Natural Resources – Air, Water and Land
1. Fill in the blanks.
(A) The layer of ozone gas absorbs ultraviolet rays that come from the sun to the earth.
(B) Of the total water available on the earth, fresh water forms 0.3 percent.
(C) Both biotic and abiotic constituents are present in the soil.
Q2. 2. Why is it said that – ?
A) The ozone layer is a protective shell of the earth.
Ans:-The ozone layer is said to be a protective shell of the earth because it plays a crucial role in shielding the planet from harmful ultraviolet (UV) rays emitted by the sun. Ozone molecules in the ozone layer absorb and scatter much of the incoming UV radiation, preventing it from reaching the Earth's surface in excessive amounts. This protective function of the ozone layer helps to safeguard living organisms, including humans, from the damaging effects of UV radiation, such as skin cancer, cataracts, and disruptions to ecosystems.
B) Water is life.
Ans:-"Water is life" is a commonly used phrase because water is essential for the survival and well-being of all living organisms. It is a fundamental requirement for various biological processes and is involved in maintaining the functioning of cells, tissues, and organs. Water serves as a universal solvent, participates in chemical reactions, aids in digestion, transports nutrients and oxygen throughout the body, regulates body temperature, and supports many other vital functions. Without access to clean and safe water, life as we know it would not be possible.
C) Seawater is useful even though it is not potable.
Ans:- Seawater is considered useful even though it is not potable (drinkable) due to its various beneficial properties and applications. While seawater contains high concentrations of salt and other minerals that make it unsuitable for direct consumption, it still has numerous uses and benefits.
Q3. What will happen if –
(A) Microbes in the soil get destroyed.
Ans:-If microbes in the soil get destroyed, it would have significant implications for the health and fertility of the soil and the overall ecosystem. Microbes play crucial roles in nutrient cycling, decomposition, and maintaining soil structure. They break down organic matter, releasing essential nutrients that are then available for plants to uptake. Additionally, certain microbes form symbiotic relationships with plants, aiding in nutrient absorption. Without these beneficial microbes, the soil's fertility could decline, affecting agricultural productivity and the health of plants.
(B) The number of vehicles and factories in your surroundings increases.
Ans:-If the number of vehicles and factories in your surroundings increases, it can have several impacts on the environment, human health, and overall quality of life. Increased vehicles and industrial emissions can contribute to higher levels of air pollution. The increased number of vehicles and factories can lead to elevated noise levels, resulting in noise pollution. More vehicles on the roads can lead to increased traffic congestion, longer commute times, and decreased efficiency in transportation systems. Industrial activities, including factories, can require significant amounts of water and resources for production processes. Increased industrialization can lead to higher demand for water resources, potentially straining local water supplies and ecosystems.
(C) The total supply of potable water is finished.
Ans:-If the total supply of potable water is completely depleted, it would have dire consequences for human health, sanitation, and overall societal well-being. Without access to potable water, there would be a severe scarcity of water for essential daily needs such as drinking, cooking, and personal hygiene. Agriculture relies heavily on water for irrigation. With no potable water available, crop yields would significantly decrease, leading to food shortages.
Q4. Match the following.
| Group A | Group B |
|---|---|
| Carbon dioxide | Generation of soil |
| Oxygen | Rain |
| Water Vapour | Plants and food production |
| Microbes | Combustion |
Solution:-
| Group A | Answer |
|---|---|
| Carbon dioxide | Plants and food production |
| Oxygen | Combustion |
| Water Vapour | Rain |
| Microbes | Generation of soil |
Q5. Name the following.
(a) Constituents of the biosphere.
Ans:-Living organisms, including plants, animals, microorganisms, and their interactions with the physical environment.
(b) Biotic constituents of soil.
Ans:-Organic matter, including plant residues, decaying plant and animal material, and living organisms such as bacteria, fungi, earthworms, and other soil-dwelling organisms.
