Assertion (A): | Current availability of CO2 levels is limiting to the C3 plants. |
Reason (R): | Carbon dioxide is the major limiting factor for photosynthesis. |
1. | (A) is True but (R) is False |
2. | Both (A) and (R) are True and (R) explains (A) |
3. | Both (A) and (R) are True but (R) does not explain (A) |
4. | (A) is False but (R) is True |
I: | Water stress causes the stomata to close, hence reducing the CO2 availability. |
II: | Water stress also makes leaves wilt, thus, increasing the surface area of the leaves and their metabolic activity as well. |
Assertion (A): | Plants that do not use PEP-carboxylase in carbon fixation are called C3 plants. |
Reason (R): | The primary carboxylation reaction in C3 plants, catalyzed by RuBisCO, produces the three-carbon 3-phosphoglyceric acids directly in the Calvin-Benson cycle. |
1. | (A) is True but (R) is False |
2. | Both (A) and (R) are True and (R) explains (A) |
3. | Both (A) and (R) are True but (R) does not explain (A) |
4. | (A) is False but (R) is True |
I: | Only green plants can prepare their own food. |
II: | In green plants, all cells, tissues and organs photosynthesise. |
1. | Only I |
2. | Only II |
3. | Both I and II |
4. | Neither I nor II |
A. | In C‐3 plants some Oxygen binds to RuBisCO |
B. | A specialized kind of leaf anatomy (Kranz Anatomy) is seen in plants exhibiting Photorespiration |
C. | Involves the activities of chloroplast, mitochondria and peroxisomes |
D. | It was traced by the work of Calvin and his co‐workers |
List I Enzyme |
List II | ||
A. | RuBISco | I. | Reduces molecular oxygen to form water |
B. | PEPCase | II. | Catalyzes the phosphorylation of glucose |
C. | Cytochrome C oxidase | III. | beta‐carboxylation of phosphoenolpyruvate |
D. | Hexokinase | IV. | Captures atmospheric CO2 |
Assertion (A): | Except for plants in shade or in dense forests, light is rarely a limiting factor for photosynthesis in nature. |
Reason (R): | Increase in incident light beyond a point causes the breakdown of chlorophyll and a decrease in photosynthesis. |
1. | (A) is True but (R) is False |
2. | Both (A) and (R) are True and (R) explains (A) |
3. | Both (A) and (R) are True but (R) does not explain (A) |
4. | (A) is False but (R) is True |
I: | is the most abundant enzyme in the world |
II: | is characterised by the fact that its active site can bind to both CO2 and O2 |
III: | has a much greater affinity for CO2 when the CO2: O2 is nearly equal |