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Friday, January 18, 2019

Improvement in Food Resources : NCERT Exercise Questions
January 18, 2019

Improvement in Food Resources : NCERT Exercise Questions

Improvement in Food Resources : NCERT Exercise Questions

Q.1     Explain any one method of crop production which ensures high yield.Sol.        Crop rotation is 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-fixing bacteria in their root nodules supply the soil with nitrogen. Therefore, these legumes are rotated with nitrogen requiring cereals such as wheat and maize. This method reduces the need of fertilizers, thereby increasing the overall yield of crops.
Q.2     Why are manures and fertilizers used in fields?Sol.      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.
Q.3     What are the advantages of inter-cropping and crop rotation?Sol.      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 field. It al so 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.
Q.4     What is genetic manipulation? How is it useful in agricultural practices?Sol.      Genetic manipulation is 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.
Q.6     How do good animal husbandry practices benefit farmers?Sol.      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.
 Q.7     What are the benefits of cattle farming?Sol.       Benefits 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.
Q.8     For increasing production, what is common in poultry, fisheries and bee-keeping?
Sol.      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.
Q.9     How do you differentiate between capture fishing, mariculture and aquaculture?Sol.      Capture fishing – It is the method of obtaining fishes from natural resources. Mariculture – It is the culture of marine fishes for commercial use. Aquaculture – It involves the production of aquatic animals that are of high economic value such as prawns, lobsters, fishes, crabs, etc.

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Improvement in Food Resources :NCERT Intext Questions
January 18, 2019

Improvement in Food Resources :NCERT Intext Questions

Improvement in Food Resources :NCERT Intext Questions

Page 204
Q.1     What do we get from cereals, pulses, fruits and vegetables?
Sol.      (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.
Page 205
Q.1     How do biotic and abiotic factors affect crop production?
Sol.      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 floods are
unpredictable. Their occurrence has a great impact on crops sometimes, destroying the entire crop.
Q.2     What are the desirable agronomic characteristics for crop improvements?
Sol.      The desirable agronomic characteristics for crop improvements are:
            (i) Tallness and profuse branching in any fodder crop.
            (ii) Dwarfness in cereals.
            These desirable agronomic characteristic shelp in increasing crop productivity.
Page 206
Q.1     What are macro-nutrients and why are they called macro-nutrients?
Sol.      Macro-nutrientsare nutrients required in relatively large quantities for growth 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.
Q.2    How do plants get nutrients?
Sol.     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.
Page 207
Q.1     Compare the use of manure and fertilizers in maintaining soil fertility.
Sol.      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 208
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 fertilizer.
           (c) Farmers use quality seeds, adopt irrigation, use fertilizer and use crop protection measures.
Sol.     (c) Farmers using good quality seeds, adopting irrigation, using fertilizers, and using crop protection measures will derive most benefits.
           (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 production of crops will increase.
Page 209
Q.1     Why should preventive measures and biological control methods be preferred for protecting crops?
Sol.     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, inter cropping 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 thuringenes is,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.
Q.2     What factors may be responsible for losses of grains during storage?
Sol.      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, blood, etc. are responsible for losses of grains. These factors act on stored grains and result in degradation, poor
germinability, discolouration, etc.
Page 210
Q.1    Which method is commonly used for improving cattle breeds and why?
Sol.     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 fields 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.
Page 211
Q.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.”
Sol.      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
Q.1     What management practices are common in dairy and poultry farming?
Sol.     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.
Q.2     What are the differences between broilers and layers and in their management?
Sol.     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 supplementse specially 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 213
Q.1     How are fish obtained?
Sol.      Fish can be obtained by two ways:
            (i) Capture fishing: It is the process of obtaining fish from natural resources.
            (ii) 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.
Q.2     What are the advantages of composite fish culture?
Sol.      An advantage of composite fish culture is that it increases the yield of fish. In a composite fish culture,five or six different species are grown together in a single fish 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 fish increases and their yield also increases.
Q.1     What are the desirable characters of bee varieties suitable for honey production?Sol.      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.
Q.2     What is pasturage and how is it related to honey production?Sol.      Pasturage is the availability of ϐlowers from which bees collect nectar and pollen. I t is related to the production of honey as it determines the taste and quantity of honey.
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Natural Resources : NCERT Intext Questions
January 18, 2019

