Textbook - NATURAL RESOURCES Questions in English

(A) The main difference lies in the chemical composition of the atmospheres.
Earth's atmosphere consists of a mixture of gases,primarily nitrogen $(78.08\%)$,oxygen $(20.95\%)$,carbon dioxide $(0.03\%)$,and water vapour in varying proportions.
In contrast,the atmospheres of Venus and Mars are composed primarily of carbon dioxide,accounting for about $95-97\%$ of their total composition.
This high concentration of carbon dioxide is likely a primary reason why life as we know it does not exist on Venus and Mars.

(N/A) The atmosphere acts as a blanket by performing the following functions:
$(a)$ It keeps the average temperature of the Earth fairly constant during day time and even during the course of the whole year.
$(b)$ It prevents a sudden increase in the temperature during day time.
$(c)$ It slows down the escape of heat from the surface of the Earth into outer space during night time.

(B) Winds are generated due to the unequal heating of atmospheric air by the Sun.
When air is heated,it becomes lighter and rises up,creating a region of low pressure.
Cooler air from high-pressure regions rushes in to fill this space,resulting in the movement of air,which we perceive as wind.
This process also facilitates the movement of water vapour,which eventually cools and condenses to form clouds.

(N/A) During the daytime,water evaporates from water bodies and enters the atmosphere.
Air also becomes hot due to sunlight and starts rising,carrying water vapour with it.
As the air rises,it expands and cools down.
This cooling of air causes the water vapour to condense. The process of condensation occurs,where small droplets grow into larger ones through the continuous condensation of other water droplets. These accumulated droplets form clouds.

(N/A) The following human activities contribute to air pollution:
$1$. Burning of fossil fuels: The combustion of coal and petroleum in vehicles and power plants releases harmful gases like $CO_2$,$SO_2$,and oxides of nitrogen into the atmosphere.
$2$. Industrial emissions: Many industries release toxic gases,smoke,and particulate matter into the air as byproducts of their manufacturing processes.
$3$. Deforestation and agricultural burning: Clearing forests and burning agricultural waste release large amounts of smoke and carbon particles,which significantly degrade air quality.

(D) Organisms need water for the following reasons:
$1$. All cellular processes take place in a water medium.
$2$. Substances dissolve in water,which is essential for chemical reactions to occur within the body.
$3$. Water is necessary for the transportation of substances from one part of the body to another.
$4$. It aids in the digestion of food and its subsequent absorption into the blood.
$5$. Water helps in maintaining the body temperature of organisms.

(A) Underground water is the major source of fresh water in most cities,towns,and villages.
It is extracted using hand pumps,borewells,and tubewells.
Other secondary sources include nearby rivers,lakes,and ponds.

(N/A) The activities that may be polluting water sources include:
$1$. Disposal of garbage or untreated sewage from cities,towns,and residential areas into water bodies.
$2$. Discharge of industrial effluents containing toxic chemicals and heavy metals.
$3$. Release of hot water from industries (thermal pollution),which increases water temperature and decreases the dissolved oxygen level,thereby disturbing the $BOD$ (Biochemical Oxygen Demand) and aquatic life.

(N/A) The formation of soil takes place through the process of weathering,which involves the following steps:
$1$. Physical weathering: Rocks near the Earth's surface are broken down by the sun's heat,which causes expansion and contraction,leading to cracks and fragmentation.
$2$. Chemical and physical action of water: Water enters the cracks in rocks,freezes,and expands,breaking the rocks apart. Fast-flowing water also causes erosion and mechanical breakdown of rocks.
$3$. Wind action: Strong winds cause erosion and abrasion,breaking down rocks into smaller particles over millions of years.
$4$. Biological weathering: Living organisms like lichens and mosses grow on rock surfaces. They release chemicals that break down the rock and physically penetrate the surface,turning it into a fine powder,which forms a thin layer of soil.

(B) The removal of the top layer of soil is known as soil erosion.
This layer is rich in humus and essential nutrients.
The primary agents causing soil erosion are flowing water and wind.
If this process continues for a long time,the land becomes infertile due to the loss of valuable nutrients.

(N/A) The methods to prevent or reduce soil erosion are as follows:
$1$. Afforestation: Planting more trees helps bind the soil particles with roots,preventing them from being washed away.
$2$. Contour Ploughing: Ploughing along the contours of the land helps in reducing the speed of water flow,thereby minimizing soil erosion.
$3$. Terrace Farming: Creating steps on hilly slopes reduces the velocity of water runoff,allowing soil to settle.
$4$. Soil Cover: Keeping the soil covered with vegetation or crop residues protects it from the direct impact of rain and wind.
$5$. Controlled Grazing: Overgrazing by livestock removes the protective plant cover,exposing the soil; therefore,controlled grazing is essential to maintain soil integrity.

(N/A) During the water cycle,water exists in three states:
$1$. Solid state: Found as snow,ice,and glaciers.
$2$. Liquid state: Found as groundwater,river water,ocean water,and rain.
$3$. Gaseous state: Found as water vapor in the atmosphere.

