KNEC KCSE BIOLOGY TOPICAL QUESTIONS AND ANSWERS

Explain structure and functions of the human eye.

4/11/2021

Comments

Explain structure and functions of the human eye. (20mks)

Conjuctiva - Protects eyeball from mechanical injury.
Cornea - Allows light to pass through
Iris - Controls amount of light passing through
Forea - Where image is formed
Sctera - Protect the eye ball; give it shape
Choroid - Absorbs stray lights
Provide nourishment to the eye.
Aqueous/vitreous humour - refract light into the eye towards retina maintain shape of eye ball.
Ciliary body - Controls curvature of the lens.
Rods - Perceive light of low intensity
Cones - Perceives light of high intensity.

Comments

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

1/11/2021

Comments

(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)

Cerebrum;

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

Nourishes the brain cells/supplies nutrients/removes metabolic wastes from brain cells.
Acts as a shock absorbs to the CNS

Comments

State the functions of the following parts of the human ear (Ossicles and Pinna)

9/9/2021

Comments

State the functions of the following parts of the human ear

(a) Ossicles (1mk)

Prevent excessive vibrations; which can damage the inner delicate membranous labyrinth
form a system of levers which amplifies and transmits the vibrations from hympanic membrane to the oval window

(b) Pinna (1mk)

Collects and concentrates sound waves into the auditory mellitus

State the functions of the following parts of the human ear (Ossicles and Pinna)

Parts of a ear

Comments

State two features of atoms that increase the rate of impulse transmission

7/9/2021

Comments

(i) Insulation by myelin sheath
(ii) Thicker diameter of axon

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Response and Co-Ordination Questions and Answers

13/11/2020

1. 1989 Q2 P1
State one structural and one functional difference between motor and sensory neurons.

2. 1990 Q15 P1
(a) How are the structures of the human eye adapted to their function?

K.C.S.E Biology Q & A - MODEL 2019PP2QN05

2/7/2020

Comments

K.C.S.E Biology Q & A - MODEL 2019PP2QN05

A person accidentally touches a hot pan and responds as illustrated in the diagram below.

(a) Explain how the response illustrated above occurs.
(b) Explain how auxins are utilised as selective weed killers in agriculture.

answers

(a) The stimulus /heat/pain is detected by temperature/pain receptor( Thermo receptors) in the skin/dermis; An impulse is generated; impulse is transmitted along a sensory neurone to the CNS/spinal cord; (chemical) transmission across synapse to relay neurone; Across a synapse to motor neurone; across a synapse to biceps muscles,/effector via motor neurone; muscles/effectors contracts; (hand moves away). This is known as (simple reflex action);
Stimulus/pain/temperature detector
Receptor-impulse-sensory neurone-synapse-relay neurone (CNS)-synapse-motor neurone- synapse-biceps-control.
(b) Selective weed killer contains auxins which are absorbed by the weeds (than desired/ beneficial plants); making the weeds to grow abnormally/accelerated die out; (weed of the beneficial plants);

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K.C.S.E Biology Q & A - MODEL 2019PP1QN10

1/7/2020

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K.C.S.E Biology Q & A - MODEL 2019PP1QN10

In an investigation, students set up the apparatus below in the laboratory and made observations after 72 hours.

(a) Explain how inclusion of the following components would affect the mouse in the experiment:
(i) light
(ii) sodium hydroxide solution
(b) State why the students preferred to use a bell jar and not a tin box in the experiment.

answers

.(a) i) light enables the potted plant to photosynthesize; producing oxygen which is
Inhaled by the mouse, (sustaining it); the illuminated light can further affect /alter some photosynthesized processes in the mouse as a result of constant direct beam of light.
(ii) Absorbs carbon(iv)oxide (mainly exhaled by the mouse); while at the same time deny the plant the needed raw material, carbon (iv) oxide to photosynthesize hence suffocating the mouse/ emitting its survival / no oxygen;
(b) bell jar is transparent, allow penetration of light for the plant to photosynthesize; tin box is opaque hence does not allow photosynthesis/ could easily heat up altering the temperature inside for the mouse/ plant;

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K.C.S.E Biology Q & A - MODEL 1996PP1QN16

14/6/2020

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K.C.S.E Biology Q & A - MODEL 1996PP1QN 16

A shoot of seedling exposed to light on one side bends towards the source of light as it grows
(a) Name the response exhibited by the shoot of the seedling
(b) Explain how the bending towards the source of light occurs

answers

(a) Phototropism
(b) Auxins / hormones; move diffuse to the demised/ away from the light side; causing elongation/ growth on the dark sides hence bending

Comments

Explain structure and functions of the human eye.

Explain structure and functions of the human eye. (20mks)

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

(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 the functions of the following parts of the human ear (Ossicles and Pinna)

State the functions of the following parts of the human ear

(a) Ossicles (1mk)

(b) Pinna (1mk)

State two features of atoms that increase the rate of impulse transmission

Response and Co-Ordination Questions and Answers

K.C.S.E Biology Q & A - MODEL 2019PP2QN05

K.C.S.E Biology Q & A - MODEL 2019PP2QN05

K.C.S.E Biology Q & A - MODEL 2019PP1QN10

K.C.S.E Biology Q & A - MODEL 2019PP1QN10

K.C.S.E Biology Q & A - MODEL 1996PP1QN16

K.C.S.E Biology Q & A - MODEL 1996PP1QN 16

TOPICS

Form 2

Form 3

Form 4

Archives

Categories

​Explain structure and functions of the human eye. (20mks)

​(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 the functions of the following parts of the human ear

(a) Ossicles (1mk)

(b) Pinna (1mk)

K.C.S.E Biology Q & A - MODEL 2019PP2QN05

K.C.S.E Biology Q & A - MODEL 2019PP1QN10

K.C.S.E Biology Q & A - MODEL 1996PP1QN 16

TOPICS

Form 2

Form 3

Form 4

Archives

Categories

Explain structure and functions of the human eye. (20mks)

(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)