Samacheer Kalvi Class 5 Science Solutions Term 2 Chapter 2 Water

Evaluation

I. Choose the Correct Answers:

 

Question 1. Which of the following microorganisms causes waterborne diseases?
(a) Bacteria
(b) Virus
(c) Protozoa
(d) All
Answer: (d) All
In simple words: Bacteria, viruses, and protozoa are all tiny living things that can make people sick if they are present in drinking water.

🎯 Exam Tip: Remember that waterborne diseases can be caused by various types of germs, not just one type, so "All" is often the correct choice when multiple pathogens are listed.

 

Question 2. Water is present in huge quantities as vapor and clouds in the
(a) sky
(b) earth
(c) atmosphere
(d) rain
Answer: (c) Atmosphere
In simple words: The atmosphere is the layer of air around the Earth where we find water vapor and clouds. This is where water stays before it falls as rain or snow.

🎯 Exam Tip: Understand the difference between the 'sky' (which is just what we see) and the 'atmosphere' (the actual layer of gases where weather happens).

 

Question 3. __________ water is free from suspended impurities.
(a) Sea
(b) Well
(c) River
(d) Underground
Answer: (d) Underground
In simple words: Water found underground is naturally filtered as it passes through layers of soil and rock, which removes dirt and other small particles.

🎯 Exam Tip: Think about how groundwater moves through the earth, which acts as a natural filter, making it cleaner than surface water sources.

 

Question 4. _________ of water is in oceans and seas.
(a) 97%
(b) 87%
(c) 47%
(d) 77%
Answer: (a) 97%
In simple words: Most of the Earth's water, about 97%, is salty and found in oceans and seas. Only a very small part is freshwater.

🎯 Exam Tip: It's important to remember this high percentage to understand why freshwater is a precious and limited resource.

 

Question 5. _________ is an artificial process of converting seawater into freshwater.
(a) Distillation
(b) Decantation
(c) Reverse Osmosis
(d) Desalination
Answer: (d) Desalination
In simple words: Desalination is a man-made way to remove salt from seawater to make it fresh and drinkable. It uses methods like reverse osmosis.

🎯 Exam Tip: Desalination is a key process for countries with little fresh water but plenty of access to oceans. Ensure you know its purpose.

II. Fill in the Blanks:

 

Question 1. The accumulated underground water comes out in the form of __________.
Answer: A Spring
In simple words: When water that has collected underground finds a way to flow out naturally, we call that a spring.

🎯 Exam Tip: Springs are natural openings where groundwater surfaces, providing a direct source of fresh water.

 

Question 2. The process of changing water into water vapor by the heat of the Sun is called __________.
Answer: Evaporation
In simple words: When the sun heats up water, the water turns into a gas called vapor and rises into the air. This process is called evaporation.

🎯 Exam Tip: Evaporation is a fundamental part of the water cycle, moving water from the Earth's surface into the atmosphere.

 

Question 3. Rainwater forms streams and __________ which join together to form rivers.
Answer: springs
In simple words: Rainwater creates small flowing water bodies like streams and also feeds underground springs. These then combine to become bigger rivers.

🎯 Exam Tip: Streams and springs are the initial stages of water flow on land, eventually converging to create larger river systems.

 

Question 4. The process of collecting and storing rainwater is called __________.
Answer: Rainwater harvesting
In simple words: Rainwater harvesting is the practice of gathering and saving rainwater, often from rooftops, for later use. This helps save water.

🎯 Exam Tip: Rainwater harvesting is an important way to conserve water and can be used for irrigation or even drinking after treatment.

 

Question 5. Cholera is caused by __________.
Answer: Bacteria (Vibrio Cholerae)
In simple words: Cholera is a serious illness caused by a specific type of bacteria called Vibrio Cholerae. It often spreads through contaminated water.

🎯 Exam Tip: Knowing the causative agents of diseases helps in understanding how to prevent and treat them effectively.

III. Match the Following:

 

Answer:

In simple words: This match helps us connect common terms with their related actions or definitions. For example, oil spills harm sea creatures, reservoirs are built by dams, and distillation is used to make saltwater fresh. Swine flu is caused by a virus.

🎯 Exam Tip: When matching, first connect the obvious pairs, then use elimination for the remaining items. For complex terms like 'Distillation', remember its primary use is purification or separation.

