Water and Water Pollution Questions in English

(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.

(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) 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) 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.

(C) Water bodies provide water for evaporation. Water vapour,formed after evaporation,condenses to cause rainfall. $A$ lack of water bodies in an area reduces humidity in the air and thus adversely affects the rainfall patterns.

(C) Water pollution is defined as the contamination of water bodies by substances that make it harmful for living organisms or unfit for use.
Adding undesirable substances (pollutants) or removing desirable substances (like oxygen) causes pollution.
Thermal pollution (a change in temperature) also negatively impacts aquatic life.
$A$ change in pressure of water bodies is a physical phenomenon that does not constitute pollution.

(A) The Earth is often referred to as the 'Blue Planet' because a significant portion of its surface is covered by water.
Scientific estimates indicate that approximately $71\%$ to $75\%$ of the Earth's surface is covered by oceans,seas,and other water bodies.
Among the given options,$75\%$ is the most accurate representation of this coverage.

(C) Aquatic organisms are adapted to a specific range of temperatures.
Marked changes in water temperature can significantly affect the metabolic activities of aquatic organisms,including their reproductive cycles and breeding patterns.
While temperature can influence plant growth and digestion rates,the most direct and critical impact of sudden or marked temperature fluctuations in an aquatic ecosystem is on the breeding and survival of aquatic animals,as many species rely on specific temperature cues for spawning and larval development.

(B) The addition of undesirable substances like pesticides,fertilizers,industrial waste,and domestic sewage into water bodies leads to pollution.
These pollutants are toxic and can kill aquatic organisms or cause various diseases.
Furthermore,the decomposition of organic waste increases the biological oxygen demand,which leads to a reduction in the dissolved oxygen levels in the water.
This decrease in dissolved oxygen adversely affects the survival and health of aquatic organisms.

(C) Although the Earth is covered by a vast amount of water,most of it is present in oceans as saline water,which is not suitable for human consumption,agriculture,or industrial use.
Fresh water,which is essential for life,is a limited resource.
Furthermore,the distribution of fresh water on Earth is highly uneven,leading to water scarcity in many regions.
Therefore,conservation is necessary to ensure the sustainable availability of fresh water for all living organisms.

(D) The mass mortality of fishes in a pond can be attributed to several environmental factors:
$(i)$ Thermal pollution: An increase in water temperature reduces the concentration of dissolved oxygen,leading to suffocation.
$(ii)$ Addition of poisonous compounds: Toxic substances like mercury or pesticides can cause direct poisoning of aquatic life.
$(iii)$ Blockage of gills: Suspended pollutants or oil spills can physically block the gills,preventing respiration and leading to death.

(N/A) Water pollution is caused by the addition of:
$(i)$ Undesirable substances like fertilizers,pesticides,or other poisonous chemicals.
$(ii)$ Sewage directly entering a water body.
$(iii)$ Hot water from power plants,which increases the water temperature and reduces dissolved oxygen,thereby killing aquatic organisms.
$(iv)$ Industrial effluents or radioactive substances discharged into water bodies.
We can contribute to reducing water pollution by taking the following measures:
$(i)$ Sewer lines should not be directly connected to water bodies.
$(ii)$ We should not dispose of garbage or domestic waste into water bodies.
$(iii)$ Prevent the dumping of toxic compounds into water bodies.
$(iv)$ Avoid washing clothes near water bodies,as detergents contain harmful chemicals.
$(v)$ Plant trees near river banks to prevent soil erosion,as erosion leads to the siltation of water bodies.

(N/A) Sedimentation tank: This tank allows heavy,insoluble solid particles to settle down at the bottom due to gravity.
$(b)$ Loading tank: This tank is used to add coagulants like alum to the water,which helps in settling down fine suspended impurities that do not settle easily by sedimentation.
$(c)$ Chlorination tank: This tank is used to add chlorine to the water to kill harmful bacteria and microorganisms,making the water safe for consumption.

(A) Freshwater resources are bodies of water that have a low concentration of dissolved salts. These include rivers,lakes,ponds,canals,and reservoirs. Since the statement lists these correctly,the answer is True.

