reproduction

• describe sexual reproduction

  two parents with fertilisation - fusing of male and female gametes - to produce genetically different offspring
• give advantages of sexual reproductions

  variation - less likely to be wiped out and more likely to adapt
• give disadvantages of sexual reproduction

  • two parents needed
  • energy and time consuming
• describe asexual reproduction

  one parent with no fertilisation producing genetically identical offspring
• give advantages of asexual reproduction

  • one parent needed
  • more time and energy efficient
  • quicker
• give disadvantages of asexual reproduction

  no variation - more likely to be wiped out and less likely to adapt
• describe meiosis

  form of cell division to produce gametes ( haploid cells )
• describe process of meiosis

  1. dna duplicated
  2. chromosomes pulled apart to opposite poles
  3. arms of chromosome pulled apart to opposite poles
  4. produce four genetically different gametes
• give number of chromosomes in ordinary cell

  46 - 23 pairs
• give female sex chromosomes

  xx
• give male sex chromosomes 


  xy