NCERT Exemplar Class 9 Science Chapter 15 Improvement in Food Resources

NCERT Exemplar Class 9 Science Chapter 15 Improvement in Food Resources are part of NCERT Exemplar Class 9 Science. Here we have given NCERT Exemplar Class 9 Science Solutions Chapter 15 Improvement in Food Resources.

NCERT Exemplar Class 9 Science Solutions Chapter 15 Improvement in Food Resources

Multiple Choice Questions

Question 1.
Which one is an oil yielding plant among the following?
(a) Lentil
(b) Sunflower
(c) Cauliflower
(d) Hibiscus
Solution:
(b) Sunflower is an oil yielding plant. Its seeds are used to extract oil.

Question 2.
Which one is not a source of carbohydrate?
(a) Rice
(b) Millets
(c) Sorghum
(d) Gram
Solution:
(d) Different plant products are rich in different nutrients like some are richer source of fats while some are richer source of minerals carbohydrates, vitamins, etc. Among the given food items rice, millets and sorghum are cereals and are rich source of carbohydrates while gram is a pulse and is a rich source of protein.

Question 3.
Find out the wrong statement from the following.
(a) White revolution is meant for increase in milk production.
(b) Blue revolution is meant for increase in fish production.
(c) Increasing food production without compromising with environmental quality is called as sustainable agriculture.
(d) None of the above
Solution:
(d) White revolution and blue revolution are the terms used to denote the period in which modem techniques and special strategies were applied to increase the production of milk and fish respectively. Sustainable agriculture refers to the agricultural improvement in a way that it does not affect environment negatively.

Question 4.
To solve the food problem of the country, which among the following is necessary?
(a) Increased production and storage of food grains
(b) Easy access of people to the food grain
(c) People should have money to purchase the grains
(d) All of the above
Solution:
(d) To feed the ever growing population, more food is required to be produced. Over the years food production in our country has increased considerably. To meet the demands of growing Indian population, our scientists adopted different methods to increase food production. It include green revolution (production of food grains), blue revolution (production of fishes), white revolution (production of milk) and yellow revolution (production of oil). All these revolutions made the country self reliant in terms of food production to certain extent. Now golden revolution is expected in the production of pulses.

Question 5.
Find out the correct sentence.
(i) Hybridisation means crossing between genetically dissimilar plants.
(ii) Cross between two varieties is called as interspecific hybridisation.
(iii) Introducing genes of desired character into a plant gives genetically modified crop.
(iv) Cross between plants of two species is called as intervarietal hybridisation.
(a) (i) and (iii)
(b) (ii) and (iv)
(c) (ii) and (iii)
(d) (iii) and (iv)
Solution:
(a) The process of crossing two genetically dissimilar plants to produce a hybrid having good traits of both is called i hybridisation. The crossing may be intervarietal (between different varieties), intergeneric (between different genera), inter-specific (between different species of the same genus). Genetically modified crops are produced by the insertion of genes of desired traits.

Question 6.
Weeds affect the crop plants by
(a) killing of plants in field before they grow
(b) dominating the plants to grow
(c) competing for various resources of crops (plants) causing low availability of nutrients
(d) all of the above.
Solution:
(d) A plant species growing spontaneously in the cultivated field is called a weed. Weeds damage our crop plants, by competing with ’ them for space, water, light and nutrients. Weeds grow very fast.

Question 7.
Which one of the following species of honey bee is an Italian species?
(a) Apis dorsata
(b) Apis florae
(c) Apis cerana indica
(d) Apis mellifera
Solution:
(d) In India, both local varieties (indigenous) as well as exotic varieties are used for commerical production of honey. The local varieties are Apis cerana indica (Indian bee), dorsata (Rock bee) and A. florea (Little bee). The exotic variety used for honey production is Apis mellifera (Italian bee).

