FREE NEET Biology Practice MCQ Test: Evolution Exercise 4 Questions Answers With Detailed Explanations [PDF]

Answer: (b)

A British scientist, J.B.S. Haldane, suggested that life originated from simple inorganic molecules. Two scientists, Stanley Miller and Harold Urey were the first to put to test, the Oparin - Haldane theory, in the year 1953. They created a condition similar to that of primitive earth (i.e. high temperature, volcanic storms, reducing atmosphere) containing ammonia ($NH_{3}$ ), water vapour ($H_{2}$O), hydrogen ($H_{2}$), methane ($CH_{4}$ ). They made electric discharge in a closed flask containing $CH_{4}$ , $NH_{3}$ , $H_{2}$ and water vapour at 800o C. As a result, some amino acids are formed.

Answer: (c)

Chemical evolution has two meanings and uses. The first refers to the theories of evolution of the chemical elements in the universe through nucleosynthesis. The second use of chemical evolution or chemosynthesis is as a hypothesis to explain how life might possibly have developed or evolved from non-life.

Answer: (a)

Answer: (a)

This is the definition of fitness.

Answer: (b)

Answer: (c)

Answer: (c)

Appearance of antibiotic-resistant bacteria is an example of pre-existing variation in the population. When a bacterial population encounters a particular antibiotic, those sensitive to it die. But some bacteria having mutations become resistant to the antibiotic. Soon, the resistance providing genes become widespread and the entire population becomes resistant to that particular antibiotic.

Answer: (d)

This option represents the incorrectly matched pair. It can be corrected as

Two mya Australopithecus probably lived in East African grasslands. Evidences show that they hunted with stone weapons but essentially ate fruits. Rest of the pairs are correct.

Answer: (b)

Answer: (c)

Answer: (a)

Answer: (d)

Answer: (b)

Variations during mutations of meiotic recombinationsare random and directionless. On the basis of Hugo deVries work, on evening primrose, It was stated that, it is mutation which causes sudden appearance of variations that results in speciation.

Mutations are sudden, heritable and persistant in successive generation. He contradicted Darwinian variations that are small and directional.

Answer: (b)

The random changes in gene frequencies in a population occurring by chance alone rather than by natural selection are called genetic drift or Sewall wright effect. The effects of genetic drift are most marked in very small isolated population, although it occurs in all populations.

Answer: (b)

Answer: (b)

Answer: (c)

Statements II and III are correct for natural selection. Statement I is incorrect and it can be corrected as Natural selection tends to increase the characters that inturn increases the chances of survival and reproduction of an organism.

Answer: (d)

In a stable population, for a gene with two alleles, 'A' (dominant) and 'a' (recessive), if the frequency of 'A' is p and the frequency of 'a' is q, then the frequencies of the three possible genotypes (AA, Aa and aa) can be expressed by the Hardy-Weinberg equation:

$p^2 + 2pq + q^2$ = 1

where $p^2$ = Frequency of AA (homozygous dominant) individuals

$q^2$ = Frequency of aa (homozygous recessive) individuals

2pq = Frequency of Aa (heterozygous) individuals

so, p = 0.6 and q = 0.4 (given)

∴ 2pq (frequency of heterozygote) = 2 × 0.6 × 0.4 = 0.48.

Answer: (c)

Answer: (c)