Write the scientific name of the fruit-fly. Why did Morgan prefer to work with fruit-flies for his experiments ? State any three reasons.

(a) Write the scientific name of the organism Thomas hunt morgan and his colleagues worked with for their experiments .Explain the correction between linkage and recombination with respect to genes as studied by them (b) How did sturtevant expain gene mapping while working wiht morgan?

Write the scientific name of the microbe used for fermenting malted cereals and fruit juices.

Give the scientific name of the plant selected by Mendel for his experiments. State three laws given by him. Explain briefly the law of independent assortment with the help of an example. Define complementary genes. Explain it with the help of diagrammatic sketches.

Mendel did not get any linkage in his experiments on pea. One of reasons was that

Answer the following questions based on Meselson and Stahl's experiment of E. coli : (a) Write the name of the chemical substance used as the only source of nitrogen in the experiment. (b) Why did they allow the synthesis of the light and the heavy DNA molecules in the organism ? (c ) How did they distinguish the heavy DNA molecules from the light DNA molecules? Explain. (d) Write the conclusion the scientists arrived at, at the end of the experiment.

Answer the following questions based on Meselson and Stahl s experiment: (a) Write the name of the chemical substance used as a source of nitrogen in the experiment by them. (b) Why did the scientists synthesise the light and the heavy DNA molecules In the organism used in the experiment ? (c) How did the scientists make it possible to distinguish the heavy DNA molecule from the light DNA molecule ? Explain. ((1) Write the conclusion the scientists arrived at after completing the experiment.