UNIT NO.2
Reproduction in Plants
(Solved Exercise)
2.1 Encircle the correct option.
2.2 Differentiate between
1.Sexual Reproduction and Asexual Reproduction
Sexual Reproduction
In sexual reproduction, male and female gametes fuse to produce a new organism.
Asexual Reproduction
In asexual reproduction, there is no fusion of male and female gametes.
2. Self pollination and cross pollination
Self pollination
Transfer of pollen grains from the anther of a flower to the stigma of the same flower (A) or to the stigma of another flower on the same plant (B) is called self-pollination. It takes place in pea, cotton and tomato, etc.
Cross Pollination
Transfer of pollen grains from the anther of a flower to the stigma of the flower on another plant of the same species is called cross-pollination. It takes place in maize, papaya and rose, etc.
3. Pollen grain and ovule
Pollen grain
Pollen grain are male reproductive structure which have sperms produced by flowering plants.
Ovule
An ovule is the female reproductive structure in plants that develops into a seed after fertilization.
4. Fertilization and double fertilization
Fertilization
One of the two sperms fuses with the egg and forms zygote. This process is called fertilization.
Double Fertilization
The other sperm fuses with two polar nuclei in the ovule to form a triploid endosperm. This is called double fertilization.
5. Budding and grafting
Budding
Budding is a form of asexual reproduction in plants where a small bud or a part of a plant is used to create a new plant.
Grafting
Grafting is a technique of asexual reproduction used to join the cut piece from a plant with some other plant in such a way that both appear to be grown as a single plant.
6. Scion and stock
Scion
Scion is a cut piece of a plant or bud used for grafting onto another plant.
Stock
The plant to which scion is attached for grafting is called stock.
2.3 Give the short answers.
1. Name three self-pollinated plants.
i. Pea ii. Cotton iii. Tomato
2. Name three cross-pollinated plants.
i. Maize ii. Papaya iii. Rose
3. Name the underground stem that undergo natural vegetative propagation.
i. Bulb ii. Tuber iii. Runners
4. What are runners?
In some plants such as strawberry and grasses, stem are spread horizontally above the ground. These stems are called runners.
5. Name different parts of the carpal (female reproductive structure).
i. Stigma ii. Style iii. Ovary
2.4 Constructed Response Question
1. Sexual reproduction in plants involves production and fusion of male and female gametes.
(a) What are gametes?
Gametes are specialized reproductive cells (sperm and egg) that fuse during sexual reproduction to form a zygote.
(b) Where are gametes are produced in plant body?
Gametes are produced in the reproductive organs of a plant, such as the anthers and ovules.
(c) How do male and female gametes approach each other for fusion?
Male and female gametes approach each other for fusion through pollination.
(d) Why do male and female gametes fuse with each other?
Male and female gametes fuse with each other to form a zygote for reproduction of a plant.
2. A flower can produced millions of pollen grains and less number of ovules. Why do you think it happen so?
The production of millions of pollen grains and fewer ovules in a flower is due to the greater dispersal advantage provided by pollen, which increases the chances of successful pollination and fertilization for the plant species.
3. What do you think is the most effective way of plants reproduction?
The most effective way of plant reproduction is through sexual reproduction, which allows for genetic diversity and adaptation to changing environments.
4. Describe the advantages of artificial vegetative propagation in plants.
Answer:
Following are the advantages of artificial vegetative propagation in plants.
- Produce better varieties of fruit and vegetables.
- Grow required food producing plants again and again.
- Produce seedless fruits, e.g., oranges, grapes, bananas, etc.
- Combine good characteristics of two different varieties in a new plant.
5. Write a brief note on each of the following.
(a) Cutting (b) Layering (c)Grafting (d) Budding
Answer:
(a) Cutting
In this process, a part of the plant such as stem having buds on it is cut and planted in the soil. After some days, buds on the underground part of the cutting grow into roots and the buds on the areal part of the cutting grow to form stem and leaves. Rose, bougainvillea, sugar cane, etc., are the plants that can be grown using this technique.
(b) Layering
Layering is the process of artificial propagation of plants during which a young branch of the plant is bent to the ground and covered with moist soil. After a few days, roots grow in the soil from the covered part of the branch. The attached stem with the roots is called layer. The branch can now be cut from the parent plant.
(c) Grafting
Grafting is a technique used to join the cut piece from a plant with some other plant in such a way that both appear to be grown as a single plant. The cut piece of the plant is called scion and the plant to which it is attached is called stock. Tissues of both these parts will soon be joined together and grow into new variety of the plant. The stock provides nutrients to the scion.
(d) Budding
Budding is a technique likewise the grafting. In this process, a bud is used as scion. Grafting and budding techniques are successfully used to get new varieties of mangoes and many other woody and nursery plants. The processes need a great deal of skill. Grafting and budding techniques give hardness, drought-tolerance or disease resistance.