Notes For All Chapters Science Class 7
Revision Notes of Ch 8 Reproduction in Plants Class 7th Science
Topics in the chapter
- What is reproduction?
- Mode of reproduction
- Asexual reproduction
- Sexual reproduction
- Pollination
- Fertilization
- Formation of fruits and seed:
- Seed dispersal
What is reproduction?
→ It is a process of production of new individuals from their parents is known as reproduction.
Mode of reproduction:
→ There are two modes of reproduction:
(i) Sexual reproduction
(ii) Asexual reproduction
Sexual reproduction:
• Two parents are involved in this reproduction.
• Fusion of a female and male cells produced gametes.
• Parents and offspring are non-identical
• Variation is present in the same species.
Asexual reproduction:
→ There is no need for production of seed to obtain new plant.
→ Single parents is involved in asexual reproduction.
→ There is no gametes produced.
→ The parent and offspring are identical.
Different types of Asexual Reproduction:
(i) Vegetative reproduction
(ii) Budding
(iii) Fragmentation
(iv) Spore formation
Vegetative reproduction
→ New plants are produced from vegetative parts of plants like roots, stems, leaves and buds, it is known as vegetative reproduction.
• Advantages of vegetative propagation
→ Method of propagation for seedless plants.
→ Exact copies of parent plant are produced.
→ Large numbers of offsprings are produced.
→ Disease free plants can be propagated.
Budding
→ Small bulb-like cellular out growth called bud.
→ It is formed on parent cell that develops into an independent organism called yeast.
Fragmentation
→ Adult organism breaks into two or more pieces and forms a new individuals called fragments.
Examples: spirogyra, focus
Spore formation
→ It is an asexual reproductive microscopic single or multi-celled spherical bodies which germinate into new plants during favorable conditions.
Examples: mosses, ferns
Sexual reproduction in Plants
→ A plant reproduces sexually with the help of flowers.
→ Stamen and pistil are the reproductive parts of a flower.
→ Stamen is the male reproductive part and pistil is the female reproductive part.
(i) Bisexual flowers: Flowers which contains both pistil and stamens are called bisexual flowers.
(ii) Unisexual flowers: Flower which contains either pistil of stamens is called unisexual flowers.
• Stamens: It is a male reproductive part.
• Pistil: it is a female reproductive part.
Pollination
→ It is a transfer of pollen grains from anther to stigma of a flower is known as pollination.
→ Pollination is a first step of seed formation.
Types of pollination
→ There are two types of pollintaion:
(i) Self-pollination
(ii) Cross pollination
(i) Self-pollination: In this pollination pollen grains are transferred from anther to stigma of the same flower.
(ii) Cross-pollination: In this pollination pollen grains are transferred from anther of one flower to stigma of another flower.
Fertilization
→ It is process of fusion of male gamete and female gamete is called fertilization.
→ Fertilization produces zygote.
→ Zygote develops into an embryo.
Formation of fruits and seed
→ After fertilization process the ovary enlarges to form the fruit.
→ Wall of ovary become the fruit wall.
→ Ovules become seeds.
→ The remaining part of the flower i.e., petals, sepals and other part usually dry up and fall off.
→ Embryo enclosed in a protective seed coat.
Seed dispersal
→ It is a process by which seeds or fruits are scattered is called dispersal.
Main method of seed dispersal
→ Wind dispersal: drumstick, dandelion and maple
→ Animal dispersal: Plants having fleshy fruits. Example: apple, strawberries.
NCERT Solutions of Reproduction in Plants Class 7
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