CBSE Class 08 Science Crop Production and Management Important question and Answers
A. One Word Answers
1.Conversion of ammonia into nitrates is called
Ans.Nitrification
2.The irrigation method in which water enters the field through channels made between two rows of crop plants is:
Ans. Furrow irrigation method
3.Crops sown during winters are
Ans.Rabi Crops
4.The method of scattering seeds in the field by hand is
Ans.Broadcasting
5.The disadvantage of broadcasting is
Ans.Seeds are unevenly distributed
6.Seed drill sows the seed at
Ans.Proper deapth and uniform distance
7.Two or more crops grown together in the same field is called
Ans.Mixed farming
8.A bacterial disease of plants is
Ans.Wilt
9.Rearing of honeybees for products like honey and wax is called
Ans.Apiculture
10.What are milch animals
Ans.Animals that provide us milk
B.Fill in the blanks
1.a. Better varieties of crops can be developed by pl ant ______.
b. ______ means producing offsprings under controll ed conditions.
c. ______ is a technique used for developing new cr op varieties by cross breeding.
d. In the breeding experiments anthers of plants ar e removed by process called ______ .
e. ______ farming technique of crop cultivation emp loys biological methods.
breeding, breeding, hybridization, emasculation , organic.
2.Fill in the blanks :-
a. ______ were the first crop known to be cultivate d.
b. ______ provide the staple food for people in eve ry part of world.
c. Grains are rich in ______.
d. If there is a shortfall in production, grains a
re made available from ______ stock .
e. ______ is the most important cereal in the world .
cereals, Grains, Starch, Buffer, Wheat.
3.ill in the blanks :-
a. ______ is large scale cultivation of vegetable, fruits & flower plants.
b. ______ is the process of loosening and turning u p of the soil.
c. ______ is the process of supplying water to crop s at different intervals.
d. ______ is result of too much water given to the soil.
e. ______ is the science dealing with growth of pla nts and animals for human use.
horticulture, tilling, irrigation, waterlogging , agriculture.
1.How does transplantation of onion seedlings in creases its production?
Ans.f irst onion is planted in nurseries and then their small plantlets called seedlings are transplanted in the field,it will help farmers to s elect only healthy seedlings that increases crop production.
2.Define nitrogen fixation and its importance?
Ans.Nitrogen fixation is the process of converting free nitrogen gas of the atmosphere into nitrogen compounds. Biological nitrogen fixation is very important for crop production. Generally bacteria like Rhizobium fix a tmospheric nitrogen into nitrates.
3.. Define water logging and its impact ?
Ans.When a lot of water is given to the crop, it st ands in the field and accumulates around roots of crop plants. This is known as water-loggin g. It causes damage to the crop because roots can’t breathe properly and salinity o f soil is also increased.
4. Which method of irrigation would be recommended for a region with uneven land surface and why ?
Ans.Sprinkler system of irrigation is best suited f or uneven land where proper distribution of water is not possible. In this system, perpendic ular pipes are put in the field at regular intervals and have rotating nozzles at the top end such that water gets sprinkled over crop plants.
5. What are contributions made by Prof. M.S.Swamin athan?
Ans. He is better known as father of green revolutio n in India.
6. Which one would you prefer a chemical pesticid e or a biopesticide? why?
Ans.Biopesticides are ecofriendly and non toxic t o humans for eg: cochineal insect is used to eliminate prickly pear (opuntia= cactus) from cr op fields.
7.Why is it good to wash foodgrains before use?
Ans.as they may contain weedicides that are toxic to us.
8. Why are manures better than fertilizers?
Ans.It does not cause soil pollution, manure improve the water holding capacity of soil it improves the texture of the soil
9.List main advantages of preparation of soil?
Ans.allows loosening and turning of soil which traps air for easy root breathing, helps earthworms to grow, brings nutrient rich soil to th e top and provides better mixing of fertilisers.
10. What are silos?
Ans.also known as granaries, they are places for st orage of grains on large scale .Packing is done within bags, bins and then stored.
11.Explain how fertilsers are different from manure.
Ans.Manure is an organic substance obtained from th e decomposition of plant or animal wastes but fertilsers are inorganic substance prepa red in factories. Fertilsers are rich in nutrients but manure has very less nutrient s. Manure cannot harm the soil if used in greater quantity but fertilsers may harm th e plants as well as soil. Manure is cheap and mostly prepared by farmers itself on the other hand fertilsers are costly and prepared in factories using chemicals.
12.What is irrigation? Describe two methods of irrigat ion which conserve water.
Ans.The supply of water to crops at different inter vals is called irrigation. The time and frequency of irrigation differ from crop to crop, s oil to soil and season to season. The main sources of irrigation are wells, tube wells, p onds, lakes, rivers, dams and canals. Irrigation is essential for proper growth of plants as without water no physiological activity is possible in living beings. The two meth ods of irrigation which conserve water are-
(a) Sprinkler system- This system is useful in une ven land where sufficient water is not available. The pipes having rotating nozzles on top are joined to regular interval. When water flows through this pipe at high pressure , nozzle throws water and sprinkle in all direction.
