Germination and Seed Dispersal for Class 6 Sainik School Exam Notes Study Material Download Free

Learn about germination and seed dispersal with detailed questions and answers for the All India Sainik Schools Entrance Examination (AISSEE). Understand seed types, dispersal methods, dormancy, and more. Get complete study material at Anand Classes

Germination and Seed Dispersal for All India Sainik Schools Entrance Examination – AISSEE

GERMINATION

Q1. What is germination? Explain its process.

Ans. Germination is the process by which a seed transforms into a seedling under favorable conditions. This process involves several stages:

1. Imbibition – The seed absorbs water, causing it to swell.
2. Activation of Enzymes – Water activates enzymes that convert stored food into energy.
3. Respiration – The seed starts to respire, producing energy for growth.
4. Emergence of Radicle – The root (radicle) grows downward to absorb water and nutrients.
5. Emergence of Plumule – The shoot (plumule) grows upward toward light.
6. Development of Seedling – The cotyledons provide nourishment until leaves develop for photosynthesis.

Q2. What are the essential conditions required for seed germination?

Ans. The three essential conditions required for germination are:

1. Water – Softens the seed coat, activates enzymes, and helps in nutrient transport.
2. Oxygen – Required for aerobic respiration to generate energy.
3. Suitable Temperature – Helps enzymes function effectively, usually between 25°C – 30°C for most seeds.

Q3. What are the different types of germination? Explain with examples.

Ans. There are two types of germination based on how the seedling develops:

1. Epigeal Germination – The cotyledons come above the ground as the hypocotyl elongates.
   • Example: Beans, Castor, Mustard
2. Hypogeal Germination – The cotyledons remain below the ground as the epicotyl elongates.
   • Example: Maize, Peas, Gram

Q4. What is dormancy in seeds? Why do some seeds fail to germinate?

Ans. Dormancy is a condition in which seeds remain inactive despite favorable conditions. Seeds may fail to germinate due to:

• Seed Dormancy – The seed requires special conditions (e.g., exposure to heat, cold, or digestion by animals).
• Lack of Water – Seeds cannot activate enzymes needed for growth.
• Lack of Oxygen – Seeds need oxygen for respiration.
• Extreme Temperatures – Too high or too low temperatures prevent enzyme activity.
• Hard Seed Coat – Some seeds have thick seed coats that prevent water absorption (e.g., Lotus).

Q5. What are the different parts of a seed? Explain their functions.

Ans. A seed consists of the following parts:

1. Seed Coat – Protects the seed from damage and infections.
2. Cotyledons – Store food for the growing seedling.
3. Radicle – Develops into the root system.
4. Plumule – Develops into the shoot system.
5. Embryo – The young plant inside the seed.

SEED DISPERSAL

Q6. What is seed dispersal? Why is it important?

Ans. Seed dispersal is the process by which seeds are spread away from the parent plant. It is important because:

• Reduces Competition – Prevents overcrowding and ensures better access to sunlight, nutrients, and water.
• Prevents Diseases – Limits the spread of infections among plants.
• Helps in Colonization – Seeds reach new locations and grow in diverse environments.

Q7. What are the different methods of seed dispersal? Give examples.

Ans. Seeds are dispersed by various natural agents:

1. Dispersal by Wind (Anemochory)

• Seeds are light and have wings or feathery structures to float in the air.
• Examples: Cotton, Dandelion, Maple, Drumstick.

2. Dispersal by Water (Hydrochory)

• Seeds have a waterproof covering and air spaces that help them float.
• Examples: Coconut, Water Lily, Lotus.

3. Dispersal by Animals (Zoochory)

• Seeds have hooks, spikes, or are enclosed in sweet fruit eaten by animals.
• Examples: Mango, Guava, Burdock, Xanthium.

4. Dispersal by Explosion/Self-Dispersal (Autochory)

• Some fruits burst open, scattering seeds by force.
• Examples: Pea, Balsam, Castor.

Q8. How does coconut seed disperse through water?

Ans. The coconut has a fibrous husk and air cavities, making it buoyant. It floats on water and reaches distant shores, where it germinates.

Q9. How do animals help in seed dispersal?

Ans. Animals help in dispersing seeds in different ways:

• By Eating Fruits – Birds and animals eat fruits and later excrete the seeds (e.g., Mango, Apple).
• By Carrying Seeds – Some seeds stick to animal fur and are carried to other locations (e.g., Burdock, Xanthium).

Q10. What is the difference between wind dispersal and animal dispersal?

Do You Know?

