Question Set B

cbse 12th Standard Biology Evolution Important Questions And Answers Study Material - QB365

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Questions:

Assertion and reason

25 x 1 = 25

Assertion: We have lost all the direct evidence of origin of life.
Reason: The persons responsible for protecting evidences were not skilled.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

Assertion : The first molecules formed for replicating cells were most probably RNA.
Reason : This was proved by origin of ribozyme T. Cech in Tetrahymena.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

Assertion: The first cells used RNA as their hereditary molecule.
Reason: DNA evolved from RNA.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

Assertion : Coacervates are believed to be the precursors of life.
Reason : Coacervates were self-duplicating aggregates of proteins surrounded by lipid molecules.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

Assertion : Darwin’s finches show a variety of beaks suited for eating large seeds, flying insects and cactus seeds.
Reason : Ancestral seed-eating stock of Darwin’s finches radiated out from South America main land to different geographical areas of the Galapagos Islands, where they found competitor-free new habitats.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

Assertion : Stanley Miller could work on experimental evidence of origin of life because of Harold Urey.
Reason : H. Urey was geochemist, cosmo chemist and teacher of S. miller.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

Assertion: Primitive atmosphere was of reducing type.
Reason: First hydrogen atoms combined with all oxygen.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

Assertion: Louis Pasteur showed that in flask open to air, new living organisms appeared in the heat killed yeast culture.
Reason: Life arises from pre-existing life.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

Assertion: Theory of chemical evolution proposed that life comes from pre-existing non-living organic molecules
Reason: The primitive earth conditions led to production of organic molecules.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

10.

Assertion : The primitive atmosphere was reducing once i.e., without oxygen.
Reason : In the primitive atmosphere, oxygen was involved in forming ozone.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

11.

Assertion : Milky way is the galaxy in the universe.
Reason : Our Earth is part of milky way.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

12.

Assertion : Big-bang theory is based on studies of Sir James Jeans.
Reason : He gave the theory of steady state.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

13.

Assertion : According to big-bang hypothesis about 20 billion years ago universe was a big ball of only neutrons.
Reason : Movement of these particles is known to generate tremendous heat which caused explosion due to temperature and pressure changes.
Codes:
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) If Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.

14.

Assertion: The first formed Earth originally had reducing atmosphere.
Reason: Hydrogen was abundant and their was no free oxygen.
Codes:
A. Assertion and reason both are correct and reason is the correct explanation of Assertion.
B. Assertion and reason both are correct and reason is not the correct explanation of Assertion.
C. Assertion is correct but reason is wrong.
D. Both Assertion and Reason are false.

15.

Assertion (A) : Hugo de Vries said mutations cause speciation
Reason (R) : Mutations are slow directional changes
(a) lf both A and R are true and R is the correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

16.

Assertion (A) : Variation due to mutation. recombination or gene flow results in changed frequency of genes and alleles in progeny
Reason (R) : This would results in speciation
(a) lf both A and R are true and R is the correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

17.

Assertion (A) : Nature selects for fitness.
Reason (R) : The organism with better adaptive mechanisms and reproductive capacity get selected by nature.
(a) lf both A and R are true and R is the correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

18.

Assertion (A) : Whales and mammals share similarities in the pattern of bones of forelimbs.
Reason (R) : These organisma suggest occurrence of divergent evolution.
(a) lf both A and R are true and R is the correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

19.

Assertion (A) : Ernst Haeckel supported the embryological similarities as an evidence of evolution
Reason (R) : The embryos of all vertebrates including humans develop a row of vestigial gill slits which are absent in adult vertebrates
(a) lf both A and R are true and R is the correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

20.

Assertion (A) : Whales, bats, cheetah and humans, share similarities in the pattern of bone of forelimbs, although they perform different functions in them
Reason (R) : The same structures developed along different directions dur to adaptations to different needs.
(a) lf both A and R are true and R is the correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

21.

Assertion (A) : Microspheres were aggregates of organır biomolecules surrounded by film of water molecule.
Reason (R) : Coacervates lack definite membrane, but exhibit some life like characters
(a) lf both A and R are true and R is the correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

22.

Assertion (A) : The first form of life arose gradually through evolutionary forces from non-living molecules
Reason (B) : This is called as alnogenesis
(a) lf both A and R are true and R is the correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

23.

Assertion (A) : Roth living and non-living objects were formed simultaneously.
Reason (R) : Richter proposed the theory of rosmozone origin in 1865
(a) lf both A and R are true and R is the correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

24.

