Observation

This was a popular question among candidates. Some of the candidates that lost some marks in this question lost them to spelling errors.

In (a) and (b), a few candidates could name the gases and state the roles of the gases involved in photosynthesis while others could not. Some candidates even wrote nitrogen as a gas involved in photosynthesis.

In (c) (i) and (ii), some candidates were able to explain variegated leaf and state the part that would test positive to iodine solution. Some candidates wrote that variegated leaf is a leaf with different plants instead of different colour parts.
(c) (iii) was not answered properly as some candidates could not give a reason why the part of a variegated leaf would test positive when treated with iodine solution.
(c) (iv) was well answered but spelling errors made some candidates lose mark.

In (d), some candidates could not correctly place the listed organisms under the headings in the table provided. Some could not even spell the names of the organisms listed for them correctly hence losing marks unnecessarily. Some candidates even wrote Venus flytrap and Housefly under parasitic and housefly under saprophytic.

 The expected answers are:

2. (a)  Gases involved in the photosynthesis of a plant

• Carbon dioxide/ Carbon (IV) oxide;
• Oxygen.                                                                       

Note: Spelling must be correct to score.

(b) Role of gases involved in photosynthesis
(i)   Carbon dioxide/ Carbon (IV) oxide: raw material for photosynthesis/to produce
glucose/starch
(ii)   Oxygen: by-product/given off during photosynthesis.  

      (c) (i)    Variegated leaf
A leaf with different colour parts/patches/green and non-green parts.       
(ii)   Part of variegated leaf that would be positive when treated with iodine solution
The green part/patch                                                                                 

          (iii)   Reasons for the answer in 2 (c) (ii)
Presence of chlorophyll/chloroplast; for trapping solar energy; to manufacture starch; which turns blue-black with iodine solution.                                   

         (iv)   Mineral elements used to manufacture chlorophyll
Magnesium/iron/nitrogen.                                                            
Note: Spelling must be correct to score.

(d) Table