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ScienceClass 9CBSE

1. The process of nitrogen-fixation by bacteria does not take place in the presence of (a) molecular form of hydrogen (b) elemental form of oxygen (c) water elemental form of nitrogen

Soln: (b) elemental form of oxygen

ScienceClass 9CBSE

The two forms of oxygen found in the atmosphere are (a) water and ozone (b) water and oxygen (c) ozone and oxygen water and carbon-dioxide

Answer is (c) ozone and oxygen Explanation: Ozone is an allotropic form of oxygen

ScienceClass 9CBSE

One of the following factors does not lead to soil formation in nature (a) the sun (b) water (c) wind polythene bags

Soln: Answer is (d) polythene bags Explanation: Polythene bags pollutes the soil and converts the soil infertile.

ScienceClass 9CBSE

1. What would happen, if all the oxygen present in the environment is converted to ozone? (a) We will be protected more (b) It will become poisonous and kill living forms (c) Ozone is not stable, hence it will be toxic (d) It will help harmful sun radiations to reach earth and damage many life forms.

Soln: Answer is (b) It will become poisonous and kill living forms Explanation: Most of the organisms live on earth required oxygen for their living If oxygen convert to ozone living beings will get killed.

ScienceClass 9CBSE

If there were no atmosphere around the earth, the temperature of the earth will (a) increase (b) go on decreasing (c) increase during day and decrease during night be unaffected

Soln: Answer is (c) increase during day and decrease during night Explanation: Because atmosphere prevent a lot of heat from reaching earth’s surface. Atmosphere also prevent escape of heat in the night. Hence atmosphere is responsible for maintain an ambient temperature

ScienceClass 9CBSE

1. of the earth is heated by radiations which are mainly (a) radiated by the sun (b) re-radiated by land (c) re-radiated by water re-radiated by land and water

Soln: Answer is (d) re-radiated by land and water Explanation: Heat from sun reaches earth and water through sunrays. This heat is reradiated by earth and water to convert atmosphere hot.

ScienceClass 9CBSE

1.      Suggest some preventive measures for the diseases of poultry birds.

Soln: Preventive measures to avoid disease in poultry are Cleaning: It is very important to maintain Poultry farms should be cleaned regularly to maintain hygiene in the farm. Sanitation: Sanitation should be maintained inside the farm Disinfectatnts : Disinfectant should be sprayed on a regular Vaccination: Birds should be vaccinated to prevent disease in

ScienceClass 9CBSE

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?

Soln: Temperature maintenance is vital for the better egg production. Even though if the size of poultry birds is large but without temperature adaptation egg production may decrease. To obtain high adaptability and small sized poultry. Cross breeding of poultry birds is done. Small size also require small food and small area to rear.

ScienceClass 9CBSE

Name two types of animal feed and write their functions.

Roughage Roughages are provided by husk, grass and chopped leaves. Roughages give complete nourishment to animals and roughages aids proper digestion in animals. Concentrates These are prepared as per the requirement of particular cattle and they are highly rick in proteins and minerals. Varieties of concentrates are available in the market.

ScienceClass 9CBSE

Discuss why pesticides are used in very accurate concentration and in very appropriate manner?

Soln: Pesticides are used in very accurate and in very appropriate manner because of following reasons Excess use of pesticides will reduce the fertility of the soil. Reduces the organic matter present in the soil Kills useful microorganisms present in the Causes air, water and soil

ScienceClass 9CBSE

Write the modes by which insects affect the crop yield.

Below are the modes by which insects decrease crop yield. Cutting: Insects cut plant parts such as leaves, fruits, flowers etc. This damages the plant, damaged leaves result in decreased rate of photosynthesis , decreased flower decreases the production of seeds. Borers: Some pests bore holes in specific plant parts and start living inside. These pest utilize plant nutrients and food which result in the decrease in the yield. Suckers Few pests suck cell sap by using their proboscis. This result in adverse effect on plant which reduces the yield.

ScienceClass 9CBSE

Why bee keeping should be done in good pasturage?

Bees need a quality nectar to produce honey. A good pasturage consists of plenty of flowers which can be used by bees to get quality nectar. This increase the quality as well as the quantity of the bees. If bees are confined to only single variety of flowers for nectar honey quality will have similar taste, consistency. Most of the farmers make honey obtained from single nectar.

ScienceClass 9CBSE

What do you understand by composite fish culture?

Soln: Composite fish culture is a method of rearing five to six varieties of fish species in a single pond. Species are selected in such a way that they should not compete with other for food because of change in their food habits. Hence fishes use food available in pond. Ex: Catla’s are surface feeders. Rohu is middle zone feeder and common caps are bottom feeders.

ScienceClass 9CBSE

1.      Give the merits and demerits of fish culture?

Soln: Merits of Fish culture Desired fishes can be obtained in large amount in small area. Improved food quality as fishes are the cheap source of proteins. Demerits of fish culture Only desired varieties of fishes are reared It is threat to biodiversity.

ScienceClass 9CBSE

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

Soln: Capture fishery is a traditional fishing where fisherman catches the fishes from natural resources like sea and rives. Culture fishery is the one where the fishes are obtained reared for the commercial purpose. Mixed cropping is the method of growing two or more crops in a single field. Inter cropping is a type of mixed cropping where two or more crops are grown in a single field in a definite patterns. Bee keeping is the method of rearing bees to obtain honey. Poultry farming is method of raising domestic fowl for the purpose of egg and meat.

ScienceClass 9CBSE

Discuss various methods for weed control.

Various methods of weed control are listed below Mechanical removal Preparation of seed bed Timely sowing of desired crop Crop rotation

ScienceClass 9CBSE

Define (i) Vermicompost (ii) Green manure (iii) Bio fertilizer

Vermicompost: Manure which is rich is organic materials. Vermicompost is prepared by using earthworms, plant and animal waste. Earthworms helps in composting organic waste to give a nutrient rich manure. Green Manure: Manure prepared by composting green plant is known as green. Green manure is usually made in the field Ex: Hemp is allowed to decompose to get green manure. Bio-fertilizers: Usage of living organisms to provide nutrient to plant and to make soil fertile is known as bio fertilizers. Ex: Blue green algae used as bio-fertilizer in paddy fields.

ScienceClass 9CBSE

Discuss the role of hybridisation in crop improvement.

Hybridization is a method of crossing two dissimilar varieties to get desirable characters in the off-springs. Hybridization improves the crop in following attributes High yield: Hybridization helps to improve crop yield Pest resistance: Crop can obtain pest resistance by incorporating pest resistance genes. Ex: BT Cotton Draught resistance: Plants obtain draught resistant genes from draught resistant varieties. Disease resistance: Plants can be immune to certain disease against which genes are incorporated.

ScienceClass 9CBSE

In agricultural practices, higher input gives higher yield. Discuss how?

Higher inputs gives higher yield refers to the facilities and financial status of a farmer. Good financial status allows farmers to take up new methodologies and technologies to increase the yield. Higher buying capacity decides cropping methods and agricultural practices.

ScienceClass 9CBSE

An Italian bee variety A. mellifera has been introduced in India for honey production. Write about its merits over other varieties.

Advantages of Italian bee variety A. mellifera over other bee varities are as follows They stings less Their honey collection capacity is In stays in a single bee hive for very long period of time Its breeding capacity is

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