BIOLOGY PAST QUESTION

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1. (a) Explain the term adaptation in relation to the mode of life of an organism.

(b) Explain how each of the following structures adapt the organisms that possess them to their modes of life:

(i) succulent leaves in Aloe sp

(ii) succulent stems and reduced leaves in cactus plants

(iii) short, strong beaks in fowls

(iv) counter shading in fish

(v) tiny scale leaves on needle-like branches of pine trees.

(c)(i) What is population?

(ii) State five effects of overpopulation on a community.

2. (a)(i) What is placentation?

(ii) Name two organs associated with the human placenta.

(b) State five functions of the human placenta.

(c) Write short notes on the following:

(i) viviparity

(ii) territoriality

(iii) seasonal migration

3. (a) List four characteristics which can be genetically transmitted in humans.

(b)(i) Name two sites eac• in plants and animals where meiosis occurs.

(ii) State two differences between meiosis and mitosis

(c) A woman with blood group ‘A’ (heterozygous) claimed that her son who has blood group ‘0’ was fathered by Mr. James who has blood group ‘A’ (homozygous). With the aid of suitable genetic diagrams

(i) prove or disprove the woman’s claim

(ii) give reasons to support your answer.

4. (a) Write short notes on each of the following:

(i) ecological niche

(ii) population density

(iii) climax continually

(b) Describe briefly the interactions between abiotic and biotic components of an ecosystem.

5. (a)(i) Name two types of germination of seeds giving one example of each type.

(ii) Describe a simple experiment to demonstrate that oxygen, water and warmth are necessary for germination of seeds.

(b) State two distinguishing features each of

(i) epiphytes

(ii) parasites

(c) Give two examples o parasitic plants.

6. (a) Write the chemical equation for each of the following processes:

(i) aerobic respiration

(ii) anaerobic respiration in plants

(iii) anaerobic respiration in animals.

(b) State four functions which the liver of a patient suffering from cancer of the liver will not be able to perform.

(c) Make a diagram 8 -10 cm long of a flame cell and label fully.

(d) Name one appropriate hormone each responsible for the following conditions in plants:

(i) ripening of fruits

(ii) breaking dormancy in seeds

(iii) weed control

(iv) leaf fall.

(a) (I) List two diseases each of plants and animals caused by bacteria.

(II) State three ways in which bacteria are useful.

b State three method by which mosquitoes can be controlled and state the reasons for each methods listed.

C Describe an experiment to demonstrate the presence of bacteria under the finger nails.

(a) List three major zone in the marine habitat, stating one characteristics feature of each zone.

b(i) Give one example of plants and animals in the marine habitat

(ii) Explain how each of the plants and animals is adapted to the habitat.

C State three behavioural adaptation of animals to seasonal changes in terrestrial habitat.

d State three characters each of the plant community in the tropical rain forest and Savannah.

(a) What is a hormone?

(b). Outline the roles played by adrenaline in an emergency situation.

(C) In a tabular form, list five differences between hormonal co-ordination and nervosa coordination.

(d) Name three animals hormones and two plants hormones.

(a) (i) Defined the law of independent assortment

(ii) State the findings from Mendel’s experiment involving white-flowered and red flowered pea plants .

(iii) illustrate these findings by means of simple diagrams.

(b) Explained why blood group A and B in man can exist both in heterozygous and homozygous conditions while blood group O can only exist in homozygous state.

(a) What is an ecosystem ?

(b) Name two abiotic factors each affect plants and animals in a territorial habitat

(C) state four factors that bring about compilation among organisms

(d) Outline the relationship between competition and Success.

6 (a)(i) Explain briefly Drawins theory of Natural Selection

(ii) List five evidence to support the occurrence of evolution.