Multiple Choice Questions
Question 1: The microorganisms present in the soil require moisture (water) and nutrients for growth and survival. Choose from the options below the habitat (place) where the soil has plenty of water and nutrients.
(a) Desert
(b) Forest
(c) Open field
(d) Cricket ground
Solution 1: (b) Forest
There will be a lot of trees in woods that hold the soil and keep the soil from erosion. The humus makes the soil nutritious and supplies plants and microorganisms with nutrients. Trees also absorb a lot of water from rainwater, which keeps the soil moist, providing microorganisms with moisture for growth.
Question 2: Availability of water and minerals in the soil for maximum absorption by roots is in the –
(a) B-horizon
(b) C-horizon
(c) A-horizon
(d) surface of soil
Solution 2: (c) A-horizon
A Horizon has porous and soft topsoil that assists in water absorption and retention.
Question 3: Soil conservation measures are mainly aimed at protecting which of the following?
(a) Plants
(b) Topsoil
(c) Subsoil
(d) Soil organisms
Solution 3: (b) Topsoil
The topsoil is covered with humus and consisting of plant and animal remains that are rotting. The humus increases the soil's texture and supplies plant growth nutrients. It is also the most fertile area and initiatives for soil protection are largely aimed at protecting topsoil. If topsoil is preserved or conserved, since it sits below the topsoil, subsoil is also conserved.
Question 4: Read the following statements with reference to the soil.
- Weathering is a very fast process of soil formation.
- Percolation of water is faster in sandy soils.
- Loamy soil contains only sand and clay.
- Topsoil contains the maximum amount of humus.
Choose the correct statements from the above.
(a) (ii) and (iv)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (i) and (ii)
Solution 4: (a) (ii) and (iv)
The deposition of soil by rock withering is a gradual process that takes years. Choice a) is also incorrect. Loamy soil is a combination of sand, silt and humus, so choice c is incorrect.
Very Short Answer Questions...........
Question 5: The soil has particles of different sizes. Arrange the words given below in increasing order of their particle size.
Solution 5: Rock > Gravel > Sand > Silt > Clay
Question 6: The components of loamy soil are ______, ______ and ______.
Solution 6: The components of loamy soil are Sand, Silt and Clay.
Question 7: Read the following statements and give the appropriate terms for each of them.
(a) The process of breakdown of rocks by the action of wind, water, sunlight.
(b) Removal of topsoil during heavy rains or strong winds.
(c) Accumulation of wastes in the soil generated by human activity which alter the features of the soil.
(d) The process of movement of water into deeper layers of soil.
Solution 7:
(a) The process of breakdown of rocks by the action of wind, water, sunlight: Weathering
(b) Removal of topsoil during heavy rains or strong winds: Erosion
(c) Accumulation of wastes in the soil generated by human activity which alter the features of the soil: Soil pollution
(d) The process of movement of water into deeper layers of soil: Percolation
Question 8: Unscramble the following jumbled words related to soil.
Solution 8:
(a) Humus
(b) Soil Profile
(c) Horizon
(d) Loam
(e) Weathering
(f) Percolation
Short Answer Questions............
Question 9: Which of the following situations – ‘A’ or ‘B’ – is advantageous for the absorption of water and minerals? Why?
Situation ‘A’: Growth and branching of roots in the C-horizon.
Situation ‘B’: Growth and branching of roots in A and B horizons.
Solution 9:
For plants, condition 'B' is useful as horizons A- and B are abundant in water, minerals and humus.
Question 10: How can a farmer convert acidic soil to neutral soil?
Solution 10: By applying a small amount of fast lime or slaken lime solution to the soil, a farmer may convert acidic soil to neutral soil.
Question 11: Is it a good practice to remove grass and small plants that are growing in an open, unused field? Give a reason to support your answer.
Solution 11: No, it is not a safe idea since the soil surface is filled by plants and their roots bind the particles of the soil to keep them securely which prevents heavy winds and rain from wiping off the top layer of dirt.
Question 12: A man digging a pit found that he could dig with ease initially but digging became difficult as he went deeper. He could not dig beyond a depth of 5 feet. Provide a suitable scientific explanation.
Solution 12: While digging the pit the man found that he could dig with ease initially because the top layer of soil is very loose but as he continues digging it became difficult due to the presence of weathered rocks.
Question 13: Locate the following zones given as boxed items in Figure 9.1 which shows a diagram of the soil profile.
Solution 13:
Question 14: Rajasthan is a desert state in India. Once while travelling to Rajasthan by train, Boojho observed several streams and rivulets of rainwater during the journey but to his surprise, he did not see streams of water in the desert region even during rains. Help Boojho find a suitable explanation for this.
Solution 14: Deserts are dotted with stretches of desert. When rain comes rainwater percolates instantly. Hence water streams are not found in deserts.
Question 15: Match the animals in Column I with their natural place of dwelling (habitat) in Column II.
Solution 15:
Long Answer Questions...................
Question 16: Continuously water-logged soils are disadvantageous for plant growth. Why?
Solution 16: Roots possess living cells that require oxygen for respiration and production of energy. This living cells consume oxygen that is found in the gaps between soil particles. But in waterlogged soils, water fills the gaps between soil particles and forces the oxygen out into the atmosphere. Thus, roots are deprived of oxygen and this affects root and plant development.
Question 17: Why is soil erosion relatively less in dense forests as compared to barren, open fields?
Solution 17: In thick trees, the tree cover (canopy) protects rainwater from actually falling on the ground/soil. Also, roots of the plants hold the soil particles and keep them together. As a result soil erosion is minimised.
But in barren, open fields the soil is vulnerable to the dropping rain. The soil particles become loose due to the effects of raindrops and the flow of water takes them away. The running water further erodes the soil surface aggravating erosion.
Question 18: Gardeners gently dig up the soil around the roots of garden herbs (plants) frequently. Give reasons.
Solution 18: Gardeners gently dig up the soil around the roots of garden herbs for the following reasons:
(a) For allowing easy root growth;
(b) For faster percolation of water;
(c) For aerating the soil/enabling air to get into deeper layers of soil;
(d) To get rid of weeds.
Question 19: In towns and cities, generally, the bore wells have to be dug very deep to get water as compared to bore wells dug in villages. Give suitable reasons.
Solution 19: In towns and cities, usually, the bore wells have to be drilled very deep to get water as opposed to bore wells dug in villages. It is so because of the following reasons:
(i) Excessive use of water in towns and cities depletes the groundwater.
(ii) Towns and Cities have asphalted highways and large fields of land are concreted. As a result, rainwater cannot percolate to recharge groundwater and the groundwater level thus declines. Villages have greater areas of the open land surface and less asphalted roads and concrete surfaces.
Thus, larger soil surface area is available for rainwater to percolate into the soil easily and recharge the groundwater. As a result, even shallow bore wells yield water in the village.
Question 20: Several terms related to soil are hidden in the squares given as Figure 9.2. Spot them and make a list. Two examples are given to you.
Solution 20:
