Chapter 15 Improvement in Food Resources Solutions
Question - 1 : - What do we get from cereals, pulses, fruits and vegetables?
Answer - 1 : -
(i) Cereals provide us with carbohydrates. Also, they are a rich source of energy.
(ii) Pulses give us proteins.
(iii) Fruits and vegetables are a rich source of vitamins and minerals. A small amount of proteins, carbohydrates, and fats are also present in them.
Question - 2 : - How do biotic and abiotic factors affect crop production?
Answer - 2 : -
A variety of biotic factors such as pests, nematodes, diseases, etc. can reduce the net crop production. A pest causes damage to agriculture by feeding on crops. For example, boll weevil is a pest on cotton. 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.
Similarly, abiotic factors such as salinity, temperature, etc. affect the net crop production. Some natural calamities such as droughts and floods are unpredictable. Their occurrence has a great impact on crops sometimes, destroying the entire crop.
Question - 3 : - What are the desirable agronomic characteristics for crop improvements?
Answer - 3 : -
The desirable agronomic characteristics for crop improvements are:
(i) Tallness and profuse branching in any fodder crop.
(ii) Dwarfness in cereals.
These desirable agronomic characteristics help in increasing crop productivity.
Question - 4 : - What are macro-nutrients and why are they called macro-nutrients?
Answer - 4 : -
Macro-nutrientsare nutrients required in relatively large quantities for growth and development of plants. They are six in number. Since they are required in large quantities, they are known as macro-nutrient. The six macro-nutrients required by plants are nitrogen, phosphorus, potassium, calcium, magnesium, and sulphur.
Question - 5 : - How do plants get nutrients?
Answer - 5 : -
Plants require sixteen essential nutrients from nature for their growth and development. All these nutrients are obtained from air, water, and soil. Soil is the major source of nutrients. Thirteen of these nutrients are available from soil. The remaining three nutrients (carbon, oxygen, and hydrogen) are obtained from air and water.
Question - 6 : - Compare the use of manure and fertilizers in maintaining soil fertility.
Answer - 6 : -
Manures increase soil fertility by enriching the soil with organic matter and nutrients as it is prepared by the decomposition of animal excreta and plant wastes. On the other hand, fertilizers are mostly inorganic compounds whose excessive use is harmful to the symbiotic micro-organisms living in soil. Their excessive use also reduces soil fertility. Hence, fertilizers are considered good for only short term use.
Question - 7 : - Which of the following conditions will give the most benefits? Why?
(a) Farmers use high-quality seeds, do not adopt irrigation or use fertilizers.
(b) Farmers use ordinary seeds, adopt irrigation and use fertilizer.
(c) Farmers use quality seeds, adopt irrigation, use fertilizer and use crop protection measures.
Answer - 7 : -
Option (c) will give the most benefits because use of good quality seeds is not only sufficient until the soil is properly irrigated, enriched with fertilizers and protected from biotic factors.
Question - 8 : - Why should preventive measures and biological control methods be preferred for protecting crops?
Answer - 8 : -
Preventive measures and biological control methods should be preferred for protecting crops because excessive use of chemicals leads to environmental problems. These chemicals are also poisonous for plants and animals. Preventive measures include proper soil and seed preparation, timely sowing of seeds, intercropping and mixed cropping, usage of resistant varieties of crops, etc. 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 thuringenesis,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.
Question - 9 : - What factors may be responsible for losses of grains during storage?
Answer - 9 : -
During the storage of grains, various biotic factors such as insects, rodents, mites, fungi, bacteria, etc. and various abiotic factors such as inappropriate moisture, temperature, lack of sunlight, flood, etc. are responsible for losses of grains. These factors act on stored grains and result in degradation, poor germinability, discolouration, etc.
Question - 10 : - Which method is commonly used for improving cattle breeds and why?
Answer - 10 : -
Cattle farming is commonly used for improving cattle breeds. The purpose of cattle farming is to increase the production of milk and draught labour for agricultural work. Dairy animals (females) are used for obtaining milk and draught animals (males) are engaged in agricultural fields for labour work such as carting, irrigation, tilling, etc. Cross breeding between two good varieties of cattle will produce a new improved variety. For example, the cross between foreign breeds such as Jersey Brown, Swiss (having long lactation periods) and Indian breeds such as Red Sindhi, Sahiwal (having excellent resistance power against diseases) produces a new variety having qualities of both breeds.