Organisms and Populations — BIOLOGY STD 12 Science — Question

How do cancer cells differ from normal cells?

At the time of Independence, the population of India was 350 million, which exploded to over 1 billion by May 2000. List any two reasons for this rise in population and any two steps taken by the government to check this population explosion.

What are recombinant proteins? How do bioreactors help in their production?

In a cross between two tall pea plants, some of the offsprings produced were dwarf. Show with the help of Punnett square how this is possible.

What is the contribution of biodiversity to medical field?

Name two fruits each with:

1. Fleshy pericarp and
2. Dry pericarp.

 

A relevant portion of β–chain of haemoglobin of a normal human is given below:

The codon for the sixth amino acid is GAG. The sixth codon GAG mutates to GAA as a result of mutation ‘A’ and into GUG as a result of mutation ‘B’. Haemoglobin structure did not change as a result of mutation ‘A’ whereas haemoglobin structure changed because of mutation ‘B’ leading to sickle shaped RBCs.

Explain giving reasons how could mutation ‘B’ change the haemoglobin structure and not mutation ‘A’.

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.

(a) Name the disease in which uncontrolled division of cells occurs, resulting in the formations of tumours. How is this disease detected?
(b) How do the interferons help in controlling the disease?

Sometimes a gene which carries a major disadvantage in homozygous state confers an advantage in heterozygous condition. Explain by giving suitable example.