Explain the following terms used in genetics: (i) Dominant - Leaving Cert Biology - Question 11 - 2019

A recessive allele is an allele that is only expressed in the homozygous condition. This means that it must be present in two copies (both alleles are recessive) for its trait to be visible in the phenotype.

Gene expression refers to the process by which information from a gene is used to synthesize a functional gene product, typically proteins. This process plays a vital role in determining the traits displayed by an organism.

The genotype of the black sheep is homozygous recessive, denoted as ww.

The genotype of the white sheep is heterozygous, denoted as Ww.

The gametes produced by the white sheep can be W and w.

The gametes produced by the black sheep can only be w.

The possible genotypes of the offspring are Ww and ww. The phenotype for Ww is white (dominant) and the phenotype for ww is black (recessive).

The term 'species' refers to a group of organisms that can interbreed and produce fertile offspring.

An example of an inherited characteristic is the beak length in finches, which varies among different species depending on their feeding habits.

Evolution is defined as a change in species over time, often through processes such as natural selection and genetic drift.

Fossils and comparative anatomy serve as substantial sources of evidence for evolution, indicating how organisms have adapted and changed.

The theory of natural selection posits that individuals with beneficial traits are more likely to survive and reproduce, passing those traits to the next generation. This process allows for gradual changes in the species over time, leading to evolution.