Biology Dormancy and Types Quiz

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Questions and Answers

What is the primary purpose of dormancy in seeds?

To conserve energy. (correct)

To accelerate germination.

To enhance growth.

To increase metabolic activity.

What causes seed coat dormancy?

Chemical substances within the seed.

Hard and impermeable seed coats. (correct)

Soft seed coats allowing embryo expansion.

Incomplete fruit maturation.

Which method is NOT used to overcome seed dormancy?

Cold stratification.

Increased sunlight exposure. (correct)

Acid treatment.

Mechanical scarification.

What characterizes dormancy due to rudimentary embryos?

Embryos require additional time to mature after harvest. Signup and view all the answers

Which type of dormancy involves both seed coat dormancy and embryo dormancy?

Double dormancy. Signup and view all the answers

What is a common characteristic of seeds experiencing dormancy due to chemical inhibitors?

They are inhibited by specific chemicals. Signup and view all the answers

What effect does cold stratification have on seeds?

It helps to break dormancy in certain seeds. Signup and view all the answers

Which example signifies dormancy due to internal factors?

Freshly harvested seeds of apple. Signup and view all the answers

What is the purpose of soaking seeds in hot water followed by cold water?

To soften the seed coat and wash off inhibitors Signup and view all the answers

What does cold stratification involve for seed germination?

Moist medium exposure at slightly above freezing temperatures Signup and view all the answers

Which of the following is used to stimulate seed germination through chemical treatment?

Potassium nitrate Signup and view all the answers

What is the expected duration for cold stratification of seeds?

1 to 4 months Signup and view all the answers

During the acid treatment process, how long are seeds typically soaked in concentrated acid?

15 to 60 seconds Signup and view all the answers

What role does dry storage play in seed germination?

Encourages after ripening for dormant seeds Signup and view all the answers

Which hormones are known to increase during the cold stratification process?

Gibberellins and cytokinins Signup and view all the answers

What type of seeds may need to undergo dry storage for successful germination?

Freshly harvested annuals and herbaceous plants Signup and view all the answers

Study Notes

Dormancy

Dormancy is a period of suspended growth, development and activity in an organism's life cycle.
Dormancy helps organisms conserve energy.
A dormant seed is not a failure.
Dormancy can be caused by seed characteristics or by surrounding conditions.

Dormancy Types

Seed coat dormancy: Seed coats are hard and impermeable to oxygen and soil, preventing germination. Examples include Malvaceae.
Rudimentary Embryo dormancy: Embryos are not fully mature when seeds are released, requiring additional time to develop. Examples include Pinus sp. and palms.
Chemical inhibitor dormancy: Seeds contain chemical substances that inhibit germination, but these are often removed by leaching or water adsorption.
Internal factor dormancy: Embryos are physiologically dormant, meaning they don't grow even when environmental conditions are suitable. They require specific conditions for germination, such as moist chilling treatment. Examples include freshly harvested seeds of apple, grape, peach, and apricot.
Double dormancy: Seeds exhibit both seed coat and embryo dormancy. Examples include Cercis occidentals.

Dormancy Breaking Techniques

Mechanical scarification: Scarification involves breaking or scratching a seed's hard coat to allow for germination.
Soaking in water: Seeds are soaked in water, often hot then cold, to soften the seed coat and remove inhibitors.
Acid treatment: Soaking seeds in concentrated hydrochloric or sulfuric acid can modify the seed coat and aid germination.
Cold stratification: Seeds undergo cold treatment in moist conditions to facilitate physiological changes within the embryo, leading to germination. This typically involves placing seeds in moist mediums like sand, peat, or vermiculite, and holding them at temperatures slightly above freezing for varying periods, often 1 to 4 months.
Dry storage: Dry storage is used to promote after-ripening in seeds. Freshly harvested seeds often need a period of dry storage before they germinate.
Chemical treatment: Chemicals like potassium nitrate, gibberellic acid, or thiourea can be used to stimulate the germination of different seed types.

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Description

Test your knowledge on the concept of dormancy in biology, including its significance and various types. This quiz will cover seed coat dormancy, rudimentary embryo dormancy, chemical inhibitor dormancy, and internal factor dormancy. Challenge yourself to understand how these dormancies affect germination and plant life cycles.