KNEC KCSE BIOLOGY TOPICAL QUESTIONS AND ANSWERS

K.C.S.E Biology Q & A - MODEL 2013PP2QN02

28/6/2020

K.C.S.E Biology Q & A - MODEL 2013PP2QN02

The diagram below represents the human ear.

(a) Name the parts labelled E, F and G.
E
F.
(b) How is each of the following adapted to its function?
(i) External auditory meatus;
(ii) Ear ossicles.
(c) Name one defect of the human ear.

answers

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K.C.S.E Biology Q & A - MODEL 2013PP1QN23

26/6/2020

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K.C.S.E Biology Q & A - MODEL 2013PP1QN23

The diagram below illustrates a defect in the eye.

Explain how the defect illustrated above can be corrected.

answers

Use of biconcave/concave lens/divergent lens; to diverge the rays and make image be focussed on the retina;

Comments

Using a relevant example in each case, describe simple and conditional reflex actions.

26/6/2020

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K.C.S.E Biology Q & A - MODEL 2012PP2QN07

Using a relevant example in each case, describe simple and conditional reflex actions.

ANSWERS

Simple reflex action - withdrawal of finger from a sharp object.
Is an automatic response to a specific stimulus;
When the finger touches a sharp object, pain receptors in the skin; are stimulated and trigger off a nerve impulse;
The nerve impulse is transmitted via the sensory neuron; to the grey matter of the spinal cord;
The impulse is then transmitted via a synapse; to the relay neuron; and then through another synapse; to the motor neuron;
The impulse is then transmitted to the effector muscles in the hand;
These effector muscles contract; and the finger is withdrawn from the hot object;

Conditioned reflex action

Is an automatic response evoked from an animal by unrelated stimulus; substituted for the one which normally elicits the response;
It develops from past experience; and involves modification of behaviour through learning; It weakens with time; and must be reinforced by repeating the unrelated stimulus;
Students salivate when the bell for lunch rings; because they have learned to associate the
ringing of the bell at lunchtime with food; from experience; every time it rings, they are offered food;

Comments

State the importance of negative phototaxis to termites.

26/6/2020

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K.C.S.E Biology Q & A - MODEL 2012PP1QN09

State the importance of negative phototaxis to termites.

answer

Reduces dehydration; Avoid predators;

Comments

Describe how accommodation in the human eye is brought about when focusing on a near object.

25/6/2020

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K.C.S.E Biology Q & A - MODEL 2011PP2QN08

Describe how accommodation in the human eye is brought about when focusing on a near object.

answers

Light rays from a near object are more diverged and need to bend more; in order to be focused properly on the retina; ciliary muscles contract; suspensory ligaments attached to the ciliary muscles relax; the lens becomes thicker; increasing its curvature/becomes more convex; light from the object is refracted more; in order to be focused/more sharply on the retina to form an image.

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What is a tropic response?

25/6/2020

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K.C.S.E Biology Q & A - MODEL 2011PP1QN28

What is a tropic response?

ANSWERS

It is a growth movement in plants in response to a unidirectional stimulus;

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K.C.S.E Biology Q & A - MODEL 2010PP2QN04

24/6/2020

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K.C.S.E Biology Q & A - MODEL 2010PP2QN04

The diagram below shows how the iris and pupil of a human eye appear under different conditions..

(a) Name the structures labelled X and Y.
X
Y
(b) (i) State the condition that leads to the change in appearance shown in the diagram labelled B.
(ii) Describe the changes that lead to the appearance of the iris and pupil as shown in the diagram labelled B.
(iii) What is the significance of the changes described in (b) (ii) above?

ANSWERS

(a) X Pupil;
Y Circular muscles;
(b) (i) Dull/dim light/low light intensity;
(ii) Circular muscles (in iris) relax; while radial muscles contract; the pupil becomes bigger; allowing more light to enter the eye;
(iii) Allows one to visualize objects/see under dim light;

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K.C.S.E Biology Q & A - MODEL 2010PP1QN26

24/6/2020

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K.C.S.E Biology Q & A - MODEL 2010PP1QN26

State one survival value for each of the following in plants:
(a) Thigmotropism in stems;
(b) Geotropism in roots.

answers

(a) Provides support;
Enables plants to grow towards light; Any one
(b) In search of nutrients
Anchorage;

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K.C.S.E Biology Q & A - MODEL 2010PP1QN06

24/6/2020

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K.C.S.E Biology Q & A - MODEL 2010PP1QN06

State one function for each of the following:
(a) Cerebellum;
(b) Medulla oblongata.

answers

(a) Co-ordinates balance;
(b) Controls heart beat/blood pressure/breathing rate;