(N/A) The harmful effects of water pollution are:
$(i)$ Addition of undesirable substances such as fertilizers,pesticides,and mercury salts used in paper industries. This results in changes to both the physical and chemical characteristics of water.
$(ii)$ Polluted water may contain disease-causing harmful bacteria such as those causing cholera,typhoid,etc.
$(iii)$ The reduction of dissolved oxygen levels adversely affects aquatic organisms.
$(iv)$ Any change in water temperature affects the breeding patterns of aquatic organisms.
$(v)$ The eggs and larvae of various aquatic animals are particularly susceptible to temperature changes.

(N/A) Water is essential for life due to the following reasons:
$1$. It regulates body temperature through processes like sweating and evaporation.
$2$. All cellular and metabolic processes occur in an aqueous medium.
$3$. It is necessary for the digestion of food and the transportation of nutrients and oxygen throughout the body via blood.
$4$. It plays a crucial role in the excretion of waste products from the body.

(N/A) The addition of undesirable substances like fertilizers,pesticides,and poisonous substances such as mercury salts into water bodies. These can also include disease-causing organisms,such as the bacteria that cause cholera.
$(b)$ The removal of desirable substances like dissolved oxygen from the water adversely affects aquatic organisms.
$(c)$ $A$ sudden change in the temperature of water bodies is dangerous and affects the breeding of aquatic life. The eggs and larvae are particularly sensitive to these temperature changes.

(N/A) $(i)$ An increase in the temperature of water bodies leads to water pollution because it reduces the amount of dissolved oxygen available for aquatic organisms. Furthermore,many aquatic species are sensitive to temperature changes; higher temperatures can kill eggs and larvae,disrupt reproductive cycles,and alter the ecological balance of the ecosystem.
$(ii)$ Two methods to prevent water pollution are:
$1$. Do not dispose of industrial or domestic waste directly into water bodies.
$2$. Avoid washing clothes or bathing animals at river banks to prevent detergents and contaminants from entering the water.

(N/A) - Most of the water on the Earth's surface is found in the liquid state in seas,oceans,rivers,lakes,ponds,etc.
- It is found in the solid state as ice on mountain peaks and in polar regions.
- Water is also found in the vapour state due to evaporation from the surface of water bodies,as moisture in the atmosphere,and through transpiration by plants and respiration by animals.

(N/A) $(i)$ Excessive use of fertilizers and pesticides in agriculture.
$(ii)$ Disposal of untreated industrial waste containing toxic substances into water bodies.
$(iii)$ Discharge of untreated domestic sewage from households into water sources.
$(iv)$ Release of synthetic detergents and soaps from household washing activities.
$(v)$ Thermal pollution caused by the release of hot water from industrial cooling processes.

(B) Water pollution is defined as the contamination of water bodies (e.g., lakes, rivers, oceans, aquifers, and groundwater) usually as a result of human activities.
$1$. The addition of undesirable substances (pollutants) like toxic chemicals, sewage, or industrial waste makes water unfit for use.
$2$. The removal of desirable substances (like dissolved oxygen) disrupts the aquatic ecosystem.
$3$. $A$ change in temperature (thermal pollution) affects the metabolic rates and survival of aquatic organisms.
$4$. $A$ change in pressure is a physical property related to depth and does not constitute water pollution.

(A) The Earth is often referred to as the 'Blue Planet' because a significant portion of its surface is covered by water.
Scientific estimates indicate that approximately $71 \%$ to $75 \%$ of the Earth's surface is covered by oceans,seas,and other water bodies.
Among the given options,$75 \%$ is the most accurate representation of the water coverage on Earth's surface.

(A) Rainfall patterns are primarily determined by the prevailing wind patterns and the presence of water bodies in an area.
Water bodies,such as oceans,lakes,and rivers,provide the moisture necessary for cloud formation through evaporation.
When moisture-laden air moves over land,it cools down and condenses to form rain.
Therefore,the proximity and number of water bodies significantly influence the amount and frequency of rainfall in a specific region.

(D) Aquatic organisms are adapted to a specific range of temperatures.
Marked changes in water temperature can disrupt the biological processes of these organisms.
Specifically,temperature fluctuations significantly affect the breeding cycles of aquatic animals,as many species rely on specific temperature cues to initiate spawning or reproduction.
While other factors like nutrient availability and digestion can be indirectly influenced,the most direct and critical impact of significant temperature change in an aquatic ecosystem is on the breeding and reproductive success of the animals.