Microbes in Human Welfare — BIOLOGY STD 12 Science — Question

Recall the experiments done by Frederick Griffith, Avery, MacLeod and McCarty, where DNA was speculated to be the genetic material. If RNA, instead of DNA was the genetic material, would the heat killed strain of Pneumococcus have transformed the R-strain into virulent strain? Explain.

What is biodiversity? Why is it a matter of concern now?

While creation and presence of variation is directionless, natural selection is directional as it is in the context of adaptation. Comment.

Three water samples namely river water, untreated sewage water and Secondary effluent discharged from Sewage treatment plant were subjected to BOD test. The samples were labelled in 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, 8mg/L and 400mg/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?

Match Ten modern animals with their ancient fossils using internet resources. Name both.

 In which phase of menstrual cycle is corpus luteum formed?

Explain about Commensalism.

Comment on the statement that "evolution and natural selection are end result or consequence of some other processes but themselves are not processes".

What is a cistron? Why is the structural gene in a transcription unit of eukaryotes called monocistronic and that in prokaryotes/bacteria called polycistronic? Give reasons.

Comment on the utility of variability in number of tandem repeats during DNA finger printing.