1. What is seed dormancy?
- A) The period when the seed germinates rapidly.
- B) A condition where seeds are unable to germinate under favorable conditions.
- C) A phase when seeds grow without any external stimuli.
- D) A process where seeds die before germination.
Answer: B) A condition where seeds are unable to germinate under favorable conditions.
Explanation: Seed dormancy is a natural mechanism that prevents seeds from germinating even under suitable environmental conditions, ensuring they only germinate when conditions are optimal.
2. Which of the following is NOT a cause of seed dormancy?
- A) Physical barriers
- B) Chemical inhibitors
- C) Temperature extremes
- D) Lack of light
Answer: D) Lack of light
Explanation: While physical barriers, chemical inhibitors, and temperature extremes are known causes of dormancy, lack of light is not a primary cause. Some seeds even require light for germination.
3. Which part of the seed is responsible for maintaining dormancy in some species?
- A) Seed coat
- B) Cotyledons
- C) Embryo
- D) Endosperm
Answer: A) Seed coat
Explanation: The seed coat can prevent water or gas exchange, keeping the seed in a dormant state. In some species, it may be impermeable to water or inhibit the action of enzymes that trigger germination.
4. What is the main function of seed dormancy in plants?
- A) To allow seeds to germinate at the earliest
- B) To synchronize germination with optimal environmental conditions
- C) To promote rapid growth
- D) To increase seed production
Answer: B) To synchronize germination with optimal environmental conditions
Explanation: Seed dormancy ensures that seeds do not germinate until conditions such as temperature, moisture, and light are favorable for survival and growth.
5. Which of the following is a common method used to break seed dormancy?
- A) Adding chemical inhibitors
- B) Cold stratification
- C) Dry storage
- D) High temperatures
Answer: B) Cold stratification
Explanation: Cold stratification is a technique used to break dormancy in seeds that require a period of cold temperatures before they can germinate, mimicking winter conditions.
6. Which plant hormone is associated with the induction of seed dormancy?
- A) Auxin
- B) Cytokinin
- C) Abscisic acid (ABA)
- D) Gibberellin
Answer: C) Abscisic acid (ABA)
Explanation: Abscisic acid (ABA) plays a key role in the induction of seed dormancy by inhibiting germination, while gibberellin promotes it.
7. What is the effect of light on seed dormancy?
- A) Light always induces dormancy
- B) Light has no effect on seed dormancy
- C) Light can break dormancy in some seeds
- D) Light prevents dormancy from occurring
Answer: C) Light can break dormancy in some seeds
Explanation: Some seeds require light to break dormancy and trigger germination, particularly those that grow in environments where light is a signal for favorable growing conditions.
8. In which type of seed dormancy is the seed coat primarily responsible for inhibiting germination?
- A) Physiological dormancy
- B) Morphological dormancy
- C) Physical dormancy
- D) Combined dormancy
Answer: C) Physical dormancy
Explanation: Physical dormancy occurs when the seed coat is impermeable to water or gases, preventing the seed from germinating until it is physically altered or damaged.
9. Which of the following dormancy-breaking methods involves exposing seeds to high temperatures followed by cooling?
- A) Scarification
- B) Stratification
- C) Fire stimulation
- D) Light exposure
Answer: C) Fire stimulation
Explanation: Some seeds require exposure to fire or heat to break dormancy. The high temperatures help break down the seed coat or trigger biochemical changes that promote germination.
10. What is scarification in relation to seed dormancy?
- A) A method to induce dormancy
- B) A method to break physical dormancy by damaging the seed coat
- C) A method to expose seeds to light
- D) A process involving cold treatment
Answer: B) A method to break physical dormancy by damaging the seed coat
Explanation: Scarification is the process of mechanically breaking or softening the seed coat to allow water and gases to enter, facilitating germination.
11. What role do chemicals like gibberellins play in breaking seed dormancy?
- A) They inhibit seed germination.
- B) They promote germination by overcoming dormancy.
- C) They induce physical dormancy.
- D) They prevent the seed from developing an embryo.
Answer: B) They promote germination by overcoming dormancy.
Explanation: Gibberellins are plant hormones that help break seed dormancy by stimulating enzymes that degrade stored food, allowing the embryo to grow.
12. Which environmental factor plays a significant role in breaking seed dormancy in desert plants?
- A) High humidity
- B) Water availability
- C) Soil pH
- D) Increased light exposure
Answer: B) Water availability
Explanation: In desert plants, the availability of water is a key factor that breaks seed dormancy, as seeds are often adapted to wait for rainfall before germinating.
13. What is the term for the required period of cold exposure needed by some seeds to break dormancy?
- A) Vernalization
- B) Scarification
- C) Hydration
- D) Germination induction
Answer: A) Vernalization
Explanation: Vernalization refers to the process by which certain seeds require a cold treatment to break dormancy and initiate germination.
14. What is the term used for seed dormancy caused by a chemical inhibitor in the seed?
- A) Physical dormancy
- B) Dormancy due to physiological inhibitors
- C) Chemical dormancy
- D) Morphological dormancy
Answer: B) Dormancy due to physiological inhibitors
Explanation: In this type of dormancy, chemical inhibitors such as abscisic acid prevent the seed from germinating even under favorable conditions.
15. Which of the following is true about physiological dormancy?
- A) It is caused by a hard seed coat.
- B) It is induced by low temperatures only.
- C) It involves biochemical factors, such as hormonal imbalance.
- D) It requires scarification for breaking dormancy.
Answer: C) It involves biochemical factors, such as hormonal imbalance.
