8.2

• What does sexual reproduction involve?

  The union of male and female sex cells to form a unique individual
• Why does sexual reproduction result in a unique individual?

  Because each sex cell contains different DNA
• Which types of organisms primarily reproduce sexually?

  Most multicellular organisms
• Can unicellular organisms reproduce sexually?

  Yes, some unicellular organisms are capable of sexual reproduction
• What is fertilisation in the context of sexual reproduction?

  The fusion of male and female haploid cells to form a diploid zygote
• What does the new individual formed through fertilisation have in terms of DNA?

  A different combination of DNA from that of either parent
• How does sexual reproduction contribute to genetic variation in a population?

  It ensures genetic variation through the combination of different DNA
• What is one source of variation in sexual reproduction?

  Random fertilisation of an egg by a successful sperm (or pollen grain)
• How does meiosis provide variation?

  Through independent assortment and random segregation of homologous chromosomes
• What is crossing over in meiosis?

  The exchange of genetic material between homologous chromosomes
• What can also be a source of variation besides meiosis?

  Mutations
• What are the advantages of sexual reproduction?

  • Offspring are not genetically identical to their parents or siblings
  • Variation exists within a population
  • Genetic health of a population is increased
  • Evolution can occur if the environment or conditions change
  • Natural selection requires variation
  • Those with favorable traits are more likely to survive and reproduce
• What are the disadvantages of sexual reproduction?

  • Takes more time and energy
  • Production of gametes is required
  • Need for two parent organisms
  • Competition for mating opportunities
  • Longer gestational periods
  • Need for parental care of the offspring
  • More complex process with higher chances of failure