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
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.
In C4 plants, the initial fixation of CO2 occurs in mesophyll cells, forming a 4-carbon compound. This compound then travels to bundle sheath cells, where it releases CO2. What is the PRIMARY advantage of this spatial separation of CO2 fixation and the Calvin cycle?
Increases the efficiency of light absorption
Minimizes photorespiration by increasing CO2 concentration around RuBisCO
Reduces the need for water
Allows the plant to fix CO2 at night
A C4 plant and a CAM plant are grown under identical environmental conditions. Which statement BEST describes their relative water use efficiency (WUE) and photosynthetic rates under prolonged high light intensity and high temperature?
The C4 plant will have both higher WUE and a higher photosynthetic rate than the CAM plant.
The CAM plant will have higher WUE than the C4 plant, but the C4 plant will have a higher photosynthetic rate.
The C4 plant will have higher WUE than the CAM plant, but the CAM plant will have a higher photosynthetic rate.
The CAM plant will have both higher WUE and a higher photosynthetic rate than the C4 plant.
Under conditions of high light intensity and limited CO2 availability, which process is most likely to be favored in chloroplasts?
Enhanced Calvin cycle activity
Increased non-cyclic photophosphorylation
Photorespiration
Increased synthesis of chlorophyll
Photorespiration is initiated by the enzyme RuBisCO's ability to also bind:
O2
CO2
N2
H2O
The primary benefit of the C4 pathway is:
Minimizing photorespiration
Increasing water use efficiency
Enhancing light absorption
Reducing the need for RuBisCO
