Reproduction in Organisms

Reproduction in Organisms

• Reproduction is the process by which living organisms produce new individuals of the same species.
• It's essential for the survival and increase in a species population.
• If organisms don't reproduce, their population decreases, and the species becomes extinct.

Significance of Reproduction

• Allows continuity of a species generation after generation.
• Plays a crucial role in evolution by transmitting favorable variations from one generation to the next.

Body Design of Organisms

• Organisms often resemble each other due to similar body designs.
• Reproduction fundamentally involves copying the blueprint of the body design (DNA).
• DNA in the cell nucleus holds the information for creating proteins.
• Different proteins lead to diverse body designs.
• DNA replication is a fundamental step in reproduction.
• DNA copies produced during reproduction are similar but not identical, allowing for variations.
• Variations are essential for survival in changing environments.
• Species lacking adaptability to changing environments face extinction.
• Variations within a species allow individuals to better adapt to environmental changes.

Types of Reproduction

• Reproduction can be broadly categorized into asexual and sexual reproduction.
• Asexual reproduction: Involves a single parent in creating new individuals.
  • Fission: A unicellular organism divides to form two or more new individuals (binary or multiple).
  • Budding: A bud-like projection forms on the organism, develops into a new individual, then separates.
  • Regeneration: A fully differentiated organism can grow new individuals from body parts.
  • Fragmentation: Multicellular organisms break into fragments, each fragment developing into a new individual.
  • Spore formation: Structures called sporangia produce spores, which develop into new individuals when conditions are favorable.
  • Vegetative propagation: New plants grow from vegetative parts of the parent plant (roots, stems, leaves).
• Sexual reproduction: Involves two parents to create a new individual.
  • Significance of Sexual Reproduction: Promotes variations and species diversity.

Sexual Reproduction in Flowering Plants

• Reproductive parts: Stamen (male) and pistil (female).
• Pollination: Transfer of pollen grains from the stamen to the stigma of the flower.
  • Self-pollination: Pollen is transferred to the stigma of the same flower or another flower on the same plant.
  • Cross-pollination: Pollen is transferred to the stigma of a different flower on a different plant.
• Fertilization: Fusion of male and female gametes (sperm and egg) to form a zygote.
  • Pollen tube: Forms after successful pollination allowing the male gamete to reach the female gamete.

Reproduction in Human Beings

• Human reproduction is sexual, involving male and female reproductive organs.
• Sexual maturity: Starts at ages varying from 10-14 years, depending on sex, where reproductive organs become functional.
• Changes during puberty: Include body hair growth, skin changes, and development of physical characteristics.
• Male reproductive system: Includes testes, epididymis, vas deferens, seminal vesicles, prostate gland, urethra, and penis.
• Female reproductive system: Includes ovaries, fallopian tubes, uterus, cervix, and vagina.

Methods of Avoiding Pregnancy

• Various methods exist for avoiding pregnancy (mechanical barriers, chemical methods, and surgical methods).

General Reproduction Terminology

• Germination: Initial stage of a seed's growth into a seedling.