Apparatus X in Fig. 1.1 is a thin glass container filled with water. Explain the function of apparatus X.
Before the apparatus shown in Fig. 1.1 is fully assembled, sodium hydrogencarbonate is added to the water surrounding the pond plant in the test-tube. Explain why sodium hydrogencarbonate is added to the water surrounding the pond plant in the test-tube.
Name the gas collected in the test-tube.
With reference to Fig. 1.2, describe how the rate of photosynthesis is related to light intensity.
Further investigations showed that at distances of less than $10\,\text{cm}$, the rate of movement of the air bubble was the same as at $10\,\text{cm}$. Explain why there was no change in the rate of movement of the air bubble at distances less than $10\,\text{cm}$.
Some of the light energy taken up by the pond plant is used in cyclic photophosphorylation. Outline the process of cyclic photophosphorylation.