendrils of climbing plants.

EVALUATION
Give three examples of tactic responses.
1. State the differences between nastic and tropic responses
2. List three forms of tropic response with relevant example of each
MOVEMENT
Living cells are metabolically very active and their contents are constantly moving because:
i. Materials constantly enter or leave the cell or move from one part of the cell to the other.
ii. Genetical information flows from the nucleus to the cytoplasm and
iii. Protein and other substances which are manufactured or broken down are transported within or out of the cell. These can be seen as protoplasmic streaming or cyclosis.
1. Cyclosis: is the circulation of protoplasm in the cell where the protoplasm flows around the cell constantly in one direction.
2. Amoeboid Movement: This is characteristics of the naked non-cellular masses of protoplasm of many of the protozoan’s, the sliming fungi, some plants and animal gametes and certain wandering cells in higher animal bodies e.g. leucocytes in man.
Amoeba moves in a slow streaming way by pulling out lobe-shaped extensions of the cell called pseudopodia.
When a pseudopodia form, a thin plasmosol flows into it and is changed into the semi-solid plasma gel. As a pseudopodium streams forward at one end of the cell another is withdrawn. By this means amoeba moves about. Human white blood corpuscles use amoeboid movement to pursue and capture bacteria in the blood plasma.
3. Organelles for Movement: These include pseudopodia, cilia and flagella. Pseudopodium is an organelle of locomotion in Amoeba. In some protozoans and tiny aquatic animals, movement is brought about by cilia and flagella. They are similar in structure composed mainly of microtubules powered by ATP.
Cilia are short hair-like structures. They are usually numerous and packed closely together. They move in a co-ordinate way to bring about movement. In the paramecium, the action of the cilia moves the whole organism at the same time it also directs a current of water containing food into the paramecium gullet. In the cells lining the human wind pipe, the beating of the cilia causes mucus to more up towards the throat.
Flagella are at least ten times longer than cilia and are fewer in number. It is a whip-like structure which can send waves of movement along its length. Flagella help to move the organisms like Euglena and Chlomydomonas and motile parts of organisms like human sperms.
Growth Movement Regulated by Auxins
Auxins are produced at the apices of shoots and roots but move to the region of sell elongation to bring about their effect. Auxin functions as hormones or chemical messengers.
1. Phototropism: When a shoot receives light from all sides, the auxins produced at the shoot apex pass down and exert a stimulating effect on the region of cell elongation, causing the shoot to grow evenly and vertically. When a shoot receives light from one side only, it bends and grows towards the light. If the shoot tip is covered, the shoot continues to grow vertically. This shows that somehow, one sided lighting causes less auxins to gather on the shaded side. This makes the cells on the shaded side grow and enlarge faster, causing the shoot to bend toward the light.
Diagram showing the growth-regulator hormone


Pituitary Gland
Called the master gland, the pituitary secretes hormones that control the activity of other endocrine glands and regulate various biological processes. Its secretions include growth hormone (which stimulates cellular activity in bone, cartilage, and other structural tissue); thyroid stimulating hormone (which causes the thyroid to release metabolism-regulating hormones); antidiuretic hormone (which causes the kidney to excrete less water in the urine); and prolactin (which stimulates milk production and breast development in females). The pituitary gland is influenced both neurally and hormonally by the hypothalamus.

Geotropism: If a young plant is placed horizontally more auxins seem to collect on the lower sides of the shoot and root. In the shoot the high auxin concentration in the lower side stimulates growth and tends to make the side grow rapidly, so that the shoot bends and grow vertically upwards.
In the root, the high auxin concentration on the lower side inhibits growth and tends to make this side grow slowly so that the root bends and grows vertically downwards.
EVALUATION
• Define cyclosis
• Describe amoeboid movement
• State two differences between flagella and cilia
• State two uses of cilia to paramecium
• Name two growth movements that are controlled by auxins in plant.
REPRODUCTION
Reproduction is the ability of living organisms to produce offspring’s i.e. new individuals of their type. It is the only way in which each kind of organism can continue to live on forever although the individual must eventually die. The two forms of reproduction are sexual reproduction and asexual reproduction
ASEXUAL REPRODUCTION
In asexual reproduction, an individual produces an offspring by itself i.e. only one parent is present. There is no fusion of nuclei and the cells that give rise to the offspring usually divide by means of mitosis. As a result, asexual reproduction often produces clones-Offspring which are identical to the parent. In rare cases the offspring may not be identical due to mutation.
Asexual reproduction is common among simple organisms and flowering plants. Forms of asexual reproduction include the following:
• Fission: It is commonly found in Bacteria and Protists. The parent organism simply divides into two or more parts, each of which can exist by itself. e.g. binary fission in bacteria.
• Budding: In budding the offspring develops as an outgrowth of the parent. The bud may form on an internal or external surface of the parents. Internal buds are formed in some sponges and released when the parent dies. External buds occur in Hydra and Coral polyps. The buds break off from the parent without causing any injury and lead an independent life.

