Question 2
- The diagram below is an illustration of a part of plant. Study it and answer questions 2 (a) to 2 (b).
- (i) Give the appropriate title to the diagram. [1 mark]
(ii) Name the parts labelled I to X. [5 marks]
(b) State one function each of the parts labeled I, II, III, VI and VIII. [5 marks]
The diagram below is an illustration of the pathway of nerve impulses in a human after accidentally touching a sharp object. Study it and answer questions 2 (c) to 2 (f).
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Observation
Some candidates could not give an appropriate title to the transverse section of leaf drawn. Some named it just a leaf. Majority of the candidates could hardly name the labelled parts in full.
A few candidates could name the illustrated pathway and spell it correctly, although majority of the candidates could not name the parts labelled on the reflex arc and even state the function of the labels.
Majority of the candidates could state the stimulus for the reaction.
Many candidates could not state the effect an injury to the parts labelled II and V would have on a person, neither could they give reasons.
The expected answers are:
- (a) (i) Title of the diagram
Tranverse section of the leaf of a flowering/dicotyledonous plant.
(ii) Name of labelled parts
I- Chloroplasts; VI- Spongy mesophyll cell;
II- Stomatal pore/opening/stoma VII- Intercellular air space;
III- Guard cell; VIII- Pallisade mesophyll cell;
IV- Lower epidermal cell/lower epidermis; IX- Upper epidermal cell/upper epidermis;
V- Stomatal air chamber/air space; X- Cuticle.
Note: spellings must be correct to score.
(b) Function of the parts labelled I, II, III, VI and VIII
I- for photosynthesis/absorption of light;
II- for gaseous exchange/diffusion of gases;
III- controls opening and closing of the stoma;
VI- to produce air spaces for gaseous exchange/site for photosynthesis;
VIII- for maximum light absorption/ photosynthesis.
(c) (i) Name of pathway
Reflex arc.
(ii) Labelled parts
- Receptor;
- Sensory Neurone/Afferent/sensory nerve fibre;
- Dorsal root;
- Association neurone/intermediate neurone/internuncial neurone;
- Effector/biceps/muscle;
- Motor neurone.
(iii) Function of the parts labelled I, II, IV, V and VI
- receives/registers the stimulus/generates impulse;
- transmits impulse;
- interprets impulse/issues commands/transfers impulse to the synapse/cell body of the motor neuron;
- lifts the arm;
- transmits impulse to the effectors.
(d) Stimulus for the reaction
Pain/pressure/touch
(e) (i) Effect on the person if II is injured
No feeling of pain/pressure/touch.
(ii) Effect on the person if V is injured
Inability to withdraw/lift hand/paralysis of arm.
(f) (i) Reason for the answer in (e) (i)
Impulses will not be transmitted from receptors to association neurone to be interpreted as pain.
(ii) Reason for for the answer in (e) (ii)
V/Effector/biceps/muscle will not be able to respond.