Question 8.
Find out the correct sentence about manure.
(i) Manure contains large quantities of organic matter and small quantities of nutrients.
(ii) It increases the water holding capacity of sandy soil.
(iii) It helps in draining out of excess of water from clayey soil.
(iv) Its excessive use pollutes environment because it is made of animal excretory waste.
(a) (i) and (iii)
(b) (i) and (ii)
(c) (ii) and (iii)
(d) (iii) and (iv)
Solution:
(b) Manures are the natural fertilisers. They are prepared by the decomposition of animal excreta and plant waste. They are bulky sources of organic matter, which supply nutrients in small quantities, but organic matter in large quantities. The examples of manure are farmyard manure (FYM), compost, vermicompost, etc. Manures enrich the soil with nutrients and replenish the general deficiency of nutrients in the soil. Manures add organic matter (called humus) to soil, which restores the soil texture for better retention of water and for aeration of soil. It increases the water holding capacity in sandy soils and drainage in clayey soil. They also avoid water – logging in clayey soils. Manures protect our environment from synthetic chemicals.

Question 9.
Cattle husbandry is done for the following purposes
(i) Milk Production
(ii) Agricultural work
(iii) Meat production
(iv) Egg production
(a) (i), (ii) and (iii)
(b) (ii), (iii) and (iv)
(c) (iii) and (iv)
(d) (i) and (iv)
Solution:
(a) The branch of agriculture that deals with the feeding, caring and, breeding of domestic animals is called animal husbandry. Human beings domesticate cattle for milk, meat, leather, transportation and draught purposes.

Question 10.
Which of the following are Indian cattle?
(i) Bos indicus
(ii) Bos domestica
(iii) Bos bubalis
(iv) Bos vulgaris
(a) (i) and (iii)
(b) (i) and (ii)
(c) (ii) and (iii)
(d) (iii) and (iv)
Solution:
(a) Generic name of cow (cattle) is Bos indicus. It is adapted for the drier regions of the country such as Gujarat and Rajasthan. Buffalo is commonly called Indian water buffalo, its generic name is Bos bubalis.

Question 11.
Which of the following are exotic breeds?
(i) Brawn
(ii) Jersey
(iii) Brown Swiss
(iv) Jersey Swiss
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv)
Solution:
(b) Exotic breeds are the breeds which have been imported from abroad and reared in India. Exotic breeds of cow are jersey, Holstein-Friesian, Brown Swiss.

Question 12.
Poultry farming is undertaken to raise following
(i) Egg production
(ii) Feather production
(iii) Chicken meat
(iv) Milk production
(a) (i) and (Iii)
(b) (i) and (ii)
(c) (ii) and (iii)
(d) (iii) and (iv)
Solution:
(a) Poultry industry deals with production of domesticated fowl for meat and eggs. The common poultry birds are chicken, turkey, duck, geese, guinea-fowl and pigeon. Eggs and high quality meat obtained from poultry gives us a balanced diet and serves as a cheap source of animal protein.

Question 13.
Poultry fowl are susceptible to the following pathogens
(a) Viruses
(b) Bacteria
(c) Fungi
(d) All of the above
Solution:
(d) Poultry fowl suffer from various diseases caused by viruses (Ranikhet, Fowl pox), bacteria (tuberculosis, cholera), fungi (Aspergillosis) and parasites (worms, mites) etc.

Question 14.
Which one of the following fishes is a surface feeder?
(a) Rohus
(b) Mrigals
(c) Common carps
(d) Catlas
Solution:
(d) Rohu (Labeo rohita) is a column feeder. Mrigal (Cirrhinus mrigala) and common carp (Cyprinus carpio) are! bottom feeders. Catla (Catla catla) is surface feeder.

Question 15.
Animal husbandry is the scientific management of
(i) animal breeding
(ii) culture of animals
(iii) animal livestock
(iv) rearing of animals
(a) (i), (ii) and (iii)
(b) (ii), (iii) and (iv)
(c) (i), (ii) and (iv)
(d) (i), (iii) and (iv)
Solution:
(d) Animal husbandry is the farming or mangement of animal livestock which includes, various aspects such as animal’s shelter, feeding, breeding, health and disease control.

Question 16.
Which one of the following nutrients is not available in fertilisers?
(a) Nitrogen
(b) Phosphorus
(c) Iron
(d) Potassium
Solution:
(c) A chemical fertiliser is a salt or an organic compound containing the necessary plant nutrients. They provide nitrogen, phosphorus and potassium to the plants.