Diagram showing cell division during growth


Comparative Embryology
Some anatomists study embryonic development to compare different organisms and help determine the evolutionary relationships between them. Sea urchins, frogs, humans, and many other animals are remarkably similar in their early development. All begin with a single cell that divides into two cells, the first step is the process of cleavage (1a, 2a, 3a). During cleavage, cell divisions occur so rapidly that the cells do not have time to grow between divisions, and the result is smaller and smaller cells. Cleavage produces a solid ball of cells called a morula (1b, 2b, 3b). Within the morula, a fluid-filled cavity called the blastocoel develops, converting a morula into a blastula (1c, 2c, 3c). In a process called gastrulation, certain cells of the blastula migrate to different regions of the blastula to create the gastrula, a structure with three cell layers (1d, 2d, 3d). The outer cell layer of the gastrula, called the ectoderm (shown in blue), forms the outer covering of all animals, and in the frog, human, and other higher animals, it also forms the nervous system. The inner layer of the gastrula, known as the endoderm (shown in yellow), gives rise to the gut in all animals, and in higher animals, other organs including the stomach, pancreas, liver, and lungs. The mesoderm, which forms between the ectoderm and endoderm, produces the simple excretory system of the sea urchin and frogs and the kidneys of humans. In higher animals, the mesoderm also gives rise to blood, bone, muscle, and other structures. Cell specialization is followed by the development of primitive organs, which marks the larval form of sea urchins and frogs, and the embryo stage of human development (1e, 2e, 3e). Size and time of development vary widely among species. The sea urchin larva, for example, forms in 12 to 76 hours and measures 0.1 to 0.3 mm (0.004 to 0.01 in), while the human embryo takes eight weeks to fully form, and measures about 30 mm (about 1.2 in) from crown to rump.
• Spore Formation: Spore are small unicellular bodies which are produced in large numbers. They are small, light and easily dispersed by air. Under favourable conditions each spore can develop into an independent organism. Spores are commonly produced by Bacteria, Fungi, Protists, Algea, Mosses and Ferns.
• Fragmentation: In this process a part of an organism breaks up or fragments from the parent organism and give rise to a new individual. It is a form of regeneration that occurs in simple organisms like algae, coelenterates and sponges.
• Vegetative propagation: It occurs mainly in higher plants where a new plant grows from any portion of an old one other than the seeds.
This is the formation of new individuals or plants by vegetative portion of the plant such as roots, stems and leaves. They are tubers, corns, bulbs, rhizomes, suckers and runners.
• Root tubers are modified roots which grow under-ground and act as food storage organs. New plants may develop from buds which arise near the point of origin with the stem e.g. cassava, sweet potato and carrots.
• Corns: These are modified underground stem which grow vertically. They produce lateral shoots which are capable of growing into new plants when detached e.g. cocoyam
• Bulbs: There are modified underground leaves adapted for food storage. New bulbs in the axils of the scale leaves. Examples of bulbs are onions and lilies.
• Parthenogenesis: This is the development of an egg without fertilization. It occurs in honey bee drones and aphids.
SEXUAL REPRODUCTION
Sexual reproduction involves two parents of different sexes (Male and female). Each parent produces gamete male and female gametes respectively. There is meiosis during which the chromosomes number is halved i.e. from diploid to haploid in the formation of gametes. The egg cell (female gamete is large and non-motile). The sperm (male gamete) is motile and small. During fertilization, the two haploid gametes (male and female) fuse to form a diploid zygote. The zygote undergoes repeated cell division and forms an embryo. The embryo undergoes repeated cell division and differentiation and develops into a young organism similar to the parents.
In lower animals and plants such as protozoa, fungi and algae, there is no formation of specialized reproductive organs. In this case, whole individuals from different strains become differentiated into male and female organisms. They join together and exchange nuclear materials.
In paramecium, after the exchange of nuclear materials they separate and each cell divides to form four daughter animals.
Conjugation in Spirogyra
In spirogyra, two filaments lie close to each other and outgrowths appear on the walls of the cell lying opposite one another. The cells meet and their walls break and a conjugation tube is formed. One of the gametes passes through the conjugation tube and merges with the gamete in the other cells and their nuclei unite. This results into formation of a zygospore.
The zygospore can withstand dry conditions and can germinate into a new individual when moisture is available. This process of reproduction is called conjugation. It also occurs in mucor.

