NCERT Solutions for Class 9 Science Chapter 15 - Improvement in Food Resources

Question 1:

What do we get from cereals, pulses, fruits and vegetables?


We get carbohydrates from cereals, proteins from pulses, vitamins and minerals from fruits and vegetables.

Question 2:

How do biotic and abiotic factors affect crop production?


Biotic factors such as diseases and insects, and abiotic factors such as drought, salinity, heat, cold results in decrease of crop production.

Question 3:

What are the desirable agronomic characteristics for crop improvement?


Desirable agronomic characteristics in crop plants give higher yield. It varies from crop to crop. Desirable characters for fodder crops are tallness and profuse branching. For cereal crops, dwarfism is a desired character so that fewer nutrients are consumed by these crops. For crops such as cotton, long fibres and high fibre strength are important.

Question 4:

What are macronutrients and why are they called macronutrients?


Macronutrients are the chemical elements required by plants in large amounts. Macronutrients are carbon, hydrogen, oxygen, nitrogen, potassium and sulphur. They are called macronutrients because they are required in large quantities.

Question 5:

How do plants get nutrients?


Plants get nutrients from air, water and soil. Nutrients are also absorbed by the roots of plants from the soil. The absorbed water is transported by the tissue throughout the plant body. Air provides carbon, hydrogen and oxygen to plants.

Question 6:

Compare the use of manure and fertilisers in maintaining soil fertility.


Manure is rich in organic matter but is poor supplier of nutrients. Hence, a cultivated field supplied only with manure suffers from deficiency of nutrients and does not give good yield. A cultivated field supplied only with fertilisers faces drainage problem and water logging due to lack of organic matter in the soil. This may harm the crop and reduce the yield. Use of fertilisers over long periods of time destroys the soil structure by killing soil microorganisms that recycle nutrients in the soil.

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 fertilisers.
(b) Farmers use ordinary seeds, adopt irrigation and use fertiliser.
(c) Farmers use quality seeds, adopt irrigation, use fertiliser and use crop protection measures.


Conditions given in option (c) are the most beneficial for farmers due to the following reasons:
1. Quality seeds will provide plants with desirable characters such as disease resistance and higher yield.
2. Proper irrigation methods fulfil water requirement of crops at the appropriate time.
3. Fertilisers provide required nutrients to the growing crops.
4. Crop protection measures check loss of produce.

Question 8:

Why should preventive measures and biological control methods be preferred for protecting crops?


Preventive measures and biological control are not harmful to crops as well as to the environment. They are ecologically safe, target specific and harmless to other organisms.

Question 9:

What factors may be responsible for losses of grains during storage?


(a) Biotic factors such as insects, fungi, bacteria, rodents, birds, mites, etc.
(b) Abiotic factors such as inappropriate moisture content and temperature in the place of storage.

Question 10:

Which method is commonly used for improving cattle breeds? Why?


Artificial insemination is commonly used for improving cattle breeds. This method is used due to the following reasons:
(a) Several cows (about 300) can be inseminated by the semen of a single bull of good variety.
(b) It avoids transportation of animals.
(c) Semen of superior quality (desired) bulls can be stored at freezing temperature for long period. Further it can be transported to remote parts of the country.

Question 11:

Discuss the implications of the following statement:
“It is interesting to note that poultry is India’s most efficient converter of low fibre food stuff (which is unfit for human consumption) into highly nutritious animal protein food.”


It means that India has the fifth largest poultry farming industry. Chickens feed on cracked grains of wheat, barley, jawar, bajra, etc. They also eat bone meal, waste meat meal, etc., which is not of much use for human beings. Hence, chickens are mainly raised on low fibre food, which is unfit for human consumption. Poultry provides both eggs and meat, which are rich source of proteins.

Question 12:

What management practices are common in dairy and poultry farming?


(a) Proper housing and hygienic conditions
(b) Vaccination for prevention of infectious diseases
(c) Selection of good quality breeds
(d) Enough space, proper light intensity and duration and maintenance of adequate temperature
(e) Proper feeding management

Question 13:

What are the differences between broilers and layers and what is the difference in their management?


