Class Nine Science NCERT Solutions Chapter 15
Chapter 15: Improvement in Food Resources
Intext Questions (Page No. 204)
1. What do we get from cereals, pulses, fruits and vegetables?
Ans. Cereals (rice, wheat) give carbohydrates which provide energy.
Pulses (soya bean, pea, and gram) give proteins which build our body. Vegetables and Fruits provide vitamins and minerals, carbohydrates, fats and proteins.
Intext Questions (Page No. 205)
1. How do biotic and abiotic factors affect crop production?
Ans. Crop production can go down due to the effect of biotic factors like disease, insects, nematodes, etc. and abiotic factors like drought, salinity, waterlogging, heat, cold and frost.
2. What are the desirable agronomic characteristics for crop improvement?
Ans. The fodder crop should be tall with profuse branching while cereals crop should be dwarf so that they are more nutritive. Agronomic character helps to give higher productivity.
Intext Questions (Page No. 206)
1. What are macronutrients and why are they called macro-nutrients?
Ans. Thirteen essential nutrients required by the plants are supplied by the soil. Out of the six nutrients are required in large quantities. Since they are required in large quantities; they are called as macro-nutrients. They are:
(i) Nitrogen (ii) Phosphorus
(iii) Potassium (iv) Calcium
(v) Magnesium (vi) Sulphur
2. How do plants get nutrients?
Ans. Plants require sixteen essential nutrients for their growth. They are supplied by air, water and soil. Air supplies carbon and oxygen, hydrogen comes from water and soil supplies other thirteen nutrients to plants.
Intext Questions (Page No. 207)
1. Compare the use of manure and fertilizers in maintaining soil fertility.
Ans. Manure contains many organic substances of biological origin which can be easily degraded and absorbed by plants. It helps in recycling of biological waste. They increase the fertility of the soil without causing any harm. On the other hand, the chemical fertilizers improve soil fertility for a short duration but cause
an environmental hazard. By the continuous use of fertilizers, the soil becomes powdery, dry and rate of soil erosion increases.
Intext Questions (Page No. 208)
1. Which of the following conditions will give the most benefits? Why?
(a) Farmers use high – quality seeds, do not adopt irrigation or use fertilisers.
(b) Farmers use ordinary seeds, adopt irrigation and use fertilisers.
(c) Farmers use quality seeds, adopt irrigation, use fertiliser and use crop protection measures.
Ans. Condition (c) will give the most benefits because:
(i) Good quality seeds will give a good yield.
(ii) Irrigation methods will overcome droughts and flood situation.
(iii) The fertiliser will fulfil the nutrient requirements of the soil providing high yield.
Intext Questions (Page No. 209)
1. Why should preventive measures and biological control methods be preferred for protecting crops?
Ans. Field crops are harmed by a large number of weeds, insect pests and diseases. Preventive measures and biological control methods are preferred for protecting crops due to the following reasons:
(i) Weeds compete for food, space and light. They take up nutrients and reduce the growth of the crop. Hence, the removal of weeds is essential.
(ii) Insect pests affect the health of the crop and reduce its yield.
(iii) The pathogens such as bacteria, fungi and viruses cause diseases in the plants.
Thus, weeds, insect pests and pathogens should be controlled to get a proper yield of the crops.
2. What factors may be responsible for losses of grains during storage?
Ans. Foodgrains produced in our country are lost every year due to improper methods of storage and inadequate storage.
The various factors responsible for such loss during storage are :
(i) Biotic factors: They include insects, rodents, bacteria, fungi, mites, worms and birds.
(ii) Abiotic factors: They include inappropriate moisture, humidity in air and temperature in the place of storage. These factors cause poor quality, loss in weight, discolouration of produce, poor germinability and poor marketability of grains.
Intext Questions (Page No. 210)
1. Which method is commonly used for improving cattle breeds and why?
Ans. Cross-breeding is the most commonly used method for improving cattle breed. Because by this method the indigenous breeds can be made high-yielding by cross-breeding with exotic (foreign) ones. During cross-breeding, the desired characters are taken into consideration. The offspring should be high-yielding, should have early maturity and excellent resistance to diseases.
Intext Questions (Page No. 211)
1. Discuss the implications of the following statement:
‘it is interesting to note that poultry is India’s most efficient converter of low fibre foodstuff (which is unfit for human consumption) into highly nutritious animal protein food’.
Ans. The food consumed by poultry birds is very cheap and fibrous by agricultural by-products. In this way, the products, which are not used by humans are consumed by poultry birds and are converted into chicken, meat and egg which are highly nutritious and used by humans.
Intext Questions (Page No. 211)
1. What management practices are common in dairy and poultry farming?
Ans. Management practices include:
(i) Keeping the shelter well designed, ventilated and hygienic.
(ii) The animals and birds are given healthy food with balanced nutrition.
(iii) Both animals and birds must be protected from various diseases. The regular check-up should be done.
2. What are the differences between broilers and layer and in their management?
Ans. The poultry bird groomed for obtaining meat is called broiler. The egg-laying poultry bird is called layer. The housing, nutritional and environmental requirements of broilers are somewhat different from those of egg layers.
The daily food requirement for broilers is protein-rich with adequate fat. The level of vitamin A and K is kept high in the poultry fields while layers require enough space and proper lighting.
Intext Questions (Page No. 213)
1. How are the fish obtained?
Ans. There are two methods of obtaining fish.
(i) Capture fishing (ii) Fish farming (or culture fishery)
(i) Capture fishing: In this method, the fish are obtained, from natural resources such as freshwater resources (i.e., canals, ponds, reservoirs and rivers).
(ii) Fish farming: It is concerned with culturing, feeding, breeding and fish production. Mariculture and aquaculture are the two methods of fish farming.
2. What are the advantages of composite fish culture?
Ans. Advantages of composite fish culture are:
(i) Fish selected for this culture differ in their feeding habits.
(ii) All these species together use all the food in the pond without competing with each other.
(iii) This increase the fish yield from the pond.