Question 17.
Preventive and control measures adopted for the storage of grains include
(a) strict cleaning
(b) proper disjoining
(c) fumigation
(d) all of the above
(d) Biotic and abiotic factors, which cause destruction of grains during storage can be prevented by following methods:

1. Cleaning of the produce before storage : The grains and other agricultural produce should be properly cleaned and dried in sun before their storage.
2. Safe and proper storage : Godown, ware houses and stores should be properly cleaned, dried and repaired. The bags of grains should be properly disjointed i.e., should not be cluttered at a place to provide proper areation.
3. Fumigation : Chemical pesticides are used as fumigants. These fumes kill the insect pests and other harmful pathogens.

Short Answer Type Questions

Question 18.
Match the column A with the column B.

Solution:
(a) (ii)
(b) (iii)
(c) (i)
(d) (iv)

Question 19.
Fill in the blanks.
(a) Pigeon pea is a good source of ______.
(b) Berseem is an important ______crop.
(c) The crops which are grown in rainy season are called ______crops.
(d) ______are rich in vitamins.
(e) ______crop grows in winter season.
Solution:
(a) protein
(b) fodder
(c) kharif
(d) Vegetables
(d) Rabi

Question 20.
What is a GM crop? Name any one such crop
which is grown in India.
Solution:
GM crops are the crops which are
developed by introducing a new gene from any other source e.g. bacteria or any other organism. Bt cotton is an example of GM crop which is made insect-resistant by introducing gene from the bacteria.

Question 21.
List out some useful traits in improved crop.
Solution:
Some of the useful traits in improved crops are:

1. Higher yield: The main aim of crop improvement is to improve the productivity 1 of economic produce, e.g., grain, vegetables and fodder.
2. Biotic and abiotic resistance: Under different situations crop suffers due to biotic | (diseases, insect-pest infestations) and abiotic stresses (drought, salinity, water logging, heat, cold and frost). Developing the crop varieties resistant to such stress will significantly improve the crop production. For example, MUW 318 is a variety of wheat which is resistant to all the rusts.
3. Photo-insensitivity and thermo – insenstivity: Most of the’ plants are sensitive to certain abiotic factors like light and temperature. Development of photo-insensitive and thermo-insensitive crop varieties will help in crossing the cultivation t boundries.
4. Wider adaptability: Developing the crop varieties with wider adaptability will help in stabilising the crop production under different environmental conditions. For examples, ICPH8 is a hybrid pigeon pea plant which takes a short duration to mature and performs well under drought as well as high moisture conditions.

Question 22.
Why is organic matter important for crop production?
Solution:
Organic matter is very much important for enhancement in food production. Organic matter is added in the form of manures to the crop. The organic matter enriches the soil with nutrients and replenish the general deficiency of nutrients in the soil. It also water and for aeration of soil. For example, the organic matter present in the manures increases the water holding capacity in sandy soils and drainage in clayey soil. It also avoids water logging in clayey soils. The organic matter also provides food for soil organisms (decomposers, such as bacteria, fungi, etc.) which in turn help in making nutrients available to plants.

Thus, organic manures help to improve the physical properties of soil, reduce soil erosion, increase the moisture holding capacity of soil and are also low cost nutrient carriers.

Question 23.
Why is excess use of fertilisers detrimental for environment?
Solution:
Excessive use of fertilisers have various deleterious effects on the environment.

1. Fertilisers change soil chemistry: Excessive use of fertilisers in long run degrades quality of soil and disturbs the ecosystem. The unused part of the fertiliser makes the soil either alkaline or acidic, depending upon its nature.
2. Fertilisers cause water pollution : High doses of these chemicals get washed off through irrigation and rainfall as drainage and reach rivers, lakes, streams and other water bodies and pollute them. In the water bodies, these salts increase the growth of algae (algal bloom). The algae deoxygenates the water, making it unfit for aquatic animals.

Question 24.
Give one word for the following.
(a) Farming without the use of chemicals as fertilizers, herbicides and pesticides is known as ______.
(b) Growing of wheat and groundnut on the same field is called as ______.
(c) Planting soyabean and maize in alternate rows in the same field is called as ______.
(d) Growing different crops on a piece of land in pre-planned succession is known as ______.
(e) Xanfhium and Parthenium are commonly known as ______.
(f) Causal organism of any disease is called as
Solution:
(a) organic farming
(b) mixed cropping
(c) intercropping
(d) crop rotation
(e) weeds
(f) pathogen

Question 25.
Match the following A and B.

