If the concentration of salt in the soil is too high and the plants may wilt even if the field is thoroughly irrigated. Explain.

Soil showing permanetly wilted plants has:

A spherical conducting shell of inner radius r_(1) and outer radius r_(2) has a charge Q. a. A charge 'q' is placed at the centre of the shell. What is the surface charge density on the inner and outer of the shell? b. Is the electric field inside a cavity (with not charge) zero, even if the shell is not spherical, but has any irregular shape? Explain.

Ramu cultivated pea plants as an inter crop in his paddy field. After harvesting, he allowed the roots of the pea plants remain in the soil for some period. a. Is the action of Ramu reasonable? b. Justify your answer.

What are the three types of wilting in plants?Explain them breifly.

Read the given statements and select the correct option. Statement 1 : Irrigation without proper drainage of water leads to waterlogging in the soil. Statement 2 : Waterlogging draws salts to the soil surface, which are deposited as a thin crust on the land surface or start collecting at the roots of the plants.

(i) The sex of the new born child is a matter of chance and neither of the parents may be considered resposible for it. What would be the possible fusion of gametes to determine to sex of the child? (ii) A pure tall plant (TT) is crossed with pure dwarf plant (tt), what would be the F_(1) and F_(2) generations? Explain.

Answer the following questions . a. The earth's magnetic field varies from point is space. Does it also change with time ? It so , on what time scate does it change appreciably ? b. The earth's core is known to contain iron. Yet geologists do not regard this as a source of the earth's magnetism why ? c. The charged currents in the outer conducting regions of the earth's core are thought to be responsible for earth's magnetism . What might be the ' battery ' (i.e., the source of energy) to sustain these currents ? d. The earth may have even reversed the direction of its field several times during its history of 4 to 5 billion years. How can geologists know about the earth's field in such distant past ? e. The earth's field departs from its dipole substantially at large distances (greater than about 30,000 km) what agencies may be responsible for this distortion ? f. Interstellar space has an extremely weak magnetic field of the order of 10^(-12) T, Can such a weak field be of any significant consequence ? Explain. [Note : Exercise 2 is meant mainly to arouse your curiosity . Answers to some question above are tentative or unknown . Brief answers wherever possible are given at the end . For details , you should consult a good text on geomagnetism.]

a. The following are the important steps in plant breeding for developing a new plant variety. List them in the correct order: i. Seed multiplication ii. Release of a variety iii. Distribution iv. Evaluation v. Creation of genetic variation vi. Selection b. In spite of the proper application of fertilizers, irrigation and pest and disease control the yield, quality and disease and pest resistance of a self pollinated crop variety is decreasing generation after generation. Suggest a possible reason for this experience. Hint: The farmer is using seed collected from his own field for raising successive crops.