This set of Class 12 Biology Chapter 7 Multiple Choice Questions & Answers (MCQs) focuses on “Evolution – Origin of Life – 2”.
1. What is most important element for origin of life?
Explanation: Water is essential for origin of life, since first life originated in the water of oceans. After a long time, the water of primitive oceans had rich mixtures of organic compounds. This produced a platform for origin of life.
2. The theory of spontaneous generation was rejected by which scientist?
Explanation: Pasteur is very famous for his Germ Theory. This theory disproved spontaneous generation, as he had done an experiment to prove that life came from pre-existing cells.
3. Which among the compounds were formed during the origin of life?
a) Urea, amino acid
b) Urea, nucleic acid
c) Proteins, nucleic acid
d) Proteins, amino acid
Explanation: Proteins, nucleic acid were the main two compounds formed during origin of life. Experiments done by many scientists also resulted to creation of proteins and nucleic acid. This shows that these compounds existed during origin of life.
4. The name of the theory given by Louis Pasteur was called as _______
a) Cellular theory
b) Recapitulation theory
c) Germ theory of disease
Explanation: Louis Pasteur found the Germ theory of diseases or Germ theory. He stated that life did not come from killed yeast in pre-sterilized flask. Whereas the flask opened to air, the new organisms arose from the killed yeast.
5. Life originated on earth about _____
a) 8 billion years ago
b) 5 billion years ago
c) 4 billion years ago
d) 3 billion years ago
Explanation: Life originated on earth about 4 billion years ago. That is life appeared 500 million years after the formation of earth. First non-cellular forms of life originated 3 billion years ago.
6. What did Stanley Miller synthesize in his evolution experiment?
d) Amino acid
Explanation: Miller created a closed flask containing an electric discharge along with gases maintained at 800°C. It resulted in the formation of amino acids. They had similarity with meteorite content which indicated that life came from outer space.
7. Nucleoproteins were the first substance to give sign of ______
Explanation: Nucleoproteins are complex structured compounds which bonding between a nucleic acid and a protein. Nucleoproteins were the first compound to give sign of life. It had the property of self-duplication.
8. Life first originated in ______
Explanation: Life first originated in water. Whether cellular or acellular, life started in water environment only, millions of years ago. Water was formed from the reaction of active hydrogen and free oxygen atoms.
9. Miller and Urey had performed an experiment to prove the origin of life. They took gases H20 and CH4 along with _______
a) N2 and H2O
b) NH3 and H2
c) CH4 and N2
d) CO2 and NH3
Explanation: Miller took a mixture of water, methane, ammonia and hydrogen in a closed flask at 800°C. It was done in a closed flask and using electric discharge tubes, and later observed the formation of amino acids.
10. It is due to the phenomenon Big bang; the origin of life took place.
Explanation: Universe was created due to Big bang theory and not life. Life originated about 4 billion years ago whereas the Big bang took place about 20 million years back.
11. At what temperature was the flask maintained in Miller’s experiment?
Explanation: It was at 800°C in which the flask was maintained along with electric discharge. A moderately high temperature was required to keep the flask sterilized. Thus, creating amino acids as the product.
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