Explain how fertilisers are different fr | Class 8 Science Chapter Crop Production and Management, Crop Production and Management NCERT Solutions

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.

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

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

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

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

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

Give two examples of each.
(a) Kharif crop
(b) Rabi crop

What are weeds? How can we control them?

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.

Describe with the help of a diagram an instrument which can be used to detect a charged body.

Sketch larynx and explain its function in your own words.

Make a labelled diagram of a candle flame.

What is metamorphosis? Give examples.

The following Table shows the total power shortage in India from 1991– 1997. Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis.

Describe the construction of a kaleidoscope.

Make sketches of animal and plant cells. State three differences between them.

What is a constellation? Name any two constellations.

Complete the crossword with the help of clues given below:
Across
1. This is necessary for photosynthesis.
3. Term for component present in the cytoplasm.
6. The living substance in the cell.
8. Units of inheritance present on the chromosomes.

Down
1. Green plastids.
2. Formed by collection of tissues.
4. It separates the contents of the cell from the surrounding medium.
5. Empty structure in the cytoplasm.
7. A group of cells.

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

How are babies produced through IVF technique? What are such babies called?

What is menstruation? Explain.

Do all the stars in the sky move? Explain.

Should the handle and bristles of a tooth brush be made of the same material? Explain your answer.

Suggest three measures to protect ourselves from lightning.

Explain how the use of CNG in automobiles has reduced pollution in our cities.

Fill in the blanks:

(a) Microorganisms can be seen with the help of a ____________.
(b) Blue green algae fix __________ directly from air to enhance fertility of soil.
(c) Alcohol is produced with the help of __________.
(d) Cholera is caused by __________.

Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?

‘Avoid plastics as far as possible’. Comment on this advice.

A blacksmith hammers a hot piece of iron while making a tool. How does the force due to hammering affect the piece of iron?