Which method is commonly used for improving cattle breeds and why?
Cross breeding is a method commonly used for improving cattle breeds. It is a process in which indigenous varieties of cattle are crossed by exotic breeds to get a crossbreed which is high yielding. Cross breeding between two good varieties of cattle will produce a new improved variety. For example, the cross between foreign breeds such as Jersey Brown, Swiss (having long lactation periods) and Indian breeds such as Red Sindhi, Sahiwal (having excellent resistance power against diseases) produces a new variety having qualities of both breeds.
How do you differentiate between capture fishing, mariculture and aquaculture?
Explain any one method of crop production which ensures high yield.
How do good animal husbandry practices benefit farmers?
What are the desirable characters of bee varieties suitable for honey production?
How do plants get nutrients?
How are fish obtained?
What is genetic manipulation? How is it useful in agricultural practices?
What are the desirable agronomic characteristics for crop improvements?
What factors may be responsible for losses of grains during storage?
How do biotic and abiotic factors affect crop production?
Which of the following has more inertia: (a) a rubber ball and a stone of the same size? (b) a bicycle and a train? (c) a five-rupees coin and a one-rupee coin?
State the universal law of gravitation.
Which of the following are matter?
Chair, air, love, smell, hate, almonds, thought, cold, cold-drink, smell of perfume.
A force of 7 N acts on an object. The displacement is, say 8 m, in the direction of the force (Fig. 11.3). Let us take it that the force acts on the object through the displacement. What is the work done in this case?
What is meant by a pure substance?
How does the sound produced by a vibrating object in a medium reach your ear?
In a reaction, 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium observations are in agreement with the law of conservation of mass.
sodium carbonate + ethanoic acid → sodium ethanoate + carbon dioxide + water
What are canal rays?
State any two conditions essential for good health.
How is our atmosphere different from the atmospheres on Venus and Mars?
Name the technique to separate
(i) butter from curd,
(ii) salt from sea-water,
(iii) camphor from salt.
What are the various energy transformations that occur when you are riding a bicycle?
Make a comparison and write down ways in which plant cells are different from animal cells.
Convert into mole.
(a) 12 g of oxygen gas
(b) 20 g of water
(c) 22 g of carbon dioxide.
Suppose you and your friend are on the moon. Will you be able to hear any sound produced by your friend?
An artificial satellite is moving in a circular orbit of radius 42250 km. Calculate its speed if it takes 24 hours to revolve around the earth.
Explain why some of the leaves may get detached from a tree if we vigorously shake its branch.
If K and L shells of an atom are full, then what would be the total number of electrons in the atom?
Calculate the number of molecules of sulphur (S8) present in 16 g of solid sulphur.
Differentiate between homogeneous and heterogeneous mixtures with examples.