Prepare for NEET Biology Photosynthesis in Higher Plants with MCQs & PYQs on NEET.GUIDE. Get free practice, previous year questions, and expert guidance to grasp light and dark reactions.
A researcher is studying a C4 plant under controlled conditions. They suddenly increase the oxygen concentration in the environment while maintaining constant light and CO2 levels. Which of the following is the MOST likely immediate consequence?
A significant decrease in the rate of photosynthesis
A slight increase in photorespiration
A significant increase in the rate of photosynthesis
No change in the rate of photosynthesis or photorespiration
In a hypothetical experiment, a scientist genetically modifies a C4 plant to lack PEP carboxylase. Which of the following would be the MOST likely outcome under normal atmospheric conditions?
The plant would switch to CAM photosynthesis.
The plant would exhibit significantly reduced CO2 fixation and increased photorespiration.
CO2 fixation would remain unchanged, but the plant would require more water.
The plant would grow more efficiently due to reduced energy expenditure in the C4 pathway.
The ratio of oxygen consumed to CO2 released during photorespiration is:
1:1
1:2
2:1
3:1
Which of the following metabolites is transported from mesophyll cells to bundle sheath cells in C4 plants during active photosynthesis?
3-Phosphoglycerate (3-PGA)
Glyceraldehyde 3-phosphate (G3P)
Pyruvate
Malate or aspartate
A plant is exposed to an environment with high CO2 and low O2 concentrations. Which process would be MOST directly and significantly inhibited under these conditions?
Calvin cycle
Photorespiration
Electron transport chain
C4 cycle
Under conditions of high temperature and light intensity, why do C4 plants show higher photosynthetic rates compared to C3 plants?
C4 plants have a higher affinity for CO2 than C3 plants.
C4 plants open their stomata more frequently than C3 plants.
C4 plants can utilize a wider range of light wavelengths compared to C3 plants.
Spatial separation of initial CO2 fixation and the Calvin cycle minimizes photorespiration.
A scientist isolates chloroplasts and provides them with in the dark. After a brief period, the is found predominantly in:
RuBP
3-PGA
Glucose
Triose phosphate
If a plant is exposed to in the dark and then transferred to light, the label will appear first in which of the following carbohydrates?
Starch
Sucrose
Triose phosphates (glyceraldehyde-3-phosphate and dihydroxyacetone phosphate)
Fructose-1,6-bisphosphate
Which enzyme in the Calvin cycle is directly responsible for incorporating CO2 into an organic molecule?
3-phosphoglycerate kinase
Glyceraldehyde 3-phosphate dehydrogenase
RuBisCO
Triose phosphate isomerase
The regeneration phase of the Calvin cycle requires ATP. What is the primary role of ATP in this phase?
Reduction of 3-PGA to G3P
Phosphorylation of intermediates to convert them back to RuBP
Fixation of CO2 to RuBP
Regeneration of NADPH