Assertion (A) : He is also called handy man.
Reason (R) : Heaps of tools found with these fossils included sharpened stones.
(a) lf both A and R are true and R is the correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

25.

Assertion (A) : Common ancestor of ferns, conifers and seed ferns in Psilophyton.
Reason (B) : The common ancestor of Psilophyton and seed fern is chlorophyte
(a) lf both A and R are true and R is the correct explanation of A
(b) If both A and R are true, but R is not the correct explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true

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Answers Key:

Assertion and reason

25 x 1 = 25

(c) If Assertion is true but Reason is false.
Explanation:
We have lost all the direct evidences of origin of life only due to destruction of fossils on account of climatic changes and not due to any person/(s).

(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation:
The first molecules formed for replicating cells were RNA. It was proved by T.Cech in Tetrahymena thermophyla. He discovered that an unprocessed RNA molecule could splice itself.

(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
Explanation:
The RNA world is proposed as the first stage in the evolution of life in which RNA catalysed all molecules necessary for survival and replication. If the first cells used RNA as their hereditary molecule, DNA evolved from an RNA template. DNA probably did not evolve as a hereditary molecule until RNA based life became enclosed in a membrane. Once cells evolved, DNA probably replaced RNA as the genetic material for most organisms.

(d) If both Assertion and Reason are false.
Explanation:
Coacervates are large colloidal aggregates formed due to intermolecular attraction from large organic molecules synthesized abiotically on primitive earth. It mainly consists of proteins, polysaccharides and water. They do not fulfill the requirement for probable precursors of life. A coacervate is a tiny spherical droplet of assorted organic molecules which is held together by hydrophobic forces from a surrounding liquid. Coacervates possess osmotic properties and form spontaneously from certain dilute organic solutions. They were even once suggested to have played a significant role in the evolution of cells and, therefore, of life itself. They are interesting not only in that they provide a locally segregated environment but also in that their boundaries allow the selective absorption of simple organic molecules from the surrounding medium. Coacervates do not have lipid outer membrane, hence they cannot reproduce.

(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.

(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation:
The Miller-Urey experiment, conducted by chemists Stanley Miller and Harold Urey in 1953, is the classic experiment on the origin of life. It established that the early Earth atmosphere, as they pictured it, was capable of producing amino acids, the building blocks of life, from inorganic substances.

(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
The interstellar dust from which earth originated was especially rich in hydrogen. It readily combine with nitrogen forming ammonia, with carbon forming methane, and with oxygen forming water leaving no free oxygen. Thus, early atmosphere of primitive earth was strongly reducing, it contains hydrogen, methane, ammonia and water vapors.

(b) If both Assertion and Reason are true but Reason is not the correct

(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
Explanation
The primitive earth conditions were so that they led to the production of organic molecules like proteins, RNA, etc.

10.

(c) If Assertion is true but Reason is false.
Explanation:
The lightest atoms of nitrogen, carbon, etc. formed the primitive atmosphere. Hydrogen atoms were most numerous and most reactive in primitive atmosphere. Hydrogen atoms combined with all oxygen atoms to form water leaving no free oxygen. Thus primitive atmosphere was reducing (without free oxygen) unlike the present oxidizing atmosphere (with free oxygen).
Formation of ozone layer is the consequence of modern oxidizing atmosphere having plenty of free oxygen. As more oxygen accumulated in the atmosphere. Due to photosynthesis, ozone began to appear in the top layers.

11.

(d) If both Assertion and Reason are false.
Explanation:
After the evolution of universe the gases condensed under gravitation and formed the galaxies and Milky Way galaxy is a part of solar system from which the earth was supposed to be formed.

12.

(b) If both Assertion and Reason are true but Reason is not the correct
Explanation:
Steady State Theory was a theory proposed in twentieth-century cosmology to explain evidence that the universe was expanding, but still retain the core idea that the universe always looks the same. It was first proposed by Sir James Jeans in the 1920s.

13.

(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion
Explanation :
Big bang theory explains the origin of universe, according to this hypothesis about 20 billion years ago the universe was the big ball made up of neutrons. Its huge explosion due to its high temperature change in pressure, the universe was formed.

14.

A. Assertion and reason both are correct and reason is the correct explanation of Assertion.

15.

16.

(b) If both A and R are true, but R is not the correct explanation of A

17.

(a) lf both A and R are true and R is the correct explanation of A

18.

(a) lf both A and R are true and R is the correct explanation of A

19.

(a) lf both A and R are true and R is the correct explanation of A

20.