CBSE Class 7 Science Soil Worksheet Set 04

I. Fill in the blanks:-

1. Water seeps __________ through sandy soil than clayey soil.

2. Soil is formed by __________ of rocks.

3. _______ soil is formed in tropical countries.

4. _______ soil is found in Gujarat.

II Choose the correct option:-

1. The smallest particles of soil are called

(a) Clay (b) Sand (c) Silt (d) Gravel

2 The hard layer of rocks below the C horizon is called

(a) Bottom Rock (b) Substratum (c) Bed Rock (d) Gravel

3 The Decomposition of Organic matter forms

(a) Humus (b) Coarse soil (c) sandy soil (d) all

4 A protozoan which help to improve the fertility of soil is

(a) Algae (b) Fungi (c) Amoeba (d) bacteria

III Name the following:-

1. Soils which are light and easy to plough.

2. Living Organisms in the soil are referred as.

3. Soil formed by weathering of volcanic rocks.

4. Soil made up of sand ,silt and clay particles which is best for the growth of plants.

IV Define the following :

1 Lateritic soil

2. Alluvial soil

V Draw the following diagrams:

1. Structure of clayey soil

2. Layers of soil

I. Fill in the Blanks

Question 1. Water seeps __________ through sandy soil than clayey soil.
Answer: faster
In simple words: Water drains quickly through sand because sand grains have big gaps between them.

Exam Tip: Use words like "faster" or "more rapidly" to describe the percolation rate in sandy soil.

Question 2. Soil is formed by __________ of rocks.
Answer: weathering
In simple words: Big rocks break down into fine powder over time to make soil.

Exam Tip: "Weathering" is the exact scientific term examiners look for when asked how rocks turn into soil.

Question 3. _______ soil is formed in tropical countries.
Answer: Laterite
In simple words: Warm and rainy tropical lands create laterite soil.

Exam Tip: Both "Laterite" and "Lateritic" are acceptable answers for tropical soils formed by heavy rain leaching.

Question 4. _______ soil is found in Gujarat.
Answer: Black
In simple words: Gujarat has dark black soil that is great for growing cotton.

Exam Tip: Black soil is also called "regur soil" and is famous for cotton farming in western India.

II. Choose the Correct Option

Question 1. The smallest particles of soil are called
(a) Clay
(b) Sand
(c) Silt
(d) Gravel
Answer: (a) Clay
In simple words: Clay grains are tiny and packed very tightly together.

Exam Tip: Remember particle sizes: clay is smallest (under 0.002 mm), followed by silt, sand, and gravel.

Question 2. The hard layer of rocks below the C horizon is called
(a) Bottom Rock
(b) Substratum
(c) Bed Rock
(d) Gravel
Answer: (c) Bed Rock
In simple words: The solid stone base deep under all soil layers is called bedrock.

Exam Tip: Bedrock lies directly beneath the C-horizon and is difficult to dig with a spade.

Question 3. The Decomposition of Organic matter forms
(a) Humus
(b) Coarse soil
(c) sandy soil
(d) all
Answer: (a) Humus
In simple words: Rotten leaves and dead bugs turn into dark, rich humus.

Exam Tip: Humus is the dark organic substance on top of the soil that provides essential nutrients to plants.

Question 4. A protozoan which help to improve the fertility of soil is
(a) Algae
(b) Fungi
(c) Amoeba
(d) bacteria
Answer: (c) Amoeba
In simple words: Amoeba is a tiny single-celled protozoan living in moist soil.

Exam Tip: Out of the given choices, only Amoeba belongs to the group called protozoa.

III. Name the Following

Question 1. Soils which are light and easy to plough.
Answer: Sandy soil
In simple words: Sandy soil is loose, so tools move through it with little effort.

Exam Tip: Sandy soil contains large sand grains and lots of air, making it light and loose to till.

Question 2. Living Organisms in the soil are referred as.
Answer: Soil organisms (soil biota)
In simple words: All tiny bugs, worms, and microbes in the dirt are called soil organisms.

Exam Tip: Writing either "soil organisms" or "soil biota" will earn full credit.

Question 3. Soil formed by weathering of volcanic rocks.
Answer: Black soil
In simple words: Black soil comes from broken lava rocks from ancient volcanoes.

Exam Tip: Mentioning "black soil" or "regur soil" directly links to the weathering of volcanic basalt rocks.

Question 4. Soil made up of sand ,silt and clay particles which is best for the growth of plants.
Answer: Loamy soil
In simple words: Loam is a balanced mix of sand, silt, and clay that crops love.

Exam Tip: Loamy soil is ideal for farming because it holds just the right amount of water and air.

IV. Define the Following

Question 1. Lateritic soil
Answer: Lateritic soil is a red-colored soil rich in iron and aluminum. It develops in warm, wet tropical areas where heavy rainfall washes away other soluble minerals.
In simple words: This is a rusty red soil made by heavy rains in hot tropical regions.

Exam Tip: Include the keywords "iron-rich", "tropical climate", and "leaching by heavy rainfall".

Question 2. Alluvial soil
Answer: Alluvial soil is fertile soil left behind by running river water along riverbanks and plains. It contains plenty of minerals and humus, which makes it great for growing food crops.
In simple words: Rivers leave this rich dirt behind on plains, making the ground great for crops.

Exam Tip: Highlight that rivers deposit this soil and that it is extremely fertile for crops like rice and wheat.

