Class 8 Science Chapter 1 MCQ

Fertilizers are not environment friendly as they are chemical substances rich in particular nutrient. Though, they increase the crop yield, the repeated and excessive use of fertilizers in the same field reduces the soil fertility. It also pollutes water bodies as they get dissolved and washed away by rain and also seeps in the water table posing threats to humans.

Maize is a kharif crop which requires high temperature, rainfall and humidity to grow, while rabi crops require low temperature for their growth.

If the field is dry for cultivation of crops, the soil preparation is done accordingly before sowing of crops. Preparation of dry soil includes adequate watering to restore the moisture content and then tilled and ploughed to allow growth of microbes and aeration. Finally, soil is turned and its crumbs are levelled and manures are mixed. The soil is ready for sowing of crops in the field.

The ginger is a modified underground stem, which is propagated vegetative by stem (rhizome) cultivation. It does not propagate by roots, leaves or seeds.

Here, all the statements are correct except option [D]. Fertilizers are the sources of water and soil pollution. Manure is an organic substance and using of it is considered better than fertilizers. Hence, your answer will be option [D].

Harvesting is a process of cutting matured crops from close to the ground. It is done manually using a sickle.

The process of separating the edible part of the harvested grains (crop) by loosening and removing the scaly, inedible chaff surrounding the grain. The process utilizes a machine called “combine” which is combination of harvester and a thresher.

Here, all the options are correct. Hence, your answer will be option [D]

Manure is a natural substance obtained by the decomposition of cattle dung, human waste and plant residues. It provides a lot of humus to the soil. Manure is relative less rich in plant nutrient but using this no pollution occur and it improves the soil texture also. Thus, as an organic component cattle dung is very important for the nutrients of plants.

In a field many other undesirable plants may grow naturally along with the crop. These undesirable plants are called weeds. The removal of weeds is called weeding. Weeds are also controlled by using certain chemicals, called weedicides.

Irrigation is the supply of water to crops at regular intervals as water or moisture is necessary for seed germination, growth and other physiological processes. Moreover, the plants readily absorb nutrients in dissolved from along with water through root hairs of roots. It does not protect crops from frost and hot air currents and manure not irrigation improves soil texture.

Soil supplies mineral nutrients to the crop. These nutrients are essential for the growth of plants. The use of manure improves soil texture as well as its water retaining capacity. It replenishes the soil with all the nutrients. Another method of replenishing the soil with nutrients is through crop rotation. This can be done by growing different crops alternately.

Conversion of dead decaying matter into ammonia and then into nitrites and nitrates by nitrifying microbes, called “Nitrification”. Conversion of air nitrogen into nitrites and nitrates by nitrogen microbes, called “Nitrogen fixation”. Conversion of nitrites and nitrates from decaying organic matter into gaseous nitrogen by denitrifying microbes, called “Denitrification”.

“Ager” meaning field or soil, “cultura” meaning cultivation. Agriculture is the cultivation of the soil. It includes growing of plant crops and rearing of animals.

Flood irrigation is required only for paddy crop. Fields are irrigated from time to time to save the crop from drought. Paddy (rice) is only crop of saplings which are planted in flooded fields. Even paddy is watered sparingly towards the maturation of the crop.

Option A is correctly suggesting the harmful effects of weeds. Weeds are the undesirable plants that grow along the main crops. Removal of weeds is necessary because they interfere and affect the major crop’s growth, by competing for light, water, nutrients and space. They also interfere during harvesting procedure. Weeds do not help in healthy growth of crop plants.

The ploughed field may have big pieces of soil called crumbs. It is necessary to break these crumbs with a plank. The field is levelled for sowing as well as for irrigation purposes. The levelling of soil is done with the help of a leveller.

Swaminathan has been called the “Father of Green Revolution in India” for his role in introducing and further developing high-yielding varieties of wheat in India. He is the founder of the MS Swaminathan Research Foundation also.

The supply of water to crops at different intervals is called irrigation. Pulley system, chain pump, dhekli and rahat (Lever system) are traditional methods of irrigation whereas sprinkler system and drip irrigation are the modern methods of irrigation.

The preparation of soil is the first step before growing a crop. One of the most important tasks in agriculture is to turn the soil and loosen it. This allows the roots to penetrate deep into the soil. The loose soil allows the roots to breathe easily even when they go deep into the soil.

Here, all the options are correct (may include in possibilities). Hence, your answer will be option [D].

Fertilisers are chemical substances which are rich in a particular nutrient. Some examples of fertilisers are urea, ammonium sulphate, super phosphate, potash, NPK (Nitrogen, Phosphorus, Potassium). The use of fertilisers has helped farmers to get better yield of crops such as wheat, paddy and maize.

Paddy, maize, soya-bean, groundnut, cotton, etc., are kharif crops. Rabi crops are wheat, gram, pea, mustard and linseed. Thus, wheat is not associated in kharif crops. So, your answer will be option [D].

Here, all the options are associated with animal husbandry. Hence, your answer will be option [D].

Drip system is the method of irrigation which conserve water and avoids wastages as water is made to fall drop by drop at the position of roots. It is the best technique for watering fruit plants, trees and gardens. Sprinkler system is also a modern method of irrigation that efficiently uses of water in the form of sprinklers. It is useful for uneven lands, while pulley and lever systems are traditional methods of irrigation where a lot of water is wasted.