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प्रश्न
What do you mean by vestigial structures? Name four vestigial organs found in man.
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उत्तर
1. Ill developed structures or structures which are of no use are sometimes found in both plants and animals. They are referred to as vestigial organs. The same organ may be functional in one organism but vestigial in another.
2. Vermiform appendix of man is one such organ. The reason could be that human ancestors were eating uncooked food with considerable amount of cellulose in it. The normal function of caecum and appendix
in mammals is the digestion of cellulose.
3. Man shows a number of other vestigial organs. About 100 have been named. A few examples are ear muscles, wisdom teeth, plica semilunaris (representing nictitating membrane of the eye), coccyx (reduced tail) etc.
4. In plants, the scale like leaves on the Indian pipe, a plant which has lost its chlorophyll and became saprophytic in nature, is vestigial.
5. There are certain flowers in which stamens do not bear anthers.
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संबंधित प्रश्न
(a) Select the homologous structures from the combinations given below:
(i) Forelimbs of whales and bats
(ii) Tuber of potato and sweet potato
(iii) Eyes of octopus and mammals
(iv) Thorns of Bougainvillea and tendrils of Cucurbita
(b) State the kind of evolution they represent.
(a) Select the analogous structures from the combination given below:
(i) Forelimbs of whales and bats
(ii) Eyes of octopus and mammals
(iii) Tuber of sweet potato and potato
(iv) Tuber of Bougainvillea and tendrils of Cucurbita
(b) State the kind of evolution they represent
Given below is the list of vegetables available in the market. Select from these the two vegetables having homologous structures:
Potato, sweet potato, ginger, radish, tomato, carrot, okra (Lady’s finger)
(A) Potato and sweet potato
(B) Radish and carrot
(C) Okra and sweet potato
(D) Potato and tomato
Find out from newspapers and popular science articles any new fossil discoveries or controversies about evolution.
Give the importance of fossil in support of organic evolution
Write a short note based on the information known to you.
Connecting link
“Appearance of melanised moths post-industrialisation in England is a classic example of evolution by natural selection.” Explain.
Choose the correct option of the following question:
Wings of Insect and Birds are examples of :
Define fossil.
The decaying process of C-14 occurs continuously in dead organisms only.
Give scientific reason.
Vertebrates have slowly originated from invertebrates.
Write a short note:
Embryological evidences
How do you differentiate homologous organs from analogous organs?
Select the correct statement.
Why do all the gametes formed in human females have an X chromosome?
Which of the following is used as an atmospheric pollution indicator?
Analogous organs arise due to ______.
What were the characteristics of life forms that had been fossilised?
How do we compute the age of a rock?
Explain natural selection with the example of industrial melanism.
