2. The main drawback of Darwin's theory is (A) Natural selection (B) survival of the fitiest (D) variation (C)struggle for existence
Answers
Answer:
D.struggle for existence
INTRODUCTION
The branch of life science for the study of 'origin of life' and evolution of different forms of life on earth was called bioevolution or evolutionary biology by Mayer (1970).
The word evolution means to unfold or unroll or to reveal hidden potentialities. Evolution simply means an orderly change from one condition to another.
Evolution is a slow but continuous process which never stops.
ORIGIN OF LIFE
Origin of life is the process by which living organisms developed from inanimate matter (which is generally thought to have occurred on Earth between 3800 - 4200 millions years ago).
First life evolved about. 3800-4200 million years back.
There are several theories about the origin of life, like big bang theory, theory of special creation, theory of eternity, cosmozoic theory etc.
BIG-BANG THEORY
This theory was proposed by Abbe Lemaitre.
According to this theory, the universe originated about 15 billion years ago due to a thermonuclear explosion of a dense entity. This thermonuclear explosion is called Big-bang. About 4.6 billion years ago, the origin of the solar system took place by the gaseous clouds formed due to this explosion.
These gaseous clouds collapsed and converted into flat disc-like structure made up of atoms and small particles due to their own gravitational pull. This flat-disc like structure is called Solar Nebula. The very hot central part of this solar nebula became still hotter and converted into the sun. Now, due to condensation of atoms and dust particles moving around the sun, the formation of the other planets took place Like, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
The solid part of our planet earth was called lithosphere and the gaseous part was known as atmosphere.
When the earth's surface cooled down and its temperature decreased to 100° C, water formed on it.
THEORY OF SPECIAL CREATION
The greatest supporter of this theory was father Suarez.
According to the Bible, life and everything was created by God in 6 days.
According to Hindu mythology, the world was created by God Brahma. According to it, life has not changed ever since its origin.
Special creation theory lacks scientific evidence so it is not accepted.
COSMOZOIC THEORY
This theory is proposed by Richter and supported by Arrhenius.
Protoplasm reached earth in the form of spores or other simple particles from some unknown part of the universe with cosmic dust and they gave rise to various forms of life.
Explanation: