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

Page No. 141

Q1. What do we get from cereals, pulses, fruits and vegetables?
Ans: Cereals like wheat and rice provide us carbohydrates for fulfilling the body’s energy requirement. Pulses like gram and peas provide us with proteins. Fruits and vegetables provide us with a ranse of vitamins and minerals in addition to some proteins, carbohydrates and fats.

Page No. 142

Q1. How do biotic and abiotic factors affect crop production?
Ans: Crop production goes down due to biotic factors like disease causing organisms (bacteria, fungi, etc.), insects and nematodes.
Crop production also goes down due to abiotic stresses like drought, salinity, water logging, heat, cold and frost.

Q2. What are the desirable agronomic characteristics for crop improvements?
Ans: For fodder crops, height and profuse branching are desirable characteristics. For cereal crops, dwarfness is desired, so that less nutrients are consumed by the crops. In this way, developing varieties of desired agronomic characters give higher productivity, i.e., higher yield.

Page No. 143

Q1. What are macro-nutrients and why are they called macronutrients? 
Ans: Sixteen nutrients are essential for plants, out of which thirteen are supplied by the soil. Among these, six are required in large quantities. As these are required in large quantities, they are called macronutrients. They are: (i) nitrogen, (ii) phosphorus, (iii) potassium, (iv) calcium, (v) magnesium and (vi) sulphur.

Q2. How do plants get nutrients? 
Ans: Plants get nutrients from air, water and soil. There are basically sixteen nutrients that are essential for plants. Of these, carbon dioxide and oxygen are obtained from air, hydrogen from water and the rest of the thirteen nutrients are supplied by the soil.

Page No. 144

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

Fertilisers have the following advantages over manures:
(i) Fertilisers have high concentration of nutrients than manures.
(ii) Fertilisers are highly specific in their effect.

Page No. 145

Q1. 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.
Ans: Conditions given in (iii) Farmers use quality seeds, adopt irrigation, use fertilisers and use crop protection measures are most beneficial for farmers because use of—
(a) quality seed that will provide genotypes for various characters such as disease resistance, good quality and higher yield.
(b) proper irrigation methods will fulfil water requirement of crop at proper time
(c) fertilisers that will provide required nutrients to the crops
(d) crop protection measures will check loss of crop and crop yield and control pest and plant diseases.
Thus, farmers will get maximum benefit for their input in the form of good seeds (genotype) and quality agronomic approaches giving maximum profit.

Page No. 146

Q1. Why should preventive measures and biological control methods be preferred for protecting crops?
Ans: Preventive measures ensure that the crops are protected from harmful biotic and abiotic factors. These factors can cause huge loss of food grains and hence need proper treatment to control them. It is, therefore, better to take preventive measures to avoid crop loss. Chemicals are poisonous to plant and animal species and cause environmental pollution. They reach human beings through food chain. On the other hand, biological control methods are safe for plants and animals and environment in general.

Q2. What factors may be responsible for losses of grains during storage?
Ans: Biotic factors responsible for damaging food grains during storage are as follows:
(i) Enzymes: Food material contain enzymes which spoil the food by their action. They are active at high temperatures. Meat, fruits, fish, vegetables, etc. should be stored at low temperatures so that these enzymes may remain inactive.
(ii) Microbes: Microorganisms like bacteria, moulds grow in stored food if the moisture content is high and they grow at high temperatures. They spoil the food forming toxic substances.
(iii) Insects: Insects like weevil, grain borer, khapra beetle, etc., infect the food grains on storage at high temperatures and water content more than 14%. They spoil food grains in different ways producing toxic substances as well as forming cocoon, laying eggs and damaging nutrient content.
The abiotic factors responsible for the damage of food grains during storage are:
(i) Moisture: Moisture content more than 14% makes the microbes to attack and insects to infest the grains,
(ii) Temperature: Rise of room temperature or storage at higher temperature increases the chances of insect infestation. It also accelerates the growth of microorganisms like bacteria and fungi.
(iii) Humidity: Humidity increases the growth of fungi and moulds. Safe storage is possible at less humid places.

