Topic Summaries

Mendelian genetics

GCSE > Biology > Edexcel > GCSE Biology Topic Summaries > Evolution and natural selection > Mendelian genetics
Previous Module
Next Module

Pathogens and non-specific immunity

Resource cycles and environmental change

Science skills: Measuring results

  • In the mid-19th century, Gregor Mendel carried out breeding experiments on plants. He observed that the inheritance of each characteristic was determined by ‘units’ that were passed on to the descendants unchanged.
    • Mendel studied the inheritance of traits in pea plants to form the laws of Mendelian inheritance. For example, crossing a yellow pea plant with a green pea plant always produced a yellow pea plant, so yellow was found to be dominant and green is recessive. These laws are followed when we carry out Punnett squares to determine the potential genotypes of offspring.
  • The importance of Mendel’s work was not recognised until after his death as little was known about genetic information at the time; most scientists still believed in blended inheritance where all characteristics are passed on.
    • Late 19th century: chromosome behaviour during cell division was first observed.
    • Early 20th century: chromosomes and Mendel’s ‘units’ observed to behave in similar ways, leading to the idea that the ‘units’, later known as genes, were located on chromosomes.
    • Mid-20th century: DNA structure and the mechanism of gene function were determined, leading to the development of gene theory.

Unlock Mendelian genetics

Subscribe to SnapRevise+ to get immediate access to the rest of this resource.

Premium accounts get immediate access to this resource.

Previous Module
Next Module