Explain modern synthetic theory of evolution.

Answer: Modern Synthetic Theory of Evolution. Julian Huxley proposed term ‘modern synthesis’. This theory was based on the work of Dobzansky. The salient features are as follows. i. According to the Modern synthetic theory of evolution, population is considered as […]

Describe the concept of “Survival of the fittest”.

Answer: Survival of the fittest. Survival of the fittest or Natural selection: i. The organisms having favourable variations succeed in the struggle for existence. ii. The organisms with unfavourable variations are unfit to survive and they perish. iii. This means […]

Write a note on “Struggle for existence”.

Answer: Struggle for Existence. Intra-specific struggle: It is the competition among the individuals of the same species. This type of struggle is very severe, because the need and approach of all competing organisms is precisely same. e.g. struggle between cow and cow, […]

Describe Darwin’s theory of natural selection. State the objections raised against this theory.

Answer: Darwin’s theory of natural selection.  Charles R. Darwin was a British biologist. He postulated the “Theory of origin of species by natural selection”. Principles of Darwinism: Darwin’s theory of organic evolution by natural selection is based on the following principles: i. […]

Give an account of Urey and Miller’s experiment.

Answer : Urey & Miller’s experiment  i. Stanley Miller and Urey designed an apparatus and created conditions similar to primitive atmosphere. ii. The apparatus had a spark chamber with two tungsten electrodes, flask for boiling water, side tube connected to a […]

Describe Oparin — Haldane theory of chemical origin of life.

Answer:  Oparin — Haldane theory of chemical origin of life.  The Russian scientist Alexander Ivanovich Oparin (1924) and British scientist J.B.S. Haldane (1929) proposed the ‘Theory of chemical evolution of life’. According to this theory, life originated from non-living matter, some three billion […]

What are polygenes? Explain with suitable example.

Answer:  Polygenes: Characters are determined by two or more gene pairs, and they have additive or cumulative effect. Such genes are called cumulative genes or polygenes or multiple factors. Example Human skin colour: i. Population derived from marriage between negro and white […]