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👑 2019 NABTEB GCE BIOLOGY ANSWERS👑
100% VERIFIED BIOLOGY OBJ ANSWERS
100% VERIFIED BIOLOGY THEORY ANSWERS
(INSTRUCTION: ANSWER FOUR QUESTIONS ONLY, AT LEAST ONE QUESTION FROM EACH PART)
(i) Asexual reproduction e.g. Binary fission in amoeba
(ii) Sexual reproduction e.g. Reproduction in man
(i) Prophase: The prophase is divided into two, Early and late prophase. During early prophase, the chromosomes become visible as they contract and nucleolus shrinks. Centrioles are formed at opposite sides of the nucleus. Spindle fibres start to form and during the late prophase, the chromosomes become shorter and fatter. Each is seen to consist of a pair of chromatids joined at the centromere and nucleus disappear. Prophase ends with the breakdown of nuclear membrane
(ii) Metaphase: Metaphase also exists in early and late forms. During early metaphase, the chromosomes arrange themselves on the equator of the spindle and at late metaphase, the chromatids draw apart at the centromere region.
(iii) Telophase: Telophase stages is equally divided into early and late forms. During the early telophase, the cell starts to constrict across the middle. During the late telophase, the constriction continues. The nucleolus reform in each daughter cell. Spindle apparatus degenerates.
-After pollination, the pollen grain absorbs a sugary liquid on the stigma, swells and germinates.
-The outer coat of the pollen grain, the ezine, splits. The pollen tube grows out and down inside the style.
-At the initial stage, the pollen grain has only one nucleus. Later, this nucleus divides into two. A larger tube nucleus and a smaller generative nucleus.
-The pollen tube grows into the ovule through the micropyle, and at the end of the pollen tube bursts. The two male nuclei are released into the embryo sec.
-One male nuclei fuses with the ovum to form a zygote.
Tropic movement is a type of response in which a part of a plant moves in response to a directional stimulus.
(i) Chemotropism: This is growth or movement of the or plant parts in response to a chemicals stimulus eg growth of a pollen tube down the style during fertilisation in response sugars in the style.
(ii) Phototropism: This is response of plants to light eg shoots of green plants bend towards light(positively) while roots bend away from it(negatively phototropic).
(iii) Hydrotropism: This is movement of parts of plant in response to water. Eg roots bend towards moisture(positively hydrotropic), while shoots bends away from it (negatively phototropic).
(i) It gives support to the body.
(ii) It protects important and delicate organs of the body.
(iii) It provides places for the attachment of muscles.
(iv) It gives shape to the body
(v) It helps to store important mineral salts such as calcium.
(vi) It aids in respiration.
(iii) Hydrostatic Skeleton
An enzyme is an organic catalyst, usually portentous in nature, which promotes or speeds up chemical changes in living cells but are not themselves used up in the process.
(i) All enzymes are protein in nature.
(ii) Enzymes are usually involved in reversible reactions.
(iii) Each enzyme is specific in action. i.e. An enzyme of a group of enzymes deals with only one process.
(iv) Enzymes accelerate the rate of chemical reaction.
(v) Enzymes like any other catalyst act in very small quantities and catalyse large amount of substrate.
The digestion of fats and oil in the duodenum is aided by a green alkaline liquid called bile which is secreted by the liver and stored in the gall bladder. The bile helps in the emulsification of fats, i.e. breaking down fats into tiny droplets. At the end of digestion in the duodenum the food now in liquid form called chyle passes to the ileum or small intestine.
Pollution is the release of toxic or harmful substances into the environment by their natural forces or man and other animals to an extent that causes biological damage to man and his resources.
-Control: Dumping of refuse or petrochemical by-product into rivers, seas or streams should be avoided.
(i) It leads to pollution.
(ii) It produces unpleasant odour.
(iii) It occupies land space.
(iv) It can cause respiratory disorder.
(v) It destroys plants and animals.
Provision of waste bin carriage where refuse will be disposed, after which it will be taken away after a specific period of time.
Conservation is the planned or controlled exploitation or judicious use of natural resources to ensure their continuous availability and to preserve the quality or original nature of the environment.
Establishment of Zoo: That is the keeping of wildlife or wild animals in a cage in a zoological garden.
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