Give reason for the above statements. Who studied the phenomenon of linkage in Drosophila?
Explain the experiment carried out by Morgan in Drosophila to demonstrate linkage. What is the observation made by him in that experiment?

What are the conclusions drawn by T.H. Morgan from the crossing experiment in Drosophila with respect to linkage?

Two ideal gas thermometers A and B use oxygen and hydrogen respectively. The following observations are made: {:("Temperature","Pressure","Pressure"),(,"thermometer A","thermometer B"),("Triple - point water",1.250 xx10^(5) Pa,0.200 xx 10^(5) Pa),("Normal melting point of sulphur",1.797 xx10^(5)Pa,0.287 xx10^(5)Pa):} (a) What is the absolute temperature of normal melting point of sulphur as read by thermometers A and B ? (b) What do you think is the reason behind the slight difference in answers of thermometers A and B ? (The thermometers are not faulty). What further procedure is needed in the experiment to reduce the discrepancy between the two readings ?

Carry out the following osmosis experi ment. Take four peeled potato to halves and scoop each one out to make potato cups one of these potato cups should be made from a boiled potato. Put each potato cup in a tray containing water . Now (a) Keep cup A empty (b) Put one teaspoon sugar in cup B ( c) Put one teaspoon sugar in the boiled potato cup D. Keep these for two hours . The observe the four potato cups and answer the following : M (i) Explain why water gathers in the hollowed portion of B and C . (ii) Why is potato A necessary for the experiment . (iii) Explain why water does not gather in the hollowed out portions of A and D.