MEIOSIS
Meiosis is the cell division that gives rise to gametes and haploid spores. In flowering plants and animals, it occurs only in the reproductive organs. When a diploid cell undergoes meiosis, the chromosomes replicate once and the nucleus and cell duplicate (divide equally) twice. This results in the diploid parent cell giving rise to four haploid cells.
Diagram

Gigantism
Gigantism results from the overproduction of growth hormone during childhood or adolescence. The arms and legs grow especially long, and height can surpass 2.4 m (8 ft). The disorder is caused by a pituitary tumor that, if untreated, usually kills the patient by early adulthood. If the tumor develops after growth of the long bones is complete, the result is a condition called acromegaly, characterized by a long face, jutting jaw, and large feet and hands.
At the start of meiosis, each member of a homologous pair of chromosomes moves to lie side by side so that all parts of the two chromosomes match exactly. Each chromosome is also made up of two chromatids while they are thus paired; genetic material is exchanged between the chromatids. This is known as crossing over and leads to greater variation in the offspring.
When the nucleus divides for the first time the chromosomes in a given pair (not chromatids) separate and move to opposite ends of the cell. This results in only half the number of the chromosomes going to each daughter cell.
During the second nuclear division, the chromatids separate and move to opposite ends of each daughter cell. This gives rise to four gamete cells, each with a haploid number of chromosomes.
Differences between mitosis and meiosis
Mitosis Meiosis
1. Occurs during the growth of somatic cells and asexual reproduction. Occurs during gamete production.
2. Two daughter cells (offspring) are formed. Four daughters cells (offspring) are formed.
3. Chromosome number of parent and daughter cells is the same. Chromosome number of daughter cells is half the number in the parent cell.
4. The chromosome and their genes in each daughter cell is identical. The chromosomes and their genes in the four daughter cell are not identical.
5. No crossing over occurs Crossing over occurs.
6. Offspring produced by mitosis are exact replicates or clones of the parent organism. Offspring produced by meiosis in sexual reproduction will show variations among themselves and their parents.

Structure and Functions of male Gonad
A typical male gonad consists of a pair of testes, which are enclosed in a fold of skin known as scrotum (scrotal sac). The scrotum hangs behind the spongy, muscular and erectile structure called penis. The scrotum, testes and penis are situated externally in the pubic region. Each testis consists of numerous tubules called seminiferous tubules.
The cells of these tubules divide repeatedly to form sperm cells in a process called spermatogenesis. A set of profusely coiled tubule known as epididymis connects each testis to the vas deferens, which conveys the sperm cells to the seminal vesicle for storage until there is the need for ejaculation. Seminal fluid secreted by the prostate gland provides a medium for sperm cells to swim and be nourished. On ejaculation, the sperms are discharged to the outside through the urethra.
The testes produce the sperm-the male gametes. It also secretes the hormones testosterone, which is responsible for producing secondary sex characteristics in males as well as stimulating sperm production.

Internal View of Male Reproductive System
The reproductive anatomy of the male human is largely external. Beginning at puberty, sperm are produced within seminiferous tubules of the testicles, a pair of glands that reside in a pouch called the scrotum. The external location of the scrotum keeps the temperature of sperm slightly below body temperature, which is necessary for their healthy development and survival. From each testicle, sperm migrate to a long, coiled tube known as the epididymis, where they are stored for one to three weeks until they mature. Also located outside the body is the penis, the erectile organ responsible for the excretion of urine and the transfer of sperm to the vagina of the female. Just before ejaculation during sexual arousal, mature sperm travel from the epididymis, a coiled tube behind each testicle, through a long duct called the vas deferens. Sperm leave the body in semen, a fluid produced by the seminal vesicles.

