There were a lot of organisms A in the crop fields in an area. These organisms used to feed on organisms B also present in the crop fields but which damaged the standing crops. One day some people arrived in the fields and killed all the organisms A so that they could remove their C for making fancy items which were in great demand. Due to the large-scale killing of A, the population of B increased too much damaging all the crops in the area and causing a famine-like situation. Apart from A, there is another organism D which can also kill and eat B. Name A, B, C and D.

Q. In an agriculture field there is a prevalence of the following organism and crop disease which are affection the crop yield badly ________________.

Q. In a village, farmers started cultivating crops all around a lake which was always filled with water. They added lot of materials W to the soil in their fields to increase the yield of crops. Soon they found that the whole surface of water in the lake was covered with a green layer made up of tiny organisms X. After some time, the fish present in the lake started dying in large numbers because they could not get sufficient Y due to a process Z which had occurred in lake water and drained out all the Y present in the water of lake.
(a) What do you think materials W are?
(b) Name (i) X, and (ii) Y.
(c) What is the process Z known as?
(d) What happens during the process Z which uses up all the Y present in lake water?
(e) What does this example tell us about the use of materials like W?

Q.

Fill in the following blanks with suitable words :

(a) The same kind of plants grown and cultivated on a large scale at a place is called___

(b) The first step before growing crops is___of soil.

(c) For growing a crop, sufficient sunlight,___and___from the soil are essential.

(d) Damaged seeds would___on top of water.

(e) Crop rotation helps in the replenishment of soil with___

(f) The supply of water to crops at different intervals is called___

(g) The unwanted plants present in a crop field are called___

(h) Dried___ leaves are used for storing food grains at home.

(i) Many people living in the___areas consume fish as a major part of their diet.

Q.

A highly poisonous animal X which inhabits crop fields is commonly known as the friend of the farmer. It eats up pests like Y and saves the crops from damage. The animal X is killed in large numbers to obtain its Z which sells in the market at a high price. What are X, Y and Z?

Q. Inter-cropping pattern is another type of ........ 1.. ...... system in which .......... 2 ,.......... or ..........3.......... crops are grown .........4.......... on the same field but they are not ..........5.......... with each other. They are grown in a set pattern. For example, a few rows of ..........6.......... alternate with a few rows of, ..........7.......... in the total field area. Such type of ..........8.......... in which two or more ..........9.......... are grown in ..........10.......... rows is called ..........11.......... pattern. The crops selected for such type of pattern should have ..........12.......... types of ..........13.......... This will help the crops to .........14.......... maximum nutrients for the ........15.......... This pattern also prevents ..........16........ and diseases to ..........17........ in all ........18.......... of one crop in the field.