IV. Answer Briefly:

 

Question 1. Write down the sources of water.
Answer: The main places we get water from include:

• River water and lake water
• Seawater
• Well water
• Springwater
• Underground water

Water can be found in many forms and places on Earth, both fresh and salty.
In simple words: We get water from rivers, lakes, the sea, wells, springs, and from underground.

🎯 Exam Tip: When asked for sources, try to list both surface water (rivers, lakes, sea) and groundwater (wells, springs, underground) for a complete answer.

 

Question 2. What is desalination?
Answer: Desalination is a special process that human beings use to change salty water from the sea into fresh drinking water. It involves removing the salt from saline water to make it usable.
In simple words: Desalination is the process of taking salt out of seawater to make it fresh water.

🎯 Exam Tip: Clearly state that desalination is an 'artificial process' and its purpose is to convert 'saline water' (seawater) into 'freshwater'.

 

Question 3. What are the processes involved in the water cycle?
Answer: The water cycle involves four main steps:

• Evaporation: Water turns into vapor and rises.
• Condensation: Water vapor cools down and forms clouds.
• Precipitation: Water falls back to Earth as rain, snow, or hail.
• Flowing back to oceans: Water flows over land and underground to return to the seas.

These steps keep water moving around the Earth, changing from liquid to gas and back again.
In simple words: The water cycle has four steps: water goes up (evaporation), forms clouds (condensation), falls down (precipitation), and then flows back to the ocean.

🎯 Exam Tip: List the four processes in order (Evaporation, Condensation, Precipitation, Collection/Runoff) to describe the continuous movement of water.

 

Question 4. What are reservoirs?
Answer: A reservoir is a large, artificial lake, or sometimes a natural one, where water is collected and stored. People build most reservoirs by creating dams across rivers. These stored water bodies are essential for various human needs.
In simple words: Reservoirs are man-made lakes, often made by building a dam, to store water.

🎯 Exam Tip: Emphasize that reservoirs are typically 'artificial' and created by 'dams' to 'store water' for future use.

 

Question 5. How can we prevent dengue fever?
Answer: We can stop dengue fever by following these steps:

• Spray your house with anti-mosquito spray to kill mosquitoes.
• Wear clothes that cover most of your skin.
• Keep doors and windows closed, especially in the early morning and evening when mosquitoes are active.
• Make sure no stagnant water collects anywhere around your home, as mosquitoes breed in it.

Taking these simple steps helps reduce the chances of mosquito bites and dengue infection.
In simple words: To prevent dengue, we should use mosquito spray, wear clothes that cover our skin, keep windows closed, and remove any standing water around our homes.

🎯 Exam Tip: Focus on methods that eliminate mosquito breeding grounds (stagnant water) and protect against mosquito bites.

V. Answer in Detail:

 

Question 1. Write the advantages of rainwater harvesting.
Answer: Rainwater harvesting has many benefits:

• It helps reduce flooding in cities by collecting excess water.
• It lessens the loss of valuable topsoil by controlling runoff.
• It increases the amount of water available underground (groundwater level).
• It helps conserve water, making sure there's enough for future use.
• It can improve plant growth by providing a reliable water source for irrigation.

Saving rainwater is a smart way to manage water and protect the environment.
In simple words: Rainwater harvesting helps stop floods, saves topsoil, increases underground water, saves water for later, and helps plants grow better.

🎯 Exam Tip: When listing advantages, try to categorize them into environmental (flood control, soil erosion) and resource management (groundwater, conservation, irrigation) benefits.

 

Question 2. write the names of Causative Agents and the symptoms for waterborne diseases.
Answer:

In simple words: Waterborne diseases are caused by different germs like bacteria and viruses. Each disease has its own symptoms, but many involve problems like stomach pain, vomiting, and fever, especially from dirty water.

🎯 Exam Tip: When listing diseases, remember to mention both the type of germ (bacteria, virus) and some key symptoms to differentiate them.

