Question

these are science questions please answer class 9​

Answer 1

Q1

Biotic factors like insects, rodents, pests, and many more spread the disease and reduce crop production.

Abiotic factors like humidity, temperature, moisture, wind, rain, flood and many more destroy the crop raise.

Q2

Manures increase soil fertility by enriching the soil with organic matter and nutrients as it is prepared by the decomposition of animal excreta and plant wastes. while Fertilizers are inorganic compounds whose excessive use is harmful to the symbiotic micro-organisms living in soil.

Q3

Plants get nutrients through soil, water and air.

Q4

The factors responsible for losses of grains during storage are:

(i) Abiotic factors like moisture (present in food grains), humidity (of air) and temperature.

(ii) Biotic factors like insects, rodents, birds, mites, bacteria and fungi.

Q5

Broilers are chickens that are grown for meat purposes. These birds will grow quickly and will require a good amount of energy and protein to sustain this fast growth.

Layers are birds that are reared to produce unfertilised eggs that will be sold to consumers to eat.

Q6

Composite fish culture increases the yield of fish. Nearly, five or six different species are grown together in a single fish pond. The survival rate of fish increases and their yield also increases without affecting the other species.

Q7

Manure and fertilizers are used in fields to increases soil fertility in order to ensure good vegetative growth that results in high crop production.

Q8

Inter-cropping helps in preventing pests and diseases to spread throughout the field. It also increases soil fertility.

Crop rotation prevents soil depletion, increases soil fertility, and reduces soil erosion. Both these methods reduce the need for fertilizers.

Q9

Aquaculture is the cultivation of aquatic products under controlled conditions.

Mariculture is the branch of aquaculture which involves cultivation of marine organisms in the open ocean.

Capture fishing involves catching fish from natural resources like pond, lake, sea , estuary etc.

Q10

The mating or crossing of two plants or lines of dissimilar genotype is known as hybridization.

Types :-

Intervarietal Hybridisation

Distant Hybridisation

Answer 2

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Biotic factors like insects, rodents, pests, and many more spread the disease and reduce crop production. Biotic factors like insects, parasites, diseases, etc. Abiotic factors like humidity, temperature, moisture, wind, rain, flood and many more destroy the crop raise.