Plant physiology MCQ
1. Macronutrients are essential elements required by plants in large quantities. Which of the following is NOT a macronutrient?
a) Nitrogen
b) Phosphorus
c) Iron
d) Potassium
Answer: c) Iron
Explanation: Iron is considered a micronutrient because it is required by plants in smaller quantities compared to macronutrients.
2. Which pathway is responsible for the movement of water and minerals through the root cortex of a plant?
a) Apoplast pathway
b) Symplast pathway
c) Transmembrane pathway
d) Vacuolar pathway
Answer: a) Apoplast pathway
Explanation: In the apoplast pathway, water and minerals move through the cell walls and intercellular spaces of the root cortex without crossing the plasma membranes.
3. Stomata play a crucial role in transpiration. What causes the opening of stomata?
a) High levels of CO2
b) Low levels of CO2
c) High humidity
d) Low humidity
Answer: b) Low levels of CO2
Explanation: Stomata open in response to low levels of CO2 in the leaf, which occurs during photosynthesis. This allows for the exchange of gases and promotes transpiration.
4. C3, C4, and CAM are three different types of photosynthetic pathways. Among them, which pathway is characterized by the initial fixation of CO2 into a 3-carbon compound?
a) C3 pathway
b) C4 pathway
c) CAM pathway
d) All of the above
Answer: a) C3 pathway
Explanation: In the C3 pathway, the initial fixation of CO2 occurs through the Calvin cycle, resulting in the formation of a 3-carbon compound (3-phosphoglycerate).
5. Photorespiration is a process that occurs in plants under certain conditions. What is the primary function of photorespiration?
a) To produce ATP
b) To fix carbon dioxide
c) To conserve water
d) To generate oxygen
Answer: b) To fix carbon dioxide
Explanation: Photorespiration involves the breakdown of organic compounds in the presence of light and the release of carbon dioxide. It is considered a wasteful process because it counteracts the carbon-fixing reactions of photosynthesis.
6. Which of the following factors does NOT affect the rate of photosynthesis?
a) Light intensity
b) Temperature
c) Humidity
d) Carbon dioxide concentration
Answer: c) Humidity
Explanation: While humidity can influence stomatal opening and water loss through transpiration, it does not directly affect the rate of photosynthesis.
7. Respiration is an essential metabolic process in plants. What is the net production of ATP molecules through glycolysis?
a) 2 ATP
b) 4 ATP
c) 6 ATP
d) 8 ATP
Answer: a) 2 ATP
Explanation: Glycolysis, the initial step of respiration, produces a net gain of 2 ATP molecules.
8. Nitrogen fixation is the process by which atmospheric nitrogen is converted into a usable form by plants. Which organisms are primarily responsible for biological nitrogen fixation?
a) Bacteria
b) Fungi
c) Algae
d) Viruses
Answer: a) Bacteria
Explanation: Certain types of bacteria, known as nitrogen-fixing bacteria
, have the ability to convert atmospheric nitrogen into forms that can be assimilated by plants.
9. Photoperiodism is a phenomenon related to plant growth and development. What does photoperiodism refer to?
a) Response of plants to light intensity
b) Response of plants to day length
c) Response of plants to temperature
d) Response of plants to humidity
Answer: b) Response of plants to day length
Explanation: Photoperiodism refers to the physiological responses of plants to the duration of light and dark periods in a 24-hour cycle.
10. Which plant hormone is primarily responsible for phototropism, the bending of plant parts towards a light source?
a) Auxin
b) Gibberellin
c) Cytokinin
d) Ethylene
Answer: a) Auxin
Explanation: Auxin is the plant hormone that promotes cell elongation and is responsible for phototropism, allowing plants to grow towards a light source.
0 Comments