Sexual and asexual reproduction: Inheritance, variation and evolution: Biology: GCSE (9:1)

• Sexual reproduction


  The production of new living organisms by fusing gametes and by combining the genetic material of two individual parents

  
• Asexual reproduction

  The production of new living organisms that are genetically identical to the parent, does not involve the fusion of gametes

  
• Binary fission


  A method of asexual reproduction that is carried out by single-celled organisms such as bacteria

  
• Gametes


  A male or female organism's reproductive cells such as the sperm and egg in animals or pollen and egg in plants

  
• Role of gametes

  Carries genetic information in the form of a single set of chromosomes, which combines with another gamete's to make a complete diploid set

  
• Fertilisation


  The fusion of the nucleus of a male gamete with the nucleus of a female gamete that results in the development of a new living organism

  
• Haploid cell


  Gamete cells that have a singly copy of each chromosome, which is 23 chromosomes in humans

  
• Diploid cell


  Body cells that have two complete copies of each chromosome, which is 23 pairs or a total of 46 chromosomes in humans

  
• Meiosis


  A type of cell division that results in four non-identical daughter cells, each with half the number of chromosomes of the parent cell

  
• When meiosis occurs

  During the formation of gamete cells in preparation for sexual reproduction

  
• Mitosis


  The process of cell division that results in the formation of two daughter cells that are genetically identical to the parent cell

  
• When mitosis occurs


  During asexual reproduction or the growth and repair of an organism's tissues, by producing new body cells

  
• Body cell


  A typical cell with two complete copies of each chromosome, that is not involved in reproduction

  
• Identical offspring


  The result of asexual reproduction where the process of mitosis leads to genetically identical individuals or clones

  
• Non-identical offspring


  The result of sexual reproduction where the process of meiosis leads to individuals with genetic variations

  
• Genetic variation


  Differences in the DNA between individuals which can result in different displayed characteristics

  
• Features of meiosis

  Two stages of division, four non-identical daughter cells produced, 23 chromosomes in each haploid cell, needed for sexual reproduction, occurs in gonads
• Features of mitosis


  One stage of division, two identical daughter cells produced, 46 chromosomes in each diploid cell, involved in asexual reproduction, can occur in body tissue
• Gonads


  The reproductive organs that produce gametes via meiosis, such as the testis or ovary