Class 10 Science How do Organisms Reproduce Notes

Class 10 Science How do Organisms Reproduce Notes

Introduction

  • Reproduction: Biological process by which organisms produce offspring to maintain their species.
  • Two main types: Asexual and Sexual reproduction.

1. Asexual Reproduction

  • Definition: Reproduction involving single parent, offspring are genetically identical to parent.

Types of Asexual Reproduction

  1. Binary Fission: Division of unicellular organism into two
    • Example: Amoeba, Paramecium
  2. Budding: Small outgrowth forms and detaches
    • Example: Hydra, Yeast
  3. Fragmentation: Body breaks into pieces, each grows into a new organism
    • Example: Spirogyra, Planaria
  4. Spore Formation: Spores develop into new organisms
    • Example: Fungi, Ferns
  5. Vegetative Propagation (in plants): New plant grows from root, stem, or leaf
    • Example: Potato (stem tuber), Ginger (rhizome)

Advantages: Fast reproduction, no mate required
Disadvantages: No genetic variation → vulnerable to diseases

2. Sexual Reproduction

  • Definition: Reproduction involving two parents and fusion of gametes, producing genetically varied offspring.

Process in Humans

  1. Gamete Formation: Sperm (male) and egg (female)
  2. Fertilization: Fusion of sperm and egg → zygote
  3. Embryonic Development: Zygote divides → forms embryo → fetus
  4. Birth: New individual is born

Sexual Reproduction in Plants

  1. Flower Structure: Sepal, Petal, Stamen (male), Carpel (female)
  2. Pollination: Transfer of pollen from anther → stigma
  3. Fertilization: Pollen fuses with ovule → seed formation
  4. Seed Dispersal: Seeds spread to new locations
  5. Germination: Seed grows into a new plant

Advantages: Genetic variation → better adaptation
Disadvantages: Slower, requires two parents