NCERT Solutions for Class 9 Science Chapter 12 Improvement in Food Resources

NCERT
SOLUTIONS
CLASS - 9th

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Book : Science Ncert Solutions | Chapter-15 Science

Class : 9th
Subject : Science
Chapter : 15
Chapter Name : IMPROVEMENT IN FOOD RESOURCES

Q1 What do we get from cereals, pulses, fruits and vegetables?

Answer. (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.

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Q1 How do biotic and abiotic factors affect crop production?

Answer. 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 �oods are
unpredictable. Their occurrence has a great impact on crops sometimes, destroying the
entire crop.

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Q2 What are the desirable agronomic characteristics for crop improvements?

Answer. 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.

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Q1 What are macro-nutrients and why are they called macro-nutrients?

Answer. Macro-nutrientsare nutrients required in relatively large quantities for growth

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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.

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Q2 How do plants get nutrients?

Answer. 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.

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Q1 Compare the use of manure and fertilizers in maintaining soil fertility.

Answer. 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.

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Q1 Which of the following conditions will give the most bene�ts? 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. (c)Farmers using good quality seeds, adopting irrigation, using fertilizers, and
using crop protection measures will derive most bene�ts.
(i) The use of good quality seeds increases the total crop production. If a farmer is using
good quality seeds, then a majority of the seeds will germinate properly, and will grow
into a healthy plant.
(ii) Proper irrigation methods improve the water availability to crops.
(iii) Fertilizers ensure healthy growth and development in plants by providing the
essential nutrients such as nitrogen, phosphorus, potassium, etc.
(iv) Crop protection measures include various methods to control weeds, pests, and
infectious agents. If all these necessary measures are taken by a farmer, then the overall

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production of crops will increase.

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Q1 Why should preventive measures and biological control methods be preferred for
protecting crops?

Answer. 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.

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Q2 What factors may be responsible for losses of grains during storage?

Answer. 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, �ood, etc. are responsible for losses of grains. These
factors act on stored grains and result in degradation, poor germinability, discolouration,
etc.

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Q1 Which method is commonly used for improving cattle breeds and why?

Answer. 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 �elds 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.

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Q1 . Discuss the implications of the following statement: “It is interesting to note that
poultry is India’s most ef�cient converter of low �bre food stuff (which is un�t for
human consumption) into highly nutritious animal protein food.”

Answer. Poultry in India is the most ef�cient converter of low �bre food stuff into highly
nutritious animal protein food. In poultry farming, domestic fowls are raised to produce
eggs and chicken. For this, the fowls are given animal feeds in the form of roughage,
which mainly consists of �bres. Thus, by feeding animals a �bre rich diet, the poultry
gives highly nutritious food in the form of eggs and chicken

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Q1 What management practices are common in dairy and poultry farming?

Answer. Common management practices in dairy and poultry farming are:
(i) Proper shelter facilities and their regular cleaning.
(ii) Some basic hygienic conditions such as clean water, nutritious food, etc.
(iii) Animals are kept in spacious, airy, and ventilated place.
(iv) Prevention and cure of diseases at the right time is ensured.

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Q2 What are the differences between broilers and layers and in their management?

Answer. Layersare meant for egg production, whereas broilers are meant for poultry
meat. Nutritional, environmental, and housing conditions required by broilers are
different from those required by egg layers. A broiler chicken, for their proper growth,
requires vitamin rich supplements especially vitamin A and K. Also, their diet includes
protein rich food and enough fat. They also require extra care and maintenance to
increase their survival rate in comparison to egg layers.

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Q1 . How are �sh obtained?

Answer. Fish can be obtained by two ways:
(i) Capture �shing: It is the process of obtaining �sh from natural resources.
(ii) Culture �shery: It is the practice of farming �shes. Farming can be done in both
freshwater ecosystem (which includes river water, pond water) and marine ecosystem.

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Q2 What are the advantages of composite �sh culture?

Answer. An advantage of composite �sh culture is that it increases the yield of �sh. In a
composite �sh culture, �ve or six different species are grown together in a single �sh
pond. Fishes with different food habitats are chosen so that they do not compete for food
among themselves. Also, this ensures a complete utilization of food resources in the
pond. As a result, the survival rate of �sh increases and their yield also increases.

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Q1 What are the desirable characters of bee varieties suitable for honey production?

