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Agricultural Science Paper 2, May/June 2009  
Questions: 1 2 3 4 5 6 7 8 9 10   Main
General Comments

Question 3

a) State four characteristics of clay.            [4 marks]

b) Mention four effects of drought on plant growth and development.  [4 marks]

c) List two symptoms of phosphorus deficiency in crops.                  [2 marks]

d) State three ways in which each of the following soil properties is important in crop production:
i) soil reaction;
ii) soil temperature.                    [6 marks]


Few candidates attempted this question.  In question 3(a), most of the candidates could state characteristics of clay. 
However, in question 3(b), many candidates were unable to mention effects of drought on plant growth and development.
In question 3(c), majority of the candidates could list symptoms of phosphorus deficiency in crops.
However, in question 3(d), majority of the candidates were unable to state way in which soil properties such as soil reaction and
soil temperature are important in crop production.

The expected answers include:
            Effects of drought on plant growth and development:   

Delay in flowering/reduction in flowers;

Poor crop development;

Decrease in production of green matter;

Reduction in photosynthesis;

Reduction in yield;


Crop failure;

Lower resistance to diseases.

Ways in which soil reaction is important in crop production

Affects the activities of soil micro organisms;

Affects the availability of certain soil nutrients;

Affects the solubility of certain elements which may be toxic to crops at higher concentration;

It determines the type of crop to grow.

Ways in which soil temperature is important in crop production

Affects the decomposition of soil organic matter;  

Influences the rate of seed germination;

Influences the rate of photosynthesis;         

Affects the distribution of crops;

Influences root development.

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