Question:
The annual cycle of photosynthesis mainly follows
the changes in CO2 concentration.
the changes in air temperature.
the changes in light.
the changes in soil temperature.
Response:
The effect of light on photosynthesis has a clear saturating pattern: more light results in more photosynthesis but eventually leaves cannot take full advantage of all the extra light.
What is the source of carbon that is assimilated in photosynthesis?
Atmospheric CO2
Soil water
Soil nutrients
Solar radiation
In general, the more carbon dioxide that is available to the plant, the faster the rate of photosynthesis - if other factors are favourable.
De-hardening in spring involves gradual re-hydration of the cells, recovery of photosynthetic capacity and a tight control of water loss.
Carbon becomes locked as part of the accumulating plant biomass as plants grow.
Leaf area increases with stand age, resulting in a decreasing rate of photosynthesis in the stand.
An increment in leaf area increases also the photosynthesis of a tree stand. However, the relationship is saturating.
Transpiration decreases as air becomes drier.
Plant respiration captures CO2.
Unlike photosynhesis, plant respiration captures atmospheric oxygen and releases carbon dioxide.
To transform atmospheric CO2 into organic molecules, plants can use the energy from
soil heat.
sun light.
atmospheric oxygen.
soil nutrients.
At low air humidity, a plant closes its stomata to prevent transpiration. The action also decreases photosynthesis
In some part of the stems, some photosynthesis may also occur.
As plants respire, they release
oxygen.
carbon dioxide.
High soil moisture leads to decreased photosynthesis.
In boreal upland forests, low soil moisture decreases the rate of photosynthesis.
Plants open its stomata to avoid losing too much water.
Plant closes its stomata to avoid losing too much water.