(b) Drip system- In this system water falls drop b y drop just at the root. It is mainly used for watering fruit plants, gardens and trees. In this method water is not wasted at all. It is mainly used in water deficient areas.
13.Explain how soil gets affected by the continuous pl antation of crop in a field.
Ans.Continuous growing of crops makes the soil poorer i n certain nutrients. To avoid this, a method of crop-rotation is adopted, which m aintains the nutrients of the soil intact.
14.What are weeds? How can we control them?
Ans.The undesirable plants in the field are called weed s which have to be removed, otherwise our own crop plants may not get sufficien t water, nutrients, space and light. So, they are removed either by manual method or by using weedicides. The manual removal includes physical removal of wee ds by uprooting or cutting them close to the ground from time to time. This is done with the help of a khurpi or harrow. By using weedicides also, we can remove weeds. Thes e weedicides only damage weeds and do not harm crops.
15.Write a paragraph in your own words on each of the following.
(a) Preparation of soil
(b) Sowing
(c) Weeding
(d) Threshing
Ans.a) Preparation of soil:- It is the first step of before growing of crop in which soil is turned and loosen it. The softening of soil allow s the deep penetration of roots into soil. The soil preparation includes ploughing, leve ling and manuring. Ploughing is done with the help of plough or tractor. Leveling i s done by leveler to make loosen soil smaller the even.
(b) Sowing: - The process of broadcasting se eds in soil to grow crop is called sowing. Sowing is done with the help of seed drill or broad casting with hands. The healthy seed is selected for proper growth. The distance be tween seeds must be sufficient for proper growth.
(c) Weeding: - The unwanted plants that grow along with main crop and compete with crop for light, food and other substance are c alled weeds. Removal of these unwanted plants is called weeding. Weeding is done with hands of using chemicals called weedicides.
(d) Threshing: - In harvested crop, the grain seed s are separated from chaff. This process is called threshing. This is carried out by using a machine called combine. Threshed seed is winnowed to obtain clean seeds.
16.What is animal Husbandry
Ans.Animal husbandry is the branch of agriculture concerned with animals that are raised for meat, fibre, milk, eggs, or other products. It includes day-to-day care, selective breeding, and the raising of livestock.
A. One Word Answers
1.Conversion of ammonia into nitrates is called
Ans.Nitrification
2.The irrigation method in which water enters the field through channels made between two rows of crop plants is:
Ans. Furrow irrigation method
3.Crops sown during winters are
Ans.Rabi Crops
4.The method of scattering seeds in the field by hand is
Ans.Broadcasting
5.The disadvantage of broadcasting is
Ans.Seeds are unevenly distributed
6.Seed drill sows the seed at
Ans.Proper deapth and uniform distance
7.Two or more crops grown together in the same field is called
Ans.Mixed farming
8.A bacterial disease of plants is
Ans.Wilt
9.Rearing of honeybees for products like honey and wax is called
Ans.Apiculture
10.What are milch animals
Ans.Animals that provide us milk
B.Fill in the blanks
1.a. Better varieties of crops can be developed by pl ant ______.
b. ______ means producing offsprings under controll ed conditions.
c. ______ is a technique used for developing new cr op varieties by cross breeding.
d. In the breeding experiments anthers of plants ar e removed by process called ______ .
e. ______ farming technique of crop cultivation emp loys biological methods.
breeding, breeding, hybridization, emasculation , organic.
2.Fill in the blanks :-
a. ______ were the first crop known to be cultivate d.
b. ______ provide the staple food for people in eve ry part of world.
c. Grains are rich in ______.
d. If there is a shortfall in production, grains a
re made available from ______ stock .
e. ______ is the most important cereal in the world .
cereals, Grains, Starch, Buffer, Wheat.
3.ill in the blanks :-
a. ______ is large scale cultivation of vegetable, fruits & flower plants.
b. ______ is the process of loosening and turning u p of the soil.
c. ______ is the process of supplying water to crop s at different intervals.
d. ______ is result of too much water given to the soil.
e. ______ is the science dealing with growth of pla nts and animals for human use.
horticulture, tilling, irrigation, waterlogging , agriculture.
1.How does transplantation of onion seedlings in creases its production?
Ans.f irst onion is planted in nurseries and then their small plantlets called seedlings are transplanted in the field,it will help farmers to s elect only healthy seedlings that increases crop production.
2.Define nitrogen fixation and its importance?
Ans.Nitrogen fixation is the process of converting free nitrogen gas of the atmosphere into nitrogen compounds. Biological nitrogen fixation is very important for crop production. Generally bacteria like Rhizobium fix a tmospheric nitrogen into nitrates.
