Human Health and Disease — BIOLOGY STD 12 Science — Question

Which property of DNA double helix led Watson and Crick to hypothesise semi-conservative mode of DNA replication? Explain.

What is GMO? List any five possible advantages of a GMO to a farmer.

In relation to energy transfer in ecosystem, explain the statement "10kg of deer's meat is equivalent to 1kg of lion's flesh".

Unambiguous, universal and degenerate are some of the terms used for the genetic code. Explain the salient features of each one of them.

A number of passengers were severely burnt beyond recognition during a train accident. Name and describe a modern technique that can help hand over the dead to their relatives.

OR

Following the collision of two trains a large number of passengers are killed. A majority of them are beyond recognition. Authorities want to hand over the dead to their relatives. Name a modern scientific method and write the procedure that would help in the identification of kinship.

Two independent monohybrid crosses were carried out involving a tall pea plant with a dwarf pea plant. In the first cross, the offspring population had equal number of tall and dwarf plants, whereas in the second cross it was different. Work out the crosses, and explain giving reasons for the difference in the offspring populations.

In a series of experiments with Streptococcus and mice F. Griffith concluded that R-strain bacteria had been transformed. Explain.

Draw a diagram of a male gametophyte of an angiosperm. Label any four parts. Why is sporopollenin considered the most resistant organic material?

1. Explain the phenomena of multiple alleles and co-dominance taking ABOblood group as an example.
2. What is the phenotype of the following:

1. I^A i
2. i i

A tRNA is charged with amino acid phenylalanine:

1. At what end of the tRNA is the amino acid attached?
2. What is the mRNA codon that codes for phenylalanine?
3. Name the enzyme responsible for this attachment.