 

Question 3. How is Dengue fever spread? What are the symptoms?
Answer: Dengue fever is a viral disease that spreads when an Aedes female mosquito bites a person during the day. These mosquitoes lay their eggs and grow in stagnant water found in places like containers and old tires around homes.
The symptoms of dengue fever can include:

• High fever, a strong headache, muscle and joint pain, and a special skin rash.
• Signs of dengue usually start 3 to 14 days after a person gets bitten.
• A drop in the number of platelets in the blood.
• Intense stomach pain.
• Frequent vomiting, sometimes with blood.

Understanding how it spreads helps in preventing the disease.
In simple words: Dengue fever spreads through the bite of Aedes mosquitoes, which breed in still water. Symptoms include high fever, headache, muscle pain, skin rash, and stomach pain.

🎯 Exam Tip: For dengue, remember the specific mosquito (Aedes) and its breeding habitat (stagnant water). Key symptoms like high fever, headache, and joint pain are crucial to mention.

Samacheer Kalvi 5th Science Guide Water Additional Questions and Answers

I. Choose the Correct Answer:

 

Question 1. The origin of river is _________.
(a) plains
(b) mountains
(c) valley
(d) ocean
Answer: (b) Mountains
In simple words: Rivers often start high up in mountains, usually from melting snow or rain, and then flow downhill.

🎯 Exam Tip: Think about the geography of rivers; they typically originate at higher elevations like mountains and flow towards lower areas.

 

Question 2. _________ is called saline water.
(a) Seawater
(b) River water
(c) Well water
(d) Underground water
Answer: (a) Seawater
In simple words: Saline water is water that contains a lot of salt. Seawater is the most common type of saline water.

🎯 Exam Tip: Remember that 'saline' means salty, and the largest source of salty water is the ocean.

 

Question 3. _________ of the world population does not get safe drinking water.
(a) 24%
(b) 25%
(c) 26%
(d) 27%
Answer: (b) 25%
In simple words: About one-quarter of all the people in the world do not have access to water that is clean and safe to drink. This is a big problem.

🎯 Exam Tip: This question highlights a significant global issue. Knowing key statistics can help in understanding the scale of the problem.

 

Question 4. _________ million people die worldwide every year due to diarrhoeal diseases.
(a) 1
(b) 2
(c) 3
(d) 4
Answer: (c) 3
In simple words: Every year, around 3 million people across the world die because of diarrhoeal diseases, which are often caused by unsafe drinking water.

🎯 Exam Tip: This statistic emphasizes the critical importance of clean water and sanitation for public health.

II. Fill in the Blanks:

 

Question 1. _________ of the total freshwater is frozen as ice caps and glaciers.
Answer: 68.7%
In simple words: Most of the world's freshwater, nearly 69%, is locked up in ice caps and glaciers, making it unavailable for direct use.

🎯 Exam Tip: It is crucial to remember that while Earth has a lot of water, most of its freshwater is frozen and not easily accessible.

 

Question 2. Agriculture consumes around _________ of the available freshwater.
Answer: 70%
In simple words: Farming uses about 70% of all the freshwater that is available for human use. This shows how much water crops need to grow.

🎯 Exam Tip: This highlights agriculture as the largest consumer of freshwater, making efficient irrigation methods very important.

 

Question 3. March 22 is observed as __________.
Answer: World Water Day
In simple words: March 22nd is a special day each year called World Water Day, when people think about the importance of fresh water and how to protect it.

🎯 Exam Tip: Remembering important environmental days helps in understanding global awareness campaigns related to resources.

 

Question 4. Contamination of water bodies by human activities is called _________ pollution.
Answer: water
In simple words: When people's actions make lakes, rivers, and oceans dirty or unsafe, it is called water pollution.

🎯 Exam Tip: Clearly define pollution as the contamination of resources, specifically water bodies by human actions.

 

Question 5. _________ mosquitoes also transmit chikungunya and yellow fever.
Answer: Aedes
In simple words: The Aedes type of mosquito is not just known for spreading dengue but also carries the germs for chikungunya and yellow fever.

🎯 Exam Tip: Recognize that certain mosquito types, like Aedes, are vectors for multiple diseases, making their control crucial.

III. Match the Following:

 

Answer:

In simple words: This table connects different types of waste and diseases to their main causes or associated substances. It helps us understand what leads to pollution and illness.

🎯 Exam Tip: Pay attention to the specific components of each type of waste and the primary agents causing the diseases for accurate matching.

