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No expanded working has been attached for this question yet. The verified answer is Option D.

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Dumping of refuse without a commensurate introduction of Oxygen to aid decomposition by aerobes calls for pollution of the river. This is because the carbon (|V) OXIde is increased coupled with the fact that the rate of decomposition is low. Aquatic organisms die as a result of this. The method of addition of measured quantity of oxygen when a given quantity of refuse is dumped at a given time in a river or sea termed B, O D (Bichemical Oxygen Demand)

(a) The principal sense organs in mammals are: (i) The eyes for seeing or viewing (ii) The nose olfactory organ for smell or smelling (iii) Ear for hearing, balancing and sense of position (iv) Tongue for taste using the taste bud (bitter, sour and sweet tastes) (v) Skin for touch, detection of temperature, pressure, pain, heat and cold. (b)(i) This type of defect is known as long sightedness (hypermetropia). inability to focus near objects clearly but can see distant objects clearly. It is as a result of short eyeball, or the lens and ciliary muscles which has lost their elasticity, Light rays from near objects are normally focused behind the retina (ii) The defect can be corrected by using a convex lens which coverages the light rays entering the eye to focus on the retina. Long sight is corrected by convex lens. The convex lens shorten the focal length, converge rays of light entering the eye from near object to focus on the retina.

(a) The female reproductive system of human consists of two ovaries located below the kidneys. Close to each ovary is the oviductal funnel which lead into the fallopian tube or oviduct. The fallopian tubes are narrow spiralling tubes that lead down into a wider tube called uterus or womb. The two horned uteri join up to form vagina. The narrow lower end of the uteri which lead into the vagina are called the cervix which regulates the opening of the vagina. The urethra opens into the vagina to form a common passage called the vestible which serves as urinogenital tract. This has an opening through vulva? (b) Mammals Amphibians (1) Fertilization is internal (2) Development is internal (vivaporous) or born young ones alive (3) Placenta is present -Fertilization is external -development is external (oviparous) lay eggs -No placenta (c) Description of male reproductive organ of a flowering plant: The male reproductive organ of a flowering plant is known as androecium which is made up of stemens. Stamens are made up of stalks called filaments, which carry the anthers. The anthers are made up of pollen sacs which contain the pollen grains containing the male gametes.

(a)(i) Priovision of land for agriculture (ii) Provision of improved seeds, cuttings and seedlings to farmers (iii) Research into proper method of storage of crops (iv) Provision of agricultural education to farmers through the extension workers or agents (v) Granting of interest free or soft loans to farmers as a way of encouragement (vi) Provision of fertilizer, herbicides, pesticides, vacines, fungicides and drugs to farmers at subsidised rate (b)(i) Application of manure and fertilizers (ii) Crop rotation (ii) Mechanical control of soil erosion such as contouring, ridging, terracing and making of cross bar (iv) planting of cover crops (v) Prevention of bush burning (c)(i) Continuous cropping:- This involves the continuous cultivation of a particular land which results in to exhaustion of the soil, reduces mineral nutrients of the soil thereby causing imbalance in the ecosystem. (ii) Bush burning - Destroys both the producers and consumers in an ecosystem, depletes the essential nutrients, reduces water holding capacity of the soil, low support of plant and animals. iT Even destroys the microbial flora and fauna or micro-organisms in the soil. Also encourages soil erosion. (iii) Use of chemicals, e.g. pesticides, herbicides and fungicides which are used to control plants and animals pests generally affect or destroy other plants and animals in the environment.

(a)(1) Voluntary action - involves the response to a stimulus that is controlled at will by the brain. in this action, an impulse is carried from a sensory neurone via the spinal cord to the brain which interprets and sends the message back through the motor neurone to effector organ. The action is not automatic. e.g. running, writing, jumping, laughing, reading, smiling. (II) Involuntary action or reflex action-It is a rapid or automatic response to a stimulus. It does not involve the brain for initiation. Therefore, the action is not under the control of the will, e.g. sneezing, coughing, knee jerk, salivation, secretion of grand, blinking (b)(i) Functions of insulin: (1) Assists in oxidation of glucose to produce energy (2) regulates the amount or level of glucose in the blood (3) assists in protein synthesis in some cells (ii) Functions of auxin (1) Promotes lateral bud development (2) promotes reproduction, flowering and fruit formation in plants (3) promotes the production of adventitious roots. (c) Experiment to show that plant roots respond positively to gravity: Aim - To demonstrate that plant roots respond positively to gravity. Apparatus: A bean seedling, Wet blotting paper, damp saw dust, cupboard. Procedure: Put some dust on a wet blotting paper and place the bean seedling on the saw dust horizontally. Carry the set up and place it inside a dark cupboard to eliminate light for few days. Observation: When observed after few days, one will discover that the root has curved and growing downwards while the shoot grow upward. Conclusion: Since the root has grown downwards and the shoot upwards, we can say that roots respond to gravity, showing positive geotropism while the shoot shows negative geotropism.

(a) Diffusion (b) Osmosis (c) Plasmolysis (d) Hepatic portal vein

They are specific in their actions, Example starch- splitting enzymes can only act on starch (ii) They work best at a particular temperature. Example - the human enzymes work best between 35^\circG and 40^\circC. They are denatured at about 60^\circC. (iii) They are protein in nature

(i) Noise causes hearing defects (ii) Noise can make us lose concentration (iii) Noise pollution quickens heartbeat rate and blood circulation

(i) Escherichia coli are bacteria found in the intestinal tract of ruminants (and other vertebrates) where they synthesize Vitamin K from cellulose (ii) - Others are protozoa living in the gut of termites - Sea anemone and the hermit crab