Question 2
(a) What are vitamins? [2 marks]
(b) Complete the table below on vitamins with their corresponding functions, deficiencies and food sources.
Vitamin |
One function |
One deficiency |
One source |
|
|
|
Citrus Fruits |
D |
|
|
|
|
|
Beri-beri |
|
|
Good eyesight |
|
|
|
|
Failure of blood to clot |
|
[15 marks]
(c) State one way each in which the following mineral elements are important to plants:
(i) Iron;
(ii) Nitrogen;
(iii) Calcium. [3 marks]
Observation
This question was also a popular question. Many candidates could define vitamins, although some definitions were not detailed as required. Some candidates could not give functions and deficiencies and sources of the expected vitamins on the table provided. The candidates that lost marks lost to incorrect spelling of the expected answer e.g scurry for scurvy, riket for rickets and some just wrote blindness instead of night blindness. Some candidates wrote vitamin E in place of vitamin K.
The importance of the given mineral elements to plants was poorly stated by many students. Some even gave the importance in animals instead of in plants; some candidates wrote that iron is important for the formation of the red blood cells and calcium for the development of strong teeth and bones.
The expected answers are:
(a) (a) Vitamins
Vitamins are organic/food substances/biocatalysts; needed in small quantities in the body; for healthy growth/development. Any 2 x 1 [2 marks]
(b) Functions, deficiencies and food sources of vitamins
Vitamin |
One function |
One deficiency |
One source |
C |
Resistance to diseases; for healthy |
Scurvy; loosening of teeth; |
|
|
Regulate calcium and phosphorus |
Rickets; poor bone development; |
Liver; fish oil; eggs; |
B |
For proper growth; |
|
Yeast; milk; groundnut; beans; rice; kidney; egg white; wheat; palm wine; |
A |
|
Night blindness/eye defect; |
Liver; red-palm oil; kidney; tomatoes; egg yolk; carrot; green vegetables; cod-liver oil; butter; margarine/cheese; peas; milk; broccoli. |
K |
For normal clotting of blood; |
|
Green vegetables; egg yolk; liver; tomatoes; unpolished cereal/whole grains. |
(c) Importance of the following mineral elements to plants
(i) Iron
Formation of chlorophyll
(ii) Nitrogen
Formation of protein/amino acids/nitrogenous bases; for normal/healthy growth;
chlorophyll formation; proper root growth.
(iii) Calcium