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Science Class 9

Class 9 : Notes | EduRev

The document Notes | EduRev is a part of the Class 9 Course Science Class 9.
All you need of Class 9 at this link: Class 9

SHORT ANSWER TYPE QUESTIONS

Q.1. Explain intensive fish farming with the help of one example.    [CBSE 2016]
Ans: Composite fish culture system is a way of intensive fish farming where five or six different species of fishes are grown in the same pond. Those fishes are taken that have different food habits and which do not compete with each other for food.
e.g. Catla, Rohu, Mrigal, Common Carp, Grass Carp are all cultivated in the same pond. Catla fish feeds on water surface, Rohu is middle-zone feeders, Mrigal and Common Carp are bottom feeders while Grass Carp feed on weeds. Thus, all the types of fishes live peacefully and proper utilization, of food resources, is taken care of which also increases the fish yield. 

Q.2. State one factor which affects the quality of honey produced.    [CBSE 2015]
Ans: The quality of honey produced depends upon the flowers available to the bees for nectar or pollen collection. 

Q.3. Give two examples of shellfishes.    [CBSE 2015]
Ans:
Shellfish include two groups: Crustaceans and Molluscs (or molluscs) Crustaceans include crabs and lobsters.
Molluscs include octopus and oysters.

Q.4. Mention the names of four marine fish of high economic value.    [CBSE 2015]
Ans: The four marine fishes are as follows:
Catla, Rohu, Common Carps and Mrigals.

Q.5. (a) Define weed. Give two examples.
(b) Why is it essential to remove weeds from agricultural fields?
(c) What are weedicides?    [CBSE 2015]

Ans: (a) Weeds are small-sized unwanted plants which grow along with a cultivated crop in the field, e.g. Xanthium, Parthenium etc.
(b) It is essential to remove the weeds from the agricultural field as they can severely reduce the crop yield by competing for light, water and nutrients.
(c) Weedicides are chemicals which are sprayed in the field to kill the weeds, e.g. atrazine. isoproturon etc.

Q.6. In the summer vacation the students of IX standard were given an investigatory project. They were asked to visit a dairy farm and note down their observations. Vinay took information from the internet and made the project while Sakshi visited the dairy, saw how and what cattle are fed with, how much milk they give per day. She also learned about the diseases they suffer from and how they are cleaned and taken care of.
(i) What kind of feed is given to cattle to increase the milk production?
(ii) Write down two symptoms of a sick animal.
(iii) Why and whose characteristics would you like to adopt between Sakshi and Vinay?    [CBSE 2015]

Ans: (i) Concentrates which are low in fibre but contains high levels of proteins and other nutrients are required as feed for cattle to increase milk production.
(ii) Symptoms of sick animals are:
(a) They don't feed normally.
(b) They don't have normal posture.
(c) I will like to adopt the characteristics of Sakshi. One cannot learn and experience the feeling of field trip simply by browsing the internet. Method adopted by Vinay if continued by him may affect the character of Vinay when he grows. One must be honest with his work as these practices give birth to a person of strong character.

Q.7. Explain the ways by which crop-production can be increased.    [CBSE 2015]
Ans: 
Crop production can be increased by adopting suitable practices in farming and are divided into 3 major groups of activities:
(i) Crop variety improvement
(ii) Crop production improvement
(iii) Crop protection improvement
(i) Crop variety improvement: This approach depends on the finding of a crop variety that can give a good yield. Varieties of crop can be selected by breeding for various useful characteristics such a disease resistance, response to fertilizer, product quality and high yield. One way of incorporating desired characters is hybridization. Another way of improving the crop is by introducing gene that would provide the desired character.
(ii) Crop production improvement: It depends on the financial condition of the farmer. Crop production is of 3 types viz. low cost, high cost and no-cost production. Use of manures and fertilizers, mixed cropping, intercropping, crop rotation are some crop production practices available for crop production.
(iii) Crop protection management: Crops in the field must be protected from weeds, pests and diseases. All these cause damages to the crop.
Crop can be protected by:
(a) Use of pesticide
(b) Use of resistant varieties
(c) Crop rotation and other cropping systems
(d) Summer ploughing

Q.8. Rahul and Rachna were practising floriculture on their farm. They sold the flowers to florists in India. They felt that if they start bee-keeping too, their income will increase. They obtained more information from the local officer.
(i) What is pasturage and how is it related to duality of honey?

(ii) Name a bee variety which is commonly used for commercial honey production.
(iii) Why society would appreciate Rahul and Rachna?    [CBSE 2015]

Ans: (i) Pasturage is the flowers available to the bees for nectar and pollen collection. The taste and quality of honey depends on the kind of flowers available in the pasturage.
(ii) Apis cerana India commonly known as Indian bee is used for commercial honey production.
(iii) Rahul and Rachna have shown how to generate additional income without additional investment. This will be an eye-opener for the youth of the society.