V. Draw the Following Diagrams

Question 1. Structure of clayey soil
Answer: Clayey soil consists of very tiny, flat particles packed closely together. Because the grains sit so near to each other, the spaces between them are extremely small. These tight gaps hold water tightly, but leave very little room for air.

In simple words: Clay grains are tiny and sit close together, leaving little space for air.

Exam Tip: Draw small, tightly packed particles with tiny gaps to show high water retention and poor air space.

Question 2. Layers of soil
Answer: A vertical slice through the ground reveals different soil zones called horizons. The top layer is rich in organic matter, followed by subsoil, weathered rock pieces, and solid bedrock at the base.

In simple words: Soil has layers starting from dark topsoil down to hard rock at the bottom.

Exam Tip: Label all four main layers: A-horizon (topsoil), B-horizon, C-horizon, and Bedrock.

VI. Give Reasons for the Following

Question 1. Protozoans help to improve the fertility of soil.
Answer: Soil protozoa eat bacteria and other tiny organisms. As they digest food, they release extra nitrogen into the soil. This nitrogen is an important nutrient that plants need to grow well.
In simple words: Protozoa eat tiny germs and leave behind nitrogen that helps plants grow.

Exam Tip: Mention that protozoans release nitrogen into the soil when feeding on bacteria.

Question 2. Red soil are red in colour.
Answer: This soil has a reddish look because it contains a large amount of iron oxide. The presence of diffused iron compounds gives the soil its red shade.
In simple words: Red soil looks red because it has a lot of iron in it.

Exam Tip: Always name "iron oxide" or "iron compounds" as the specific reason for red soil's color.

VII. Answer the Following in Not More Than 20 Words

Question 1. What role does the oxygen present in air play in the formation of soil?
Answer: Oxygen reacts with minerals in rocks through oxidation. This reaction weakens and crumbles rocks into soil grains.
In simple words: Oxygen rusts rock minerals, causing the rocks to break down into soil.

Exam Tip: Keep the response under 20 words by focusing on rock oxidation and breakdown.

Question 2. How do changes in temperature help in weathering rocks?
Answer: Rocks heat up and expand by day, then cool and shrink at night. This repeated shift cracks and shatters them.
In simple words: Daily heating and cooling makes rocks expand, crack, and break into pieces.

Exam Tip: Use the words "expansion" and "contraction" to explain temperature-driven rock weathering.

VIII. Answer the Following in Not More Than 40 Words

Question 1. What happens to the rainwater that seeps through the top soil?
Answer: Rainwater filters down through the soil layers into the subsoil. Some of it gets soaked up by plant roots. The rest travels deeper until it reaches the non-porous bedrock, collecting as groundwater.
In simple words: Sinking rainwater feeds deep plant roots and gathers as clean underground water.

Exam Tip: Mention both plant root absorption and the replenishment of underground water reserves.

Question 2. What characteristics of soil have a role to play in the growth of the plants?
Answer: Key soil features include texture, ability to hold moisture, and air space between particles. The amount of humus, richness in plant minerals, and soil acidity (pH) also decide how well crops grow.
In simple words: Soil texture, moisture, air gaps, and mineral nutrients help crops grow well.

Exam Tip: List at least three properties: water-holding capacity, aeration, and nutrient content.

IX. Answer the Following in Not More Than 100 Words

Question 1. What are the advantages and disadvantages of sandy and clayey soil?
Answer: Sandy Soil:
- Advantages: It is well-aerated, light, and drains water quickly. Farmers can plough it easily.
- Disadvantages: It holds very little moisture and washes away nutrients rapidly. It dries out too fast for many crops.

Clayey Soil:
- Advantages: It retains a lot of water and contains plenty of plant nutrients, making it suitable for crops like paddy.
- Disadvantages: It has poor airflow and turns sticky when wet. When dry, it hardens into tough blocks that roots struggle to penetrate.
In simple words: Sand breathes well but loses water fast; clay holds water well but lacks air.

Exam Tip: Structure the answer by comparing water retention and air circulation for each soil type.

Question 2. What are the organisms living in the soil called? How do they help to improve the fertility of soil?
Answer: Organisms living in the soil are known as soil organisms or soil biota. Common examples include earthworms, bacteria, fungi, and insects.

How they boost fertility:
1. Making humus: Microbes break down dead leaves and animal waste, turning them into nutrient-rich humus.
2. Aerating the ground: Burrowing creatures like earthworms dig tunnels. These tunnels let air and water reach plant roots easily.
3. Nutrient recycling: Soil bacteria convert raw organic matter into soluble minerals that crops can readily take in.
In simple words: Soil creatures break down dead leaves into plant food and dig tunnels to let in air.

Exam Tip: Mention earthworms as "farmer's friends" because their burrows loosen the soil and improve aeration.

X. Answer the Following Questions Based on the Diagram

Question 1. Give suitable heading to the diagram.
Answer: Composition of Soil

In simple words: This circle chart shows the parts that make up natural soil.

Exam Tip: A title such as "Composition of Soil" or "Components of Soil" is standard for this pie chart.

Question 2. Which component of the soil is best for the growth of the plant?
Answer: Component 5, which represents organic matter or humus, is best for plant development. It enriches the ground with plant food, improves moisture retention, and supports useful soil microbes.
In simple words: Humus provides the best nutrients to help plants grow healthy and strong.

Exam Tip: Identify component 5 as humus or organic matter, which supplies essential minerals for crops.