Structure and Functions of the Female Gonad
The female mammalian gonad consists of a pair of ovaries suspended by connective tissues at the lower dorsal portion of the abdominal cavity. Ovaries produce the ova (singular-ovum), the female gamete. When the ovary releases an ovum, it is captured by an oviduct (also called fallopian tube). The oviduct conveys the ovum to the muscular uterus. Each oviduct has a funnel-shaped end, which opens close to the ovary in the abdominal of ova.
The uterus is connected to the outside of the organism through the vagina (or birth canal). Externally, the vagina opens at the vulva.
The ovary plays the following important roles, namely the production of female sex hormones oestrogen and progesterone. Oestrogen stimulates and maintains the development of the female secondary sex characteristics, whereas progesterone stimulates and promotes the growth of the uterine lining in readiness for implantation of an embryo.

EVALUATION
• Define reproduction
• State two differences between sexual and asexual reproduction
• State three differences between mitosis and meiosis
• List three forms of asexual reproduction
• State three functions of male gonad
• Name two hormones produced by the female gonad and state their functions.
GENERAL EVALUATION
OBJECTIVE QUESTIONS
Choose the correct options to the following questions
1. Growth may broadly be defined as (a) the increase in height of a plant (b) the increase in height of a stem (c) a permanent change in size, complexity and form of organism (d) a change in form of animals
2. One of the properties of cell responsible for the continuity of species is (a) growth (b) reproduction (c) nutrition (d) excretion
3. Which of the following structures or organelles is used for the elimination of liquid waste in paramecium (a) food vacuole (b) oral groove (c) anal pore (d) contractile vacuole?
4. Which of the following is the method of asexual reproduction in yeast? (a) binary diffusion (b) budding (c) mating (d) conjugation
5. Which of the following is not a plant hormone? (a) Abscisic acid (b) auxin (c) cytokinin (d) thyroxine
ESSAY QUESTIONS
1a. what is growth?
b. What is the basis of growth?
c. Name the region of fastest growth in plants
d. What are the factors that affect growth.
2a. What is vegetative propagation?
b. Describe two artificial methods of propagation used by farmers
c. Compare sexual and asexual reproduction
3a. Define cyclosis
b. Name three organelles used for movement in aquatic unicellular organisms.
c. Describe an experiment to show how auxins can cause phototropic response in shoot.
4a. State five differences between mitosis and meiosis
b. List the four major phases of cell division in mitosis
5a. Define reproduction
b. State three functions of (i) mammalian testes (ii) mammalian ovary
c. Make a large labelled diagram of a named flower to show the reproductive parts.
WEEKEND ASSIGNMENT
Read Nelson Functional Biology for Senior Secondary Schools, Book 1 by Kola Soyibo etal pages 69-86
PRE-READING ASSIGNMENT
Read about some properties and functions of the cell - growth, movement and reproduction.
WEEKEND ACTIVITY
Make a large labelled diagram of one half of a named flower to show the reproductive parts.
REFERENCE TEXTS
1. Nelson Functional Biology for Senior Secondary Schools Book 1 by Kola Soyibo etal, pages 69-86
2. Modern Biology for Senior Secondary Schools by Sarojini T.Ramalingan pages 232-256
3. Exam Focus Biology for WASSCE and SSCE by Egunyomi pages 43, 69-70, 77.

TOPIC: TISSUES AND SUPPORTING SYSTEMS
CONTENT:
(a) Introduction
(b) Skeleton and supporting system in animals: (i) Biological significance (importance) (ii) forms
(c) Types of skeletons
(d) Bones of the vertebral column
(e) Function of skeleton in animals

SUB-TOPIC 1: INTRODUCTION
What would animals including you look like as well as incapable of doing without the support of bones and cartilage? Sitting, standing, crawling, walking, swimming, flying, and more, would be impossible.
Multicellular organisms have some form of rigid support system that give them shape that enable them to exhibit movement of various degrees as well as withstand forces of wind and water. The framework and the tissues that support it is known as tissue and supporting system.

