Biotechnology and its Applications — BIOLOGY STD 12 Science — Question

Why are coral reefs not found in the regions from west Bengal to Andhra Pradesh but are found in Tamil Nadu and on the east coast of India?

A student on a school trip started sneezing and wheezing soon after reaching the hill station for no explained reasons. But on return to the plains, the symptoms disappeared. What is such a esponsecalled? How does the body produce it?

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?

A tRNA is charged with the amino acid methionine:

1. At what site in the ribosome will the tRNA bind?
2. Give the anticodon of this tRNA.
3. What is the mRNA codon for methionine?
4. Name the enzyme responsible for this binding.

Name the category of virus that carries reverse transcriptase? What is the purpose of this enzyme?

How does tobacco smoking lead to oxygen deficiency in human body?

Why are menstrual cycles absent during pregnancy.

How does the dead organic matter get decomposed in nature? Explain.

Why are cloning vectors necessary in cloning? Name any two such vectors that are used in experiment with E. coli.