Page 67 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

D. Match the following.

Column A Column B
1. Protection of soil from soil erosion (a) Soil conservation

2. Rodents (b) Burrows in soil
3. Deforestation (c) Increase the fertility of soil

4. Earthworm (d) Soil erosion

5. Humus (e) A-horizon of moist soil
Ans. 1. (a) 2. (b) 3. (d) 4. (c) 5. (e)

E. Very short-answer questions
1. Give the formula to calculate the percentage of water absorption by soil.

Ans. Percolation rate (mL/min) = Amount of water (mL)/Percolation time (min).
2. Name the layer of soil where plants grow.

Ans. A-horizon or topsoil.

3. Name the liquid that can dissolve most of the minerals that holds the rocks together.
Ans. Water

4. Which soil is known as agriculture soil?
Ans. Loamy soil

5. Which soil horizon contains bedrock?
Ans. R-horizon

6. Name the organism known as farmer’s friend.

Ans. Earthworm
7. When does soil erosion occur?

Ans. Soil erosion occurs when the pollutants, that cause pollution, reduce the quality of
the soil and there is a high-level presence of man-made chemicals and other non-

desirable substances.
8. How many layers does the soil profile have?

Ans. Four layers

9. What kind of soil is suitable for growing potato and corn?
Ans. Sandy soil

10. Which soil is rich in humus?
Ans. Loamy soil

F. Short-answer questions.
1. Describe how clayey soil is useful for crops.

Ans. Clayey soil is useful for crops because it retains water well and is rich in nutrients.
This makes it ideal for crops that need a lot of water, such as rice and sugarcane.

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