Photosynthesis and respiration exam questions

Question 1

The net productivity of the plants in the field was higher in August than in July (despite lower temp). Use (net prod=gross prod+respiratory losses) and your knowledge of photosynthesis and respiration to suggest
why. (2)

Answer 1

1. Respiration slower /less respiration;
2. Light-dependent reaction/photosynthesis less affected by
   temperature increase;
3. Lower (energy) loss;

Question 2

Large areas of tropical forest are still found on some Caribbean islands. The
concentration of carbon dioxide in the air of these forests changes over a period of
24 hours and at different heights above ground.
Use your knowledge of photosynthesis and respiration to describe and explain how the
concentration of carbon dioxide in the air changes:
 over a period of 24 hours
 at different heights above ground.

Answer 2

1. High concentration of/increase in
carbon dioxide linked with
respiration at night/in darkness;
2. No photosynthesis in dark/night /
photosynthesis only in light/day;
3. In light net uptake of carbon dioxide
/ use more carbon dioxide than
produced / (rate of) photosynthesis
greater than rate of respiration;
4. Decrease in carbon dioxide
concentration with height;
5. (At ground level)
less photosynthesis / less
photosynthesising tissue / more
respiration / more micro-organisms /
/ micro-organisms produce carbon
dioxide;

Question 3

Plants produce ATP in their chloroplasts during photosynthesis. They also produce ATP during respiration. Explain why it is important for plants to produce ATP during respiration in addition to during photosynthesis. (5)

Answer 3

1. In the dark no ATP
production in
photosynthesis;
2. Some tissues unable to
photosynthesise/produce
ATP;
3. ATP cannot be moved from
cell to cell/stored;
4. Plant uses more ATP than
produced in photosynthesis;
5. ATP for active transport;
6. ATP for synthesis (of named
substance);