Sub-topic 1: SKELETON AND SUPPORTING SYSTEM IN ANIMALS.
Skeleton is the framework which gives support and shape to an animal. This supporting framework can be on the inside of the organism: in higher animals such as reptiles, birds and mammals, the organisms have a skeleton which form the central core of the body. It is covered by muscles, blood vessels, nerves and skin.
In man the various structures such as tendons, ligaments, interstitial tissues and bones make up the skeletal and supporting system in animals.
BIOLOGICAL SIGNIFICANCE OF SKELETON
Most living organisms whether they are plants or animals, posses a form of rigid frame work called skeleton. Skeleton consists of various tissue and supporting systems in both plants and animals. Skeleton is biologically significant in the life of living organisms. Without skeleton, soft tissues will not have adequate support, protection and shape. Their bodies will collapse and animals may not be able to move parts or all of their bodies. Body movement in a complex animal is brought about by muscles which work by pulling on some kind of support. This support is the rigid framework – skeleton- in animals to affect work and movement. Aquatic multicellular animals need a supporting system to succeed in their hunt for food. As a result, most complex animals have evolved supporting structures or skeletons which provide support against gravity, but the skeletons are flexible enough to allow movement.
EVALUATION
• What is Skeleton?
• State three biological significance of skeleton in the life of living organisms.

FORMS OF SKELETON
There are three basic forms of animal skeleton: chitin, cartilage and bone. These are the main types of materials found in the skeleton of animals.

Exoskeleton of a Goliath Beetle
Instead of an internal skeleton, the goliath beetle, like other insects and crustaceans, has an exoskeleton covering the outside of the body. This exoskeleton provides support for the body much as an internal skeleton does in higher animals. It also provides protection from predators. The exoskeleton is composed of a hard, waterproof, proteinaceous material called chitin. The one main drawback to this type of skeleton is that it does not grow along with the rest of the animal and must periodically be shed in a process called molting.

CHITIN
Chitin is a tough light and flexible material that is a major component of the skeletons of arthropods. It is a non-living substance and incapable of growth. It consists of cellulose-like carbohydrate and some deposits of proteins and minerals. Animals with chitinous skeleton can only grow by moulting because the exoskeleton restricts the growth and size of the organism. The skeleton of insects is composed of chitin and a thin, waterproof layer of wax.

Arthroscopic Knee Surgery
Cartilage disks, or menisci, in the knee act as cushions between the bones of the upper and lower leg. Under normal circumstances the menisci stretch and give, but under heavy stress, such as strenuous and repetitive activity, the cartilage can be torn. This painful condition causes the knee to lock in position or buckle unexpectedly. Physicians use a tool called an arthroscope to view the inside of joints and evaluate cartilage damage. An arthroscope is a thin fiber-optic viewing instrument that is inserted into the joint through a small incision in the knee. Arthroscopes may also be equipped with surgical tools, enabling the correction of many knee problems without invasive surgery.

CARTILAGE
This tissue is found in the skeletons of complex vertebrates. It consists of living cells (chondroblasts) and carbohydrate and protein fibres. It is a tough and flexible tissue that has great tensile strength. It acts as a shock absorber, cushioning the effect of bones moving against bones when we move.
Cartilage does not have its own blood supply but depends on the oxygen and nutrients that diffuse across it from nearby tissues. It is usually found inside animals and can be replaced by bones as in young embryos. It is the skeletal material found as endoskeleton of cartilaginous fish such as rays and sharks, in human babies and in several part of adults (but in very small portions) e.g. Pinna, tip of the nose and end of long bones.
Cartilage occurs in three forms: elastic, fibro and hyaline cartilage.
- Elastic cartilage is present in the external ear and epiglottis. It also supports the Eustachian tube and the external ear canal.
- Fibro cartilage is tougher than hyaline cartilage and is found in the discs between the small bones (vertebra) of the vertebral column.
- Hyaline cartilage makes up the rings which support the trachea and bronchi and keep them open. It covers the surfaces of movable joints and also supports the protruding part of the nose.


Joint Damage Caused by Arthritis
The term arthritis refers to more than 100 different diseases causing pain, stiffness, and inflammation in the joints. Healthy joints are composed of cartilage and lubricating fluid, called synovial fluid, encased in a joint capsule, or synovial membrane. In osteoarthritis, the most common form of arthritis, joint cartilage is destroyed and, in some cases, bony outgrowths known as bone spurs develop. In rheumatoid arthritis, white blood cells in the synovial membrane divide, grow, and multiply, producing inflammation, pain, and stiffness in the joint, which may eventually lead to cartilage destruction.




