KNEC KCSE BIOLOGY TOPICAL QUESTIONS AND ANSWERS

Funnel shaped to collect and concentrate sound waves into the external auditory meatus;
In some animals its large and when flapped creates air currents lining about cooling effect to the animals;

(ii) Eardrum

Its thin and flexible to enable transformation of sound waves into vibrations

(ii) Cochlea

It’s coiled to offer a large surface area for the attachment of the sensory cells.
Has numerous sensory cells to perceive sound vibrations.
Has thin membrane that vibrates more increasing the intensity of sound vibrations;
It’s filled with a fluid to enhance transmission of sound waves in it.

Comments

Name two types of active immunity

1/11/2021

Comments

Name two types of active immunity (2mks)

Natural active immunity;
Artificial active immunity;

Comments

Form two students set up an experiment as shown in the diagram below;

1/11/2021

Comments

Form two students set up an experiment as shown in the diagram below;

(a) Which process was being investigated? (1mk)

Anaerobic respiration
Rej: Respiration alone

(b) Why was it necessary to boil the glucose solution? (1mk)

To expel all the dissolved oxygen;

(c) Write a word equation representing the chemical reaction taking place above in the boiling tube (1mk)

Comments

Study the bones below and answer the questions that follow;

1/11/2021

Comments

Study the bones below and answer the questions that follow;

(a) Identify the function of the part labeled Q (1mk)

Offers a large surface area for muscle attachment

(b) Name the bone that circulates with the bone above at the proximal end (1mk)

Humerus;
Rej: Humerous or other wrong spellings for humerus

(c) List down two types of support tissue in plants (2mks)

Cellulose
Colenchyma tissue.
Selerenchyma tissue.
lignified xylem and tracheids;

Comments

List three characteristics that distinguish arthropods from organisms in kingdom Monera

1/11/2021

Comments

List three characteristics that distinguish arthropods from organisms in kingdom Monera (3mks)

Arthropods are large multicellular organisms;
Arthropods have jointed appendages;
Arthropods body is covered by an exoskeleton;
Arthropods have segmented bodies;
Arthropods exhibited sexual reproduction with an internal fertilization

Comments

State three ways how HIV and AIDS is transmitted in human population

1/11/2021

Comments

State three ways how HIV and AIDS is transmitted in human population (3mks)

Having sexual (unprotected) intercourse with an infected person;
Blood transfusion with infected blood;
From infected mother to child during birth;
Use of unsterilized, infected surgical instruments;
Sharing cutting/piercing instruments with infected people

Comments

What are the effects of releasing excess nutrients into lake Naivasha by the nearby flowers farms?

1/11/2021

Comments

What are the effects of releasing excess nutrients into lake Naivasha by the nearby flowers farms? (3mks)

Oxygen depletion due to excessive growth of aquatic plants leading to suffocation and death of aquatic animals;
Entrophication hinder light penetration affecting photosynthesis in submerged hydrophytes;
Cause water surface blockage affecting navigation/fishing.

Comments

State the function of Juvenile hormone in insect metamorphosis

1/11/2021

Comments

a) State the function of Juvenile hormone in insect metamorphosis (1mk)

leads to the formation of larval utricle;

b) (i) Give a reason why most insects are serious crop pests at the larval stage (1mk)

Growth rate in rapid/fast/high and shed cuticle several times hence feed a lot to have (desired) energy;

(ii) What happens at growth phase in insects growth curve (1mk)

Cells elongate before the cuticle harden;
Some cell division take place;

Comments

State two physiological mechanisms of controlling the human body temperatures during a hot day

1/11/2021

Comments

(a) State two physiological mechanisms of controlling the human body temperatures during a hot day (2mks)

Vasodilation/blood flows on the surface;
Hair lies on the skin/hair lies flat on the skin;
Metabolic rate decreases;
Sweating;

b) Name two ways in which loop of Henle is adapted to its function (2mks)

It is long to increase surface area for reabsorption of water.
It is lined with a network of capillaries to enhance reabsorption of water;
It is u-shaped to bring about counter current multiplier effect/to concentrate salts in the medulla to bring about reabsorption of water