IV. Answer Briefly:

 

Question 1. Why is underground water free from suspended Impurities?
Answer: Underground water is clean and free from floating dirt because nature filters it. As rainwater seeps down through the ground, it passes through many layers of soil, sand, and rock. These layers act like a natural filter, trapping the impurities and making the water clean.
In simple words: Underground water is clean because the soil acts like a natural filter, cleaning the water as it moves through the ground.

🎯 Exam Tip: The key reason is the natural filtration provided by the soil layers; mentioning this "natural filter" is essential.

 

Question 2. What are balls of ice?
Answer: When water falls from the sky during very cold weather, it can freeze into snow or hail. Hailstones are small pieces of ice that fall during thunderstorms. These hailstones are what we call balls of ice.
In simple words: Hailstones are small, hard balls of ice that fall from the sky, usually during a storm.

🎯 Exam Tip: Distinguish between snow (frozen flakes) and hail (frozen balls) as both are forms of ice precipitation.

 

Question 3. Define – Freshwater.
Answer: Freshwater is water that we get naturally from sources like ice sheets, large ice caps, glaciers, icebergs, ponds, lakes, rivers, and underground streams. It has very little salt or no salt in it, making it suitable for drinking and other uses.
In simple words: Freshwater is natural water from ice, lakes, rivers, or underground, and it has very little or no salt.

🎯 Exam Tip: The core definition of freshwater is its 'low salt content' and its various natural sources. List a few examples like rivers and lakes.

 

Question 4. Write the advantages of Wastewater treatment.
Answer: Treating wastewater has several benefits:

• It helps keep the environment clean by removing harmful substances.
• It prevents water pollution, protecting rivers, lakes, and oceans.
• It stops the spread of waterborne diseases by cleaning contaminated water.
• It ensures that enough water is available for irrigation, as treated water can be reused.

Wastewater treatment is a crucial step for environmental health and resource management.
In simple words: Treating dirty water makes the environment clean, stops water pollution, prevents sickness, and helps make water available for farming.

🎯 Exam Tip: Focus on the direct positive impacts: environmental cleanliness, disease prevention, and water reuse.

V. Answer in Detail:

 

Question 1. Write a short note on Farm Ponds.
Answer: A farm pond is a man-made pit dug into the ground on a farm. These ponds are typically square or rectangular in shape. Their main purpose is to collect and store rainwater, which is then used to water crops. A small raised bank, called a bund, is built around the pond to stop the soil on its edges from washing away.
The size and depth of a farm pond depend on the type of soil, how much water the farmer needs, what the pond will be used for, and the cost of digging it. Water from these ponds can be carried to the fields by hand, by using pumps, or by a combination of both. Farm ponds are an important part of water management in agriculture.
In simple words: Farm ponds are dug to collect rainwater for irrigation. They are often square or rectangular and have raised edges to prevent soil erosion.

🎯 Exam Tip: Describe a farm pond's physical characteristics, its primary purpose (rainwater storage for irrigation), and some factors influencing its construction.

 

Question 2. write the names of Causative Agents and the symptoms for waterborne diseases.
Answer:

In simple words: Waterborne diseases are caused by different germs like bacteria and viruses. Each disease has its own symptoms, but many involve problems like stomach pain, vomiting, and fever, especially from dirty water.

🎯 Exam Tip: When listing diseases, remember to mention both the type of germ (bacteria, virus) and some key symptoms to differentiate them.

 

Question 3. How is Dengue fever spread? What are the symptoms?
Answer: Dengue fever is a viral disease that spreads when an Aedes female mosquito bites a person during the day. These mosquitoes lay their eggs and grow in stagnant water found in places like containers and old tires around homes.
The symptoms of dengue fever can include:

• High fever, a strong headache, muscle and joint pain, and a special skin rash.
• Signs of dengue usually start 3 to 14 days after a person gets bitten.
• A drop in the number of platelets in the blood.
• Intense stomach pain.
• Frequent vomiting, sometimes with blood.

Understanding how it spreads helps in preventing the disease.
In simple words: Dengue fever spreads through the bite of Aedes mosquitoes, which breed in still water. Symptoms include high fever, headache, muscle pain, skin rash, and stomach pain.