BONE
Bone is the main skeletal structure found in vertebrates. It consists of living bone cells (osteocytes), protein fibres (collagen) and minerals, mainly calcium phosphate and calcium carbonate. The minerals, are mainly calcium phosphate and calcium carbonate. Minerals are non-living matter and make up two-thirds of the mass of a bone. As a result, bone is a stronger and more rigid tissue than cartilage. Bones have their own blood supply to nourish them.
In a young vertebrate embryo, the skeleton is made up of cartilage. As the embryo grows, bone cells replace cartilage cells. This causes the cartilage tissue to harden into bone through the addition of minerals. This process is known as ossification.
The long bones such as humerus, femur, and tibia, consist of a hard outer layer called shaft and a spongy and hallow cavity filled with bone marrow. The middle part, in the hollow is occupied by the yellow marrow and it consists of fat cells. Red marrow fills the spongy spaces in the two ends. A layer of hyaline cartilage covers their articulating surfaces. The numerous tiny openings in the bones allow circulation of blood and sensitivity.
Differences between a bone and a cartilage
Bone Cartilage
Made up of living cells surrounded by non-living cells made up mainly of living cells.
Made up mainly of minerals Not made up of minerals.
Made up of a hard substance Made up of soft substances
Inflexible particularly in adults Very flexibe or elastic
Never replaced by cartilage Can be replaced by bone


TYPES OF SKELETON
Skeletal tissue differs as observed in invertebrates and vertebrates. The types are as follows:
1. Hydrostatic skeleton: this is the simplest type of skeleton. It depends on turgor pressure of its body fluid.
A typical example of an organism with this type of skeleton is Earthworm. The muscle in the body wall works against its fluid. The walls of each of the body segment have two sets of muscles. One set is longitudinal, while the other is circular. By contracting and relaxing antagonistically, movement is affected in the organism and a form of shape is affected.

Earthworm
Earthworms have a segmented, compartmentalized, cylindrical body and range in length from several centimeters (a few inches) to nearly 3.3 m (11 ft). They have no eyes, ears, or lungs. Earthworms breathe when air that is present between soil particles diffuses through their thin skins, and they are forced to the surface if these air pockets fill with rainwater. When a worm moves, it uses its longitudinal muscles to extend the front of its body into the soil ahead of it, pulling the back part up behind it. Setae, tiny projections from each segment of the worm, stick into the surrounding soil to keep the worm from slipping. The digging action of earthworms helps to aerate and mix the soil. Earthworms actually consume some of the soil as they dig, and their faecal deposits, called castings, also help enrich the soil.

2 Exoskeleton: anthropods like these, spiders, insects, have hard cuticle of chitin and some hardening m. ineral salt like phosphates and carbonates of calcium. The outermost layer is of this cuticle is usually covered with a thin layer of wax that keeps the organism waterproof. This outer head covering is the skeleton is outside the visceral of the organism, it is known as an exoskeleton. Shells of molluses of snail are also Exoskeletons.
3. Endoskeleton: this term describes the skeleton of higher animals i.e. vertebrates such as Man, birds etc. This skeleton is inside the body of the animal and it is covered by tissues and muscles. This type of skeleton is made up of bones and cartilage. The muscles are attached to the skeleton by tendons.
Questions
What are vertebrates? Differentiate between Endoskeleton and Exoskeleton
VERTEBRATE SKELETONS
The skeletons of vertebrates are made up of bones and cartilage. They are Endoskeleton. All the bones are joined together to allow movement. Vertebrate skeleton has a central spinal column. This column is a flexible stack of bones called vertebrae. All vertebrates’ skeletons are built on the same plan. The vertebrate skeleton is divisible into two parts.
(a) Axial skeleton: it consists of the skull, spinal column (vertebrae) and Ribs.
(b) Appendicular skeleton: this consists of the limbs (fore-limbs-hands and hind limbs-legs) in Man, Shoulder (Pectoral girdles) Hip bone (Pelvic girdle).

SUGGESTED PRACTICAL:
1. Illustrate skeletal support using clay and plasticine.
2. Practical examination of samples of: Arthropods such as spider, cockroach, millipede.
3. Examine an intact mammalian skeleton. Identify and name the main parts of the skeleton.
4. Students to draw and label the fore-limb.