Comments

List down two differences between closed and open circulatory systems

31/10/2021

Comments

a) List down two differences between closed and open circulatory systems (2mks)

Open system

Blood flows at low pressure
Blood flows in haemowel/sinuses body cavity/coacom /directly in contact with cells.
Blood lacks pigments for transport of O₂ and Co₂

Closed system

Blood flows at high pressure
Blood is confined in vessels/closed vessels/body vessels;
Blood has pigment for transport of O₂ and Co₂

b) Name two ways in which heart muscles are special (2mks)

Can contract continuously without fatigue;
Their contraction is stated by the muscles themselves (and not by the nerves/myogemic);

Comments

Distinguish between homologous structures and analogous structures

31/10/2021

Comments

a) Distinguish between homologous structures and analogous structures (2mks)

Homologous structures have a similar embryonic origin but modified to perform different function;
Analogous structures have different embryonic origin but modified to perform similar function;

b) State a major shortcoming in Jean Baptiste de Lamarck’s theory of evolution (1mk)

That a phenotypically acquired characteristics can be transmitted to the offspring by their parents;

Comments

<<Previous

State three ways in which blood capillaries are structurally adapted to their functions.

​a) Identify the type of asexual reproduction exhibited by yeast cells (1mk)

​b) List down the functions of the following parts; (3mks)

i) Testis

​ii) Fallopian tube

​iii) Urethra

State the importance of breathing through the nose than through the mouth. (2mks)

​(a) A passenger was involved in a road accident. He couldn’t move his limbs and neck. Which part of the brain was affected? (1mk)

(b) (i)State two functions of cerebrospinal fluid. (2mks)

​State how the following parts of the mammalian ear are adapted to their functions. (3mks)

​(i) Pinna

(ii) Eardrum

​(ii) Cochlea

Name two types of active immunity (2mks) ​

​(a) Which process was being investigated? (1mk)

(b) Why was it necessary to boil the glucose solution? (1mk)

(c) Write a word equation representing the chemical reaction taking place above in the boiling tube (1mk)

(a) Identify the function of the part labeled Q (1mk)

​(b) Name the bone that circulates with the bone above at the proximal end (1mk)

(c) List down two types of support tissue in plants (2mks)

​List three characteristics that distinguish arthropods from organisms in kingdom Monera (3mks)

State three ways how HIV and AIDS is transmitted in human population (3mks)

What are the effects of releasing excess nutrients into lake Naivasha by the nearby flowers farms? (3mks)

​a) State the function of Juvenile hormone in insect metamorphosis (1mk)

​b) (i) Give a reason why most insects are serious crop pests at the larval stage (1mk)

​(ii) What happens at growth phase in insects growth curve (1mk)

(a) State two physiological mechanisms of controlling the human body temperatures during a hot day (2mks)

b) Name two ways in which loop of Henle is adapted to its function (2mks)

a) List down two differences between closed and open circulatory systems (2mks)

Open system

Closed system

b) Name two ways in which heart muscles are special (2mks)

​a) Distinguish between homologous structures and analogous structures (2mks)

​b) State a major shortcoming in Jean Baptiste de Lamarck’s theory of evolution (1mk)

TOPICS

Form 2

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Form 4

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a) Identify the type of asexual reproduction exhibited by yeast cells (1mk)

b) List down the functions of the following parts; (3mks)

ii) Fallopian tube

iii) Urethra

(a) A passenger was involved in a road accident. He couldn’t move his limbs and neck. Which part of the brain was affected? (1mk)

State how the following parts of the mammalian ear are adapted to their functions. (3mks)

(i) Pinna

(ii) Cochlea

Name two types of active immunity (2mks)

(a) Which process was being investigated? (1mk)

(b) Name the bone that circulates with the bone above at the proximal end (1mk)

List three characteristics that distinguish arthropods from organisms in kingdom Monera (3mks)

a) State the function of Juvenile hormone in insect metamorphosis (1mk)

b) (i) Give a reason why most insects are serious crop pests at the larval stage (1mk)

(ii) What happens at growth phase in insects growth curve (1mk)

a) Distinguish between homologous structures and analogous structures (2mks)

b) State a major shortcoming in Jean Baptiste de Lamarck’s theory of evolution (1mk)