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Overview of reproduction and genetic variation

Inheritance, variation and evolution • Reproduction

Key concepts

What you'll likely be quizzed about

  • Sexual reproduction involves the fusion of a male gamete (sperm) and a female gamete (ovum).
  • In flowering plants, the male gamete is pollen and the female gamete is an ovule containing the egg cell.
  • Fertilisation merges two haploid gametes to form a diploid zygote, which develops into a new organism.
  • Gametes form through meiosis, a specialized cell division that halves the chromosome number, producing genetically distinct gametes in the sex organs (ovaries and testes).

Flashcards

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What is vegetative reproduction?

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Asexual reproduction in plants via runners, bulbs, or tubers, forming new individuals without seeds.

Key notes

Important points to keep in mind

Sexual reproduction requires fusion of two gametes and produces genetically varied offspring.

Meiosis halves the chromosome number, introducing variation via independent assortment and crossover.

Asexual reproduction employs mitosis and produces clones unless mutations occur.

Advantages of sexual reproduction include variation and adaptability; disadvantages include time, energy, and fewer offspring.

Advantages of asexual reproduction include speed and numerous offspring; disadvantages include low genetic diversity and vulnerability.

Human sex chromosomes: all ova carry X; sperm carry X or Y; XX = female, XY = male.

Identical twins arise from one fertilised ovum splitting; fraternal twins arise from two separate fertilisations.

Terminology check: gamete = sex cell, haploid = half set, diploid = full set, zygote = fertilised egg.

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