1. Which of the following is a common environmental stress factor for plants?
a) Light intensity
b) Soil salinity
c) Atmospheric pressure
d) All of the above
Answer: b) Soil salinity
2. What is the primary response of plants to drought stress?
a) Stomatal closure
b) Increased transpiration
c) Leaf expansion
d) Fruit production
Answer: a) Stomatal closure
3. Which hormone is most involved in plant responses to water stress?
a) Cytokinins
b) Abscisic acid (ABA)
c) Auxins
d) Gibberellins
Answer: b) Abscisic acid (ABA)
4. Which process helps plants reduce water loss during drought stress?
a) Photoinhibition
b) Guttation
c) Transpiration
d) Stomatal closure
Answer: d) Stomatal closure
5. Which mechanism is crucial for plants to tolerate high salinity levels?
a) Photosynthesis enhancement
b) Accumulation of compatible solutes
c) Dehydration of cells
d) Increased stomatal opening
Answer: b) Accumulation of compatible solutes
6. Which of the following is a plant response to excessive heat stress?
a) Increased transpiration
b) Heat shock proteins synthesis
c) Enhanced photosynthesis
d) Reduced stomatal conductance
Answer: b) Heat shock proteins synthesis
7. What is the role of heat shock proteins (HSPs) in plants?
a) Promoting fruit ripening
b) Protecting proteins from denaturation under heat stress
c) Enhancing water absorption
d) Increasing cell division
Answer: b) Protecting proteins from denaturation under heat stress
8. What effect does cold stress have on plant cells?
a) Increases membrane fluidity
b) Decreases membrane permeability
c) Enhances enzyme activity
d) Increases transpiration rate
Answer: b) Decreases membrane permeability
9. Which of the following compounds is associated with cold stress tolerance in plants?
a) Proline
b) Auxin
c) Ethylene
d) Abscisic acid
Answer: a) Proline
10. What is the function of antifreeze proteins in plants?
a) Reducing freezing point of water
b) Enhancing photosynthesis
c) Protecting plants from dehydration
d) Stimulating cell division
Answer: a) Reducing freezing point of water
11. Which mechanism do plants use to tolerate oxidative stress caused by pollutants?
a) Synthesis of reactive oxygen species
b) Production of antioxidants
c) Increasing transpiration
d) Enhanced stomatal opening
Answer: b) Production of antioxidants
12. How do plants respond to high light intensity (photoinhibition)?
a) Increased chlorophyll production
b) Activation of photoprotective mechanisms
c) Decreased leaf area
d) Enhanced root growth
Answer: b) Activation of photoprotective mechanisms
13. Which of the following is a common response of plants to environmental stress?
a) Growth inhibition
b) Increased root elongation
c) Increased leaf area
d) Enhanced flowering
Answer: a) Growth inhibition
14. Which molecule accumulates in plants under salt stress and helps maintain cell turgor?
a) Glucose
b) Potassium
c) Sodium
d) Inorganic ions and organic solutes (e.g., proline)
Answer: d) Inorganic ions and organic solutes (e.g., proline)
15. Which of the following is responsible for triggering the stress response in plants under drought conditions?
a) High oxygen levels
b) Increased transpiration rates
c) Low levels of abscisic acid
d) High levels of abscisic acid
Answer: d) High levels of abscisic acid
16. What happens when a plant experiences osmotic stress due to salinity?
a) The plant increases water absorption
b) The plant experiences water loss
c) Stomatal closure increases
d) Photosynthesis rate increases
Answer: b) The plant experiences water loss
17. Which enzyme is responsible for scavenging reactive oxygen species during stress?
a) Superoxide dismutase
b) Amylase
c) Ligase
d) DNA polymerase
Answer: a) Superoxide dismutase
18. What is the role of abscisic acid in drought stress?
a) Promotes cell division
b) Stimulates stomatal closure
c) Increases nutrient uptake
d) Enhances chlorophyll synthesis
Answer: b) Stimulates stomatal closure
19. Which of the following is an adaptation to water stress in plants?
a) Reduction in root growth
b) Decrease in leaf size
c) Stomatal opening during the day
d) Increased photosynthetic rate
Answer: b) Decrease in leaf size
20. In response to salt stress, which organelle plays a major role in detoxification?
a) Nucleus
b) Mitochondria
c) Vacuole
d) Endoplasmic reticulum
Answer: c) Vacuole
21. What is the main strategy for plants to survive extreme drought conditions?
a) Increased transpiration
b) Production of drought-resistant seeds
c) Altering leaf structure to reduce transpiration
d) Increased chlorophyll content
Answer: c) Altering leaf structure to reduce transpiration
22. What are phytohormones that are involved in stress tolerance in plants?
a) Gibberellins and cytokinins
b) Auxins and ethylene
c) Abscisic acid and cytokinins
d) Abscisic acid and auxins
Answer: d) Abscisic acid and auxins
23. Which protein plays a critical role in plant response to heat stress?
a) Rubisco
b) Heat shock proteins
c) Actin
d) Ligase proteins
Answer: b) Heat shock proteins
24. Which of the following can increase a plant’s ability to tolerate high salt conditions?
a) Developing salt glands to excrete excess salt
b) Increasing stomatal density
c) Increasing transpiration
d) Reducing root growth
Answer: a) Developing salt glands to excrete excess salt
25. How do plants cope with high light intensity stress?
a) By producing more antioxidants
b) By increasing leaf size
c) By producing more chlorophyll
d) By activating photoprotective mechanisms
Answer: d) By activating photoprotective mechanisms
26. Which of the following is the most likely mechanism for cold stress tolerance in plants?
a) Increased root depth
b) Accumulation of sugars and other cryoprotectants
c) Increased stomatal opening
d) Decreased leaf surface area
Answer: b) Accumulation of sugars and other cryoprotectants
27. In which part of the plant does the response to water stress primarily occur?
a) Roots
b) Stem
c) Leaves
d) Flowers
Answer: c) Leaves
28. Which physiological process is crucial in a plant’s response to high temperature stress?
a) Increased transpiration rate
b) Heat shock protein synthesis
c) Stomatal opening
d) Root elongation
Answer: b) Heat shock protein synthesis
29. What is the role of the plant’s vacuole in response to salt stress?
a) Accumulation of salt
b) Storing sugars
c) Photosynthesis
d) Reducing water absorption
Answer: a) Accumulation of salt
30. What does an increase in ABA levels in plants generally indicate?
a) High water availability
b) Low temperature
c) Water stress
d) Excess sunlight
Answer: c) Water stress