🎯 Exam Tip: For dengue, remember the specific mosquito (Aedes) and its breeding habitat (stagnant water). Key symptoms like high fever, headache, and joint pain are crucial to mention.

Evaluation

I. Choose the correct answers:

 

Question 1. Which of the following microorganisms causes waterborne diseases?
(a) Bacteria
(b) Virus
(c) Protozoa
(d) All
Answer: (d) All
In simple words: Many tiny living things, like bacteria, viruses, and protozoa, can make people sick if they are present in the water we drink. This is why clean water is so important.

🎯 Exam Tip: Remember that waterborne diseases can be caused by various types of microorganisms, not just one specific kind. Listing "All" covers the broad range of pathogens.

 

Question 2. Water is present in huge quantities as vapor and clouds in the
(a) sky
(b) earth
(c) atmosphere
(d) rain
Answer: (c) Atmosphere
In simple words: Water exists as tiny invisible gas particles and visible clouds in the air around the Earth. The atmosphere holds a lot of water.

🎯 Exam Tip: Distinguish between "sky" (general term) and "atmosphere" (the specific layer of gases around Earth) when discussing scientific concepts.

 

Question 3. __________ water is free from suspended impurities.
(a) Sea
(b) Well
(c) River
(d) Underground
Answer: (d) Underground
In simple words: Water found deep under the ground is usually clean because the soil acts like a natural filter. This filtration removes dirt and small particles.

🎯 Exam Tip: Understand the natural filtration process where soil layers remove impurities from water as it seeps underground.

 

Question 4. __________ of water is in oceans and seas.
(a) 97%
(b) 87%
(c) 47%
(d) 77%
Answer: (a) 97%
In simple words: Most of the water on Earth is salty water found in oceans and seas. Only a very small part is fresh water.

🎯 Exam Tip: Remember this significant percentage to highlight the vast amount of saline water compared to freshwater on Earth.

 

Question 5. __________ is an artificial process of converting seawater into freshwater.
(a) Distillation
(b) Decantation
(c) Reverse Osmosis
(d) Desalination
Answer: (d) Desalination
In simple words: Desalination is a special process made by humans to remove salt from ocean water. This way, we can make salty water drinkable.

🎯 Exam Tip: Desalination is a key process for regions facing water scarcity, as it makes ocean water usable for various purposes.

II. Fill in the blanks:

 

Question 1. The accumulated underground water comes out in the form of __________.
Answer: The accumulated underground water comes out in the form of a **spring**. A spring is a natural place where groundwater flows out from the ground. Many rivers start as springs.

🎯 Exam Tip: Understand that springs are natural outlets for groundwater, making them important sources of fresh surface water.

 

Question 2. The process of changing water into water vapor by the heat of the Sun is called __________.
Answer: The process of changing water into water vapor by the heat of the Sun is called **Evaporation**. Evaporation is a key part of the water cycle, moving water from Earth's surface into the atmosphere.

🎯 Exam Tip: Clearly define evaporation as the change of liquid water into a gaseous state (vapor) due to heat, especially from the sun.

 

Question 3. Rainwater forms streams and __________ which join together to form rivers.
Answer: Rainwater forms streams and **springs** which join together to form rivers. Streams are small, narrow bodies of flowing water. These smaller water bodies combine to create larger rivers.

🎯 Exam Tip: Recognize the sequence: rainwater forms small streams and springs, which then merge to create larger rivers.

 

Question 4. The process of collecting and storing rainwater is called __________.
Answer: The process of collecting and storing rainwater is called **Rainwater harvesting**. This method helps save water for later use, especially in areas with limited water sources.

🎯 Exam Tip: Understand that rainwater harvesting is an important technique for water conservation and management, especially in dry regions.

 

Question 5. Cholera is caused by __________.
Answer: Cholera is caused by **Bacteria (Vibrio Cholerae)**. This specific type of bacteria spreads through contaminated water or food. It leads to severe diarrhea and dehydration.

🎯 Exam Tip: Remember the specific bacterium, Vibrio Cholerae, as the cause of cholera, linking it to contaminated water.

III. Match the following:

 

Question 1. Match the following:
Answer:

In simple words: This table correctly pairs each item from the first list with its related term or effect from the second list. Matching involves understanding the connection between each item.

