What is called the unit of heredity?
a. Genes
b. Alleles
c. Cells
d. Chromosomes

Answer

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Hint: Heredity can be defined as the sum of all biological processes by which particular characteristics are transmitted from parents to their offspring.

Complete Answer:
Genes are the units of heredity and are the instructions that make up the body’s blueprint.
- Option a: Genes are said to be the basic physical and functional unit of heredity. They are made up of DNA. Genes are the functional units of heritable material that are found within all living cells. Every member of a species possesses a set of genes specific to that species. It is this set of genes that provides the constancy of the species. Every individual has two copies of each gene,i.e., one inherited from each parent. Therefore, this is the correct option.
- Option b: An allele is an alternate form of a gene. It occurs alternatively at a given site (locus) on a chromosome. Alleles may occur in pairs, or maybe in multiple forms, thereby affecting the expression (phenotype) of a particular trait. The combination of alleles constitutes the genotype of an individual. Therefore, this is an incorrect option.
- Option c: Cells are the basic structural, functional, and biological unit of all living things. The human body is composed of trillions of cells. The cell carries out various specialized functions. It also contains the body’s hereditary material i.e. gene. Cells possess many parts that carry out different functions. Therefore, this is an incorrect option.
- Option d: Chromosomes carry genetic information in the form of genes. It is present In the nucleus of each cell. The DNA molecule is packaged into thread-like structures called chromosomes. Therefore, this is an incorrect option.

Thus, the correct option is a) Genes.

Note: All the genes present in all the individuals are not the same. Alleles that are alternate forms of the same gene with small differences in their sequence of DNA bases, contribute to each person’s unique physical appearance or features.