Human Health and Disease — BIOLOGY STD 12 Science — Question

When Morgan conducted dihybrid cross on Drosophila like Mendel did with pea plants, the F₂ ratio deviated significantly from that of Mendel's F, ratio. Write the explanation Morgan and his group gave to the observations they obtained from their experiment.

There are many animals that have become extinct in the wild but continue to be maintained in Zoological parks.

1. What type of biodiversity conservation is observed in this case?
2. Explain any other two ways which help in this type of conservation.

Three water samples namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant were subjected to BOD test. The samples were labelled A, B and C but the laboratory attendant did not note which was which. The BOD values of the three samples A, B and C were recorded as 20 mg/L, 8 mg/L and 400 mg/L respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?

Write the sex chromosomal complement of the following:

A couple where both husband and wife are producing functional gametes, but the wife is still unable to conceive, is seeking medical aid. Describe any one method that you can suggest to this couple to become happy parents.

Amazonian rain forest has the greatest biodiversity on earth. List any two hypothesis that are proposed by the biologists to account for the greater biological diversity.

What are biofertilizers? Name the two elements which are made available by them.

Poaching of tiger is a burning issue in today's world. What implication would this activity have on the functioning of the ecosystem of which the tigers are an integral part?

Co-extinction and introduction of alien species too are responsible for the loss of biodiversity. Explain, how.