🎯 Exam Tip: When matching, carefully read both columns to find the most accurate and direct relationship between items. Sometimes one item might seem to fit multiple answers, but there is usually one best match.

IV. Answer briefly:

 

Question 1. Write down the sources of water.
Answer: The main sources of water on Earth include:

• River water and lake water
• Seawater
• Well water
• Spring water
• Underground water

These different sources provide water for various human and environmental needs. Each source has unique characteristics and uses.

🎯 Exam Tip: When listing sources, try to categorize them (e.g., surface water, groundwater, saline water) for a more complete answer.

 

Question 2. What is desalination?
Answer: Desalination is an artificial process that converts saline water (seawater) into freshwater. This technique is very important in places where fresh water is scarce. It involves removing salt and other minerals from water.

🎯 Exam Tip: Define desalination clearly by mentioning it's an artificial process and its main goal: converting saltwater to freshwater.

 

Question 3. What are the processes involved in the water cycle?
Answer: The water cycle consists of the following four main processes:

• Evaporation: Water changes into vapor and rises into the air.
• Condensation: Water vapor cools down and forms clouds.
• Precipitation: Water falls back to Earth as rain, snow, or hail.
• Flowing back to oceans: Water on the land flows into rivers and eventually returns to the oceans.

These processes continuously move water around the Earth, powering our climate and ecosystems.

🎯 Exam Tip: List the four key processes of the water cycle in sequence and briefly explain each one to show a complete understanding.

 

Question 4. What are reservoirs?
Answer: A reservoir is a man-made (artificial) lake where water is stored. Most reservoirs are created by building dams across rivers. They can also be formed from natural lakes that have been modified. Reservoirs are vital for storing drinking water, irrigation, and generating electricity.

🎯 Exam Tip: Emphasize that reservoirs are artificial or modified natural lakes used for water storage, often created by dams.

 

Question 5. How can we prevent dengue fever?
Answer: We can prevent dengue fever by taking these steps:

• Spray your house with anti-mosquito spray to kill mosquitoes.
• Try to wear clothes that cover most of your skin.
• Close doors and windows, especially during early morning and evening when mosquitoes are active.
• Do not leave still water lying anywhere inside or around your house.

Stopping mosquito breeding is the most effective way to prevent this disease. Dengue is caused by mosquito bites.

🎯 Exam Tip: Focus on methods that either kill mosquitoes, protect against bites, or eliminate their breeding grounds (stagnant water).

V. Answer in detail:

 

Question 1. Write the advantages of rainwater harvesting.
Answer: Rainwater harvesting has many advantages:

• It can help reduce flooding in cities.
• It helps to reduce the loss of topsoil due to runoff.
• It can increase the level of groundwater, replenishing underground water reserves.
• Groundwater can be conserved for future use.
• It can improve plant growth by providing a reliable water source.

By collecting and storing rainwater, we can ensure a more sustainable water supply and reduce environmental problems.

🎯 Exam Tip: List a variety of benefits, covering environmental, conservation, and practical uses, to show a comprehensive understanding of rainwater harvesting.

 

Question 2. How can we prevent waterborne diseases?
Answer: To prevent waterborne diseases, we should follow these practices:

• Maintain good personal hygiene, such as washing hands often, and improve basic sanitation in our surroundings.
• Use chlorinated and boiled water for drinking. Chlorination and boiling kill harmful germs.
• Drink milk that has been boiled or pasteurized.
• Properly dispose of infectious wastes so they don't contaminate water sources.

Taking these steps helps ensure that the water we use is safe and free from disease-causing germs.

🎯 Exam Tip: Focus on two main areas: ensuring water quality (boiling, chlorination) and preventing contamination (hygiene, waste disposal) for a complete answer.

Samacheer Kalvi 5th Science Guide Water Additional Questions and Answers

I. Choose the correct answer:

 

Question 1. The origin of river is __________.
(a) plains
(b) mountains
(c) valley
(d) ocean
Answer: (b) Mountains
In simple words: Most rivers start high up in the mountains, often from melting snow or glaciers. The water then flows downhill to create a river.

🎯 Exam Tip: Understand that mountains act as natural water towers, collecting precipitation and releasing it into river systems.

