Question 21N.2.SL.TZ0.1d
| Date | November 2021 | Marks available | [Maximum mark: 2] | Reference code | 21N.2.SL.TZ0.1d |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Suggest | Question number | d | Adapted from | N/A |
Suggest reasons for the decreases in biomass of autotrophs as temperature rises, despite the increases in photosynthesis.
[2]
biomass of autotrophs decreases as temperature rises because of:
a. more herbivory/grazing/feeding by (zooplankton/heterotrophs);
b. higher populations/numbers/biomass of zooplankton/heterotrophs;
c. more mortality/more decomposition/decay of autotrophs/phytoplankton;
d. respiration (rate higher than photosynthesis rate in autotrophs/phytoplankton);
Enzymes do not denature at the temperatures used in this experiment. Also, the autotrophs are phytoplankton living in seawater so transpiration cannot be the cause of biomass reductions at higher temperatures. The data in previous graphs showed higher biomasses of heterotrophs at higher temperatures and thus greater rates of herbivory were the obvious explanation for reduced autotroph biomass.