3.. Define water logging and its impact ?
Ans.When a lot of water is given to the crop, it st ands in the field and accumulates around roots of crop plants. This is known as water-loggin g. It causes damage to the crop because roots can’t breathe properly and salinity o f soil is also increased.
4. Which method of irrigation would be recommended for a region with uneven land surface and why ?
Ans.Sprinkler system of irrigation is best suited f or uneven land where proper distribution of water is not possible. In this system, perpendic ular pipes are put in the field at regular intervals and have rotating nozzles at the top end such that water gets sprinkled over crop plants.
5. What are contributions made by Prof. M.S.Swamin athan?
Ans. He is better known as father of green revolutio n in India.
6. Which one would you prefer a chemical pesticid e or a biopesticide? why?
Ans.Biopesticides are ecofriendly and non toxic t o humans for eg: cochineal insect is used to eliminate prickly pear (opuntia= cactus) from cr op fields.
7.Why is it good to wash foodgrains before use?
Ans.as they may contain weedicides that are toxic to us.
8. Why are manures better than fertilizers?
Ans.It does not cause soil pollution, manure improve the water holding capacity of soil it improves the texture of the soil
9.List main advantages of preparation of soil?
Ans.allows loosening and turning of soil which traps air for easy root breathing, helps earthworms to grow, brings nutrient rich soil to th e top and provides better mixing of fertilisers.
10. What are silos?
Ans.also known as granaries, they are places for st orage of grains on large scale .Packing is done within bags, bins and then stored.
11.Explain how fertilsers are different from manure.
Ans.Manure is an organic substance obtained from th e decomposition of plant or animal wastes but fertilsers are inorganic substance prepa red in factories. Fertilsers are rich in nutrients but manure has very less nutrient s. Manure cannot harm the soil if used in greater quantity but fertilsers may harm th e plants as well as soil. Manure is cheap and mostly prepared by farmers itself on the other hand fertilsers are costly and prepared in factories using chemicals.
12.What is irrigation? Describe two methods of irrigat ion which conserve water.
Ans.The supply of water to crops at different inter vals is called irrigation. The time and frequency of irrigation differ from crop to crop, s oil to soil and season to season. The main sources of irrigation are wells, tube wells, p onds, lakes, rivers, dams and canals. Irrigation is essential for proper growth of plants as without water no physiological activity is possible in living beings. The two meth ods of irrigation which conserve water are-
(a) Sprinkler system- This system is useful in une ven land where sufficient water is not available. The pipes having rotating nozzles on top are joined to regular interval. When water flows through this pipe at high pressure , nozzle throws water and sprinkle in all direction.
(b) Drip system- In this system water falls drop b y drop just at the root. It is mainly used for watering fruit plants, gardens and trees. In this method water is not wasted at all. It is mainly used in water deficient areas.
13.Explain how soil gets affected by the continuous pl antation of crop in a field.
Ans.Continuous growing of crops makes the soil poorer i n certain nutrients. To avoid this, a method of crop-rotation is adopted, which m aintains the nutrients of the soil intact.
14.What are weeds? How can we control them?
Ans.The undesirable plants in the field are called weed s which have to be removed, otherwise our own crop plants may not get sufficien t water, nutrients, space and light. So, they are removed either by manual method or by using weedicides. The manual removal includes physical removal of wee ds by uprooting or cutting them close to the ground from time to time. This is done with the help of a khurpi or harrow. By using weedicides also, we can remove weeds. Thes e weedicides only damage weeds and do not harm crops.
15.Write a paragraph in your own words on each of the following.
(a) Preparation of soil
(b) Sowing
(c) Weeding
(d) Threshing
Ans.a) Preparation of soil:- It is the first step of before growing of crop in which soil is turned and loosen it. The softening of soil allow s the deep penetration of roots into soil. The soil preparation includes ploughing, leve ling and manuring. Ploughing is done with the help of plough or tractor. Leveling i s done by leveler to make loosen soil smaller the even.
(b) Sowing: - The process of broadcasting se eds in soil to grow crop is called sowing. Sowing is done with the help of seed drill or broad casting with hands. The healthy seed is selected for proper growth. The distance be tween seeds must be sufficient for proper growth.
(c) Weeding: - The unwanted plants that grow along with main crop and compete with crop for light, food and other substance are c alled weeds. Removal of these unwanted plants is called weeding. Weeding is done with hands of using chemicals called weedicides.
(d) Threshing: - In harvested crop, the grain seed s are separated from chaff. This process is called threshing. This is carried out by using a machine called combine. Threshed seed is winnowed to obtain clean seeds.
16.What is animal Husbandry
Ans.Animal husbandry is the branch of agriculture concerned with animals that are raised for meat, fibre, milk, eggs, or other products. It includes day-to-day care, selective breeding, and the raising of livestock.
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