Explanation: Physiological dormancy is typically caused by biochemical factors, including the balance of hormones like abscisic acid and gibberellins, rather than physical barriers.
16. Which of the following is the main characteristic of morphologically dormant seeds?
- A) They lack a developed embryo.
- B) They are impermeable to water.
- C) They require a period of cold temperatures.
- D) They contain chemical inhibitors.
Answer: A) They lack a developed embryo.
Explanation: Morphologically dormant seeds have an underdeveloped embryo, and they require a period of maturation before they can germinate.
17. Which seed dormancy type involves the requirement for both physical and physiological factors to be overcome?
- A) Primary dormancy
- B) Secondary dormancy
- C) Combined dormancy
- D) Resting dormancy
Answer: C) Combined dormancy
Explanation: Combined dormancy involves both physical and physiological factors that prevent seed germination, such as a hard seed coat and chemical inhibitors.
18. Which of the following processes is necessary for seeds with physical dormancy to germinate?
- A) Chemical treatment
- B) Exposure to light
- C) Mechanical or environmental damage to the seed coat
- D) Exposure to cold temperatures
Answer: C) Mechanical or environmental damage to the seed coat
Explanation: Seeds with physical dormancy need the seed coat to be damaged either mechanically or through environmental processes like fire or abrasion to allow germination.
19. Which of the following is NOT an example of a dormancy-breaking mechanism?
- A) Fire exposure
- B) Cold stratification
- C) Scarification
- D) Seed dehydration
Answer: D) Seed dehydration
Explanation: Seed dehydration generally prolongs dormancy rather than breaking it. Techniques like cold stratification and scarification are used to break dormancy.
20. What is the role of enzymes in breaking seed dormancy?
- A) They protect seeds from damage.
- B) They degrade inhibitors and promote germination.
- C) They prevent seed germination by inhibiting metabolic processes.
- D) They help in water absorption during dormancy.
Answer: B) They degrade inhibitors and promote germination.
Explanation: Enzymes help break down chemical inhibitors, like abscisic acid, and promote the biochemical processes necessary for seed germination.
21. Which of the following is commonly used to break seed dormancy in horticulture?
- A) Cutting the seed coat
- B) Exposing seeds to light
- C) Using growth hormones
- D) Providing artificial rainfall
Answer: A) Cutting the seed coat
Explanation: Cutting the seed coat, a form of scarification, is often used in horticulture to break physical dormancy in seeds, allowing water and gases to enter the seed.
22. Which of the following plants typically requires fire for seed germination?
- A) Sunflowers
- B) Pine trees
- C) Apple trees
- D) Mango trees
Answer: B) Pine trees
Explanation: Certain species of pine trees require exposure to fire to break their seed dormancy, as heat can open their cones and release the seeds.
23. Which method of dormancy breaking is most suitable for seeds that need exposure to cold?
- A) Hydration
- B) Cold stratification
- C) Fire exposure
- D) Mechanical scarification
Answer: B) Cold stratification
Explanation: Cold stratification involves exposing seeds to cold temperatures for a period to break dormancy, commonly used for seeds that naturally experience winter.
24. Which of the following is a consequence of seed dormancy?
- A) Increased seed germination rates
- B) Protection from unfavorable conditions
- C) Reduced seed longevity
- D) Enhanced seed coat permeability
Answer: B) Protection from unfavorable conditions
Explanation: Dormancy protects seeds from germinating during unfavorable conditions, ensuring they only sprout when the environment is optimal for survival.
25. Which group of plants often experiences morphological dormancy?
- A) Grasses
- B) Conifers
- C) Annuals
- D) Perennials
Answer: B) Conifers
Explanation: Conifers, especially pine trees, often experience morphological dormancy, where the embryo is not fully developed and requires time to mature.
26. Which factor can trigger the breaking of seed dormancy in some species?
- A) Increased soil salinity
- B) Elevated temperature
- C) Soil compaction
- D) Extended periods of darkness
Answer: B) Elevated temperature
Explanation: Elevated temperatures, often associated with fire or hot weather, can break dormancy in certain seed species adapted to such environments.
27. Which process involves soaking seeds in water to break dormancy?
- A) Stratification
- B) Scarification
- C) Hydration
- D) Vernalization
Answer: C) Hydration
Explanation: Hydration involves soaking seeds in water to soften the seed coat and trigger biochemical processes that break dormancy.
28. Which environmental factor influences the breaking of dormancy in desert plants?
- A) Rainfall
- B) High humidity
- C) Low temperature
- D) Excess sunlight
Answer: A) Rainfall
Explanation: Rainfall is a critical factor for desert plants as it triggers the breaking of dormancy, signaling that the conditions are right for germination.
29. Which hormone’s activity increases to break seed dormancy?
- A) Cytokinin
- B) Abscisic acid (ABA)
- C) Gibberellin
- D) Ethylene
Answer: C) Gibberellin
Explanation: Gibberellin promotes the breakdown of seed dormancy by stimulating enzymes that degrade stored reserves, facilitating the growth of the embryo.
30. Which of the following is a key characteristic of secondary dormancy?
- A) Dormancy that develops after seeds have been exposed to suitable conditions.
- B) A dormant phase that occurs in seeds under prolonged cold exposure.
- C) Dormancy that happens when seeds are subjected to unfavorable conditions during germination.
- D) Dormancy that results from an undeveloped embryo.
Answer: C) Dormancy that happens when seeds are subjected to unfavorable conditions during germination.
Explanation: Secondary dormancy occurs when seeds that initially had the potential to germinate fail to do so due to unfavorable environmental conditions.