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K.C.S.E Biology Q & A - MODEL 2009PP2QN04

23/6/2020

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K.C.S.E Biology Q & A - MODEL 2009PP2QN04

(a) (i) Explain the changes that take place in the pupil and iris of a human eye when a person moves from a dark room to a room with bright light
(ii) What is the significance of the changes explained in (a) above
(b) How does the human eye obtain nutrients?
(c) Explain why images that form on the blind spot are not perceived

answers

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State two characteristics of the image formed on the retina

22/6/2020

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K.C.S.E Biology Q & A - MODEL 2008PP1QN13

State two characteristics of the image formed on the retina

ANSWERS

inverted; Real; reversed; diminished

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Name the part of retina where image is formed

22/6/2020

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K.C.S.E Biology Q & A - MODEL 2008PP1QN13

Name the part of retina where image is formed

ANSWERS

Yellow spot/ cornea ( centralis)

Comments

Describe the structure and functions of the various parts of the human ear

22/6/2020

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K.C.S.E Biology Q & A - MODEL 2007PP2QN07

Describe the structure and functions of the various parts of the human ear

answers

The ear is an organ involved in perceiving sound and maintaining body balance and posture. It is made of the following sections
Pinna – That is funnel shaped structure made of skin and cartilage. It receives sound waves and directs them to the ear tube.
External/auditory meatus – That is a canal lined with air and wax. It allows passage of sound waves to the middle ear. The hairs and wax trap dust particles that enter the ear.
Tympanic membrane – That is a thin flexible sheet-like structure receives sound waves and pass the vibration to the ossicles.
Middle ear that is composed of Tiny bones known as ossicles – They are anvil and incus. They amplify vibration from the tympanic membrane.
Eustachian tube – That connects the ear to the nasal cavity. It balances pressure on both sides of the tympanic membrane.
Oral window – That is a thin flexible membrane that opens into the inner ear. it receives vibrations from the ossicles and passes them to the inner ear.
Inner ear that is compost of;
Vestibular apparatus- That are the semicircular canals, utricles and saccules. They help in maintenance of body balance and posture.
Cochlea – That is a coiled structure that has sensory cells for hearing. It connected to the auditory nerve that is involved in transmission of sounds to the brain

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K.C.S.E Biology Q & A - MODEL 2007PP1QN22

21/6/2020

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K.C.S.E Biology Q & A - MODEL 2007PP1QN22

The diagram below represents a neurone

(i) Name the neurone
(ii) Name the parts labeled P and Q
P………………………………………………………………………..
Q……………………………………………………………………….
(c) State a function of myelin sheath

ANSWERS

(b) Motor neutron
(ii) P- Dendrites
Q- Axoplasm (Axon)
(d) Insulates the axon

Comments

Where in the human body are relay neurons found

21/6/2020

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K.C.S.E Biology Q & A - MODEL 2007PP1QN22

Where in the human body are relay neurons found

ANSWER

In the central nervous system (spinal cord)

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K.C.S.E Biology Q & A - MODEL 2013PP2QN02

K.C.S.E Biology Q & A - MODEL 2013PP2QN02

K.C.S.E Biology Q & A - MODEL 2013PP1QN23

K.C.S.E Biology Q & A - MODEL 2013PP1QN23

Using a relevant example in each case, describe simple and conditional reflex actions.

Using a relevant example in each case, describe simple and conditional reflex actions.

State the importance of negative phototaxis to termites.

State the importance of negative phototaxis to termites.

Describe how accommodation in the human eye is brought about when focusing on a near object.

Describe how accommodation in the human eye is brought about when focusing on a near object.

What is a tropic response?

What is a tropic response?

K.C.S.E Biology Q & A - MODEL 2010PP2QN04

K.C.S.E Biology Q & A - MODEL 2010PP2QN04

K.C.S.E Biology Q & A - MODEL 2010PP1QN26

K.C.S.E Biology Q & A - MODEL 2010PP1QN26

K.C.S.E Biology Q & A - MODEL 2010PP1QN06

K.C.S.E Biology Q & A - MODEL 2010PP1QN06

K.C.S.E Biology Q & A - MODEL 2009PP2QN04

K.C.S.E Biology Q & A - MODEL 2009PP2QN04

State two characteristics of the image formed on the retina

State two characteristics of the image formed on the retina

Name the part of retina where image is formed

Name the part of retina where image is formed

Describe the structure and functions of the various parts of the human ear

Describe the structure and functions of the various parts of the human ear

K.C.S.E Biology Q & A - MODEL 2007PP1QN22

K.C.S.E Biology Q & A - MODEL 2007PP1QN22

Where in the human body are relay neurons found

Where in the human body are relay neurons found

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