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NCERT Solutions for Class 9th: Ch 15 Improvement in Food Resources Science

In text Questions

Page No: 204

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

Answer

→ Cereals provide us with carbohydrates. Also, they are a rich source of energy.
→ Pulses give us proteins.
→ Fruits and vegetables are a rich source of vitamins and minerals. A small amount of proteins, carbohydrates, and fats are also present in them.

Page No: 205

1. How do biotic and abiotic factors affect crop production?

Answer

Biotic factors such as pests, insects and diseases reduce the crop production. A pest causes damage to our crops by feeding. Weeds also reduce crop productivity by competing with the main crop for nutrients and light.
Similarly, abiotic factors such as temperature, wind, rain etc. affect the net crop production. For example droughts and floods have a great impact on crops sometimes, destroying the entire crop.

2. What are the desirable agronomic characteristics for crop improvements?

Answer

The desirable agronomic characteristics for crop improvements are:
→ Tallness and profuse branching in any fodder crop.
→ Dwarfness in cereals.

Page No: 206

1. What are macro-nutrients and why are they called macro-nutrients?

Answer

Macro-nutrients are those nutrients which are required in large quantities for growth and development of plants. 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.

2. How do plants get nutrients?

Answer

Plants get nutrients 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.

Page No: 207

1. 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.

Page No: 208

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 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 benefits.
→ 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.
→ Proper irrigation methods improve the water availability to crops.
→ Fertilizers ensure healthy growth and development in plants by providing the essential nutrients such as nitrogen, phosphorus, potassium, etc.
→ 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 production of crops will increase.

Page No: 209

1. 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. Biological methods cause harm neither to crop nor to the environment.

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

Answer

Factors causing loss of grains during storage:
→ Biotic Factors: Insects, rodents, fungi and bacteria etc.
→ Abiotic Factors: Moisture Content and Temprature etc.

Page No: 210

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

Answer

Cross Breeding is commonly used for improving cattle breeds.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 and Indian breeds such as Red Sindhi, Sahiwal produces a new variety having qualities of both breeds.

Page No: 211

1. 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."

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.

1. What management practices are common in dairy and poultry farming?

Answer

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

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

Answer

Layers are 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.

Page No: 213

1. How are fish obtained?

Answer

Fish can be obtained by two ways:
→ Capture fishing: It is the process of obtaining fish from natural resources.
→ Culture fishery: It is the practice of farming fishes. Farming can be done in both freshwater ecosystem (which includes river water, pond water) and marine ecosystem.

2. 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:
→They should yield high quantity of honey.
→ They should not sting much.
→ They should stay in the beehive for long durations.
→ They should breed very well.

1. What are the advantages of composite fish culture?

Answer

The advantages of composite fish culture are:

→ Fish can be grown in crop fields especially paddy.
→ Intensive Fish farming is possible because plenty of water is available during crop seasons.
→ In this system both local and imported fish species can be cultivated.

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

Answer

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

Page No: 214

Excercise

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

Answer

Inter cropping is a method of crop production which ensures high yield. It is a practice of growing two or more crops simultaneously. in the same field in rows. In inter cropping definite row patterns are followed such as one row of main crop of is followed by two row of intercrop.
In inter cropping there is greater utilisation of the interspaced area, light, nutrients, water and air. As a result productivity per unit area increased.

2. Why are manures and fertilizers used in fields?

Answer

Manures and fertilizers are used in fields 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.

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

Answer

Inter-cropping and crop rotation both are used to get maximum benefit on limited land. Inter-cropping helps in preventing pests and diseases to spread throughout the field. 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.

4. 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.
Genetic manipulation is useful in developing varities with Higher yield, Good Quality, Biotic and Abiotic resistance, short maturity period, wider adaptability and desirable agronomic characteristics

5. How do storage grain losses occur?

Answer

There are various biotic and abiotic factors that act on stored grains and result in degradation, poor germinability, discolouration, etc.

Biotic factors include insects or pests that cause direct damage by feeding on seeds. They also deteriorate and contaminate the grain, making it unfit for further consumption.

Abiotic factors such as temperature, light, moisture, etc., also affect the seed. They decrease the germinating ability of the seeds and make them unfit for future use by farmers. Unpredictable occurrence of natural calamities such as droughts and floods also causes destruction of crops.

