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NCERT Solutions for Class 9 Science chapter 15 – Improvement in Food Resources

Back Exercise

Question 1.
Explain any one method of crop production which ensures high yield.
Answer:
Rotation of crops is a method of crop production which ensures high yield. Crop rotation is growing of different crops on the same piece of land in a preplanned succession. Crop rotation is done for one year, two year and three year cycle. Crops chosen are such that they withdraw nutrients from different layers of the soil. Crop rotation involving a leguminous crop ensures that the soil gets naturally enriched with nitrogen.
Crop rotation is useful in

1. Weed control,
2. Reduction in pest infestation,
3. Elimination of soil borne diseases,
4. Saving of nitrogen fertilizer
5. Improving soil structure and fertility,
6. Raising of 2-4 crops in a year from the same land giving higher returns to the farmer,
7. Yield of individual crops is also higher due to improved soil structure, soil fertility, fewer weeds, fewer insects and diseases.

One Year Rotation    :  Rice—Wheat, Maize—Mustard
Two Year Rotation    :  Maize-Potato-Sugarcane-Pea
Three Year Rotation  :  Rice-Wheat-Mung-Mustard-Sugarcane-Burseem

Question 2.
Why are manures and fertilizers used in fields ? (CCE 2011)
Answer:
Manures and fertilizers are added to fields mainly to replenish minerals which get depleted due to withdrawal by crop plants and leaching down to lower strata of soil.

1. Manures add small quantity of all minerals to the soil. They improve soil hydration, soil aeration and activity of soil micro-organisms, some of which are required for solubilisation of heavy minerals.
2. Fertilizers are nutrient specific which contain one or more minerals in concentrated form. They meet the immediate and complete mineral requirement of high yielding varieties. However, they harm soil structure and cause pollution of crops, soil, ground water and nearby surface waters. A combination of both manure and fertilizer is highly useful.

Question 3.
What are advantages of intercropping and crop rotation ?
Answer:

Advantages of Intercropping :

1. Intercropping increases productivity per unit area.
2. The fertility of the soil is maintained.
3. The spread of diseases and pests is controlled.
4. Optimum utilization of resources.
5. The space and time of growing more than one crop are saved.
6. Maximum utilization of nutrients present in the soil.

Advantages of Crop Rotation:

1. The soil fertility is maintained for a prolonged period.
2. The growth of weeds and pests is prevented.
3. A lot of chemical fertilizers are not required.
4. The physical and chemical nature of the soil remains unaltered

Question 4.
What is genetic manipulation ? How is it useful in agricultural practices (CCE 2013)
Answer:
Genetic manipulation is a process in which genes of desirable characters are taken from a plant and transferred to another plant by the technique of hybridisation.
Genetic manipulations help in obtaining traits which are not possible naturally such as dwarfness in cereals, tall and profuse branching in fodder crops. It helps in obtaining higher yield, resistance to pests, less maturity period, resistance to severe environmental conditions such as droughts, high alkalinity, floods etc.

Question 5.
How do storage grain losses occur ?
Answer:
Both abiotic and biotic factors damage stored grains.
Abiotic Factors

1. Moisture Content of Grains: Moisture content of grains is generally higher than optimum 14%. Higher moisture content of grains increases their respiration, which heats the grains and reduces their keeping quality. Microorganisms, fungi and insects attack such grains.
2. Dampness and Humidity of Air: Dampness of godowns and humidity of air cause growth ol moulds over and inside the grains.
3. Temperature: Temperature of 30°C and above is harmful to stored grains due to activity of microorganisms, insects, pests and activation of enzymes of the grains.

Biotic Factors

1. Rodents: Six rats consume food equivalent to an average human being. They damage 5-6 times more grains by cutting and contamination (by urine, hair and excreta).
2. Birds: Birds are often seen in large number around godowns. They are able to puncture bags and eat the stored grains. The birds also contaminate the stored grains with their excreta and feathers. Bird excreta often contains Salmonella, the bacterium causing food poisoning.
3. Insects and Worms: Insects and their larvae feed on stored grains either internally (internal feeders like Pulse Beetle, Rice Weevil, Lesser Grain Borer) or externally (external feeders, e.g., Khapra Beetle, Rust Red Flour Beetle). They damage the grains, decrease their quality and cause contamination with webs, cocoons, excreta, dead remains and toxins.
4. Microorganisms: Bacteria, yeasts and moulds attack stored grains and cause their rotting. Rotting brings about discolouration, loss of weight, bad odour and aflatoxin contamination of grains which also lose their ability to germinate.