• Coconut can travel thousands of kilometers across oceans before germinating.
• Squirrels unknowingly help in seed dispersal by burying nuts, which later grow into trees.
• Some seeds, like Lotus, can remain dormant for hundreds of years and still germinate.
• Balsam and Pea plants use a special bursting mechanism to scatter their seeds forcefully.

Germination – Advanced Questions

Q11. What is the difference between monocot and dicot seed germination?

Q12. What is the role of enzymes in seed germination?

Ans. Enzymes help in breaking down stored food into simpler substances that provide energy for the seedling to grow. Examples include:

• Amylase – Converts starch into sugar.
• Protease – Breaks down proteins into amino acids.
• Lipase – Converts fats into fatty acids and glycerol.

Q13. What are the advantages of seed dormancy?

Ans. Seed dormancy provides the following benefits:

1. Survival in Unfavorable Conditions – Prevents germination during extreme cold, drought, or unsuitable seasons.
2. Dispersal Over Time – Seeds can remain dormant for years and germinate when conditions are ideal.
3. Prevention of Overcrowding – Ensures that all seeds do not germinate at the same time, allowing better survival chances.

Q14. How can dormancy be broken in seeds?

Ans. Dormancy in seeds can be broken by:

• Scarification – Scratching or weakening the seed coat using sandpaper or acids.
• Stratification – Exposing seeds to cold temperatures to trigger germination.
• Light Exposure – Some seeds require light to germinate (e.g., Lettuce).
• Water Treatment – Soaking seeds in warm water to soften the seed coat.

Q15. Why do seeds need oxygen for germination?

Ans. Oxygen is required for aerobic respiration, which produces energy (ATP) needed for the growth of the embryo. Without oxygen, the seed cannot generate enough energy to sprout.

Seed Dispersal – Advanced Questions

Q16. How does wind dispersal help in plant survival?

Ans. Wind dispersal:

• Helps plants grow in new areas where they have less competition.
• Allows seeds to reach long distances, increasing plant diversity.
• Prevents overcrowding near the parent plant.

Q17. What are some adaptations in seeds for dispersal by wind?

Ans. Seeds dispersed by wind have:

• Feathery Structures – Dandelion seeds have parachute-like pappus.
• Winged Seeds – Maple and Drumstick seeds have wings for gliding.
• Lightweight Bodies – Grass seeds are tiny and easily carried by air.

Q18. How does water dispersal benefit plants growing near rivers and seas?

Ans. Water dispersal allows seeds to:

• Travel over long distances without damage.
• Germinate in wet and coastal environments.
• Avoid competition by reaching new islands and shores.

Q19. How do birds and animals contribute to seed dispersal?

Ans. Birds and animals help in seed dispersal by:

1. Eating Fruits – Seeds pass through digestion unharmed and are excreted far from the parent plant.
2. Carrying Seeds in Fur – Hooks and spines attach to fur and drop off later.
3. Storing Nuts and Fruits – Animals like squirrels bury seeds, some of which grow into new plants.

Q20. What are some examples of plants that use self-dispersal (explosive mechanism)?

Ans. Some plants have seed pods that dry up and burst open, scattering seeds. Examples include:

• Balsam
• Pea
• Castor

More Conceptual Questions

Q21. Why do some seeds float on water while others sink?

Ans. Seeds that float have:

• Air spaces (like Lotus and Coconut).
• Lightweight, waterproof coverings (like Water Lily).

Seeds that sink are denser and lack air spaces.

Q22. How does gravity influence seed dispersal?

Ans. Heavy seeds like coconuts and chestnuts fall directly under the parent plant. These seeds often roll or are carried away by animals.

Q23. Why do some plants produce a large number of seeds?

Ans. Producing many seeds increases the chances of survival, as not all seeds will:

• Germinate successfully.
• Escape being eaten by animals.
• Land in a suitable growing location.

Q24. How do desert plants ensure seed dispersal and germination?

Ans. Desert plants like Cacti and Mesquite produce seeds that:

• Stay dormant until rain arrives.
• Are dispersed by wind or animals to spread in dry areas.

Q25. How do farmers use knowledge of seed germination for better crop production?

Ans. Farmers:

• Select high-quality seeds that germinate quickly.
• Use water and fertilizers to improve germination.
• Break seed dormancy using methods like soaking in warm water.

Do You Know?

• Some seeds require fire to germinate! (e.g., Pine and Eucalyptus).
• Squirrels unknowingly plant trees when they forget buried nuts.
• Orchid seeds are so tiny that they rely on fungi for nutrients to germinate.
• A single dandelion plant can produce over 2000 seeds!

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