(c) Fossil fuel.
Ans:-petrol, diesel, kerosene, coal, oil, and natural gas.
(d) Inert gases in air.
Ans:-Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn)
(e) Gases that are harmful to the ozone layer.
Ans:-carbon tetrachloride, chlorofluorocarbons
Q6. True or false ?
(a) Land and soil are the same thing.
Ans:-False. Land and soil are not the same thing. Land refers to the surface of the Earth, including areas covered by soil, water bodies, rocks, and other geological features. Soil, on the other hand, is the upper layer of the Earth's crust that consists of mineral particles, organic matter, water, air, and living organisms.
(b) The water in a lake is called ground water.
Ans:-False. The water in a lake is not called ground water. Groundwater refers to the water that is located beneath the Earth's surface, filling the spaces between soil particles and rocks in the subsurface. Lakes, on the other hand, are surface water bodies formed by various geological processes, such as tectonic activity, glacial activity, or volcanic activity.
(c) It takes about 1000 years to form a 2.5 cm thick layer of soil.
Ans:- True. It take 1000 years to form a 2.5 cm thick layer of soil. The time required for soil formation depends on various factors such as climate, parent material, topography, organisms, and time. The rate of soil formation can vary significantly, ranging from a few decades to thousands of years. The formation of even a thin layer of soil can take hundreds or thousands of years, depending on the specific conditions.
(d) Radon is used in decorative lights.
Ans:- False. Neon is used in decorative lights. Radon is a radioactive gas that is colorless, odorless, and tasteless. It is a naturally occurring gas that is formed from the decay of uranium and radium in rocks and soil. Due to its radioactivity, radon poses health risks and is considered a hazardous substance. It is not used in decorative lights or any other common applications.
7. Answer in your own words.
(a) Explain with the help of a diagram how soil is formed.
Ans:-The soil on the land is formed by a natural process. The abiotic components of soil are supplied through the weathering of the bedrock. Due to the heat, cold and water of the sun, wind and rain respectively, the bedrock breaks down into pieces. Stones, sand and soil are formed from these pieces. Microbes, worms and insects are found among them. Rodents like mice and rats are also found here. The roots of trees growing on the land also help weathering of rocks. The process of soil formation is slow and continuous. It takes about a thousand years for a 2.5 cm thick layer of mature soil to form.
(b) Why is there a shortage of water even though it occupies about 71% of the earth’s surface ?
Ans:- The majority of the Earth's water, approximately 97%, is salt water found in oceans and seas. This water is not directly usable for drinking, irrigation, or most industrial purposes. Freshwater, which accounts for only about 0.3% of the total water, is essential for human consumption and various activities but is a relatively scarce resource.
(c) What are the various constituents of air ? Write their uses.
Ans:-Nitrogen – Helps living things to build the necessary proteins. It is useful in the production of ammonia and in airtight packaging of foodstuffs.
Oxygen – Necessary for respiration in living things and for combustion.
Carbon dioxide – Plants use it for producing their food. Used in fire extinguishers.
Argon – Used in electric bulbs.
Helium – Used for obtaining low temperature and also for generating lift in airships.
Neon – Used in decorative lights and for street lighting.
Krypton – Used in fluorescent tubes.
Xenon – Used in flash photography.
(d) Why are air, water and land considered to be valuable natural resources ?
Ans:- Air, water, and land are considered valuable natural resources due to their vital roles in sustaining life and supporting various human activities. Air is essential for the survival of all living organisms. Water is a fundamental resource for all life forms on Earth. It is essential for drinking, sanitation, agriculture, industry, and energy production. Land is a valuable resource that provides space for human settlement, agriculture, industry, and infrastructure development. It supports the growth of food crops, grazing for livestock, and the cultivation of forests for timber and other resources.
3 Comments
Adarsh Yadav
ReplyDeleteAdarsh Yadav
ReplyDeleteAdarsh Yadav
ReplyDelete