Question

What is the external appearance of an individual trait called?

Answer 1

Hint: Two alleles for a given gene in a diploid organism interact and express to produce physical characteristics or traits. It was first proposed by Wilhelm Ludvig Johannsen.
The external appearance of an individual trait is known as ‘Phenotype'.

Complete answer:
- The physical observable traits expressed by an organism are referred to as its phenotype. For example, biochemical properties, hair color, height, skin color, the shape of different body parts, etc. all show phenotypic characters.
- The physical expression of characteristics is accomplished through the expression of genes carried on chromosomes and through environmental influence on it.
- The genetic makeup of an individual consists of both physically visible and non-expressed alleles and is called its genotype.
- Dominant alleles lead to the expression of the associated character whereas a recessive allele is unable to express itself in the presence of a dominant allele.
- Phenotypic variation occurring due to underlying heritable genetic variation is a prerequisite for evolution by natural selection.
- The existence of two or more clearly different phenotypes in the same population of a species is known as polymorphism.
- In nature, natural selection is mostly influenced by the environmental factors which initially work on individuals, favoring the survival of those organisms with phenotypes best suited to their current environmental conditions.

Note:
- A trait is defined as any quantifiable feature or expression that a person acquires from his or her parents which are controlled by the genetic material.
- The expression of alleles is governed by the ‘Law of Dominance' given by Gregor Mendel.
- The term ‘phenotype' was coined by the Danish botanist and geneticist Wilhelm Ludvig Johannsen.