	(A)		(B)
(a)	Cattle used for tilling and carting	(i)	Milk producing female
(b)	Indian breed of chicken	(ii)	Broiler
(c)	Sahiwal, Red Sindhi	(iii)	Drought animals
(d)	Milch	(iv)	Local breed of cattle
(e)	Chicken better fed for obtaining meat	(v)	Aseel

Solution:
(a) (iii)
(b) (v)
(c) (iv)
(d) (i)
(e) (ii)

Question 26.
If there is low rainfall in a village throughout the year, what measures will you suggest to the farmers for better cropping?
Solution:
Poor rainfall pose a threat to the productivity of rain fed crops.

• These crops then need supply of water from external sources. Under such conditions various irrigation systems can be adopted to supply water from different water resources. Some of irrigation methods like sprinkler, drip and surface irrigation can be used that reduces the water wastage and supply the required amount of water.
• Drought resistant and early maturing varieties of crops should be cultivated that have less water requirement.
• Soil should be enriched with more humus content so as to increase the water holding capacity as it retains water for longer duration.

Question 27.
Group the following and tabulate them as energy yielding, protein yielding, oil yielding and fodder crop.
Wheat, rice, berseem, maize, gram, oats, pigeon gram, sudan grass, lentil, soyabean, groundnut, castor and mustard.
Solution:
The given crops can be grouped into the following categories:

1. Energy-yielding:
   • Wheat
   • Rice
   • Maize
2. Protein yielding:
   • Gram
   • Pigeongram
   • Lentil
   • Soybean
3. Oil-yielding:
   • Groundnut
   • Castor Mustard
   • Soybean
4. Fodder crops:
   • Sudangrass
   • Berseem
   • Oat

Question 28.
Define the term hybridisation and photoperiod.
Solution:
Hybridisation: Hybridisation can be defined as a crossing between genetically dissimilar plants to produce a new kind (hybrid). This method incorporates the desired (good) characteristics of both parents in one variety. The crossing may be intervarietal, intergeneric or interspecific.

Photoperiod: Period of illumination for a flower or plant is termed as photoperiod. Plant’s response to relative lengths of day light and darkness. Flowering plants can be classified as Day neutral, Long day or Short day plants according to the photoperiod in which they flower.

Question 29.
Fill in the blanks.
(a) Photoperiod affect the ______.
(b) Kharif crops are cultivated from ______to ______.
(c) Rabi crops are cultivated from ______to ______.
(d) Paddy, maize, green gram and black gram are ______ crops.
(e) Wheat, gram, pea, mustard are ______crops.
Solution:
(a) flowering of plants
(b) June, October
(c) November, April
(d) Kharif
(e) Rabi

Question 30.
Cultivation practices and crop yield are related to environmental condition. Explain.
Solution:
Cultivation practices and crops yield are related to environmental condition. Various crops require different climatic conditions, temperature and photoperiod, for their growth and completion of life cycle. On the basis of seasonal variations, crops in India can be classified into three main groups :

• Rabi crop: It is a winter season crop grown from November to April.
• Kharif crop: It is a rainy season crop grown from June to October.
• Zaid crop: It is a summer season crop grown from April to June.

Question 31.
Fill in the blanks.
(a) A total of ______ nutrients are essential to plants.
(b) ______ and ______are supplied by air to plants.
(c) ______ is supplied by water to plants.
(d) Soil supplies ______nutrients to plants.
(e) ______ nutrients are required in large quantity and called as .
(f) ______ nutrients are needed in small quantity for plants and are called ______.
Solution:
(a) 16
(b) Carbon, oxygen
(c) Hydrogen .
(d) 13
(e) Six, macronutrients
(f) Seven, micronutrients

Question 32.
Differentiate between compost and vermi- compost?
Solution:
Compost:

1. Compost is prepared from farm and town refuse such as vegetable and animal refuse, faecal matter of human beings, weeds, straw, rice husks, forest litter, etc. It is a biological process in which both aerobic and anaerobic microorganisms decompose the organic matter.
2. It takes about 3 to 6 months for decomposition of organic refuse.

Vermicompost:

1. Vermicompost is the degradation of organic waste through the consumption by earthworms.
2. It takes about 1-2 months to prepare a vermicompost.