AXIAL SKELETON
HUMAN SKULL: The human Head consists of several flat bones which form the skull. The skull is hollow and houses and protect the soft tissues of the brain. The upper and lower jaws are also part of the human skull. The jaws contain the teeth. The skull also have socket and cavities which contains and protect the delicate sense organs the like the eyes and ears.

Diagram of the adult human skull (side view)
Human Skull, Side View
This bony profile elaborates the many functions served by the human skull. The cheekbones so exaggerated in some people are actually formed by the fusion of two bones, the zygomatic arch and a section of the temporal bone. The zygomatic anchors one of the two main chewing muscles, the other of which attaches to the flattened side of the cranium. The thoroughness with which we can chew our food is attributable to the wide range of movement (upwards and downwards, side to side, grinding) possible where the lower jaw joins the rest of the skull. The hole just behind the jaw is the ear canal.
The skull is the topmost part of the body. It pivots on the top of the backbone on the first two vertebrae called atlas and axis respectively.


Human Skull, Front View
Inside the familiar features of the skull lie some of the most important and vulnerable parts of the body. The bones of the cranial region enclose the center of all intellectual, emotional, and vital activity—about 1500 cc of brain tissue, the consistency and sturdiness of which resembles jelly. Bony orbits protect our delicate eyeballs, and the fragile organs and bones of the inner ear lie deep within the skull. The sense of smell, less well protected than hearing and sight, relies on nasal passages that protrude on a cartilaginous frame from the center of the face.

STARNUM AND RIBS:
The sternum and twelve pairs of ribs form the Rib Cage. The ribs articulate with thoracic vertebrae at the back, curve to the front and get attached to the sternum by the means of elastic cartilage. First ten pairs of ribs are attached to the sternum. The other two pairs are not attached and are referred to as floating ribs. The rib cage houses and protects vital organs such as the heart, lungs and other contents of the thorax as well as help in breathing.
VERTEBRAL COLUMN: (BACK BONE)
The vertebral column is made up of 33 bones. These bones of the column are built on the same plan. All 33 small irregular bones are joined to form a strong fairly flexible S - shaped rod in the middle of the body. Each vertebra has a hole through which the spinal cord pass from the skull to the coccyx hence it is called Vertebral Column .
Atlas: The first vertebrae of the column is called atlas
Diagram of atlas vertebrae

Atlas and Axis
The top two vertebrae in the spinal column are specialized to allow the head a greater range of movement than would be possible with normal vertebrae. A stable ball-and-socket joint accommodates both side-to-side and up-and-down motion.

The second vertebra of the column is called Axis. Axis has a projection called Ondotoid process. It projects upward into a space in the Axis. This peg-like projection allows pivoting and rotation movements of the skull.
Diagram of Axis Vertebrae
The 33 bones are divisible into five sections:
Cervical vertebrae 7 - Neck
Thoracic vertebrae 12 - chest
Lumbar vertebrae 5 - waist area
Sacral vertebrae 4 - fused bones
Cervical vertebrae are 7 in number. They are the bones of the neck region, the first two of which are the Atlas and Axis which are structurally different from the remaining 5.
Diagram of a Typical Cervical
Lumber vertebra: these are 7 in number. They are lower back and carry most of the weight of the body. They have a large centrum.
Diagram of Lumber vertebra
Sacra vertebra: these are 5 bones fused together. Together, they are called sacrum. They connect the pelvic girdle to the backbone.
Coccyx: they are the bones of the tail. They are 4 small fused bones which ends the vertebral column.
Function of the vertebral Column
It supplies the thorax and the abdomen.
It houses and protects the spinal cord.
Vertebra all have holes through which spinal nerves pass to all parts of the body.
Intervertebral discs located between vertebrae permits smooth movement between the vertebrae well as absorb shocks of landing as the animal moves.
JOINTS
A joint is a place where two separate bones meet in order to effect different movements which is one of the functions of the skeletal system. Joints are held in place by tough ligaments.
Parts of Joint
A typical joint has two separate bones. Each ends with a “cap-like” layer of cartilage and synovial fluid encased in a capsule. The cartilage and fluid keeps the friction-free.

