NCERT Class X Science Class: Chapter –9. Heredity and Evolution – Part-8

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Long Answer Questions

Question 37:

Does geographical isolation of individuals of a species lead to? Formation of a new species? Provide a suitable explanation.

Answer:

Yes, geographical isolation gradually leads to genetic drift. This may impose limitations to sexual reproduction of the separated population. Slowly the separated individuals will reproduce among themselves and generate new variations. Continuous accumulation of those variations through a few generations may ultimately lead to the formation of a new species.

Image the geographical isolation

Image the Geographical Isolation

Image the geographical isolation

Question 38:

Bacteria have a simpler body plan when compared with human beings. Does it mean that human beings are more evolved than bacteria? Provide a suitable explanation.

Answer:

This is a debatable issue. If appearance of complexity is concurrent with evolution then, human beings are certainly more evolved than bacteria. But if we take the totality of life characteristics into account, then it is hard to label either organism as evolved.

Question 39:

All the human races like Africans, Asians, Europeans, and Americans and others might have evolved from a common ancestor. Provide a few evidences in support of this view.

Answer:

  • Common body plan, structure, physiology and metabolism

  • Constant chromosome number

  • Common genetic blue print

  • Freely inter-breeding

Question 40:

Differentiate between inherited and acquired characters. Give one example for each type.

Answer:

Characters that are passed on from parents to offspring are inherited characters e.g., colour of seeds, colour of eyes.

Characters appearing in an individual’s life time but cannot be transmitted to next generation are acquired characters e.g., obese body, loss of a finger in an accident.

Question 41:

Give reasons why acquired characters are not inherited.

Answer:

Acquired characters do not produce change in the DNA of germ cells, so they cannot be inherited. Only those characters which have a gene for them can be inherited.

Image the theory of evolution

Image the Theory of Evolution

Image the theory of evolution

Question 42:

Evolution has exhibited a greater stability of molecular structure when compared with morphological structures. Comment on the statement and justify your opinion.

Answer:

We see immense diversity in size, form, structure and morphological features in the living world. But at the molecular level these, diverse types of organism’s exhibit unbelievable similarity. For instance, the basic biomolecules like DNA, RNA, carbohydrates, proteins etc. exhibit remarkable similarity in all organisms.