Question (Tick [√] the correct option):
Assertion (A): The Indo-Gangetic Plains are densely populated.
Reason (R): The Indo-Gangetic Plains have fertile land for cultivation and are suitable climatic conditions.
Options:
i. Both A and R are true, and R is the correct explanation of A.
ii. Both A and R are true, but R is not the correct explanation of A.
iii. A is true, but R is false.
iv. A is false, but R is true.
Answer: Option i. Both A and R are true, and R is the correct explanation of A.
b. Identify the soil horizon from the characteristics given.
“It is composed of organic matter, humus, and minerals.
All plants and animals thrive in this layer.”
(I) A horizon (ii) C horizon (iii) O horizon (iv) D horizon.
c. Complete the analogy.
Laterite soil : Infertile soil in the Western Ghats:: _______ : Very fertile soil in Northern Plains
(i) Black soil (ii) Mountain soil (iii) Alluvial Soil (iv) Desert Soil
Answer. Alluvial soil
d. Runa has collected a sample of soil. The soil is not very fertile and high in iron content. It is used to grow oil seeds and millet. Which soil is most likely collected by her?
(i) Red soil (ii) Regular soil (iii) Alluvial soil (iv) Desert Soil
Answer. red soil.
e. Suraj is a farmer. He grows crops across the slope and along the contours of the hilly area. Identify the soil conservation technique used by him.
That practice is called contour farming.
(i) Contour barrier (ii) Rock dam (iii) Intercropping (iv) Contour Farming
Answer. Contour Farming
Q2. Short questions (10-20 words)
a. Why is the conservation of land important?
Answer. To protect fertility, prevent erosion, secure food, and maintain ecosystem balance.
b. What is the importance of time in soil formation?
Answer. Soil needs years or centuries to form; more time means deeper, richer soil.
c. Name the regions of India where desert soil is commonly found.
Answer. Desert soil is found in western Rajasthan, parts of Gujarat and some arid zones.
d. Mention any one characteristic of laterite soil. What are the crops mainly grown in this type of soil?
Answer. Laterite soil is rich in iron and aluminium but low in organic matter. Grown: tea, coffee, cashew, and plantation crops.
e. What are contour barriers? How does this technique help in soil conservation?
Answer. Contour barriers are structures across slopes to slow water flow. They reduce erosion and runoff, retain soil and moisture.
Q3. Answer the following questions in (50-70 words each)
a. Explain how land is classified based on relief.
Answer. Land relief classification depends on height, slope, and shape. There are plains (flat lowland), plateaus (flat but elevated), hills, and mountains (steep slopes). Each type affects soil depth, erosion rate, climate, and vegetation. Plains have deep, fertile soil and ease of farming. Hilly and mountainous areas have thin soil, are hard to cultivate, risk erosion and landslides.
b. Describe the soil profile with the help of a well-labelled diagram.
Answer. A soil profile is a layered structure under the surface. Layers or horizons are:
- O horizon (organic matter)
- A horizon (topsoil: rich in humus)
- B horizon (subsoil: leached materials, minerals)
- C horizon (weathered rock bits)
- R horizon (bedrock).
Each layer has different color, texture, nutrient content and supports different life.
c. What is the difference between residual soil and transported soil?
Answer. Residual soil forms directly from the weathering of rock beneath it; it stays where it forms. Transported soil is moved from its original place by water, wind, glaciers before settling. So residual retains local rock’s traits; transported may mix many origin materials.
d. What is the difference between alluvial and black soils?
Answer. Alluvial soil is deposited by rivers, found in plains, generally very fertile, loamy texture, used for rice, wheat etc. Black soil (also called regur) is clayey, retains moisture, cracks when dry, good for cotton; high iron, calcium but low in phosphorous.
e. State the important features of intercropping and crop rotation. Explain how these practices are helpful in soil conservation.
Answer. Intercropping means growing different crops together in same field; crop rotation means changing crops seasonally. These practices enrich soil nutrients, reduce pests and diseases, improve soil structure, prevent soil exhaustion. They help conservation by reducing need for chemical fertilizer, reducing erosion, maintaining fertility.
Q4. Give reasons.
a. Why 90% of the population occupies only 30% of the total land area.
Answer. Most people live in plains, cities, river valleys where farming, roads, schools, jobs are better. Mountains, deserts, forests make up large land but are hard to live in because of rough terrain, steep slopes, scarce water, fewer roads. That’s why people cluster in fertile, flat areas.
b. Why mountain slopes have a thin layer of soil.
Answer. On mountain slopes, rain water or snowmelt washes soil down the slope (erosion). Also, steep slopes reduce the accumulation of soil materials. Soil formation is slower due to rock exposure, less plant deposit. So the soil layer remains thin.
c. Why mountain soil is fertile.
Answer. Mountain soil gets fresh material from rocks weathering, plus decaying leaves and plants from the forest. This adds nutrients. Also water from rainfall or snow helps dissolve nutrients. Even though the soil layer is thin, it can be rich if plants and organisms contribute organic matter.
5. Think Ahead [HOTS]
What would happen if the earth lost all of its fertile soil?
Answer. If all fertile soil disappeared, food crops would fail and agriculture would collapse. People would not be able to grow enough food, leading to hunger and famine. Ecosystems would degrade: plants and trees couldn’t grow well, animals and insects would suffer. Economy would suffer, many people forced to move. Soil is the base for all terrestrial life.