Movable Joints
The elbow shown in this X ray is an example of a movable joint, a joint with full mobility. The bones of movable joints are covered with cartilage and are lubricated by a thick fluid known as synovial fluid. There are several types of movable joints including ball-and-socket, hinge, gliding, and pivot joints. The elbow is a hinge joint.
Types of Joints
There are two main types of joints
1. Immovable: fixed joint as in the cranium.
2. Movable: they do not permit movement of bones in the /skull cranium. On the basis of the function of the joint or degree of movement possible, movable joints include:
(i) Hinged joints: found at the knees, elbows and fingers. This type of joint allows movement in one plane.
(ii) Gliding Joints: found at the wrist and ankles. The bones glide over each other, permitting movements in several planes. This movement permits fine dexterity movements such as writing, knitting, moulding etc.
(iii) Ball and socket Joint: this is located at the shoulder and hip. Movement at this joint is in many places.

FUNCTIONS OF SKELETON IN ANIMALS
1. It gives the animal shape.
2. It supports and protects soft tissues and organs e.g. brain, heart; the weight of the body e.g. lumbar vertebrae.
3. It brings about movement. It provides surfaces for attachment of muscles which pull on the bones by contracting and relaxing to effect mouth.
4. Red blood cells are produced in the marrow of long bones of the skeleton.
5. It also stores mineral salts.
6.
Pelvis
The human pelvis consists of the hipbone on the sides and front, and the sacrum and coccyx behind. The pelvis supports the spinal column and rests on the lower limbs.
PECTORAL AND PELVIC GIRDLES
Pectoral girdle: in humans the pectoral girdle holds the upper limbs or arms to the axial skeleton. It consists mainly of four separate bones: two large flat triangular shoulder blades or scapulae are attached to the vertebral co.umn by muscles. Each scapula has a depression called glenoid cavity into which the head of the upper arm bone or humerus fits to form the shoulder joint. The clavicles are attached to a scapula at one end and to the sternum at the other end. The pectoral girdle is not rigid. It enables the arm and shoulders to fairly freely.
Pelvic Girdle: in humans, the pelvic girdle or hips consists of two bones, the right and left pelvis. These are joined to the sacrum at the back and held together by fibro cartilage at the back and held together by fibro cartilage at the facets in front, to form a complete, rigid girdle. On the outer edge of the pelvis is a deep cavity, the acetabulum, into which the head of the thigh bone or femur fits to form the hip joint. The pelvic girdle is designed to receive the weight of the upper body and persists on to the legs (if you are standing), or to the surface on which you are sitting. The rigid structure of the girdle restricts the movements of the hips and legs.
Diagram of Pectoral girdle and Pelvic girdle on page 261 of Modern Biology for SSS, figure 12.5



Bones of the Leg
The human leg includes all the bones between the hipbone and the foot. The large bone at the top of the leg is the femur (thighbone), which is the strongest bone of the body. The femur has a rounded head that fits into a socket in the hipbone to form a ball-and-socket joint. This joint enables the leg to move freely in almost any direction. At the knee the femur connects to the tibia (shinbone) to form a hinged joint, which permits back-and-forth movement. The joint is protected in front by a small triangular bone, called the patella (kneecap). The tibia is the supporting bone of the lower leg. It is attached via ligaments to a smaller bone called the fibula. The fibula provides an attachment site for leg muscles and does not provide supportive strength for the leg.
FORE AND HIND LIMB
The fore and hind limbs of all terrestrial vertebrates are built on a basic penladactly plan. It consists of a long bone, followed by a pair of long bone placed side by side, a set of nine small bones in three rows, five thin long bones and finally five digits.
Forelimb consists of the following:
• Humerus which has a rounded head for articulation with the glenoid cavity of the scapula;
• Radius and ulna lie side by side as the long bones of the forearm, they articulate with the deeply grooved lower end of the humerus.
• Carpals are the nine small irregular bones of the wrist that are arranged in three rows.
• Metacarpals are the fire finger bones and
• Digits are the five long tiny bones that are made up of small bones called phalanges.
The hind limb consists of the following:
 Femur has a round head which fits into the acebulum of the pelvic girdle. It is the longest bone in the body.
 Tibia and fibula, the latter is smaller than the former.
 Fibula, a small bone which is joined to the tibia at its distal end;
 Patella or kneel cap is a small round bone in front of the knee joint.
 Tarsals are the ankle bones.
 Metatarsals are the foot bones.
 Digits are the toes.



EVALUATION
 Name two bones of the pectoral girdle.
 Name three bones each of the (a) fore-limb (b) hind limb.
 Define a joint. Give two examples each of (a) hinge joint (b) ball and socket joint.