 

Question 2. __________ is called saline water.
(a) Seawater
(b) River water
(c) Well water
(d) Underground water
Answer: (a) Seawater
In simple words: Saline water means salty water. The water in oceans and seas naturally contains a lot of salt.

🎯 Exam Tip: Define "saline" as referring to water with a high salt content, primarily found in oceans.

 

Question 3. __________ of the world population does not get safe drinking water.
(a) 24%
(b) 25%
(c) 26%
(d) 27%
Answer: (b) 25%
In simple words: About one-fourth of all people in the world do not have access to clean and safe drinking water. This is a major global challenge.

🎯 Exam Tip: Keep this statistic in mind to highlight the widespread issue of water scarcity and lack of access to safe drinking water.

 

Question 4. __________ million people die worldwide every year due to diarrhoeal diseases.
(a) 1
(b) 2
(c) 3
(d) 4
Answer: (c) 3
In simple words: Around 3 million people die each year from diseases that cause diarrhea. Many of these diseases are caused by unsafe drinking water.

🎯 Exam Tip: This number emphasizes the severe impact of poor sanitation and unsafe water on global health, especially from preventable diseases.

II. Fill in the blanks:

 

Question 1. __________ of the total freshwater is frozen as ice caps and glaciers.
Answer: **68.7%** of the total freshwater is frozen as ice caps and glaciers. This means a large portion of Earth's freshwater is not easily accessible. It is stored in solid form at the poles and high mountains.

🎯 Exam Tip: Remember this percentage to understand how much of the world's freshwater is locked up in ice and not readily available for human use.

 

Question 2. Agriculture consumes around __________ of the available freshwater.
Answer: Agriculture consumes around **70%** of the available freshwater. This large amount is used for growing crops and raising livestock. It shows how important water is for food production.

🎯 Exam Tip: Note this statistic to highlight agriculture as the largest consumer of freshwater, emphasizing the need for efficient irrigation methods.

 

Question 3. March 22 is observed as __________.
Answer: March 22 is observed as **World Water Day**. This day is celebrated to bring attention to the importance of freshwater and to advocate for its sustainable management. It raises awareness about global water issues.

🎯 Exam Tip: Remember important environmental days like World Water Day and their significance for awareness and action.

 

Question 4. Contamination of water bodies by human activities is called __________ pollution.
Answer: Contamination of water bodies by human activities is called **water** pollution. This occurs when harmful substances from human sources enter rivers, lakes, and oceans. It damages ecosystems and human health.

🎯 Exam Tip: A simple, direct definition of water pollution links it clearly to human activities contaminating water sources.

 

Question 5. __________ mosquitoes also transmit chikungunya and yellow fever.
Answer: **Aedes** mosquitoes also transmit chikungunya and yellow fever. These are the same type of mosquitoes that spread dengue fever. They are known for biting during the daytime.

🎯 Exam Tip: Identify Aedes mosquitoes as carriers of multiple diseases, not just dengue, which is crucial for public health.

III. Match the following:

 

Question 1. Match the following:
Answer:

In simple words: This table links different types of waste to their specific components, and diseases to their causes. It shows how various pollutants and germs are related to specific issues.

🎯 Exam Tip: Pay attention to the specific categories of waste and their common components, as well as the agents causing different diseases.

IV. Answer briefly:

 

Question 1. Why is underground water free from suspended impurities?
Answer: Underground water is free from suspended impurities because it gets filtered naturally. As rainwater passes through several layers of the soil, the soil acts like a natural filter. It removes dirt, dust, and other tiny particles, making the water clean. This natural purification process is very effective.

🎯 Exam Tip: Explain the natural filtration process where soil layers trap impurities, resulting in cleaner underground water.

 

Question 2. What are balls of ice?
Answer: In very cold conditions, water falling from the sky can become snow or hail. Hailstones are small balls of ice. They are formed when raindrops are carried upward into very cold parts of the atmosphere and then freeze, falling to the ground as solid ice. They are different from snowflakes, which are delicate ice crystals.

🎯 Exam Tip: Distinguish between snow and hail, specifying that hailstones are indeed balls of ice formed by freezing raindrops.

