31
If a green plant is kept in dark with proper ventilation, can this plant carry out photosynthesis? Can anything be given as supplement to maintain its growth or survival?
Explanation
The plant in given conditions can not carry out photosynthesis. Light is must for any green plant to make its own food.
The plant should be watered properly for its survival.
32
Photosynthetic organisms occur at different depths in the ocean. Do they receive qualitatively and quantitatively the same light? How do they adapt to carry out photosynthesis under these conditions.
Explanation
Plant present at various depth in ocean are mostly algae. These show great variations in its photosynthetic pigments. These can absorb different wave lengths of light and performs photosynthesis.
Green algae-chlorophyll-a, (absorbs red) and b(absorbs blue violet).
Brown algae-chlorophyll-a, c and fucoxanthin (absorbrs yollow).
Rhodophyceae-chlorophyll-a, $d$ and phycoerythrin.
33
In tropical rain forests, the canopy is thick and shorter plants growing below it, receive filtered light. How are they able to carry out photosynthesis?
Explanation
The plants carry out photosynthesis in presence of light. The quality and intensity of light affect only the rate of photosynthesis. So, plants growing in different canopy will carry out photosynthesis, but rate could be different depending upon the intensity and quantity of light received.
34
What conditions enable RuBisCO to function as an oxygenase? Explain the ensuing process.
Explanation
RuBisCo is an enzyme which has dual nature. It acts as carboxylase, when $\mathrm{CO}_2$ concentration is good enough in atmosphere. But if $\mathrm{O}_2$ concentration increases, its nature changes and it binds with $\mathrm{O}_2$ and acts as oxygenase enzyme, which forces $\mathrm{CO}_2$ to enter $\mathrm{C}_2$ cycle thus leading to photorespiration and loss of $\mathrm{CO}_2$.
35
Why does the rate of photosynthesis decrease at higher temperatures?
Explanation
Photosynthesis is an enzyme specific process. All enzymes act at an otptimum temperature (i.e., $25-35^{\circ} \mathrm{C}$ ). If temperature increases, enzyme get denature, thus leading to fall in the rate of photosynthesis.