Page No. 147

Q1. Which method is commonly used for improving cattle breeds and why?
Ans: The method commonly used for improving cattle breeds is cattle farming. Cattle farming is carried out to increase milk production and drought labour for agricultural work. To produce new improved variety, cross-breeding between two varieties of cattle is done. e.g. cross between foreign breeds Jersey/Brown Swiss with Indian breeds Red Sindhi/Sahiwal produces cows having good qualities of both the breeds.

Page No. 148

Q1. 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.”
Ans: The feed consumed by poultry birds is fibrous and cheap. Moreover, it is formulated using- agricultural by-product. In this way, the product not used by human population are converted into chicken meat and the eggs produced by poultry birds, which are highly nutritious and are used by humans.

Q2. What management practices are common in dairy and poultry farming?
Ans: Management practices common in dairy and poultry farming are:
(i) Proper cleaning and hygienic conditions in housing and shelters.
(ii) Well ventilated and maintenance of temperatures in shelters and housing.
(iii) Prevention and control of diseases and pests.
(iv) Proper feeding management.

Q3. What are the differences between broilers and layers and in their management?
Ans: The differences between Broilers and Layers with respect to their purpose of breeding and daily flood requirement are as follows:
- Time purpose of breeding of broilers are for meat and layers are for egg laying poultry.
- The daily food requirement or ration of Broilers are rich in protein with adequate fed. They are fed with supplementary feed rich in Vitamin A and K for good growth rate. The egg laying birds utilise more fibrous cheaper diets formulated using agricultural byproducts.
The necessary steps taken to prevent the occurrence of infectious diseases in poultry farm are as follows:
(i) Proper cleanliness, sanitation and spraying of disinfectants at regular interval in poultry house.
(ii) Appropriate vaccination to prevent the occurrence of infectious diseases.
Therefore, proper hygienic conditions in housing and poultry feed are necessary for prevention and control of diseases.

Page No. 150

Q1. How are fish obtained?
Ans: Fishes are obtained by two method: capture fishing and culture fishing. Capturing fishes from natural resources (like fresh and marine water) is called capture fishing, and fish farming using various culture methods is called culture fishing.

Q2. What are the advantages of composite fish culture?
Ans: The advantages of composite fish culture are:
(a) The species are selected in such a way that they do. not compete for food among themselves, and have different types of food habits. Due to this, the food available in all parts of the pond is used. For example, Catlas are surface feeders, Rohu feed in the middle-zone of the pond, while Mrigals and common carps are bottom feeders. Also, Grass Carps feed on the weeds.
(b) All these species together use all the food in the pond without competing with each other.
(c) This culture increases the fish yield from the pond.

Q3. What are the desirable characters of bee varieties suitable for honey production?
Ans: The desirable characters of bee varieties suitable for honey production are:
(i) Gentleness in nature, do not sting much.
(ii) High honey collection capacity.
(iii) Prolific queen production with less swarming.
(iv) Ability to protect itself from enemies.

Q4. What is pasturage and how is it related to honey production?
Ans: The flora/crops found around an apiary to collect honey and pollen grains is called pasturage. Pasturage flora of honey bee includes mango, coconut, almond, apple, tamarind, sisam, mahua, etc. The quality and taste of honey depends upon the flora/pasturage around the apiary from which bees collect the nectar and pollens. For instance, the Kashmir region having almond plant pasturage around apiary produces almond honey which is good in quality, taste as well as aroma.