Question 6.
How do good animal husbandry practices benefit farmers ? (CCE 2011)
Answer:
Good animal husbandry practices keep the animals healthy and more productive. There is higher yield of animal products— milk, eggs, meat.

1. Shelter: Diseases spread if the animal shelters are dingy and crowded. If they are spacious, hygienic and well lighted, the animals remain healthy.
2. Vaccination: Vaccination of young animals prevents the occurrence of common diseases.
3. Segregation of Sick Animals: When sick animals are noticed, they are immediately segregated. Cleanliness drive is undertaken and the remaining animals are given prophylactic doses of medicines to prevent the spread of disease. The livestock remains healthy and productive.
4. Proper Diet: A proper optimum diet with feed additives enhances growth and yield of animals.
5. Breeding: Breeding for more milk, longer lactation period, more egg laying, better convertibility of food and other good characteristics have allowed various branches of animal husbandry to give better yield.

Question 7.
What are the benefits of cattle farming ? (CCE 2011)
Answer:

Benefits of cattle farming are:

• Cattles are used in agricultural purpose.
• Generation of good quality cattle.
• Milking and meat purpose.
• Skin of cattle is used for leather and wool industry.
• Good quality and quantity of milk can be produced.
• Draught labour animals can be produced for agricultural work.
• New variety that are resistant to diseases can be produced by crossing two varieties with the desired traits.

Question 8.
For increasing production, what is common in poultry, fisheries and bee-keeping ?
Answer:

Question 9.
How do you differentiate amongst capture fishing, mariculture and aquaculture.
Answer:
1. Capture fishing is one of the most common forms of fishing. It is a type of fishing where the fishes are obtained from the natural resources like river, lake or seas.
2. Mariculture is the cultivation of aquatic, marine life forms for food in the open ocean, ponds, or raceways that are filled with seawater.
3. Aquaculture refers to the breeding, rearing, and harvesting of plants and animals in all types of water environments including ponds, rivers, lakes, and the ocean.

In-Text Questions

Question 1.
What do we get from cereals, pulses, fruits and vegetables ?
Answer:
Cereals: Mostly carbohydrates
Pulses: Mostly proteins
Fruits: Vitamins, minerals, organic acids.
Vegetables: Vitamins, minerals, small quantities of proteins, carbohydrates and oil.

Question 2.
How do biotic and abiotic factors adversely affect crop production ?
Answer:
Biotic factors are living organisms that reduce crop productivity due to either directly feeding on them (e.g., insects, rodents) or causing diseases (e.g., nematodes, mycoplasmas, bacteria, viruses, fungi).
Abiotic factors are non-living components of environment that affect growth of crop plants like excess of water (water-logging), scarcity of water (drought), salinity, heat, cold or frost. Water logging reduces aeration of soil which is harmful to growth and functioning of roots. In drought, water is not available to meet the requirement of the plants for transpiration, growth and photosynthesis. Frost, cold and heat reduce are also harmful for the plants.

Question 3.
What are the desirable agronomic characteristics for crop improvement ? ( CCE 2015)
Answer:
They are different for different crops.
Cereals should be dwarf but with large ears. Dwarfness makes their stem stronger. They can withstand lodging effect of strong winds. Nutrient requirement is also less. Large ears produce more grains.
Legumes should have more pods which generally develop in relation to stem branching. Therefore, more branching and good foliage increase their productivity.
Fodder crops meant for feeding catde must have profuse branching, good foliage, juicy stems and large size.

Question 4.
What are macro-nutrients and why are they called macro-nutrients ?
Answer:
Macronutrients are essential elements required for growth and reproduction of plants. They are called macronutrients because they are required in larger quantities forming more than 1 mg per 1 gm of dry matter. Example - Phosphorus, Nitrogen, Sulphur.

