KNEC KCSE BIOLOGY TOPICAL QUESTIONS AND ANSWERS

Describe how the tapeworm is adapted to a parasitic mode of life

15/6/2020

K.C.S.E Biology Q & A - MODEL 1997PP1QN19

Describe how the tapeworm is adapted to a parasitic mode of life

answers

Has hooks/suckers: for attachment to wall of intestines: long; to increase surface area for absorption of food: award increase in S.A for absorption once. Secretes enzymes/to neutralize digestive enzymes; (mucus inhibitor substance/anti enzymes) Hermaphroditic: to ensure reproductive/ self fertilization. Production of many eggs: to ensure survival
Segment for egg dispersal: More than one host; for transmission: e.g T solium – pig (Intermediate host) T. Saginata. Long to fit in the intestine/ increase surface area for ( flatten) Absorption of food; Anaerobic survive in the gut with low Oxygen

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What is parasitism?

15/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 1997PP1QN19

What is parasitism?

answers

An association between two organism; where one benefits; and the other is adversely affected. Or an association where an organism lives in or on another living or organism: obtaining from it and causing harm without necessary killing it.

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Describe how new plants arise by asexual reproduction

14/6/2020

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K.C.S.E Biology Q & A - MODEL 1996PP1QN 22

Describe how new plants arise by asexual reproduction

ANSWERS

Lower plants/example Bryophyta/pterophyta; produces spores which develops to new plants; budding an overgrowth arises from plant drop off; and develops into a new plant; common in lower plants yeast.
Fragmentation – e.g Spirogyra; breaks off and grows into a new plant
Vegetative propagation: common in higher plants involves growth of new plants from buds/bubils
Root stem/ tubers/ leaves: possesses buds; which develops to new plants
Corns; have terminal buds that grows vertically and produce a new plant
Runners; have lateral buds that produce new plants

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Explain how the mammalian skin is adapted to perform its functions

14/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 1996PP1QN 21

Explain how the mammalian skin is adapted to perform its functions

ANSWERS

The cornified layer is made up of dead cells, that prevent entry of bacteria and prevent physical damage; melanin protects the body against U-V variation; sebaceous glands produce a chemical/ ring substance which is of blood vessel; which when the body temperature is high dilate and heat is lost or when body temp is low blood vessels constrict.
And heat is retained. Hair when it is called, stands and traps air between themselves; to retain heat/ stop heat loss or when it is hot hair lies flat close on the skin; so does not trap air, and therefore heat is retained and sweat is lost; the skin has sweat glands which produces sweat;
sweat evaporates thus cooling the body.