N.C.E.R.T. Simplified

Ch. 5 The Fundamental Unit of Life Ch. 6 Tissues Ch. 15 Improvement in Food Resources

Q. List 2 demerits of the continuous use of fertilisers. A. 1. It can destroy the soil fertility because the organic matter in the soil is not replenished.       2. The microorganisms in the soil are harmed. Q. How do insects and pests damage crops? A. Generally, insect pests attack the plants in 3 ways-     1. They cut the root, stem, and leaves.     2. They suck the cell sap from various parts of the plant.     3. They bore into the stem and fruits. They thus affect the health of the crop and reduce yields. Q. How can insects pests in a crop plants and stored grains be controlled? A. They can be controlled by-     1. By using pesticides ( herbicides and insecticides). These are sprayed on crop plants or used for treating soil and seeds.     2. By using resistant varieties of crops     3. By summer ploughing in which fields are ploughed deep in summers to destroy weeds and pests. Q. Define hybridization. List any 2 advantages. A. Hybridization refers to the