Answer. Bee varieties having the following desirable characters are suitable for honey
production:
(i) They should yield high quantity of honey.
(ii) They should not sting much.
(iii) They should stay in the beehive for long durations.
(iv) They should breed very well.

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Q2 What is pasturage and how is it related to honey production?

Answer. Pasturage is the availability of �owers from which bees collect nectar and
pollen. It is related to the production of honey as it determines the taste and quantity of
honey.

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Q1 Explain any one method of crop production which ensures high yield.

Answer. Crop rotationis one of the methods of crop production that ensures high yield. It
is the method of growing two or more varieties of crops on the same land in sequential
seasons. A crop utilises some particular nutrients in larger quantities from the soil.
Then, if the same crop is grown in subsequent seasons those nutrients will get depleted
in the soil. Therefore, crops having different nutrient requirements are rotated. For
example, legumes which have nitrogen-�xing bacteria in their root nodules supply the
soil with nitrogen. Therefore, these legumes are rotated with nitrogen requiring cereals

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such as wheat and maize. This method reduces the need of fertilizers, thereby increasing
the overall yield of crops.

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Q2 Why are manure and fertilizers used in �elds?

Answer. Manures and fertilizers are used in �elds to enrich the soil with the required
nutrients. Manure helps in enriching the soil with organic matter and nutrients. This
improves the fertility and structure of the soil. On the other hand, fertilizers ensure a
healthy growth and development in plants. They are a good source of nitrogen,
phosphorus, and potassium. To get an optimum yield, it is instructed to use a balanced
combination of manures and fertilizers in the soil.

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Q3 What are the advantages of inter-cropping and crop rotation?

Answer. Inter-cropping and crop rotation both play an important role in increasing the
yield of crops. Inter-cropping helps in preventing pests and diseases to spread
throughout the �eld. It also increases soil fertility, whereas crop rotation prevents soil
depletion, increases soil fertility, and reduces soil erosion. Both these methods reduce
the need for fertilizers. It also helps in controlling weeds and controls the growth of
pathogens and pests in crops.

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Q4 What is genetic manipulation? How is it useful in agricultural practices?

Answer. Genetic manipulationis a process where the gene for a particular character is
introduced inside the chromosome of a cell. When the gene for a particular character is
introduced in a plant cell, a transgenic plant is produced. These transgenic plants exhibit
characters governed by the newly introduced gene.
For example, let us assume there is a wild plant that produces small fruits. If the gene
responsible for a larger fruit size is introduced in this plant, this plant becomes
transgenic, and starts producing larger fruits. Similarly, genes for higher yield, disease
resistance, etc. can be introduced in any desired plant. Therefore, gene manipulation
plays an important role in agricultural practices. It helps in improving crop variety. It
ensures food security and insect resistant crops. It also improves the quality and yield of
crops.

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Q5 How do storage grain losses occur?

Answer. The factors responsible for loss of grains during storage are:
1. Abiotic factors like moisture (present in foodgrains), humidity (of air) and
temperature.
2 Biotic factors like insects, rodents, birds, mites and bacteria.

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Q6 How do good animal husbandry practices bene�t farmers?

Answer. Cattle farming is one of the methods of animal husbandry that is most bene�cial
for farmers. Using this method, better breeds of draught animals can be produced. Such
draught animals are engaged in agricultural �elds for labour work such as carting,
irrigation, tilling, etc.

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Q7 What are the bene�ts of cattle farming?

Answer. Bene�ts of cattle farming:
(i) Good quality and quantity of milk can be produced.
(ii) Draught labour animals can be produced for agricultural work.
(iii) New variety that are resistant to diseases can be produced by crossing two varieties
with the desired traits.

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Q8 For increasing production, what is common in poultry, �sheries and bee-keeping?

Answer. The common factor for increasing production in poultry, �sheries, and bee
keeping is the proper management techniques that are to be followed. Regular cleaning
of farms is of utmost importance. Maintenance of temperature and prevention and cure
of diseases is also required to increase the number of animals.

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Q9 How do you differentiate between capture �shing, mariculture and aquaculture?

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Book : Science Ncert Solutions | Chapter-15 Science

Answer. Capture �shing – It is the method of obtaining �shes from natural resources.
Mariculture – It is the culture of marine �shes for commercial use.
Aquaculture – It involves the production of aquatic animals that are of high economic
value such as prawns, lobsters, �shes, crabs, etc.

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