Some organisms suspend their metabolic activities to survive in unfavourable conditions. Explain with the help of any four examples.

(a) State the role of DNA ligase in biotechnology.

13.

Draw a schematic diagram of a part of double stranded dinucleotide DNA chain having all the four nitrogenous bases and showing the correct polarity. 

Name of parasite the causes filariasis in humans. Mention its two diagnostic symptoms. How is this transmitted to others? 

Name the source of streptokinase. How does this bioreactor molecule function in our body?

How do mycorrhizae act as biofertilizers? Explain. Name a genus of fungi that forms a mycorrhizal association with plants.

(a) State the difference between meiocyte and gamete with respect to chromosome number.

Explain the work carried out by Cohen and Boyer that contributed immensely in biotechnology. 

Where is sporopollenin present in plants? State its significance with reference to its chemical nature. 

It is established that RNA is the first genetic material. Explain giving three reasons.