Question 5.
How do plants get nutrients ?
Answer:
Plants obtain nutrients from air, water and soil. Air is the source of carbon and oxygen. Hydrogen is obtained from water. The remaining thirteen elements are got directly from soil through root absorption.

Question 6.
Compare the use of manure and fertilizers in maintaining soil fertility.
Answer:

Question 7.
Which of the following conditions will give the most benefits ? Why ?
(a) Farmers use high quality seed but do not adopt irrigation or use fertilizers.
(b) Farmers use ordinary seeds, adopt irrigation and use fertilizers.
(c) Farmers use quality seeds, adopt irrigation, use fertilizers and crop protection measures.
Answer:
(C) Farmers are benefitted when they use quality seeds, irrigation, fertilizers and crop protection measures. Ordinary seeds cannot yield very high due to poor quality while quality seeds without necessary inputs yield low.

Question 8.
Why should preventive measures and biological control methods are preferred for protecting crops ?
Answer:
Preventive measures and biological control methods do not allow any measurable loss in quality and quantity of crops. They also do not cause any degradation of the environment. Cost is also very small. Preventive measures protect the crops from pests. Biological control methods eliminate the pests without harming crops and other human interests.

Question 9.
What factors may be responsible for huge losses during storage ?
Answer:

1. Abiotic Factors: Excess moisture in grains, dampness and high temperature in storage place.
2. Biotic Factors: Insects, mites, rodents, birds, fungi and bacteria.

Question 10.
Which method is commonly used for improving the cattle breeds and why ? (CCE 2011)
Answer:
Cross breeding indigenous breeds with exotic breeds. Foreign or exotic breeds have higher milk yield and longer lactation period as compared to indigenous breeds. The local breeds are hardy and resistant to several diseases. Therefore, indigenous breeds should be cross¬bred with exotic breeds. There are two methods of cross breeding — natural and artificial insemination.

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 humant consumption) into highly nutritious animal protein food. ”
Answer:
Poultry in India is the most efficient converter of low fibre 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 fibres. Thus, by feeding animals a fibre rich diet, the poultry gives highly nutritious food in the form of eggs and chicken.

Question 12.
What management practices are common in dairy and poultry farming ? (CCE 2011, 2012, 2013, 2015)
Answer:

1. Proper shelter, its hygiene, aeration and lighting.
2. Proper feed and feed additives.
3. Proper drinking water.
4. Health care including vaccination.
5. Sunlight feasible and airy ventilated shelter for animals

Question 13.
What is the difference between broilers and layers and in their management ? (CCE 2011, 2012)
Answer:
Broilers are fast growing young chicken of 6-10 weeks age which are known for the good quality and taste of their meat.
Layers are sexually mature hens which are raised for egg laying.
Broilers are given diet rich in protein, with adequate fat, vitamins A and K. They are provided with best of space, hygiene and temperature. Layers are given inferior quality feed. Light is required for good egg laying. Temperature variations may occur to some degree.

Question 14.
How are fishes obtained ?
Answer:
There are two methods of obtaining fish, capture fishery (capturing fish) from natural waters and culture fishery in freshwater ecosystem like river, pond and lake also including marine.. In both cases the fish are caught with the help of nets.

Question 15.
What are the advantages of composite fish culture ?
Answer:

1. There is no competition for food or space amongst different types of fish.
2. Food available in different parts of the pond are utilised due to their different food habits and different habitats.
3. The fish yield is high as some six types of fish are growing simultaneously.

Question 16.
What are the desirable characters of bee varieties suitable for bee keeping ? (CCE 2012, 2015)
Answer:

1. The variety of bee should yield large amount of honey.
2. The bees should stay for a longer period in bee hives.
3. The bees should not sting much.
4. Bee should be disease resistant.

Question 17.
What is pasturage and how it is related to honey production ? (CCE 2013)
Answer:
Pasturage is flora or crop available to honey bees for collection of nectar and pollen. Pollen is food for honey bees. Nectar is transformed into honey. The amount and quality of honey depend upon type and extent of pasturage.