Question 33.
Arrange these statements in correct sequence of preparation of green manure.
(a) Green plants are decomposed in soil.
(b) Green plants are cultivated for preparing manure or crop plant parts are used.
(c) Plants are ploughed and mixed into the soil.
(d) After decomposition it becomes green manure.
Solution:
(b) Green plants are cultivated for preparing manure or crop plant parts are used.
(c) Plants are ploughed and mixed into the soil.
(a) Green plants are decomposed in soil.
(d) After decomposition it becomes green manure. For preparing the manure, green manure crops are cultivated in the field for about 6 to 8 weeks and mulched and ploughed into field in the tender stage, i.e., at flowering stage. These buried crops get decomposed before sowing of next crop and becomes a green manure.

Question 34.
An Italian bee variety A. mellifera has been introduced in India for honey production. Write about its merits over other varieties.
Solution:
For the production of honey on the commercial basis, Italian variety of honey bee, Apis mellifera is commonly used throughout the country. This variety has been domesticated in India due to its various desirable good characters such as gentleness in nature, good honey collection capacity, prolific queen production with less swarming and a good ability to protect itself from enemies.

Question 35.
ln agricultural practices, higher input gives higher yield. Discuss how?
Solution:
In agricultural practices, higher inputs give higher yield. Higher inputs in the form of sowing of seeds of improved variety, application of better manures and fertiliser, proper spraying of pesticides and weedicides, improved threshing and harvesting of crops leads to increase in crop productivity. This also means the higher money inputs to raise the yield. Financial condition of farmers allow them to take up different farming practices and technologies. The farmer’s purchasing capacity for input decides cropping system and production practices.

Long Answer Type Questions

Question 36.
Discuss the role of hybridisation in crop improvement.
Solution:
The crossing between genetically dissimilar plants to produce a new kind (hybrid) is called hybridisation. Crossing may be between two different varieties (intervarietal), between two different species (interspecific) and between different genera (intergeneric).

Cross-breeding of two varieties of plants is carried out to obtain an improved variety of plants which will combine in it both the desired characteristics of parent crop plants. For example, the new improved variety of crop plants, thus obtained will give high yield of food grains and it will be disease resistant too. This process of cross breeding of different plants to obtain a new improved variety of crops is called hybridisation.

Selection and hybridisation are often combined in breeding. In India crops are grown in diverse types of soil and different climatic conditions by poor to progressive farmers. Keeping in mind climatic factors, input application, disease and pest resistance, quality and adaptability etc. a large number of varieties have been developed by hybridisation. Such varieties are high- yielding, resistant to diseases and pests, have better quality and early to late maturing time.

Question 37.
Define
(i) Vermicompost
(ii) Green manure
(iii) Biofertiliser
Solution:
(i) Vermicompost
Vermicompost is a kind of manure, rich in organic matter and nutrients, which is derived from organic wastes of plant and animal origin by the activity of earthworms. The latter promotes soil aeration, crush and mix soil particles and convert the nutrients into simpler forms.
The earthworms are popularly known as farmer’s friend or Nature’s ploughman. Most common species of earthworm used for decomposition are Dichogaster bolani.

(ii) Green manure
Green manure is a kind of manure which is prepared in the field itself to enrich the soil in nitrogen and phosphorous. Green leguminous and non-leguminous plants are mulched by ploughing and then left in the field to decompose by activity of natural decomposers such as bacteria and fungi. The most commonly used green manure in India are — sun hemp, sweet clover, cow-pea, berseem, cluster bean etc.

(iii) Biofertilisers
Organisms which enrich the soil with nutrients are called biofertilisers. Biofertilisers are used for the specific crop plants such as pulses, legumes, oil seeds and rice. Biofertilisers are renewable and non-pollutant sources of plant nutrients such as nitrogen. They are not alternatives to chemical fertilisers but can play a supplementary role in supplying nitrogen to specific crops under specific soil conditions.

Two biofertilisers, Rhizobium and blue green algae (Nostoc and Anabaena) are being used in cultivating pulses, legumes, oil seeds and wet-land rice.
Some of the biofertilisers are given below :

• Legume (Rhizobium symbiosis).
• Azolla (Anabaena symbiosis).
• Free-living bacteria (Azotobacter) living in soil.
• Cyanobacteria (Anabaena, Nostoc).
• Mycorrhiza (symbiotic association of fungi with roots of higher plants).

