160 SOUTH AFRICAN BOTANY 
3. What conditions are essential in order that a green plant 
may form starch? Give an account of the experimental evi- 
dence on which your answer is based. 
4. Explain how you would proceed to make a water-culture. 
Indicate the effect on a plant of the omission of salts contain- 
ing Iron and Nitrogen respectively. 
5. Describe some experiment by which you could measure 
the rate of transpiration. 
6. What is respiration? How would you show that it takes 
place in germinating seeds? How must your experiment be 
modified if green leaves are used instead of seeds, and why ? 
7. What is meant by “ nitrification” ? What is its import- 
ance in plant life and under what conditions does it occur ? 
8. What is heliotropism? Give an account of any experi- 
ments you have performed to investigate the nature of the 
heliotropic phenomena in stems and roots. 
9. For what different purposes do you consider that a plant 
requires to be supplied with water? How are some plants 
able to withstand long-continued drought uninjured? Give 
examples. 
10. Name several different species of plants that you have 
found growing by the sea-side, and not inland. State exactly 
where and how each was growing, and mention any characters 
possessed by each that you think fitted it to its particular 
circumstances. 
11. Write a list of plants you have found growing with their 
leaves submerged in water. How do such plants obtain the 
gases they require for respiration and photo-synthesis ? Com- 
pare the structure of their leaves with that of the leaf of a land 
plant. 
12. Give a short account of the conditions of growth and 
the nature of the vegetation in one of the following :— 
(a) A wood ; 
(b) A kopje ; 
(c) A marsh ; 
(d) A wide stretch of open veldt. 
13. What is a parasite? Give examples. How is a parasite 
distinguished from (a) an epiphyte, (6) a saprophyte ? 
14. Explain, in detail, how you would test for the presence 
