Biology: Evolution of Life

Total Questions: 23

11. Match List-I with List-II and select the correct answer using the codes given below: [I.A.S. (Pre) 1998]

List-I	List-II
A. Theory of mutation	1. Beadle and Tatum
B. Theory of evolution	2. Jacob and Monod
C. One gene one enzyme hypothesis	3. Darwin
D. Operon concept	4. De Vries

	A	B	C	D
(a)	3	4	1	2
(b)	4	3	1	2
(c)	4	3	2	1
(d)	3	4	2	1

Correct Answer: (b)

Solution:Theory of mutation - De Vries
Theory of evolution - Darwin
One gene one enzyme hypothesis - Beadle and Tatum
Operon concept - Jacob and Monod

12. The main factor of evolution is — [39th B.P.S.C. (Pre) 1994]

(a) Mutation
(b) Achieved quality
(c) Sexual reproduction
(d) Natural selection

Correct Answer: (d) Natural selection

Solution:According to Darwin's theory of evolution, natural selection is one of the basic mechanisms of evolution. It refers to the process where organisms with traits better suited to their environment are more likely to survive and reproduce, passing those advantageous traits on to their offspring. While natural selection is a central mechanism, other evolutionary processes like mutation, genetic drift, and gene flow also play a role in shaping populations and the evolutionary process.

13. In the context of organic evolution, the loss of limbs in snakes is explained by the phenomenon of : [I.A.S. (Pre) 2002]

(a) Use and disuse of organs
(b) Adaptation to living in burrows
(c) Natural selection
(d) Inheritance of acquired characters

Correct Answer: (a) Use and disuse of organs

Solution:Lamarckism (or Lamarckian inheritance) is the idea that an organism can pass one characteristic that it acquired during its lifetime to its offspring (also known as inheritance of acquired character). It is named after Lamarck who incorporated the following two ideas into his theory of evolution, which are considered to be generally true:

Use and disuse of organs – Individuals lose characteristics which they do not require (or use) and develop characteristics that are useful.
Inheritance of acquired traits – Individuals inherit the acquired traits of their ancestors.
In the context of organic evolution as explained by Lamarck, the loss of limbs in snakes is explained by the phenomenon of the use and disuse of organs.

14. The reason of large-scale diversity among life organisms is- [56th to 59th B.P.S.C. (Pre) 2015]

(a) Adaptation
(b) Cooperation
(c) Mutation
(d) Polyploidy

Correct Answer: (c) Mutation

Solution:Three basic and three accessory factors have been recognized to provide genetic variability to the gene pool of a population. Amongst the basic factors, gene and chromosomal mutations have been recognized as the ultimate sources of biological changes and hence, the ultimate 'raw material' of evolution. Gene recombination, the third basic factor, then increases the variability of individual genotypes in a population.

15. Among living organisms, which one of the following is the most responsible factor for bringing about the origin of a new species? [I.A.S. (Pre) 2002]

(a) Isolation
(b) Mutation
(c) Mutation
(d) Natural selection

Correct Answer: (b) Mutation

Solution:In biology, a mutation is a permanent change of the nucleotide sequence of the genome of an organism, virus, or extra-chromosomal DNA or other genetic elements. Mutations result from damage to DNA which is not repaired or to RNA genomes (typically caused by radiation or chemical mutagens), errors in the process of replication or from the insertion or deletion of segments of DNA by mobile genetic elements. Mutations play a part in both normal and abnormal biological processes including evolution, cancer, and the development of the immune system. Among living organisms, it is the most responsible factor for bringing about the origin of a new species.

16. Latest ancestor of modern human is: [39th B.P.S.C. (Pre) 1994]

(a) Java man
(b) Cro-Magnon man
(c) Neanderthal man
(d) Peking man

Correct Answer: (b) Cro-Magnon man

Solution:Cro-Magnon is a common name that has been used to describe the first early modern humans. The earliest known remains of Cro-Magnon-like humans are radiocarbon dated to 43,000 years before. Cro-Magnons were robustly built and powerful. Their body was generally heavy and solid with a strong musculature. The face was short and wide. The chin was prominent. The brain capacity was about 1,600 cubic centimeters, larger than the average for modern humans. However, recent research suggests that the physical dimensions of so-called "Cro-Magnon" are not sufficiently different from modern humans to warrant a separate designation.

17. The word 'Denisovan' is sometimes mentioned in media in reference to : [I.A.S. (Pre) 2019]

(a) Fossils of a kind of dinosaurs
(b) An early human species
(c) An eye system found in North-East India
(d) A geological period in the history of the Indian subcontinent

Correct Answer: (b) An early human species

Solution:The Denisovans or Denisova hominins are an extinct species or subspecies of archaic human that ranged across Asia during the Lower and Middle Paleolithic. The first identification of a Denisovan individual occurred in 2010, based on mitochondrial DNA (mtDNA) extracted from a juvenile female finger bone excavated from the Siberian Denisova's Cave in the Altai Mountains in 2008. Nuclear DNA indicates close affinities with Neanderthals. Additional specimens from Denisovan's Cave were subsequently identified, as was a single specimen from the Baishiya Karst Cave on the Tibetan Plateau. DNA evidence suggests they had dark skin, eyes, and hair, and had a Neanderthal-like build and facial features. However, they had larger molars which are reminiscent of Middle to Late Pleistocene archaic humans and australopithecines.

18. Archaeopteryx is - [40th B.P.S.C. (Pre) 1995]

(a) Most ancient bird of Jurassic age
(b) Reptile of Jurassic period
(c) Reptile of Triassic period
(d) Reptile of both Triassic and Jurassic period

Correct Answer: (a) Most ancient bird of Jurassic age

Solution:Archaeopteryx is a connecting link between reptilia and aves. It is a creature in which we found the character of both reptiles and birds. Archaeopteryx, dating from about 150 million years ago during the Jurassic period when many dinosaurs lived, is one of the oldest-known birds. It is the first bird and modified from reptiles.

19. 'Archaeopteryx' is a connecting link between which of the following classes of animal? [R.A.S./R.T.S. (Pre) 2008]

(a) Amphibia and Aves
(b) Reptilia and Aves
(c) Reptilia and Mammalia
(d) Aves and Mammalia

Correct Answer: (b) Reptilia and Aves

20. Mammoth is the ancestor of- [R.A.S./R.T.S. (Pre) 2008]

(a) Dog
(b) Horse
(c) Camel
(d) Elephant

Correct Answer: (d) Elephant

Solution:Extinct mammoth is more closely related to today's African elephant or Asian elephant. Modern elephants and woolly mammoths share a common ancestor, that lived about 6 million years ago.

Genetic studies show that Asian elephants are more closely related to mammoths than African elephants. The split between the ancestor of mammoths and Asian elephants happened around 6 million years ago. African elephants diverged from this lineage earlier. The woolly mammoth (Mammuthus primigenius) evolved from steppe mammoths (Mammuthus trogontherii) in Asia, spreading to Europe and North America over time.

« Previous 123 Next »