The light dependent stage of photosynthesis includes cyclic and non-cyclic photophosphorylation. Describe two differences between cyclic and non-cyclic photophosphorylation.
Biochemical reactions involving carbon dioxide alter the external surroundings of the aquatic plant, $Elodea\ canadensis$, and the pond snail, $Lymnaea\ stagnalis$. Carbon dioxide dissolves in water and produces carbonic acid. A student prepared 8 test-tubes. Each test-tube contained $30\ \text{cm}^3$ of distilled water with a pH indicator, bromothymol blue. Fig. 5.1 shows the arrangement of these 8 test-tubes. The test-tubes were left for 12 hours.
Explain the role of test-tube 1 and test-tube 5.
Explain why test-tube 1 and test-tube 5 were included.
Explain the outcomes of test-tubes 2, 3 and 4.
Explain the change in colour in test-tube 6.