inheritance

• Define ‘gametes’.

  Sex cells.
• How are gametes formed?


  Meiosis.
• How is a gamete different from a normal body cell?

  Half the genetic information
• Name the gametes in plants.

  Egg + pollen
• Name the gametes in animals.


  Sperm + Egg.
• Name the organ that produces female gamete in animals and plant.

  Ovaries.
• Name the organ that produce male gametes in plant.

  Anther.
• Name the organ that produce male gametes in animals.

  Testes.
• How many divisions do a cell undergo in meiosis?

  Twice.
• State the three key steps in meiosis.

  Copies of the DNA are made.

  The cell divides twice to form 4 gametes, each with a single set of chromosomes.

  All 4 cells are genetically different from each other.
• Describe the cells produced by meiosis.

  4 cells, genetically different.
• How many chromosomes are there in a human gamete?

  23.
• Name the process where a sperm and egg cell fuse together.

  Fertilisation.
• Explain why meiosis is necessary for fertilisation to occur?

  Cells have to be haploid so that when they fuse they create a diploid cell with the right number of chromosomes.
• Name the structure formed by fertilisation (fusion of the male and female gametes).

  Zygote.
• When a new cell is formed through fertilisation, how does it divide?

  By mitosis - Zygote becomes an embryo once it starts dividing to form a ball of cells.
• Define 'mitosis'.


  Cell division that produces two genetically identical daughter cells.
• Which type of reproduction is based only on mitosis?

  Asexual.
• Define 'cloning'.


  Production of identical offspring by asexual reproduction/mitosis.
• By which cell division type does cloning occur?

  Mitosis.
• What are the advantages of asexual reproduction?

  Fast, only one parent needed (no need to find a mate).
• Describe the cells produced by meiosis.

  4 cells, genetically different.
• Describe the cells produced by mitosis.

  2 cells, genetically identical (clones).
• By which cell division type does asexual reproduction rely on?

  Mitosis.
• State one difference between asexual and sexual reproduction.

  A: no fertilisation/genetically identical offspring; S: fertilisation/genetic variation.
• The genetic material in the nucleus of a cell is...

  DNA.
• Describe the structure of DNA.

  A polymer made up of two strands forming a double helix.
• Name the structure within which DNA is contained.

  Chromosomes.
• What is gene?


  A small section of DNA on a chromosome.
• What is the function of a gene?


  To code for a particular sequence of amino acids in order to make a specific protein.
• What is a genome?


  The entire genetic material of an organism.
• What is a change in the DNA sequence called?

  A mutation.
• What are chromosomes?


  Structures in the nucleus that carry genes.
• How many chromosomes are in one human body cell?

  46.
• State 3 ways in which understanding of the human genome will be important?

  To search for genes linked to different types of disease.

  To understand and treat inherited disorders.

  To trace early human migration patterns.
• What percentage of your chromosomes have you inherited from your father?

  50%.
• What percentage of your chromosomes have you inherited from your father?

  50%.
• What is an allele?

  A different version of a gene.
• What is a genotype?


  The alleles of an organism for a particular gene (e.g. RR).
• What is a phenotype?


  The displayed characteristic or physical appearance caused by alleles (e.g. red flowers).