KNEC KCSE BIOLOGY TOPICAL QUESTIONS AND ANSWERS

Explain why the rate of transpiration is reduced when humidity is high

23/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN29

Explain why the rate of transpiration is reduced when humidity is high

answers

When humidity in high the air around the leaf gets saturated with water vapour hence) less space for water vapour from the leaf to occupy/ low saturation deficit/ low diffusion gradient/ the difference in concentration of water vapour in the atmosphere and in the air spaces is greatly/ highly reduced.

Comments

Name a disease that causes thickening and hardening of arteries

23/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN28

Name a disease that causes thickening and hardening of arteries

answer

Arteriosclerosis/ rej Atheroma – due to the deposition of cholesterol which makes human narrow

Comments

State three structural differences between arteries and veins in mammals

23/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN28

State three structural differences between arteries and veins in mammals

answers

Comments

State two ways in which anaerobic respiration is applied in industries

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP1QN27

State two ways in which anaerobic respiration is applied in industries

answers

Baking/ brewing
Formation of dairy products- cheese, yoghourt, sour milk
Formation of organic acids- oxalic acid, vinegar ( Ethamic acid, citric acid, butyric acid)

Comments

How are the mitochondria adapted to their functions?

23/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN26

How are the mitochondria adapted to their functions?

answers

Inner membrane is highly folded/ have cristae to provide a large surface area/ for attachment of respiratory enzyme.

Comments

State two ways in which aerenchyma tissues in aquatic plants are adapted to their function

23/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN25

State two ways in which aerenchyma tissues in aquatic plants are adapted to their function

answers

Thin walled for easy diffusion of gases/ store a lot of air/ have large air spaces which store air for buoyancy/ for gaseous exchange

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN24

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP1QN24

Explain how the following factors determine the daily energy requirement in human:
(a) Age
(b) Occupation
(c) Sex

answers

(a) Young people are actively/ rapidly growing hence require more energy than older people
(b) Manual workers require more energy than secretary workers
(c)Males are more muscular hence require more energy than females

Comments

state the function of iron in the human body

23/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN23

state the function of iron in the human body

answers

A component of haemoglobin/ formation of haemoglobin

Comments

Explain how the carnassials teeth of a dog are adapted to their function

23/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN22

Explain how the carnassials teeth of a dog are adapted to their function

answer

Large/ powerful for cracking/ breaking/ crushing bone/ slide past each other/ scissor- like for shearing/ cutting/ slicing (off) flesh/ tendons/ skin from bone

Comments

Explain what happens in humans when concentration of glucose in the blood decreases below the normal level

23/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN21

Explain what happens in humans when concentration of glucose in the blood decreases below the normal level

answer

Pancreases releases glucagons to stimulate liver cells to convert stored glycogen to glucose; fat converted to glucose/ reduces rate of respiration.

Comments

Other than using the quadratic, give two methods of estimating population of grass

23/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN20

Other than using the quadratic, give two methods of estimating population of grass

answers

Belt transect
Line transects

Comments

Name one process that is responsible for loss of energy from one trophic level to the next

23/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN19

Name one process that is responsible for loss of energy from one trophic level to the next

answers

Respiration/ defecation/ excretion

Comments

State three effects of dumping untreated sewage into a river

23/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN19

State three effects of dumping untreated sewage into a river

answers

Leads to eutrophication; causes water bone disease
Kill organisms in water;/ reduce amount of oxygen in the water/ reduce the quality of water for consuming change water PH; ? interferes with food charus/ trophic levels.

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN18

23/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN18

Explain how the following factors affect the rate of photosynthesis:
(a) Concentration of carbon (iv) oxide
(b) Light intensity

ANSWERS

(a) Rate of photosynthesis increases as CO2 concentration increases up to a certain level/ optimum level and ( vise versa)Reverse:
b)The rate of photosynthesis decreases with decrease in CO2 concentration until it stop rate of photosynthesis increases as the light intensity up to an optimum level (and vice versa)

Comments

Explain why plants do not require specialized excretory organs

23/6/2020

Comments

K.C.S.E Biology Q & A - MODEL 2009PP1QN17

Explain why plants do not require specialized excretory organs

ANSWERS

Some wastes e.g gases easily diffuse out Waste products are mainly made from carbohydrate and hence are not as harmful as proteineous materials/ waste products are formed slowly / little accumulation of wastes/ plants are leas active/ some waster products ( such as 02 and are usable- recycled; some waste products are store in non- toxic forms in leaves, flowers, fruits and old bark.

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Explain why the rate of transpiration is reduced when humidity is high

Explain why the rate of transpiration is reduced when humidity is high

Name a disease that causes thickening and hardening of arteries

Name a disease that causes thickening and hardening of arteries

State three structural differences between arteries and veins in mammals

State three structural differences between arteries and veins in mammals

State two ways in which anaerobic respiration is applied in industries

State two ways in which anaerobic respiration is applied in industries

How are the mitochondria adapted to their functions?

How are the mitochondria adapted to their functions?

State two ways in which aerenchyma tissues in aquatic plants are adapted to their function

State two ways in which aerenchyma tissues in aquatic plants are adapted to their function

K.C.S.E Biology Q & A - MODEL 2009PP1QN24

K.C.S.E Biology Q & A - MODEL 2009PP1QN24

state the function of iron in the human body

state the function of iron in the human body

Explain how the carnassials teeth of a dog are adapted to their function

Explain how the carnassials teeth of a dog are adapted to their function

Explain what happens in humans when concentration of glucose in the blood decreases below the normal level

Explain what happens in humans when concentration of glucose in the blood decreases below the normal level

Other than using the quadratic, give two methods of estimating population of grass

Other than using the quadratic, give two methods of estimating population of grass

Name one process that is responsible for loss of energy from one trophic level to the next

Name one process that is responsible for loss of energy from one trophic level to the next

State three effects of dumping untreated sewage into a river

State three effects of dumping untreated sewage into a river

K.C.S.E Biology Q & A - MODEL 2009PP1QN18

K.C.S.E Biology Q & A - MODEL 2009PP1QN18

Explain why plants do not require specialized excretory organs

Explain why plants do not require specialized excretory organs

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