Question 38.
Discuss various methods for weed control.
Solution:
An unwanted plant species growing spontaneously at a habitat (or in the cultivated field) is called a weed. Weeds damage our crop plants, by competing with them for space, water, light and nutrients. Some of the important weeds of our crop fields are Parthenium (gajar ghas), Xanthium (gokhroo), Cyprus rotundus (motha) etc. The overall loss caused by weeds in India had been estimated at 27% of field crop production. Therefore, eradication of weeds from crop fields during the early stage of crop growth is our prime concern. Some of the most commonly used methods of weed control are :

1. Hand pulling: Individual weed plants are pulled by hand.
2. Tillage: Tillage is mechanical agitation of soil by over turning etc. destruction of weeds and reduction of their seeds in the soil is called tillage.
3. Mowing: Mowing of field also prevents seed production of weeds and removes weed growth.
4. Flooding: Flooding of fields after harvesting is a popular method for controlling perennial weeds.
5. Cropping and competition method : Weeds are also controlled by proper seed bed preparation, timely sowing of crops, intercropping, crop rotation, summer ploughing, adopting most effective methods of irrigation and application of fertilisers. Thus, crop plants better compete with the weeds and restrict their growth.
6. Use of chemical herbicides: An enormous variety of chemical compounds have been synthesised, tested for herbicidial activity and the successful ones have been applied to the fields.

Question 39.
Differentiate between the following:
(i) Capture fishery and Culture fishery
(ii) Mixed cropping and Inter cropping
(iii) Bee keeping and Poultry farming
Solution: (i)

	Bee Keeping	Poultry Farming
(a)	Practice of rearing honey bees for the commercial production of honey and wax is called apiculture or bee keeping.	Practice of raising domestic fowls for commerical production of egg and meat is called poultry farming.
(b)	Varieties of honey bees used for production of honey are Apis cerana indica, A. dorsata and A. florae.	The common poultry birds are chicken, turkeys, ducks, geese, guinea-fowls and pigeons.

	Mixed cropping	Intercropping
(a)	The method of growing one or more crop simultaneously on same piece of land in an irregular manner is called mixed cropping.	When two or more crops are grown simultaneously on the same field in a set pattern instead of mixing with each other, it is called inter cropping.
(b)	It aims at reducing the chances of failure of a crop.	Its main aim is to increase the productivity.
(c)	Harvesting and threshing of individual crops cannot be done easily.	Harvesting and threshing of individual crops can be done easily and at different times.

	Capture fishery	Culture fishery
(a)	Method of obtaining-fish from natural resources, is called capture fishery.	Method of obtaining fish from fish farms, is called culture fishery.
(b)	No seeding or rearing of fish is required.	Fish is reared and grown in fish farms.
(c)	It is carried out both in inland and marine water resources.	It is carried out mostly in inland water resources and near seashore.

Question 40.
Give the merits and demerits offish culture
Solution:
Culture fishery is a kind of business and research activity concerned with the culturing, feeding, breeding and production of fishes in marine and fresh water ecosystem. The basic advantage (merit) of fish culture is that it decreases our dependence on natural sources of fish. We can obtain fish of desired species in desired numbers by aclturing them.
Some merits of culture fishery are :

1.  Fish as food : Various species of fishes are cultivated extensively as food. Some of the species grown are rohu, mrigal, catla etc.
2.  Fish for controlling diseases: Various fish species are, reared to control diseases like malaria, yellow fever etc. The larvivorous fishes like Gambusia are reared which eat up the larvae of mosquito and prevent the spreading of disease.
3. Economic value: Besides fishes, various oysters are also reared in culture fishery. These oysters are cultivalted for pearls they make, which are of high economic importance.
4. Source of income : The fishing industry has brought a lot of income to the farmers in particular and the country on the whole. Blue Revolution is also gaining popularity on the same lines as “green revolution’.
5. Fishes are also reared for other by-products like fish oil, manure, glue, leather etc. Thus, fish farming is advantageous, economical and profitable from business point of view. There are, however certain problems or demerits associated with fash farming/culture fishery. They are :
   • It poses a threat to biodiversity. Only economically important and valued fishes are grown ( fish monoculture) which leads to extinction of rare and economically less important fishes.
   •  Sometimes, such exotic species are introduced which cause extinction of local fish species.

Question 41.
What do you understand by composite fish culture?
Solution:
Practice of culturing a combination of five or six species of fish in a single fish pond is termed as composite fish culture. Selection of several species of fish for culturing in a pond helps to enhance yield with same cost and to utilise most of the available food in the water reservoir.
Fishes are selected on the basis of following characteristics.