6. How do good animal husbandry practices benefit farmers?

Answer

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

7. What are the benefits of cattle farming?

Answer

Benefits of cattle farming:
→ 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.

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

Answer

The common factor for increasing production in poultry, fisheries, 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.

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

Answer

→ Capture fishing the method of obtaining fishes from natural resources

→ Mariculture is the culture of marine fishes for commercial use.

→ Aquaculture involves the production of aquatic animals that are of high economic value such as prawns, lobsters, fishes, crabs, etc.

NCERT Solutions for Class 9th: Ch 14 Natural Resources Science

In text Questions

Page No: 193

1. How is our atmosphere different from the atmospheres on Venus and Mars?

Answer

Earth's atmosphere is a mixture of nitrogen (79%), oxygen (20%), and a small fraction of carbon dioxide, water vapours and other gases. This makes the existence of life possible on Earth. However, the atmospheres on Venus and Mars mainly consist of carbon dioxide. The amount of carbon dioxide on these planets can range from 95% to 97%.

2. How does the atmosphere act as a blanket?

Answer

The atmosphere acts as a blanket by performing the following functions:
→ It keeps the average temperature of the Earth fairly constant during day time and even during the course of whole year.
→ It prevents a sudden increase in the temperature during day time.
→ It slows down the escape of heat from the surface of the Earth into outer space during night time.

3. What causes winds?

Answer

An uneven heating of the Earth's surface causes winds. On being heated, air becomes lighter and rises up. As a result, a region of low pressure is created. Then, air from a high pressure region moves to a low pressure region, causing wind.

4. How are clouds formed?

Answer

During day time, on being heated, a large amount of water evaporates from various water bodies and goes into the air. A part of this water vapour also reaches the atmosphere through biological activities such as transpiration and respiration. This causes the air in the atmosphere to heat up. When this heated air rises, it expands and cools, which results in the condensation of water vapour forming water droplets. The presence of dust and other suspended particles in air also facilitates the process of condensation. The formation of water droplets leads to the formation of clouds.

5. List any three human activities that you think would lead to air pollution.

Answer

Three human activities leading to air pollution are:
→ Smoke from industries e.t.c.
→ Burning of fossil fuels like coal and petroleum→ Deforestation.

Page No: 194

1. Why do organisms need water?

Answer

The organisms need water:
→ For different cellular process.
→ For transportation of substance from one place to another inside the body.

2. What is the major source of fresh water in the city/town/village where you live?

Answer

Rivers.

3. Do you know of any activity which may be polluting this water source?

Answer

The discharge of waste water from homes, industries, hospitals, etc. into the river pollutes this fresh water source.

Page No: 196

1. How is soil formed?

Answer

Soil is formed by breaking down of rocks at or near the surface of the Earth through various physical, chemical, and biological processes by various factors such as the sun, water, wind, and living organisms.→ Sun: During day time, the rocks are heated up by solar rays. This causes the rocks to expand. During night time, these rocks cool down and contracts, thus the cracks devlop in the rock and they break down.
→ Water: It helps in breaking of rocks in two ways:
(i) It goes into the cracks and crevices formed in the rocks. When this water freezes, its volume increases. As a result, the size of the cracks also increases. This helps in the weathering of rocks.
(ii) Water moving in fast speed carries big and small particles of rock downstream. These rocks rub against each other, resulting in breaking down of rocks.These smaller particles are carried away by running water and deposited down its path.→ Wind: Strong winds carry away rocks, which causes rubbing of rocks. This results in the breaking down of rocks into smaller and smaller particles.
→ Living Organism: Some living organisms like lichens help in the formation of soil. Lichens grow on rock surfaces and converts them into powdery form and make soil layer. In the same way, the plants like moss also help in the making of fine soil particles.

2. What is soil erosion?

Answer

The blowing away or washing away of land surface bywind or water is known as soil erosion.

