B13.2: Cell division in sexual reproduction

• What is the purpose of meiosis?

  To create gametes for sexual reproduction
• How many daughter cells are produced by meiosis?

  Four daughter cells
• What is the genetic material content of daughter cells produced by meiosis?

  They contain half the genetic material
• Where does meiosis take place in animals and plants?

  In the reproductive organs
• What are the reproductive organs in humans?

  Ovaries and testes
• What type of cells does meiosis produce?

  Gametes (sex cells)
• How many chromosomes do gametes have?

  Half the original number of chromosomes
• What are the stages of meiosis?

  1. DNA replication forms chromatids
  2. Cell divides twice to form gametes
  3. Homologous chromosomes pair randomly
  4. Four genetically different gametes produced
• What does a single chromosome look like?

  A single line
• What happens to homologous chromosomes during meiosis?

  They pair up at the equator
• What is the result of two gametes fusing?

  A diploid cell is formed
• How many sperm can testes produce in 24 hours?

  Around 400 million sperm
• What is the journey of sperm to fertilize an egg?

  It travels over 100,000 times its length
• What is the difference between meiosis and mitosis?

  Meiosis produces gametes, mitosis produces somatic cells
• What type of cells does mitosis produce?

  Diploid cells with the same chromosomes
• What is the chromosome number in human gametes?

  23 chromosomes
• What happens during fertilization?

  Two sex cells join to form a zygote
• What is the chromosome number in a zygote?

  46 chromosomes
• How does sexual reproduction introduce variation?

  • Gametes produced by meiosis are different
  • Fusion of gametes combines genes from both parents
  • New combinations of alleles create variation
• What is the result of asexual reproduction?

  Offspring identical to parent
• What is the role of mitosis in asexual reproduction?

  To produce identical offspring
• How do the processes of meiosis and mitosis differ in terms of chromosome number?

  Meiosis produces haploid cells, mitosis produces diploid cells
• What is the significance of having haploid gametes in sexual reproduction?

  Prevents doubling of chromosome number each generation
• What are the key differences between meiosis and mitosis?

  • Meiosis:
  • Occurs in gonads
  • Produces 4 non-identical gametes
  • Haploid cells (23 chromosomes)
  • Mitosis:
  • Occurs in somatic cells
  • Produces 2 identical cells
  • Diploid cells (46 chromosomes)
• What is the final outcome of fertilization in humans?

  A zygote with 46 chromosomes
• What happens to the zygote after fertilization?

  It undergoes mitosis to develop
• Why is it important that gametes are genetically different?

  It increases genetic diversity in offspring