NCERT Class-9 Science Solutions: Chapter 15-Improvement in Food Resources Part 7 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Long Answer Questions

Question 36:

Discuss the role of hybridization in crop improvement.


Hybridization refers to crossing between genetically dissimilar plants. It may be inter varietal, inter specific and inter generic. Two crops of good characters (desired character) are selected and crossed to obtain a new crop having desired characters of parental crops. This method of hybridization improves crops with respect to yield, disease resistance, pest resistance etc.

Image Role of Hybridization in Crop Improvement

Question 37:


  1. Vermicompost
  2. Green manure
  3. Bio fertilizer


  1. Vermicompost:- Compost is a kind of manure which is rich in organic matter and nutrients. The compost prepared by using earthworms to hasten the process of decomposition of plants and animals refuse is called as Vermicompost.
Image the Vermicompost
  1. Green manure:- The manure which is prepared by decomposing green plants in field itself is called green manure. For example — sun hemp is grown in fields, mulched by ploughing and allowed to decompose in field for the preparation of green manure.
Image Green Leaf Manure Crops
  1. Bio fertilizer:- Living organisms, which are used as fertilizer to supply the nutrients to plants, are called as bio fertilizers. For example, blue green algae, which fix nitrogen in soil, rice fields, are called as bio fertilizer
Image the Bio Fertilizer

Question 38:

Discuss various methods for weed control.


Various modes of weed control are

  1. Mechanical removal
  2. Proper seed bed preparation to avoid the weed growth
  3. Timely sowing of crop to avoid the growth of weed
  4. Intercropping and crop rotation also help in weed control

Question 39:

Differentiate between the following

  1. Capture fishery and Culture fishery
  2. Mixed cropping and Inter cropping
  3. Bee keeping and Poultry farming


Differences between capture fishery:

Capture vs Culture Fish
Capture FisheryCulture Fishery
It is a way of obtaining fish from natural resources.It is a way of obtaining fish from fish farms.
There is no seeding and rising of fish.The fish is reared
It is undertaken in both land and marine waters.It is undertaken mostly in land and near seashore.

Differences between intercropping and mixed copping:

Intercropping vs Mixed Cropping
IntercroppingMixed Cropping
Its main aim is to increase productivity per unit.Its main aim is to reduce chances of crop failure.
The crops are grown in specific pattern of rows.There is no set pattern of rows of crops.
Pesticides can be sprayed easily per individual crops.Pesticides cannot be sprayed easily to individual plants.

Differences between bee keeping and poultry farming:

Bee Keeping vs Poultry Farming
Bee keepingPoultry Farming
It is a practice of rearing and management of honeybee.It is the practice of raising domestic fowl.
Bees obtain food (nectar) from flower.Poultry birds are provided food by the reapers.
It provides honey and wax.It provides eggs and meat (flesh) .

Question 40:

Give the merits and demerits of fish culture?


Merits of Fish Culture

  1. Quality and quantity of desired fishes can be increased
  2. Fishes are cheap source of animal protein thus increases quality of food
  3. Export of fishes bring foreign currency

Demerits of Fish Culture

  1. It is a threat to biodiversity
  2. Only economically important and valued fishes will be cultured

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