Important questions based on NCERT syllabus for Chapter 15 - Improvement in Food Resources:
Question-1: How do biotic and abiotic factors affect crop production?
Solution: 1. A variety of biotic factors such as pests, nematodes, disease etc. can reduce the net production.
2. A pest causes damage to agriculture by feeding on crops. For example, boll weevil is a pest on cotton.
3. It attacks the cotton crop, thereby reducing its yield. Weeds also reduce crop productivity by competing with the main crop for nutrients, light and space.
4. Abiotic factors such as salinity, temperature etc. affect the net crop production.
5. Some natural calamities like droughts and floods are unpredictable.
6. Their occurrence has a great impact on crops sometimes, destroying the entire crop.
Question-2: What do we get from cereals, pulses, fruits and vegetables?
Solution: (i) Cereals provide us with carbohydrates. Also they are a rich source of energy.
(ii) Pulses give us proteins.
(iii) Fruits are a rich source of vitamins and minerals.
(iv) Vegetables are also rich source of vitamins and minerals.
A small amount of proteins, carbohydrates and fats are also present in them.
Question-3: Why should preventive measures and biological control methods be preferred for protection of crops?
Solution: 1. Preventive measures and biological control methods should be preferred for protection of crops because excessive use of chemicals leads to environmental problems. These chemicals are also poisonous for plants and animals.
2. Preventive measures include proper soil and seed preparation, timely sowing of seeds, intercropping and mixed cropping, usage of resistant varieties of crops, etc.
3. On the other hand, biological control methods include the usage of bio-pesticides that are less toxic for the environment. An example of bio-pesticides is Bacillus thuringiensis, which is an insect pathogen that kills a wide range of insect larvae. Therefore, both preventive measures and biological control methods are considered eco-friendly methods of crop protection.