(N/A) Two biologically important compounds that contain both oxygen and nitrogen are amino acids and nucleic acids ($DNA$ and $RNA$). Amino acids are the building blocks of proteins and contain an amino group $(-NH_2)$ and a carboxyl group $(-COOH)$. Nucleic acids contain nitrogenous bases,sugars,and phosphate groups,all of which involve both nitrogen and oxygen atoms.

(N/A) The human activities that lead to an increase in the $CO_2$ content of the air are:
$1$. Deforestation: Trees absorb $CO_2$ for photosynthesis. Large-scale cutting of trees reduces this absorption,leading to an increase in atmospheric $CO_2$.
$2$. Combustion of Fossil Fuels: Burning coal,petroleum,and natural gas for transportation,electricity generation,and industrial processes releases significant amounts of $CO_2$ into the atmosphere.
$3$. Industrial Processes: Many industrial activities,such as cement production and chemical manufacturing,release $CO_2$ as a byproduct of their chemical reactions.

(B) The greenhouse effect is a natural process where certain gases in the atmosphere,such as $CO_2$,methane $(CH_4)$,and nitrous oxide $(N_2O)$,trap heat radiating from the Earth's surface.
These gases prevent the heat from escaping into space,which helps maintain the Earth's average temperature at a level suitable for life.
However,an excessive increase in the concentration of these greenhouse gases due to human activities leads to an abnormal rise in the Earth's temperature,a phenomenon known as global warming.

(A) The two forms of oxygen found in the atmosphere are:
$1$. Elemental oxygen: It is normally found in the form of a diatomic molecule $(O_2)$ in the lower part of the atmosphere. It constitutes about $21\%$ of the air and is non-poisonous.
$2$. Ozone: It is found in the stratosphere layer of the atmosphere. It contains three atoms of oxygen $(O_3)$.

(N/A) The atmosphere is essential for life due to the following reasons:
$1$. It maintains an appropriate climate for the sustenance of life. It keeps the average temperature of the Earth steady during the day and throughout the year.
$2$. It prevents sudden increases in temperature during daylight hours.
$3$. The gases it contains are required for sustaining life on Earth. These gases include $Oxygen$,$Carbon$ $dioxide$,and $Nitrogen$.
$4$. $A$ thick layer of $Ozone$ in the stratosphere filters harmful $UV$ radiations from reaching the Earth. $UV$ rays produce harmful effects on all living organisms.

(N/A) Water is essential for life because of the following reasons:
$1$. It provides a medium to carry out all cellular processes.
$2$. All biochemical reactions that occur in our body and within cells take place between substances dissolved in water.
$3$. It is required for the transportation of materials from one part of the body to another.
$4$. It helps to maintain body temperature.
$5$. Water makes up about $70\%$ of the body weight of all living organisms.

(N/A) Living organisms depend on soil in the following ways:
$1$. Soil provides anchorage to plants by binding their roots. Plants absorb essential nutrients from the soil for their growth and development.
$2$. Soil serves as a natural habitat for various microorganisms like bacteria,fungi,and algae,as well as larger organisms like earthworms. These organisms play a crucial role in maintaining soil fertility.
$3$. Many animals,such as rats and rabbits,use soil to build their burrows or homes.
$4$. Earthworms live and perform their activities within the soil,contributing to its fertility by releasing nitrogen-rich excreta.
Regarding aquatic organisms,they are not totally independent of soil. Aquatic organisms rely on aquatic plants for food and oxygen. These aquatic plants require minerals for their survival,which are transported from the soil to water bodies by rivers,rainwater,and surface runoff. Without the continuous supply of minerals from the soil,aquatic life would not be sustainable.

(N/A) Meteorologists collect information regarding the patterns of temperature,wind speed,air pressure,and other features that influence weather.
These data are gathered using remote sensing technology and weather forecast satellites.
This information is then compiled by meteorological departments,which prepare weather reports displayed on maps.
Finally,these reports are transmitted to the public through radio,television,and newspapers.

(A) Yes,isolating human activities to specific and limited areas would help in reducing pollution.
$1$. By concentrating industrial activities in designated zones,we can implement centralized waste management and pollution control measures.
$2$. This prevents the widespread contamination of natural resources such as water bodies,agricultural land,and fertile soil.
$3$. It allows for better monitoring and regulation of pollutants,thereby minimizing the overall environmental impact on human health and ecosystems.

(N/A) Forests influence the quality of air,soil,and water resources in the following ways:
$A.$ Influence of forests on air:
Forests help to maintain the balance of $O_2$ and $CO_2$ in the atmosphere. They reduce the level of $CO_2$ in the air,thereby helping to mitigate the greenhouse effect.
They regulate the temperature of the environment and increase the rate of photosynthesis in the surrounding region.
$B.$ Influence of forests on soil quality:
Trees spread their roots deep into the Earth and bind soil particles firmly,which significantly reduces soil erosion.
Forests play a crucial role in maintaining nutrient cycles (biogeochemical cycles) in the ecosystem.
$C.$ Influence of forests on water quality:
The water cycle is maintained through the process of transpiration from trees. Forests help in water conservation and ensure the availability of water on the Earth's surface through various water sources.