Short Answer TypeA male honeybee has 16 chromosomes whereas its female has 32 chromosomes. Give one reason.
Name a free-living and a symbiotic bacterium that serve as bio-fertilizer. Why are they called so?
Name the calls HIV (Human Immunodeficiency Virus) gains entry into after infecting the human body. Explain the events that occur in these cells.
Explain the relationship between CFCs and Ozone in the stratosphere.
CFCs find wide use as refrigerants. CFCs discharged in the lower part of atmosphere move upward and reach stratosphere. In stratosphere, UV rays act on them reacting with the Cl atoms. Cl atoms acts as catalysts and degrades ozone releasing molecular oxygen. Cl atoms are not consumed in the reaction. Hence whatever CFC are added to stratosphere, have permanent and continuing effects on ozone level. 
Following are the features of genetic codes. What does each one indicate ? [2]
Stop codon; Unambiguous codon; Degenerate codon; Universal codon.
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