Q.9. Name the environmental factors related to cultivation practices and crops yield. Explain how they are related to crop yield. [CBSE 2015]
Ans: Different crop requires different climatic conditions, temperature and photoperiods for their growth and completion of life cycle. Photoperiods are related to the duration of sunlight. Growth of plants and flowering are dependent on sunlight. There are some crops which are grown in rainy season. There are some other crops which are grown in winter season. Thus, environmental factors are related to collective practices and crop yield.

Q.10. India is a country with three fourth of the population engaged in agriculture. Even though financial conditions of some farmers do allow them to take higher-level farming practices and improved agriculture technology, yet they are hesitant to use of HYV seeds with traits such as resistance to diseases and pests, high quality that would finally result in higher yield. The Government’s Kisan channel solved all their apprehensions.
(i) What is meant by genetically modified crops?
(ii) What are the desired agronomic characters for fodder and cereal crops?
(iii) In your opinion, what should be done so that the modern agriculture technology is adopted by most of the farmers? [CBSE 2015]
Ans: (i) Genetically modified crops are those plants in which the DNA have been modified using genetic engineering techniques.
(ii) For fodder-profuse branching, and for cereal-dwarfness
(iii) Modern agriculture technology will be adopted by the farmers, the farmers have scientific temper, and they are made aware and given the knowledge to enhance agriculture practices.

Q.11. Give one word for the following and give one example of each:
(a) Growing one row of crop alternately with the other crop.
(b) Growing two or more crops simultaneously in the same field.

(c) Growing of different crops on a land in pre-planned succession.    [CBSE 2015]
Ans: (i) Intercropping, e.g. soybean + Maize.
(ii) Mixed cropping, e.g. wheat + gram.
(iii) Crop rotation, e.g. potato, oats, peas and rye.

LONG ANSWER TYPE QUESTION

Q.1. (a) Name two common sources from which list are captured.
(b) Why are mussels and shellfish cultivated?
(c) As marine fish stock gets depleted, how tin demand for more fish can be met?
(d) How are marine fish caught?
(e) Name two marine fish of high economic value, which are also cultured in seawater   
[CBSE 2016]
Ans: (a) Following are two common sources from which fish are captured:
(i) Natural resources, e.g. sea, ocean, river, etc.
(ii) By fish farming in freshwater and marine water,
(b) Mussels have high nutritive value. It is a good source of vitamins and have desirable fatty acids that improve brain function and also gives important minerals like zinc that boosts immunity. Similarly, shell fish is also rich in vitamins, minerals, fish oil and it also brings in good revenue as sea food.
(c) The demand for more fish can be met with mariculture. Mariculture is the practice of cultivating only marine organisms for commercial purposes.
Advantages of mariculture are as follows:
(i) It is cultivated for food and products that give economical value and is important for industrial fishing:
(ii) Farming of marine fish, prawn, shellfish are done in open ocean or artificial ponds filled with sea water.
(d) Generally, fishes can be caught by hand gathering, netting, spearfishing, angling and trapping.
For commercial purposes, fishes from high seas are caught by-long lines, gill nets, purse seines and bottom trawlers.
(e) The marine fishes that are cultivated in the sea and has high economic value are:
(i) Bhetki
(ii) Mullets
(iii) Pearl Spot.

Q.2. (a) Distinguish between macronutrients and micronutrients on the basis of
(i) their functions
(ii) amount required by plants.

(b) Classify the following elements as macro or micronutrients in plants
(i) Nitrogen
(ii) Zinc
(iii) Copper
(iv) Potassium

(c) In what way deficiency of these nutrients harmful to crops?    [CBSE 2015]
Ans: (a)
 Notes | EduRev
(b) (i) Nitrogen- Macronutrient
(ii) Zinc- Micronutrient
(iii) Copper- Micronutrient
(iv) Potassium- Macronutrient
(c) Deficiency of nutrients affects physiological processes in plants including reproduction, growth and susceptibility to diseases.

Q.3. Define genetically modified crops. How are they made? Explain the significance of genetically modified crops with suitable example.   [CBSE 2015]
Ans: Genetically modified crops are those plants in which the DNA have been modified using genetic engineering techniques. The aim of making GM crop is to introduce a new trait into the plant which does not occur naturally in the species.
Technique: In GM crop, genes are added or removed using genetic engineering technique. In this technique, DNA from another species of the same kingdom is bound to tiny particles of gold or tungsten which are subsequently shot into plant tissue under high pressure. The accelerated particles penetrate both, the cell wall and membranes. The DNA gets separated from the metal and is integrated into the plant DNA inside the nucleus.
Significance: GM crop has increased yield of crop. Due to higher yield, it gives more income and has made the economic conditions of farmers cultivating GM crop better. While on one hand, farming land area is almost constant, and the human population is increasing every day. GM crop has made it possible to feed the growing population even though the farming land remains constant.

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