Mendel – GCSE Biology B (Triple) OCR Revision

Gregor Mendel is often referred to as the ‘father of genetics’. He was a 19th century Austrian monk who conducted experiments on pea plants.
Mendel’s studies led to the formation of the basic principles of genetics that are still used today.
Mendel discovered the laws of inheritance, which explain how traits are passed from parents to offspring.

The First Law (Law of Segregation) states that each organism has two alleles for each trait, and that these alleles segregate (separate) during the production of gametes.
The Second Law (Law of Independent Assortment) proposes that different traits are inherited independently of one another. However, this is not always the case due to linkage between genes that are located close together on the same chromosome.
According to the Third Law (Law of Dominance), when an organism has two different alleles for a trait, the dominant one will express itself in the phenotype.

Mendel conducted experiments by cross-pollinating different varieties of pea plants.
He observed seven characteristics: plant height, pod shape and color, seed shape and colour, and flower position and colour.
By breeding plants with specific traits, Mendel was able to track how these traits appeared in subsequent generations. This led to his discovery of dominant and recessive traits.
However, it is important to note that while Mendel’s laws are helpful in understanding simple genetic traits, they do not account for all forms of inheritance. Complex traits are often influenced by multiple genes and environmental factors.

Mendel’s laws form the basis of modern genetics and have been expanded upon with the discovery of DNA, chromosomes and gene linkage.
The understanding of heredity that arose from Mendel’s work is fundamental to many fields, including agriculture, medicine and conservation.