Revision: Mapping Our Genes Science and Technology 2 SSC (English Medium) 10th Standard Maharashtra State Board

The transmission of characters from the parents to their offsprings is called heredity. 

The term heredity may be defined as "transmission of genetically based characteristics from parents to offspring".

or

The proportion of an allele in the gene pool, to the total number of alleles at a given locus, is called gene frequency.

Mutation breeding, sometimes referred to as “variation breeding”, is the process of exposing seeds to chemicals or radiation in order to generate mutants with desirable traits to be bred with other cultivars.

Organic evolution can be defined as slow, gradual, continuous and irreversible changes through which the present-day complex forms of the life developed (or evolved) from their simple pre-existing forms.

The total genetic information encoded in the sum total of genes in a Mendelian population is called gene pool.

Evolution is a slow and continuous process whereby complex forms of life have emerged from simpler forms over millions of years.

The study of ancient life with the help of fossils is called palaeontology. Fossils are the dead remains of plants and animals that lived in the past in various geological layers.

The evidence of evolution indicated in the given diagram is vestigial organ.

Vestigial organs: Vestigial organs are useless organs that are degenerated or underdeveloped due to non-functionality through several years.

Vestigial organs are degenerate organs that are inadequately developed and non-functional. They could be useful in certain related and unrelated species, as well as in ancestors.

Homologous organs are those organs, which are structurally similar but perform different functions.

A species (both singular and plural) is a natural population of individuals or groups of individuals who are similar in all key morphological and reproductive characteristics, allowing them to interbreed freely and produce fertile offspring.

Large number of organisms get buried due to disasters like floods, earthquakes, volcanoes, etc. Remnants and impressions of such organisms remain preserved underground. These are called fossils.

• Mendel is the father of modern genetics; he discovered the basic principles of heredity.
• Hugo de Vries (1901) proposed the mutation theory explaining sudden genetic changes.
• Walter Sutton (1902) linked chromosomes with heredity through his study on grasshoppers.
• Avery, McCarty & McLeod (1944) proved DNA is the genetic material in living organisms.
• Jacob & Monod (1961) developed a model of protein synthesis, leading to recombinant DNA technology.

• Morphological similarities are observed in body parts of animals (e.g., mouth, eyes, nostrils, ears, hairs).
• In plants, similarities are seen in leaf shape, venation, petiole, etc.
• These structural similarities indicate a common ancestry and evolutionary relationship.