This set of Class 12 Biology Chapter 7 Multiple Choice Questions & Answers (MCQs) focuses on “Biological Evolution – 1”.
1. _________ is the evolution from coacervates to simple cell structure.
a) Chemical evolution
b) Biological evolution
c) Organic evolution
d) Inorganic evolution
View Answer
Explanation: The evolution starting from coacervates to the formation of a simple cell structure is known as Biological evolution. It is also called as Biogemy. This shows how cells originated during evolution.
2. Which of the following is related to protobionts?
a) Large colloidal drop like structures
b) Formed from micro molecules
c) Do not absorb molecules from the atmosphere
d) Does not contain proteins, nucleic acids, etc.
View Answer
Explanation: Macromolecules synthesized in primitive oceans came together to form large colloidal drop like structures called protobionts. They grew up by absorbing molecules from the atmosphere. They also contained proteins, nucleic acids, lipids, etc.
3. Protobiont was formed by a cluster of ______
a) micro molecules
b) nucleic acids
c) lipids
d) macro molecules
View Answer
Explanation: Each and every protobiont was formed by a cluster of macromolecules. The basic building blocks of protobionts is macromolecules. These molecules were synthesized abiotically in the primitive ocean.
4. Protobionts were unable to reproduce.
a) True
b) False
View Answer
Explanation: It is true that protobionts were unable to reproduce. It is because many chemical reactions such as decomposition of glucose took place inside the protobionts. This totally disallowed them to reproduce which was one of the drawbacks.
5. What were the first sole living molecules according to Oparin?
a) Diploid
b) Coacervates
c) Mycoplasma
d) Bacteria
View Answer
Explanation: The first sole living organisms were Coacervates. According to Oparin, these coacervates gave rise to a cell. Oparin’s coacervates had the ability to grow and exhibit a simple form of metabolism. But a lipid membrane and reproduction were absent.
6. Who discovered proteinoid microspheres with a primitive membrane?
a) Oparin
b) Haldane
c) Fox
d) Thomas
View Answer
Explanation: A scientist named Fox in 1957 discovered proteinoid microspheres which had a primitive membrane. In his research, he heated a mixture of amino acids at temperature 130 – 180°C and poured it into cold water with lipids. He found out that the microsphere got separated.
7. Who among the scientist did not prove that RNA molecules have enzymatic activity?
a) Zaug
b) Thomas Cech
c) Altman
d) Oparin
View Answer
Explanation: Zaug, Thomas Cech and Altman proved that RNA molecules have enzymatic activity. Ribozymes also called as RNA enzymes were able to replicate or produce primordial RNA. It was also believed that earth was an ‘RNA world’ about 4 billion years ago.
8. Life originated millions of years ago as ________
a) protobionts
b) eobionts
c) coacervates
d) bacteria
View Answer
Explanation: It was estimated about 3.9 billion years ago that, life originated as Eobionts (protocell). They evolved during the Precambrian era. They were anaerobic as well as heterotrophic in nature.
9. What was the mode of respiration for the prokaryotes during biological evolution?
a) Aerobic
b) Anaerobic
c) Cellular
d) External
View Answer
Explanation: These prokaryotes were single-celled and consisted of naked DNA. They were chemoheterotrophs. Dependent on surrounding materials for food and energy.
10. The organisms that perform chemosynthesis for survival are called _____
a) Chemoautotrophs
b) Chemoheterotrophs
c) Chemical organisms
d) Photoautotrophs
View Answer
Explanation: Chemoautotrophs are the organisms that perform chemosynthesis for food and survival. They produce organic molecules from inorganic molecules. They are anaerobic in nature.
11. What was utilized by photoautotrophs during photosynthesis when H2O was absent?
a) HF
b) HCl
c) H2S
d) H2N2
View Answer
Explanation: Photoautotrophs were anaerobic and utilized hydrogen from sources other than H2O like H2S. So, no oxygen was produced and the atmosphere was kept reducing. This type of photosynthesis was mainly done by planktonic sulfur bacteria.
Sanfoundry Global Education & Learning Series – Biology – Class 12.
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