This post provides you a complete solution of Chapter 12 Class 9th for Rajasthan Board of Secondary Education.
This post contains
all the main and important topics which have complete and detailed description.
Intext Questions
Answers of Questions on Page 141
Q.1 What do we get from
cereals, pulses, fruits and vegetables?
Ans.
The cereals provide us carbohydrates. The pulses give us
proteins and fruits and vegetables give us a range of
vitamins and minerals. Fruits and vegetables give
carbohydrates, protein fat and lots of fibres.
Answers
of Questions on Page 142
Q.1How do biotic and abiotic factors affect crop
production?
Ans.
Biotic factors are living organisms that affect crop
production-
i. By reducing crop productivity due to directly feeding on
them (e.g. insects, rodent)
ii.By causing disease (e.g. viruses, bacteria, fungi,
mycoplasmas etc.)
Abiotic factors are non-living components of
environment like water, temperature, light, cold, frost etc.
These affect crop production –
i. Water logging reduces aeration of soil which is harmful
to growth and functioning of roots.
ii. In drought, water is not available to meet the
requirement of the plants for transpiration, growth and
photosynthesis.
iii. Frost, cold and heat reduce metabolic activities and
are, therefore, harmful.
iv. These factors are also responsible for spoilage of food
grains during storage.
Q.2 What are the desirable agronomic characteristics for
crop improvement?
Ans.
The desirable agronomic characteristics for crop
improvement are following-
(i) Tallness and profuse branching for fodder crops.
(ii) Dwarfness in cereals, pulses, etc.
(iii) Number of flowers size of leaves and flowers etc.
Answers of Questions on Page 143
Q.1 What are macronutrients
and why are they called macro nutrients?
Ans.
The macronutrients are carbon, hydrogen oxygen,
nitrogen, phosphorus, potassium, magnesium and
sulphur. They are called macronutrients because they are
required by crop plants in larger amounts. Many macro
nutrients are required by plants for following functions-
Ø They
are constituents of protoplasm.
Ø Calcium
is present in cell wall
Ø Mg
is a constituent of chlorophyll.
Q.2 How do plants get
nutrients?
Ans.
Plants get nutrients from air, water and soil. Air is the
source of carbon and oxygen. Hydrogen is obtained from
water. The remaining 13 elements are obtained directly
from soil through root
absorption.
Answers of Questions on Page 144
Q.1 Compare the use of
manure and fertilizers in maintaining soil fertility.
Ans.
Manures enrich the soil with nutrients and
organic matter and increase soil fertility. The bulk of
organic matter in manures helps in improving the soil
texture. This increases the water holding capacity in
sandy soil. In clayey soils, the large quantities of organic
matter help in drainage and in avoiding water logging.
Fertilizers are nutrient specific and concentrated source
of nutrients. But their continuous use of chemical
fertilizers can destroy soil fertility because the organic
matter in the soil is not replenished and micro-organisms
in the soil
are harmed by the fertilizers used.
Answers of Questions on Page 145
Q.1 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
fertilizers.
(c) Farmers use seeds, adopt irrigation, use fertilizers and
use crop protection measures.
Ans.
The condition at (c) will give the most profit because all
these conditions are required for good crop production.
Farmers use High quality seeds, adopt irrigation, use
fertilizers, and crop protection methods. High quality
seeds germinate properly and grow to healthy plants.
Irrigation is essential for all vital processes of plants and
helps crop plants to fight against drought stress.
Fertilizers provide nutrients and crop protection measures
protect the plant from diseases.
Answers of Questions on Page 146
Q.1 Why should
preventive measures and biological control methods be preferred for protecting
crops?
Ans.
Plants are harmed if attacked by pests. Preventive
measures and biological control methods are preferred for
protecting crop plants because they not only prevent the
stored food materials from getting, spoiled, getting
infested by insects, bacteria and microorganisms.
Thesemethods prevents crops from chemicals which are
sometimes added to control the pests attacking stored
food grains. These chemical are toxic, some pesticide
lead to bio-magnification. Biological methods are eco
friendly.
Q.2 What factors may be
responsible for losses of grains during storage?
Ans.
The factors responsible for losses of grains during storage
are-
(i) Biotic factors: Bacteria, insect, fungi, birds, mites,
rodents.
(ii) Abiotic factors: Moisture, humidity and temperature.
Answers of Questions on Page 147
Q.1Which method is
commonly used for improving cattle breeds and why?
Ans.
Cross breeding is commonly used for improving cattle
breeds. Exotic breeds have higher milk yield and longer
lactation period as compared to desi breeds and the local
breeds are hardy and resistant to several diseases.
Therefore, they are crossed with each other.
There are two methods of cross breeding natural and
artificialinsemination. Artificial insemination is preferred
as frozen semen can be transported, required in small
quantity and protects the
cows from contagious diseases.
Answers of Questions on Page 148
Q.1 Discuss the implications of the following statement.
“It is interesting to note that poultry in India’s most
efficient converter of low fibre food stuff (which is unfit
for human consumption) into highly nutritious animals
protein food”.
Ans.
The low fibre food stuff (unfit for human consumption)
is the feed of fowl. They convert this nutrient poor feed
into nutrient rich food. When these fowls are consumed
by human as meat then it provides high nutritious animal
protein. For this reason, it is said that, “poultry is India’s
most efficient converter of low fibre food stuff into
highly nutritious animal protein food.
Answers of Questions on Page 148
Q.1 What management
practices are common in dairy and poultry farming?
Ans.
