Question

Define Heredity. Explain the mechanism of hereditary changes.

Answer 1

Hint: Heredity is the process of passing on genetic information from one generation to the next.

Heredity is also known as an inheritance which is the process of passing off the traits from parents to their offsprings. This can occur either through asexual reproduction or sexual reproduction.

Complete answer:

Heredity is the biological process responsible for passing on physical traits from one generation to another.

Through heredity, variations between individuals can accumulate and cause species to evolve by natural selection.

Mechanism of hereditary changes:

Mating: it is the first step for reproduction, where the Union or fusion of male gamete sperm takes place with the female gamete ovum or egg. This process is called fertilization.

Growth: Growth and development of a body occur through the repeated division in the zygote either through meiosis or mitosis.

Chromosomes: The nucleus of the zygote consists of chromosomes which act as the carrier of the genetic traits of both the parents to their offspring.

Genes: Genes are the small parts on the chromosomes which are the basic physical and functional unit of heredity. Each gene carries a specific trait responsible for a particular character in an individual.

Chance factors: Each sperm and ovum contains 24 pairs of chromosomes making it 48 pairs in total. On fertilization, half chromosomes from both of them will be fertilized while the rest will be left out. The chosen chromosomes are not specific; they are by chance and may change each time.

Note: Changes in heredity can occur through – natural selection (appropriate allele will survive), genetic drift (sudden change in small population due to variations), mutations (sudden inheritable changes in the genetic material), and recombination (change in the sequence of alleles due to crossing over in meiosis).