BASIC SCIENCE FOR CLASS 8 AMARNATH MISHRA,PHD GEETA MEHTA ,PHD DEEPTI LEHRI,PHD RAJESH MOHAN, PHD CH-1 FOOD PRODUCTION (all exercise only answer )

                    Biology 

                 Ch-1 

            Food Production

                   Only answer 

                         EXERCISE

A. Answer the following question in not more than 20 words. 

1. Agriculture is the practice of cultivating plants and livestock.

2. Tea and coffee are two plantation crops.
3. The major activities involved in growing a crop are: preparation of the land, sowing of seeds, irrigation, weeding, pest control, harvesting, and threshing.
4. Weeds are unwanted plants that grow in crop fields and compete with the crop for water, nutrients, and sunlight.
5. Three ways of removing weeds from the crop field are: hand weeding, mechanical weeding, and chemical weeding.
6. Pests are organisms that damage crops or livestock.
7. Animal proteins are considered to be better than plant proteins because they contain all the essential amino acids that the human body needs.
8. Kharif crops are sown during the monsoon season.
9. Animal husbandry is the practice of raising livestock for food, fiber, and labor.
10. The two things that have to be controlled in a cold storage are temperature and humidity

B. Answer the following question in not more than 40 words. 

1. (a) Crop rotation is considered a good agricultural practice because it helps to prevent the build-up of pests and diseases, and it also helps to improve soil fertility.

(b) Pulses are alternated with crops like wheat or paddy because they help to fix nitrogen in the soil, which is essential for the growth of these crops.

2. (a) Green manure is a type of crop that is grown and then plowed back into the soil to improve its fertility.

(b) Compost is prepared by mixing organic materials, such as leaves, grass clippings, and food scraps, with soil and letting them decompose.

3. (a) Biological control of weeds and pests is the use of natural enemies, such as predators, parasites, and diseases, to control these pests.

(b) Biological control is better than using weedicides and pesticides because it is more environmentally friendly and it does not harm beneficial insects.

4. Root nodules are small, round structures that form on the roots of legumes. They contain bacteria that fix nitrogen from the air, which the plant can then use.

5. Surface irrigation is a method of irrigation in which water is applied to the surface of the soil. Two modes of irrigation under this category are furrow irrigation and basin irrigation

 

C. Answer the following question in not more than 100 words. 

1. Chemical fertilizers are a type of plant food that is made from minerals. They are often used to increase crop yields. However, they can also have negative environmental impacts, such as polluting water supplies and harming wildlife.

2. The nitrogen cycle is a natural process that recycles nitrogen from the atmosphere into the soil. This process is essential for plant growth, as nitrogen is a key nutrient for plants.

3. The main sources of irrigation in India are canals, wells, and tanks. Canals are artificial waterways that are used to transport water from rivers or reservoirs to fields. Wells are holes that are dug into the ground to reach groundwater. Tanks are artificial reservoirs that are used to store rainwater.

D. Complete the following. 

1. The practice of growing fruit, vegetables, flowers and ornamental plants is agriculture.

2. The process of using the vapours of a chemical to disinfect a place and get rid of pests is called fumigation.

3. A buffer stock of grains is maintained to provide food during emergencies.

4. A mutually beneficial association between two organisms is called symbiosis.

5. Seeds have to be sown at the right depth and with adequate spaces in between.

6. Biological control is the method of controlling weeds or pests by using their natural enemies.

7. A fallow field is one that is left uncultivated for one or more seasons

All choose the correct option