Class 8 Science - Chapter Crop Production and Management NCERT Solutions | Give two examples of each. (a) Kharif c

Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.

Complete the following word puzzle with the help of clues given below. 

Down
1. Providing water to the crops.
2. Keeping crop grains for a long time under proper conditions.
5. Certain plants of the same kind grown on a large scale.

Across
3. A machine used for cutting the matured crop.
4. A rabi crop that is also one of the pulses.
6. A process of separating the grain from chaff.

If wheat is sown in the kharif season, what would happen? Discuss.

Write a paragraph in your own words on each of the following.
  (a) Preparation of soil                 (b) Sowing
  (c) Weeding                                (d) Threshing

Explain how fertilisers are different from manure.

Match items in column A with those in column B.
               A                                       B
  (i) Kharif crops                    (a) Food for cattle
  (ii) Rabi crops                     (b) Urea and super phosphate
  (iii) Chemical fertilisers       (c) Animal excreta, cow dung urine and plant waste
  (iv) Organic manure           (d) Wheat, gram, pea
                                             (e) Paddy and maize

What is irrigation? Describe two methods of irrigation which conserve water.

Explain how soil gets affected by the continuous plantation of crops in a field.

What are weeds? How can we control them?

Select the correct word from the following list and fill in the blanks.
                 float, water, crop, nutrients, preparation

(a) The same kind of plants grown and cultivated on a large scale at a place is called _____________.
(b) The first step before growing crops is _____________ of the soil.
(c) Damaged seeds would _____________ on top of water.
(d) For growing a crop, sufficient sunlight and _____________ and _____________ from the soil are essential.

Which of the following can be beaten into thin sheets?
  (a) Zinc     (b) Phosphorus     (c) Sulphur     (d) Oxygen

Fill in the blanks
(a) Most liquids that conduct electricity are solutions of , ______________ and ______________.
(b) The passage of an electric current through a solution causes ______________ effects.
(c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the terminal of the battery.
(d) The process of depositing a layer ofany desired metal on another material by means of electricity is called .

Give two examples each of situations in which you push or pull to change the state of motion of objects.

Fill in the blanks:
(a) Friction opposes the _____________ between the surfaces in contact with each other.
(b) Friction depends on the _____________ of surfaces.                                                                                                                                                                      (c) Friction produces __________.
(d) Sprinkling of powder on the carrom board ________ friction.
(e) Sliding friction is ___________ than the static friction.

List conditions under which combustion can take place.

Indicate whether the following statements are True (T) or False (F).
(a) Unicellular organisms have one-celled body. (T/F)
(b) Muscle cells are branched. (T/F)
(c) The basic living unit of an organism is an organ. (T/F)
(d) Amoeba has irregular shape. (T/F)

Which of the following cannot be charged easily by friction?
(a) A plastic scale
(b) A copper rod
(c) An inflated balloon
(d) A woollen cloth.

Fill in the blanks:
(a) A place where animals are protected in their natural habitat is called                  .
(b) Species found only in a particular area is known as                          .
(c) Migratory birds fly to far away places because of                     changes.

Suppose you are in a dark room. Can you see objects in the room? Can you see objects outside the room. Explain.

What are the different ways in which water gets contaminated ?

Make a sketch of the human nerve cell. What function do nerve cells perform?

Discuss the effects of deforestation on the following:
(a) Wild animals
(b) Environment
(c) Villages (Rural areas)
(d) Cities (Urban areas)
(e) Earth
(f) The next generation

Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away from the roadside. Which house would you suggest your parents should buy? Explain your answer.

Write a short paragraph on the harms caused by microorganisms.

Which of the following is NOT a member of the solar system?
(a) An asteroid
(b) A satellite
(c) A constellation
(d) A comet

Explain how you can locate the Pole Star with the help of Ursa Major.

Explain why chloroplasts are found only in plant cells?

Identify the part which vibrates to produce sound in the following instruments:
(a) Dholak (b) Sitar (c) Flute

Clear, transparent water is always fit for drinking. Comment.

Explain briefly the life cycle of a frog.