Natural Resources : NCERT Intext Questions

Natural Resources : NCERT Intext Questions


Page 193
Q.1     How is our atmosphere different from the atmospheres on Venus and Mars?
Sol.      Earth’s atmosphere is different from those of Venus and Mars. This difference lies essentially in their  compositions. 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%.
Q.2     How does the atmosphere act as a blanket?
Sol.      The atmosphere acts as a blanket by performing the following functions:
           (a) It keeps the average temperature of the Earth fairly constant during day time and even during the course of whole year.
           (b) It prevents a sudden increase in the temperature during day time.
           (c) It slows down the escape of heat from the surface of the Earth into outer space during night time.
Q.3     What causes winds?
Sol.      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.
Q.4     How are clouds formed?
Sol.      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.
Q.5     List any three human activities that you think would lead to air pollution.
Sol.     The following three human activities would lead to air pollution:
           (i) Burning of fossil fuels such as coal and petroleum
           (ii) Industrialization
           (iii) Deforestation
Page 194
Q.1     Why do organisms need water?
Sol.     Organisms need water for the following reasons:
           (i) All cellular processes need water as a medium. Usually, the reactions that take
place in our body or within the cells occur between substances that are dissolved in water.
           (ii) Since most of the substances are transported in a dissolved form, water is neces sary.
Q.2     What is the major source of fresh water in the city/town/village where you live?
Sol.     River is a major source of fresh water.
Q.3     Do you know of any activity which may be polluting this water source?
Sol.      The discharge of waste water from homes, industries, hospitals, etc. into the river pollutes this fresh water source.
Page 196
Q.1     How is soil formed?
Sol.      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.
           (i) Sun: During day time, the rocks are heated. This causes the rocks to expand. During night time, these rocks cool down and contract. Since all parts of the rock do not undergo expansion and contraction at the same rate, this causes the formation of cracks in these rocks. These cracks lead to the breaking up of huge rocks into smaller pieces.
           (ii) Water: Water catalyses the process of formation of soil in two ways.
           (a) Water goes into the cracks and crevices formed in the rocks. When this water free zes, its volume increases. As a result, the size of the cracks also increases. This helps in the weathering of rocks.
            (b) Running water wears away hard rocks over long periods of time. 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.
           (iii) Wind: Strong winds carry away rocks, which causes rubbing of rocks. This results in the breaking down of rocks into smaller and smaller particles.
           (iv) Living organisms: Some living organisms like lichens help in the formation of soil. Lichens also grow on rocks. During their growth, lichens release certain substances, which cause the rock surface to powder down forming a thin layer of soil. On this thin layer of soil, some small plants like moss also grow. They further cause the breaking down of the rock particles.
Q.2     What is soil erosion?
Sol.      The blowing away or washing away of land surface by wind or water is known as soil erosion.
Q.3     What are the methods of preventing or reducing soil erosion?
Sol.     The methods of preventing or reducing soil erosion are:
           (i) Prevention of deforestation
           (ii) Plantation of trees
Page 201
Q.1     What are the different states in which water is found during the water cycle?
Sol.     During the water cycle, water is found in solid state (snow, ice, etc.), liquid state (ground water, river water, etc.), and gaseous state (water vapours).
Q.2     Name two biologically important compounds that contain both oxygen and nitrogen.
Sol.     Two biologically important compounds that contain both oxygen and nitrogen are:           (i) Amino acids
           (ii) Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)
Q.3     List any three human activities which would lead to an increase in the carbon dioxide  content of air.
Sol.     (i) Burning of fuels in various processes like heating, cooking, transportation, and industry.
           (ii) Human induced forest fires
           (iii) The process of deforestation includes the cutting down of trees. This decreases the uptake of carbondioxide for photosynthesis. Eventually, the content of carbon dioxide increases.
Q.4     What is the greenhouse effect?Sol.     Some gases like carbon dioxide, methane, nitro us 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. An increase in the content of such gases would lead to a situation of global warming.
Q.5     What are the two forms of oxygen found in the atmosphere
Sol.     The two forms of oxygen found in the atmosphere are:
           (i) Diatomic molecular form with chemical formula O2.
           (ii) Triatomic molecular form with chemical formula O3 known as ozone.

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