Biology 2.4 - Variation and Inheritance

• What are the two types of inheritance?

  Monogenic (single gene) inheritance and polygenic inheritance
• What are the two types of variation?

  Discrete variation and continuous variation
• Monogenic (single gene) inheritance facts?

  • Discrete variation
  • Distinct groups
  • Controlled by one gene
• Polygenic variation facts?

  • Continuous variation
  • A range of values
  • Controlled by many genes
• Define allele?

  A version of a gene
• Define gene?

  A section of a chromosome which codes for a protein
• Define recessive?

  Only seen in the phenotype when homozygous
• Define dominant?

  Always seen in the phenotype if present
• Define homozygous?

  Both alleles are the same
• Define heterozygous?

  One allele is dominant, and the other recessive
• Define genotype?

  The alleles present (letters)
• Define phenotype?

  The physical characteristics visible
• Why may the expected phenotype ratio be achieved?

  Fertilisation is a random process
• What is a punnett square?

  A diagram used to predict the possible genetic outcomes of two individuals.