3. What are the methods of preventing or reducing soil erosion?

Answer

The methods of preventing or reducing soil erosion are:
→ Plantation of tress and plants→ Prevention of deforestation
→ Prevent excessive grazing

Page No: 201

1. What are the different states in which water is found during the water cycle?

Answer

Water is found in three different states during the water cycle:
→ Solid (Snow, Ice)
→ Liquid Water (ground water, river water, etc.)
→ Gaseous State (Water vapours)

2. Name two biologically important compounds that contain both oxygen and nitrogen.

Answer

Two biologically important compounds that contain both oxygen and nitrogen are:
(i) Amino acids
(ii) Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)

3. List any three human activities which would lead to an increase in the carbon dioxide content of air.

Answer

Three Human activities are:

→ Burning of fuels in various processes like heating, cooking, transportation, and industry.
→ Human induced forest fires
→ The process of deforestation includes the cutting down of trees. This decreases the uptake of carbon dioxide for photosynthesis. Eventually, the content of carbon dioxide increases.

4. What is the greenhouse effect?

Answer

Some gases like carbon dioxide, methane, nitrous oxide prevent the escape of heat from the Earth's surface by trapping it. This increases the average temperature of the Earth. This is called the green house effect. 

5. What are the two forms of oxygen found in the atmosphere?

Answer

The two forms of oxygen found in the atmosphere are:
→ Diatomic molecular form with chemical formula O₂.
→ Triatomic molecular form with chemical formula O₃known as ozone.

Excercise

1. Why is the atmosphere essential for life?

Answer

The atmosphere is essential for life because it maintains an appropriate climate for the sustenance of life by carrying out the following activities:
→ Atmosphere keeps the average temperatureof the Earth fairly constant during day time.
→ It prevents a sudden increase in temperature during day time.
→ It also slows down the escape of heat from the surface of the Earth into outer space during night time.

2. Why is water essential for life?

Answer

Water is essential for life because of the following reasons:
→ Most biological reactions occur when substances are dissolved in water. Thus, all cellular processes need water as a medium to take place.
→ Transportation of biological substances needs water as a medium.

3. How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource?

Answer

Almost all living organisms are dependent on soil. Some depend directly, while some depend indirectly.
Plants need soil for getting support as well as nutrients to prepare their food.
On the other hand, organisms depend on plants for food and other substances that are essential for life. Herbivores depend directly upon plants, and carnivores depend upon animals, which in turn depend upon plants for food. This makes them depend on soil indirectly.
Organisms that live in water are not totally independent of soil as a resource. These organisms depend on aquatic plants for food and other substances. These aquatic plants in turn require minerals for their sustenance. These minerals are carried to water bodies from soil by rivers, rain water, etc. Without the supply of minerals from the soil to the water bodies, it is impossible to imagine aquatic life.

4. You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?

Answer

The meteorological department of the government collects data on the elements of weather such as maximum and minimum temperatures, maximum and minimum humidity, rainfall, wind speed, etc. They are able to study these elements using various instruments. The maximum and minimum temperature of a day is measured by a thermometer known as the maximum-minimum thermometer. Rain fall is measured by an instrument known as the rain gauge. Wind speed is measured by anemometers. There are various instruments used to measure humidity.

Page No: 202

5. Write a note on how forests influence the quality of our air, soil and water resources.

Answer

Forests influence the quality of our air, soil, and water resources in various ways. Some of them are:
→ Forests balance the percentages of carbon dioxide and oxygen in the atmosphere. The increasing amount of carbon dioxide caused by human activities is balanced by a larger intake of carbon dioxide by plants during the process of photosynthesis. Simultaneously, a large amount of oxygen is released.
→ Forests prevent soil erosion. Roots of plants bind the soil tightly in a way that the surface of the soil cannot be eroded away by wind, water, etc.
→ Forests help in the replenishment of water resources. During the process of transpiration, a huge amount of water vapour goes into the air and condenses to form clouds. These clouds cause rainfall that recharge water bodies.

6. We know that many human activities lead to increasing levels of pollution of the air, water-bodies and soil. Do you think that isolating these activities to specific and limited areas would help in reducing pollution?

Answer

Yes. Isolating human activities to specific areas would help in reducing levels of pollution. For example, setting up of industries in isolated regions will control pollution to some extent. The pollution caused by these industries will not contaminate water resources, agriculture land, fertile land, etc.