The principles of feeding, breeding and weeding are
same in both.
(i) Proper shelter is required. It must be hygienic and
ventilated.
(ii) Proper feed and feed additives.
(iii) Proper drinking water.
(iv) Health care including vaccination so that they can be
protected from viral and bacterial, fungal infections.
(v) Selective breeding.
Q.2 What is the
difference between broilers and layers and in their management?
Ans.
Difference between broilers and
layers.
Answers of Questions on Page 150
Q.1 How are fishes
obtained?
Ans.
There are two methods of obtaining fish- (i) capture
fishery- fishes are captured form natural sources. (ii) Fish
farming- It is also called culture fishery. In both case the
fishes are caught
with the help of net.
Q.2 What are the
advantages of composite fish culture?
Ans.
The advantages of composite fish culture are-
(i) Five or six fish species are used in a single pond. The
species of fishes do not compete for food among them
because they have different types of food habits.
(ii) Food available in all the parts/zones of the pond is
utilized due to their food habits.Catlas are surface
feeders, Rohus feed in the middle part of pond and
Mrigals and commom carps are bottom feeders and
Grass carps feed on the weeds.
(iii) The fish yield is high as many types of fish are grown
simultaneously.
Answers of Questions on Page 150
Q.1 What are the
desirable characters of bee species suitable for honey production?
Ans.
The desirable characters of bee species suitable for bee keeping are-
(i) Good honey collection capacity.
(ii)The bees should stay in given beehives for longer period.
(iii) Gentleness in nature.
(iv) Prolific queen production with less swarming.
(v) They should have capacity of breeding well.
(vi) Ability to protect itself from diseases and enemies.
Q.2 What is pasturage
and how is it related to honey production?
Ans.
Pasturage is the availability of flowers for nectar and
pollen collection for the honey bee. The quality and taste
of the honey is determined by the kind and quantity of
pasturage.
Answers of End Exercise
Questions on Page 151
Q.1Explain any one
method of crop production which ensure high yields.
Ans.
Plant breeding is the method which
ensures high yields. Some commonly used plant breeding methods for improvements
are hybridization, mutation, polyploidy and DNA recombination technology.
Hybridization
refers to crossing between genetically different plants. The crossing between
interverital, interspecific or intergeneric. The plants from different
areas/places are picked up with desired trait and then crossed to obtain
desired characteristics.
Q.2 Why are manures and
fertilizers used in fields?
Ans.
Manures and fertilizers are added to the soil of crop field
to increase the fertility of soil and productivity of crop.
They replenish the nutrients and overcome the deficiency
of nutrients in
the soil of the field
Manures contains large amount of organic matter that
helps in improving the soil structure. Whereas fertilizers
supply nitrogen, phosphorus and potassium, they ensure
good vegetative growth,
giving rise to healthy plants.
Q.3 What are the
advantages of inter cropping and crop rotation?
Ans.
Advantages of inter-cropping-
i.
It helps to maintain soil
fertility.
ii.
Increase productivity per
unit area.
iii. It
saves time and labour.
iv. Both crops can be sown, harvested and threshed
separately.
v. Chance of spreading the diseases and pests are less.
Advantages of inter-cropping-
i. It reduces the need of fertilizers as nitrogen supply is
maintained in the crop field when legume crops are
alternated with other crops.
ii. It improves the soil
fertility.
iii. It
helps in weed control.
iv. It minimize pest control
v. It prevents change in the
chemical nature of the soil.
Q.4 What is genetic
manipulation? How is it useful in agriculture practices?
Ans.
Genetic manipulation is the incorporation of desirable
genes of the organism into an organism of choice to have
desired result. Genetic manipulation useful in agricultural
practices because it produces crops which have higher
yield, improved quality, has biotic
and abiotic resistance.
The Genetically modified crop has desirable agronomic
characters, wider adaptability and its maturing duration
can be changed. This can be done through hybridization.
Hybridization involves crossing between genetically
different
plants.
It is useful in agriculture practices in the following
manner-
i. It provides better quality
ii. Increase yield
iii Improves adaptability to adverse environmental
conditions
iv. Gives desirable characteristics
v. Shorts the maturity period
Q.5 How do storage
grain losses occur?
Ans.
Two main factors responsible for loss of grains during
storage are-
i. Biotic factors – The organisms which influence the
storage of grains are known as bitotic factors like –
insects, rodents, birds, fungi bacteria, mites etc.
ii.Abiotic factors – The climatic factors including
temperature, moisture, humidity are called abiotic factors
Q.6 How do good animal
husbandry practices benefit farmers?
Ans.
Good animal husbandry practices benefit in the following
way-
(i) Improve the breeds of domesticated animals. These
breeds are resistant, against disease have increased life
span and lactation period.
(ii) Help the farmers to increase the quality and yield of food stuff such as egg, milk, meat etc.
Q.7 What are the
benefits of cattle farming?
Ans.
The cattle farmers are benefited in following ways-
(i) They get milk from cattle.
(ii) They use cattle in agricultural operation like ploughing, harrowing etc.
(iii) They are used in driving cart for transportation of men and materials.
(iv) They provide manure and fuel. Agriculture and cattle farming is complementary to each other.
(v) Provide extra income.
(vi) They provide meat, fibre and skin.
Q.8 For increasing
production, what is common in poultry, fisheries and beekeeping?
Ans.
Variety improvement, shelter rearing,
sanitation, disease control and marketing.
Q.9 How do you
differentiate between capture fishing, Marin-culture and aquaculture?
Ans.
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