Page No. 151

Q1. Explain any one method of crop production which ensures high yield.
Ans: One method of crop production which ensures high yield is crop rotation.
Crop Rotation: It is defined as the practice of growing different crops on a piece of land in a preplanned succession. Depending upon the duration, it is done for different crop combinations.
If crop rotation is done properly then two or three crops can be grown in one year with good harvests.
Advantages of Crop Rotation:
(i) Crop rotation helps in replenishment of soil fertility.
(ii) It prevents depletion of selective nutrients.
(iii) It prevents building up of diseases and pests of particular crop.
(iv) It enhances the production by increasing the soil fertility.

Q2. Why are manure and fertilizers used in fields?
Ans: Manures and fertilisers are major sources of nutrients for the plants. Therefore, the deficiency of plant nutrients and organic matter in the soil is made up by adding manures and fertilisers to the crop field.

Q3. What are the advantages of inter-cropping and crop rotation?
Ans: Advantages of intercropping:
(a) In intercropping, two or more crops are simultaneously grown on the same field in a definite row pattern.—a few rows of one crop and adjoining to that a few rows of another crop. This practice reduces intraspecific competition.
(b) This ensures that both crops can give better yield.
(c) There is maximum utilisation of nucleus and minimum spread of pests.
Advantages of crop rotation:
(a) It makes the soil fertile and helps in the increase of crop yield.
(b) It also decreases the demand of nitrogenous fertilisers as leguminous plants grown during crop rotation fix the atmospheric nitrogen.
(c) The selected rotation of crops also helps in pest control, as pests do not find their favorite crop in the next season and it becomes difficult for them to survive there.

Q4. What is genetic manipulation? How is it useful in agricultural practices?
Ans: Genetic manipulation is a process in which gene of a particular character is introduced inside the chromosome of a cell. When the gene of a particular character is introduced in a plant cell, a transgenic plant is produced. These transgenic plants exhibit the characters governed by the newly introduced gene. Genetic manipulation is useful in developing varieties with higher yield, good quality, disease resistance, short maturity period , wider adaptability and desirable agronomic characteristics.

Q5. How do storage grain losses occur?
Ans: Storage grain losses occur due to the following factors:
(i) Biotic factors such as rodents, birds, insects, bacteria, mites, etc.
(a) Damage due to rodents: The rodents damage stored as well as standing crops. They consume a large amount of crops and also contaminate food grains by their excreta, urine, etc.
(b) Damage caused by birds: Birds eat fruits and vegetables. Food grains are also contaminated by feathers and excreta.
(c) Damage due to insects and microorganisms: Infestation done by insects and microorganisms reduce the nutritive value of food grains and spoil them.
(d) Action of Enzyme: Enzymes present in fruits, meat and fish catalyse metabolic reaction and damage them.
(ii) Abiotic factors such as:
(a) Effect of temperature: The micro organisms and enzymes are most active between 25-40°C and damage food substances.
(b) Effect of moisture content in foodgrain: If the moisture content in stored foodgrains is more than 14% it leads to growth of microorganisms, fungi and moulds. It leads to dry or wet heatine of food trains.
(c) Effect of material of container: The metallic containers used to store foodgrains are harmful and poisonous.

Q6. How do good animal husbandry practices benefit farmers?
Ans:  Good animal husbandry practices increase profit of farmers. It also keep the animals healthy. Healthy animals need less time an effort on nursing than sick animals. Improved animal husbandry practices help in meeting the demands of milk, egg and meat.

Q7. What are the benefits of cattle farming?
Ans: The main benefits of cattle farming are:
(а) To get milk from cattle directly and other milk products like butter, cheese, indirectly.
(b) Bullock labour is used for agricultural practices such as tilling, irrigation and carting.

Q8. For increasing production, what is common in poultry, fisheries and bee-keeping?
Ans: For increasing production, the practices common in poultry, fisheries and bee-keeping are the rearing and breeding of birds (fowl), fishes and honey bees is done scientifically by man. Best breed of animals are used in poultry, fisheries and bee-keeping to get high yield and good profit.

Q9. How do you differentiate between capture fishing, mariculture and aquaculture?
Ans: