Question

Environmental factors, such as nutrition and temperature, can influence the phenotype of an individual.

For example, skin color is controlled by multiple genes, making it a ____________ trait.

However, skin color is also controlled by ____________ , making it subject to environmental influence.

Many human disorders, such as ____________ are controlled by genes but influenced by environmental factors as well.

For example, the coat color of Siamese cats is controlled by a gene, but temperature activates or deactivates the ____________ responsible for coat color.

Answer 1

1. Polygenic trait. Traits which are controlled by multiple genes are called polygenic traits.
2. Melanin, the skin pigment that controls skin colour. Melanin is secreted in response to exposure to sunlight by melancytes through the process of melanoogenesis.
3. Marfan syndrome ( a connective tissue disease) is controlled by both genes as well as environmental factors. OR Neurodegenerative diseases.
4. tyrosinase. Tyrosinase enzyme is secreted due to mutation in TYR gene, this enzyme is heat sensitive and is directly involved in melanin production. Thus at colder temperatures it gives darker colours.