Hybridisation refer to crossing between

Which of the following nutrients is not provided by soil to plants?

Which one of the following sets of plants includes weeds only?

Catla, Rohu and Mrigals constitute

Which one of the following is known as rock bee?

List the factors for which variety improvement is done.

How do biotic and abiotic factors affect crop production?

What are macro and micro-nutrients of Plants? Name two of each kind.

What are macro-nutrients and why are they called macro-nutrients?

Name four kinds of water resources available for irrigation.

What is a fertilizer? Name two fertilizers. How is it different from manure?

Compare manure and fertilizer in three points.

What desirable traits are focused to develop by cross-breeding indigenous and exotic breeds of fowl?

Mention any four desirable traits for which new varieties are produced?

Differentiate between layers and broilers.

Define crop rotation. How are crops selected for crop rotation?

Describe the factors responsible for grain loss during storage. Discuss the various measures for safe storage of grain.

What prevantive and control measures should be taken before storage of grains?

In large part of india most farmers use wells and tube wells for irrigation .There was a time when they used to dig very low to draw ground water.Now they have to dig more deep wells to tap water from the deeper strata and then lift water by pumps for iirrigation This is due to lowering of ground water level.Ground water level.Ground water is the rainwater that seeps through the soil and collects over non-porus rocks.
Think over the information given above and answer the following questions.
1. Why does ground water level is decreasing?
2. How can we recharge ground water level?
3. What can we do in this regard?