Strategies for Enhancement in Food Reproduction — BIOLOGY STD 12 Science — Question

Write any four differences between bacteria and cyanobacteria.

A sugarcane plant has been affected by virus. How can a virus-free cane be developed from it? Explain the procedure.

Define a climax community. How does a sere differ from a seral community?

Name the host plant and its part that Meloidegyne incognita infects. Explain the role of Agrobacterium in the production of dsRNA in the host plant.

List all the wastes that you generate, at home, school or during your trips to other places, could you very easily reduce? Which would be difficult or rather impossible to reduce?

Why is pedigree analysis done in the study of human genetics? State the conclusions that can be drawn from it.

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?

What is geitonogamy? Give its one similarity to autogamy and xenogamy.

In an aquarium two herbivorous species of fish are living together and feeding on phytoplanktons. As per the Gause’s Principle, one of the species is to be eliminated in due course of time, but both are surviving well in the aquarium. Give possible reasons.

i. Construct a complete transcription unit with promotor and terminator on the basis of the hypothetical template strand given below.

ii. Write the RNA strand transcribed from the above transcription unit along with its polarity.