CBSE – 7th Standard Science

Free

Chapter 12 – Reproduction in Plants

Chapter 12

Reproduction in Plants

  • The production of new individuals from their parents is known as reproduction.
  • Most plants have roots, stems and leaves. These are called the vegetative parts of a plant.
  • Flowers are the reproductive parts of a plant.
  • A flower may have either the male part or the female part or both male and female parts.
  • There are several ways by which plants produce their offspring. These are of two types. asexual and sexual reproduction.Asexual vs. Sexual Reproduction

image001

  • In asexual reproduction new plants are obtained without production of seeds or spores.
  • It is a type of asexual reproduction in which new plants are produced from roots, stems, leaves and buds.
  • Since reproduction is through the vegetative parts of the plant, it is known as vegetative propagation.

image002

  • The roots of some plants can also give rise to new plants. Ex. Sweet potato, dahlia
  • Plants such as cacti produce new plants when their parts get detached from the main plant body. Each detached part can grow into a new plant.
  • The small bulb-like projection coming out of cell is called a bud.

image003

  • The bud gradually grows and gets detached from the parent cell and forms a new yeast cell.
  • This process continues and number of yeast cells are produced in a short time.
  • The spores are asexual reproductive bodies. Each spore is covered by a hard protective coat to withstand unfavorable.
  • Spore germinates and develops into a new individual.
  • Plants such as moss and ferns reproduce by means of spores.
  • When water and nutrients are available algae grow and multiply rapidly by fragmentation.
  • An alga breaks up into two or more fragments these fragments or pieces grow into new individuals.
  • The flowers are the reproductive parts of a plant.
  • The stamens are the male reproductive part and the pistil is the female reproductive part The transfer of pollen from the anther to the stigma of a flower is called pollination.
  • If the pollen lands on the stigma of the same flower it is called self-pollination.
  • When the pollen of a flower lands on the stigma of another flower of the same plant, or that of a different plant of the same kind, it is called cross-pollination
  • The flowers which contain either only the pistil or only the stamens are called unisexual flowers. unisexual flowers may be present in the same plant or in different plants.
  • The flowers which contain both stamens and pistil are called bisexual flowers. Both the male and the female.
  • Anther contains pollen grains which produce male gametes. A pistil consists of stigma, style and ovary.
  • The ovary contains one or more ovules.
  • The female gamete or the egg is formed in an ovule.
  • In sexual reproduction a male and a female gamete fuse to form a zygote.
  • The process of fusion of male and female gametes is called fertilization. The zygote develops into an embryo.
  • After fertilisation, the ovary grows into a fruit and other parts of the flower fall off. The fruit is the ripened ovary.
  • The seeds develop from the ovules. The seed contains an embryo enclosed in a protective seed coat
  • Seeds are dispersed to different places it prevents competition between the plant and its own seedlings for sunlight, water and minerals.
  • It also enables the plants to invade new habitats for wider distribution.
  • Seeds and fruits of plants are carried away by wind, water and animals.
  • Winged seeds, light seeds of grasses or hairy seeds of hairy fruit get blown off with the wind to far away places.
  • Some seeds are dispersed by water.
  • These fruits or seeds usually develop floating ability in the form of spongy or fibrous outer coat.
  • Some seeds are dispersed by animals, especially spiny seeds with hooks which get attached to the bodies of animals and are carried to distant places.
  • Some seeds are dispersed when the fruits burst with sudden jerks and seeds are scattered far from the parent plant.
  • Seed dispersal helps the plants to (i) prevent overcrowding, (ii) avoid competition for sunlight, water and minerals and (iii) invade new habitats.

Course Curriculum

Post a comment

Your email address will not be published. Required fields are marked *