Broilers are domestic fowls raised for meat production. Broilers are fed with protein, fat and vitamin-A and vitamin-K rich feed for good growth rate.
Layers are hens, which start laying eggs at the age of around 20 weeks. Layers require enough space, proper light intensity and duration for laying eggs. Layers are usually fed with feed containing normal proportions of all nutrients

Question 14:

How fishes are obtained?


Fishes are obtained by capture and culture fisheries. In capture fisheries, fishes are caught from natural water bodies (both freshwater and marine). In culture fisheries, fishes are reared in artificial water resources.

Question 15:

What are the advantages of composite fish culture?


Composite fish culture is done by a combination of five or six fish species in a single fish pond. The species are selected on the basis of food habits so that they do not compete for food among themselves. As a result, the food available in all parts of the pond is utilised without competing with each other. In fact, fishes help in each other’s growth. This increases the fish yield from the pond.

Question 16:

What are the desirable characters of bee varieties suitable for honey production?


Desirable characters in bee varieties for honey production are:
(a) They should be able to produce a large amount of honey.
(b) They should have good breeding capacity and prolific egg production.
(c) They should stay in beehives for a longer time.
(d) They should have good defence mechanism.

Question 17:

What is pasturage and how is it related to honey production?


Pasturage includes all those plants which provide pollen grains and nectar to honey bees. It includes mango, neem, jamun, coconut, rose, maize, sorghum, sunflowers, etc. The quality and taste of honey depends upon the nature of flora from which the nectar is collected. To get high yield of honey, the bee keeping area must have a good pasturage with longer honey flow period.

Question 18:

Explain any one method of crop production which ensures high yield.


A high-yielding crop production method is intercropping. In this method, two or more crops are grown simultaneously on the same field in a definite pattern—a few rows of one crop alternate with a few rows of the second crop. The crops selected are such that their nutrient requirements are different. This ensures maximum utilisation of the nutrients supplied. It also prevents pests and diseases from spreading to all the plants belonging to one crop in a field.

Question 19:

Why are manure and fertilisers used in fields?


Manure and fertilisers supply essential nutrients to the soil and improve the texture of the soil. Therefore, they help in good vegetative growth, giving rise to healthy plants that give high crop production.

Question 20:

What are the advantages of intercropping and crop rotation?


Advantages of intercropping:
(a) It provides additional income yield per unit area and minimises chances of crop failure.
(b) Maintains soil fertility
(c) Controls weeds and reduces soil runoff.
(d) Both the crops can be harvested and threshed separately
Advantages of crop rotation:
(a) Improves soil fertility
(b) Reduces pest infestation and diseases
(c) Helps in weed control
(d) Improves soil texture

Question 21:

What is genetic manipulation? How it is useful in agricultural practices?


Genetic manipulation is defined as the process of transferring desirable genes such as profuse branching in fodder crops, high yield in grain crops, short maturity period, tolerance, etc. from one plant to another. Genetic manipulation is done through hybridisation or by introducing a desired gene.
It is useful in agricultural practices due to the following: (a) It helps in increasing yield and quality of crops. (b) It provides varieties that are better adapted to adverse environmental condition and have desirable features.

Question 22:

How do storage grain losses occur?


The loss of storage grains occur due to biotic and abiotic factors. Abiotic factors include moisture and unfavourable temperature. Biotic factors include insects, rodents, birds, mites and bacteria.

Question 23:

How do good animal husbandry practices benefit farmers?


Animal husbandry is the scientific management and care of farm animals. It also includes developing genetic qualities and behaviour that are advantageous to human beings. It benefits farmers by:
(a) Producing improved breeds of domestic animals
(b) Increasing production of animal-based products such as milk, egg and meat
Healthy farm animals that provide good yield of commercially-viable products leads to increased income and opportunities of growth for farmers.

Question 24:

What are the benefits of cattle farming?


(a) Cattle farming provides farmers with milk that can be used personally or sold commercially to earn extra income.
(b) It provides good quality meat, fibre and hide.
(c) It also provides good breed of draught animals.

Question 25:

For increasing production, what is common in poultry, fisheries and bee keeping?


Scientific rearing of these animals, introduction of exotic breeds and cross breeding are common practices that help increase production in poultry, fisheries and bee keeping.

Question 26:

How do you differentiate between capture fishing, mariculture and aquaculture?