Textbook Questions and Answers
Keywords:
- Cotyledon: Baby leaves present inside a seed.
- Germination: To grow into a young plant under favorable conditions.
- Pod: A long, narrow seedcase containing peas or beans.
- Grafting: Joining a part of one plant to a part of another plant.
- Layering: Making a part of a stem grow roots by covering it with soil.
- Ornamental plants: Decorative plants.
Q.1] Assertion and Reasoning Questions
1. Assertion (A): Coconut and lotus seeds float on water.
Reasoning (R): Their seeds are heavy and sink quickly.
Ans: (c) A is true, but R is false.
2. Assertion (A): Plants do not need animals for seed dispersal.
Reasoning (R): Animals carry seeds to new places by eating fruit or sticking seeds to their fur.
Ans: (d) A is false, but R is true.
Q.2) Answer the following questions:
1. What is meant by the dispersal of seeds?
Ans: Dispersal of seeds is the process by which seeds are scattered to distant places by agents of dispersal such as wind, water, animals, and human beings.
2. You found a coconut floating in a river. Which method of seed dispersal does it show? Explain.
Ans: It shows dispersal by water because the fibrous or spongy outer covering helps the coconut float and travel to new places.
3. Explain the structure of a seed with the help of a labeled diagram.
Ans: A seed has three main parts:
- i) Seed coat: A hard outer cover that protects the seed.
- ii) Cotyledons (seed leaves): Store food for the baby plant.
- iii) Embryo: Develops into a new plant.(Structure of a seed diagram labeled with: seed coat, embryo, cotyledon)
4. Why is seed dispersal important?
Ans: Seed dispersal is important because:
- i) It prevents overcrowding.
- ii) It reduces competition for sunlight, water, nutrients, and space.
- iii) It helps plants grow in new places.
5. A farmer wants to grow many rose plants in a short time. Which method should he use?
Ans:
- i) The farmer should use stem cuttings.
- ii) Roses grow easily from stem cuttings.
- iii) New plants grow faster this way than from seeds.
6. Explain any three methods of seed dispersal.
Ans:
- i) Dispersal by wind: The seeds are light or have wings or hair for dispersal by wind (e.g., Dandelion seeds).
- ii) Dispersal by humans: Humans eat the fleshy part of the fruit and throw away the seeds.
- iii) Dispersal by explosion: Pods of some plant fruits burst open and scatter the seeds in different directions (e.g., Balsam seeds).
Q.7) How do birds and animals help in seed dispersal?
Ans:
- Birds eat fruits and later drop the seeds through their droppings.
- Some seeds have hooks or spines that stick to the fur of animals.
- Birds and animals throw away fruit seeds in different places, which then grow into new plants.
- Squirrels hide nuts in the ground; forgotten nuts grow into new plants.
- Animals carry seeds to faraway places where new plants grow.
Q.9) Rohan visited a place where many small plants were watered regularly and protected from insects. After a few weeks, those plants were sent for planting.
1. What is the place visited by Rohan called?
Ans: A nursery.
2. Why are young plants kept there before planting?
Ans: To grow healthy under proper care.