Value Based Questions in Science for Class 9 Chapter 15 Improvement in Food Resources

These Solutions are part of Value Based Questions in Science for Class 9. Here we have given Value Based Questions in Science for Class 9 Chapter 15 Improvement in Food Resources

Question 1.
Shyam has been cultivating wheat crop year after year in the same field. Recendy he has observed decline in the yield despite best inputs. Agriculture inspector of the area suggested him to sow soyabean for one or two years before again using the field for wheat crop. What is the rationale behind this suggestion ?
Sowing the same crop in the same field year after year results in depletion of nutrients from the particular depth of the soil, growing and multiplication of soil borne pathogens and pests of the crop, growth of weeds, infections and infestations.
Growing soyabean in the field will improve soil structure and fertility as it will draw water and nutrients from different level and add nitrogen salts. Weeds, soil borne pathogens and pests of wheat crop will be eliminated as they do not find their host.

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Question 2.
Why should fumigation be preferred over spraying in godowns ?

  1. In fumigation, the worker does not come in contact with the fumigant. There is some contact with the pesticide during spraying. In spraying, the worker suffers irritation in eyes, nose, vomiting, etc.
  2. No residue remains over articles in fumigation. In spraying some residue can enter the sprayed articles.
  3. Fumigants are volatile while sprays are seldom volatile.
  4. Fumigation disinfects the whole area. Spraying disinfects only the sprayed articles.
  5. The volume of fumigant is small while the volume of sprayed pesticide is generally large.

Question 3.
What is the need of crossing the exotic cattle with Indian cattle when exotic cattle have higher yield as compared to the hybrid cattle ?
There is no doubt that the hybrid produced by cross breeding exotic breed with local breed yields less milk as compared to the exotic breed. However, exotic breed cannot be incorporated in our dairy farms and farm houses due to :

  1. Different climatic conditions. Most of the exotic breeds have come from colder countries. Colder areas are limited in our country.
  2. The exotic breeds will fall prey to local pests and pathogens easily as they are not resistant to them.
  3. The feed available locally does not match with the feed required by the exotic breeds.
    Therefore, there is no alternative bur to import a few exotic cattle and cross-breed them with local cattle for obtaining hybrid cattle acclimitised to local climate and resistant to local diseases.

Question 4.
Why should organic foods be preferred over conventional foods ?
The conventional foods are raised using chemical fertilizers and chemical pesticides. These agrochemicals pass into conventional foods in small traces. Repeated use of conventional foods increases the concentration of agrochemicals in our bodies. They become toxic. As a result a number of ailments and harms can occur to us.
On the other hand, organic foods are free from any traces ol agrochemicals as they are raised by using manures, biofertilizers and biopesticides. Being nontoxic, organic foods should be preferred over conventional foods. Agrochemicals used in raising conventional foods are highly pollutants. They pollute soil, ground water and surface waters. Eutrophication of ponds and lakes is due to them. Manure used in raising organic foods is environmentally clean method of disposing off and recycling organic wastes.

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