1. The selected species are fast growing. For example, when common Indian carps (rohu, catla and mrigal) and exotic carps (silver carp, grass carp and common carp) are selected for culturing, they give 8-9 times more yield.
2. The fishes selected should not compete with each other for space and nutrition. They should live in distinct zones inside the pond. For example, catla and silver carp live mostly in surface zone, rohu and grass carp live in middle zone and mrigal and common carp live at the bottom.
3. The feeding habits of species selected should be distinct. For example, silver carp feeds on phytoplanktons, catla feeds on zooplanktons, rohu and mrigal feed on decaying plants and detritus, grass carp feeds on aquatic plants and weeds. Thus, they can be grown together.
   Composite fish farming is advantageous, economical and profitable from business point of view.

Question 42.
Why bee keeping should be done in good pasturage?
Solution:
Bee keeping also called apiculture is an important enterprise of agriculture and is concerned with commercial production of honey and wax.
As honey bees feeds on flowers for collecting nectar, which is eventually converted into honey, availability of flowering plants in the vicinity is a major factor in bee keeping.

In fact, the taste of honey depends upon the type of flowers, available. Pasturage refers to theland area covered with flowering plants which are available for collection of nectar and pollen. It plays an important role in the quantity and quality of honey. Mostly, bee farms or apiaries are estabilished in good and desirable locations where abundance of flowering plants (flora) is available in 1 to 2 kms radius for nectar and pollen collection.

Question 43.
Write the modes by which insects affect the crop yield.
Solution:
Insects affect the crop yields in both useful and harmful ways. Harmful insects attack the plants and are called insect pests. Insect pests are of following types :
Chewing insects : Insect pests of this category cut the roots, stem and leaves with the help of their chewing mouth parts. They chew and swallow the pieces of plant parts. E.g., grasshoppers, caterpillars, locusts etc.
Sucking insects : These insects puncture the plant parts and suck the cell sap with the help of their needle like hollow beaks. E.g., leaf hoppers, aphids, bugs, etc.
Internal feeders : These insects bore into stem and fruits. They live inside the plant parts and harm the crop yield. E.g., weevils, borers, etc.
Every year Insect pests cause a significant damage to the crops and thereby reduce the productivity. Various methods like use of chemical pesticides, natural insecticides like neem, nicotine etc. and various biological methods are employed to control the pest infestation and reduce the damage done by them. Useful insects are those which assist in pollination thus, ensure fruit formation and those which feed on harmful)nsect pests. E.g., lady bird beetle feeds on aphids thus controls this pest.

Question 44.
Discuss why pesticides are used in very accurate concentration and in very appropriate manner?
Solution:
The chemicals used to eliminate pests are called pesticides. Pesticides include insecticides (for killing insects), weedicides (killing weeds), rodenticides (for killing rats), fungicides (killing fungi) etc. Pesticides are used in very accurate concentration and in
very appropriate manner because excessive and regular use of these chemicals is not only hazardous, contaminates food and water but also affects the quality of produce which adversely affects the health of consumers.
These pesticides should be used in accurate concentration because they have harmful effects on the environment also. They are non-biodegradable and once they enter the food chain they go on accumulating in the trophic level, a phenomenon called biomagnification. Such an accumulation of pesticides may be poisonous to both plants and animal species. Moreover, the runoff from fields carry pesticides into the water bodies. These have adverse effect on the aquatic animals and may cause their death also.

Question 45.
Name two types of animal feed and write their functions.
Solution:
The food required by dairy animals is called feed. The dairy animals must get adequate, palatable, laxative, appetising and balanced ration with sufficient greens and ’ all nutrient in appropriate amounts. Large quantity of water is also required for milk production.
Two types of normal feed for dairy animals are :
(i) Roughage
(ii) Concentrates ‘
Roughage: This part of cattle feed contains mostly fibres which come from hay (straw of cereals or Bhusa), green fodder (cow pea, berseem etc.) and silage.
Concentrates: These are mixtures of substances containing less fibres and relatively excessive amount of protein, fat, carbohydrates, vitamins, minerals etc. – A balanced ration containing all nutrients in proper amounts plus sufficient water must be offered to dairy animals at frequent intervals. Besides this, various additives which contain micronutrients, antibiotics etc. must also be given to cattle to promote their milk production.

