Chapter 8:
Reproduction in Plants

Class 7 Science | CBSE Curriculum

Learn asexual and sexual reproduction, vegetative propagation, pollination, fertilisation, seed dispersal, flower structure explained with more than 100 practice questions.

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Time:
05:00

Quick Revision: Reproduction in Plants

  • Asexual Reproduction: New plants without seeds. Methods: Vegetative propagation (roots, stems, leaves), Budding (yeast), Fragmentation (algae), Spore formation (ferns, fungi).
  • Vegetative Propagation Examples: Potato (eyes/tubers), Ginger (rhizome), Bryophyllum (leaf buds), Sweet potato (roots), Rose (stem cuttings).
  • Sexual Reproduction: Involves fusion of male and female gametes. Flower is the reproductive part.
  • Flower Parts: Stamen (male: anther + filament) produces pollen grains. Pistil (female: stigma + style + ovary) contains ovules with egg cells.
  • Unisexual vs Bisexual: Unisexual flowers have either stamens or pistil (e.g., papaya, corn). Bisexual flowers have both (e.g., mustard, rose).
  • Pollination: Transfer of pollen from anther to stigma. Self-pollination (same flower/plant) vs Cross-pollination (different plant). Agents: wind, water, insects.
  • Fertilisation: Fusion of male gamete (pollen tube) with female gamete (egg) → Zygote (2n) → Embryo.
  • Fruit & Seed: Ovary → Fruit; Ovule → Seed (contains embryo + seed coat).
  • Seed Dispersal: Wind (winged seeds, e.g., maple, drumstick), Water (coconut), Animals (spiny hooks, e.g., Xanthium), Explosion (balsam, castor).
  • Advantages of Seed Dispersal: Prevents overcrowding, reduces competition, allows colonisation of new areas.

Chapter Summary:

Reproduction in Plants explains how plants produce offspring through two main modes: asexual and sexual reproduction. Asexual reproduction does not involve seeds or gamete fusion. Methods include vegetative propagation (from roots, stems, leaves), budding (e.g., yeast), fragmentation (e.g., Spirogyra), and spore formation (e.g., ferns, mosses, bread mould). Vegetative propagation produces genetically identical clones and is faster than seed propagation.

Sexual reproduction involves flowers as reproductive structures. Stamens (male) produce pollen grains containing male gametes. The pistil (female) contains ovules with egg cells. Pollination is the transfer of pollen to the stigma—either self-pollination (same flower/plant) or cross-pollination (different plant of same species), aided by wind, water, or insects. Fertilisation occurs when male and female gametes fuse to form a zygote, which develops into an embryo. After fertilisation, the ovary becomes a fruit, and ovules become seeds containing the embryo.

Seed dispersal by wind, water, animals, or explosive mechanisms prevents overcrowding, reduces competition, and helps plants colonise new habitats. Understanding these processes reveals how plants perpetuate their species and maintain biodiversity.