Biological Evolution, Its Mechanism & Evolution of Man

1 Mark Questions

1. What is 'saltation' according to de Vries? [Delhi 2014 c]

Ans. According to de Vries 'saltation' is single step large mutation that means mutation causes species formation

2.State the significance of Coelacanth in evolution. [Delhi 2012] or

Coelacanth was caught in 1938 in South Africa. Why is it very significant in the evolutionary history of vertebrates? [All India 2010 C]

Ans. The discovery of Coelacanth (lobe fins), first amphibians is significant as they prove that amphibians have evolved from fish-like organisms. Lobe fins were the ancestors of modern day frogs and salamanders

1. Name the common ancestor of the great apes and man. [All India 2011] Ans. Dryopithecus is the common ancestor of great apes and man.
2. Mention how is mutation theory of Hugo de Vries different from Darwin's theory of natural selection? [Foreign 2011]

Ans. Hugo de Vries theory It states that evolution occurs due to single step large mutations called saltation, whereas

Darwin's theory states that the speciation occurs gradually through a number of generations, with accumulation of minor variations.

1. What does Hardy-Weinberg equation p² +2pq + q² -1, convey?[Foreign 2011]

Ans.It indicates genetic equilibrium which means the allele frequencies in a population are stable and remain constant from generation to generation.

1. When does a species become founders to cause founder effect? [Foreign 2010]

Ans. When the change in the allele frequency is very different in the original drifted population, it becomes founder effect

1. Study the ladder of human evolution given above and answer the following questions.

(i)Where did Australopithecus evolve?

(ii)Write the scientific name of Java man. [Delhi 2010 C]

1.5 mya Java man Homo habilis more man like 2.0 mya Australopithecus-hunted with stones

Ans.(i)Australopithecus evolved in East African grasslands.

1. Java man - Homo erectus.

8.According to Hardy-Weinberg's principle, the allele frequency of a population remains constant. How do you interpret the change of frequency of alleles in a population? [All India 2009]

Ans. The change of frequency of alleles will be interpreted as resulting in evolution.

1. What causes speciation according to Hugo de Vries? [All India 2008 C]

Ans. According to Vries, single step large mutation (saltation) caused evolution.

10.Mention the key concepts about the mechanism of biological evolution/speciation according to

1. de Vries (ii) Darwin. [Delhi 2008 C]

Ans.(i) de Vries He said that mutation caused speciation and hence, called it saltation.

1. Darwin Branching descent and natural selection are the two key concepts of Darwin's theory of evolution

2 Marks Questions

1. Explain how natural selection operates in nature by taking an example of white winged and dark winged moths of England [2014 c]

Ans. In England, prior to industrialisation the tree trunks were covered with white lichens, and therefore white moths could survive and got protected from predators due to white colour, whereas black (a dark winged moths) could be easily identified due to dark colour and declined in numbers.

But as industrialisation progressed, the lichens were replaced by soot and dust particles and