Explain any one method of crop production which ensures high yield.
One of the methods of crop production that ensures high yield is crop rotation. This method involves growing two or more varieties of crop in the same fertile land in a sequential and seasonal order in a definite pattern. A crop utilises some particular nutrients in larger quantities from the soil and thus the soil gets enriched in this process. Therefore, crops having different nutrient requirements are rotated. For example, legumes which have nitrogen-fixing bacteria in their root nodules supply the soil with nitrogen.
How do you differentiate between capture fishing, mariculture and aquaculture?
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?
Which method is commonly used for improving cattle breeds and why?
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?
An object has moved through a distance. Can it have zero displacement? If yes, support your answer with an example.
What are the immunisation programmes available at the nearest health centre in your locality? Which of these diseases are the major health problems in your area?
Explain the working and application of a sonar.
Classify each of the following as a homogeneous or heterogeneous mixture.
soda water, wood, air, soil, vinegar, filtered tea.
A ball is thrown vertically upwards with a velocity of 49 m/s. Calculate
(i) the maximum height to which it rises,
(ii) the total time it takes to return to the surface of the earth.
How is our atmosphere different from the atmospheres on Venus and Mars?
The following is the distance-time table of an object in motion:
Time in seconds Distance in metres
0 0
1 1
2 8
3 27
4 64
5 125
6 216
7 343
(a) What conclusion can you draw about the acceleration? Is it constant, increasing, decreasing, or zero?
(b) What do you infer about the forces acting on the object?
A trolley, while going down an inclined plane, has an acceleration of 2 cm s-2. What will be its velocity 3 s after the start?
The volume of a 500 g sealed packet is 350 cm3. Will the packet float or sink in water if the density of water is 1 g cm-3? What will be the mass of the water displaced by this packet?
How is a prokaryotic cell different from a eukaryotic cell?