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)
Cerebrum;
(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)
Parts of a ear
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
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
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; 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 |
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