Question 46.
What would happen if poultry birds are larger in size and have no summer adaptation capacity? In order to get small sized poultry birds, having summer adaptability, what method will be employed?
Solution:
Following difficulties will be faced for
rearing up of large size fowls that are unable to adapt during summers :

1. Large sized fowls cannot be raised as broilers, asi broiler chicks should be dwarf (small sized) so that they yield more and consume less.
2. As the birds are unable to adapt in summer their efficiency will be hampered during high temperature conditions (summers). More expenditure needs to be done on their maintenence and providing them suitable conditions for increasing their productivity. Cross breeding methods should be employed for production of small sized species which are well adapted to summer conditions. Various cross breeding programmes between desi (indigenous) and exotic (foreign) breeds are being carried out for the production of cross breeds with desirable traits. Other desired traits besides temperature adaptability and dwarf size are as follows :
   • They should require less expenditure for their maintenance.
   • The cross breeds should lay more number of eggs and produce good quality chicks.

Question 47.
Suggest some preventive measures for the diseases of poultry birds.
Solution:
The poultry birds suffer from various diseases caused by viruses (flu, dermatitis, fowl pox, ranikhet disease), bacteria (tuberculosis, cholera, diarrhoea), fungi (aspergillosis), and also parasites (worms, mites, lice), etc.
These diseases reduce the bird growth, decrease egg production, decrease fertility and may even cause death.
Following are some preventive measures for diseases of poultry bird :

1. Disease-free chicks should be raised in proper sanitary conditions^ from healthy parents.
2. Poultry house should cleaned and disinfected by spraying disinfectants at regular intervals.
3. Fresh and balanced feed should be given to the birds to avoid nutritional diseases.
4. (iv) Overcrowding of birds, ill ventilation and dampness should be avoided to prevent the spreading of disease.
5. Newly hatched chicks should be vaccinated in time. Vaccination prevents the occurrence of infectious diseases and reduces loss of poultry during an ou tbreak of disease.

Question 48.
Figure15.1 shows the two crop fields [Plots A and B] have been treated by manures and chemical fertilisers respectively, keeping other environmental factors same. Observe the graph and answer the following questions.
(i) Why does plot B show sudden increase and then gradual decrease in yield?
(ii) Why is the highest peak in plot A graph slightly delayed?
(iii) What is the reason for the different pattern

(i) In plot B, chemical fertilisers were added. With the addition of chemical fertilisers the yield of the crop increased initially, but with continued use of chemical fertilisers the crop yield decreased significantly. This happened because chemical fertilisers are nutrient specific and give only short-term benefits. Their prolonge use destroys the soil fertility and cause a gradual decline in the crop production.

(ii) In plot A manures were used to improve the soil fertility. Manures are rich source of organic matter and release nutrients slow in comparison to the fertilities. Therefore the highest peak in plot of graph slightly delayed. Manures enrich the soil with nutrients and organic matter, which further increases the soil fertility. Manure also improve the soil structure. Addition of manures into the soil have long term benefits and improve the soil fertility which considerably increased the crop yield.

(iii) Manures are natural ways of enriching the soil with organic nutrients, whereas chemical fertilisers are chemicals that enrich the soil with a particular elements. Fertilisers have adverse effect on soil fertility as their prolonged use can kill the useful microorganisms present in the soil and ultimately make the soil unfit for sustaining plant life and their prolonged effects include reduction in crop productivity.
Manures, on the other hand improves the soil fertility by adding organic nutrients to the soil and their prolonged use will cause the crop production to increase.

Question 49.
Complete the crossword puzzle (Fig.15.2).

Across
1. Oil yielding plant (9)
3. Crop grown in winter season (4)
5. Fixed by Rhizobium (8)
9. Common honey bee (4) Downward
2. Animal feed (6)
4. A micronutrient (5)
6. Unwanted plant in crop fields (4)
7. An exotic breed of chicken (7)
8. Bottom feeders in fish pond (7)
10. A marine fish (4)
Solution:
Across
1. SUN FLOWER
3. RABI
5. NITROGEN
9. APIS Downward
2. FODDER
4. BORON
6. WEED
7. LEGHORN
8. MRIGALA
10. TUNA

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