Question

Alternatives forms of genes are called as
(a) DNA
(b) RNA
(c) Alleles
(d) Genetic materials

Answer 1

Hint: This is the variant form of genes that are located at a genetic locus on a chromosome. Gene is the basic functional and physical unit of heredity and is made up of DNA.

Complete answer:
Alternative forms of genes are called Alleles. Alleles are a pair of genes that occupy a specific location on a particular chromosome and control the traits. Alleles may appear as a pair or in multiple form allele which represents a particular trait in the progeny. A pair of alleles will determine the same trait, for example, one allele will lead to blue colour eye lens, the other will lead to the black colour eye lens. Allele makes the genotype of an organism. If both the alleles show similar traits, they are said to be homozygous genotypes, while if they show different traits, they are said to be heterozygous genotypes.

Alleles usually follow the laws of inheritance -
> Law of dominance: One of the two alleles in a pair are dominant in case of heterozygous genotype. The dominant one will always be shown unless a homozygous recessive allele is present.

> Law of segregation: Alleles do not show any blending, either the dominant allele shows or the recessive one. During gamete formation, the alleles segregate, and the gamete receives only one of the two alleles in the pair.

However, some exceptions are present to the law of inheritance -
> Incomplete dominance - When neither of the two alleles is completely dominant and both the alleles are shown, like in case of flower colour in dog flower.
> Codominance - When both the alleles are equally dominant and so again, both of them show, like in the case of human blood groups.

So, the correct answer is ‘Alleles’.

Notes:
-Locus is the location where a gene is found on the chromosome.
-A Punnet’s square is a graphical representation to calculate the possibility of all the types of genotypes of the offspring in a genetic cross.
-William Bateson coined the term Allele.