Notes of Ch 12 Reproduction in Plants Class 7th Science

Revision Notes of Ch 12 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.

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