 

Question 3. Define – Freshwater.
Answer: Freshwater is water that contains very low concentrations of dissolved salts and other solids. It is naturally obtained from sources like ice sheets, ice caps, glaciers, icebergs, ponds, lakes, rivers, streams, and underground sources. Freshwater is essential for most living organisms and human consumption. It is much less common than saltwater.

🎯 Exam Tip: Define freshwater by its low salt content and list several common natural sources where it can be found.

 

Question 4. Write the advantages of Wastewater treatment.
Answer: Wastewater treatment offers several advantages:

• It ensures that the environment remains clean and healthy.
• It helps prevent water pollution by removing harmful substances before water is released.
• It stops the spread of waterborne diseases, protecting public health.
• It ensures that there is enough water for irrigation, as treated water can often be reused.

Treating wastewater is a critical step in managing water resources responsibly and protecting our planet.

🎯 Exam Tip: Focus on the environmental and health benefits of wastewater treatment, including resource recovery and disease prevention.

 

Question 5. What are the major sources of Water pollution?
Answer: The major sources of water pollution include:

• Industrial waste from factories.
• Sewage and domestic waste from homes and cities.
• Chemical fertilizers and insecticides used in agriculture.
• Synthetic detergents from household and industrial use.
• Oil spills from ships or offshore drilling.

These sources introduce harmful substances into water bodies, damaging aquatic life and making water unsafe for use. Controlling these sources is key to clean water.

🎯 Exam Tip: Categorize pollution sources into industrial, domestic, agricultural, and accidental (like oil spills) for a comprehensive answer.

 

Question 6. Name the Causative Agents and write the Symptoms for Dengue Fever and Swine Flu.
Answer: Here are the causative agents and symptoms for Dengue Fever and Swine Flu:

• Dengue fever:
• Causative Agent: Virus (Flavi Virus)
• Symptoms: High fever, severe headache, muscle and joint pain, vomiting with blood, and stomach pain.
• Swine Flu:
• Causative Agent: Virus (Influenza)
• Symptoms: Infection in respiratory tracts, indigestion, and nasal secretions.

These viral diseases can cause serious health issues and require proper medical attention. Knowing the symptoms helps in early detection and treatment.

🎯 Exam Tip: For each disease, clearly state the causative agent (type of virus) and list at least three distinct symptoms.

V. Answer in detail:

 

Question 1. Write a short note on Farm Ponds.
Answer: A farm pond is a man-made structure dug into the ground on a farm. These ponds are typically square or rectangular in shape. Rainwater is collected and stored in these ponds mainly for irrigation purposes. A small mound or "bund" usually surrounds the pond. This bund helps prevent soil erosion on the pond's banks and ensures the stored water remains contained. The size and depth of a farm pond depend on the type of soil, the amount of water needed by the farmer, and the cost of digging. Water can be moved from the pond to the fields by hand, by pumping, or by both methods. Farm ponds are an excellent way to manage water locally and support agricultural activities, especially during dry periods.

🎯 Exam Tip: Describe what a farm pond is, its common shape, its primary purpose (irrigation), and mention how it's constructed and used.

 

Question 2. Write the names of Causative Agents and the symptoms for waterborne diseases.
Answer:

In simple words: This table lists several common waterborne diseases, the specific germs (bacteria or viruses) that cause them, and the main symptoms they show. Understanding these links is important for preventing and treating these illnesses.

🎯 Exam Tip: Present information in a clear table format, ensuring each disease is paired with its correct causative agent and at least two distinct symptoms.

 

Question 3. How is Dengue fever spread? What are the symptoms?
Answer: Dengue fever is a viral disease that spreads through the bite of infected Aedes female mosquitoes. These mosquitoes usually bite during the daytime. They often breed in still water found in containers, old tires, and other places around homes. Preventing mosquito breeding is crucial to control the spread of dengue. The symptoms of dengue fever typically appear three to fourteen days after a person gets infected. They may include:

• High fever, severe headache, muscle, and joint pain, along with a special skin rash.
• Deficiency of platelets in the blood, which can lead to bleeding problems.
• Intense stomach pain.
• Regular vomiting, sometimes with blood.

These symptoms can range from mild to severe, and in serious cases, dengue can be life-threatening.

🎯 Exam Tip: Clearly state the vector (Aedes mosquito) and how it spreads, then list key symptoms like fever, pain, rash, and platelet deficiency.