CBSE Class 6 Science Water Worksheet Set 03

Learning Objectives
1. Water is a natural resource.
2. Water cycle.
3. Role of transpiration, evaporation, vaporisation in water cycle.
4. Formation of hail, snow, precipitation and rains.
5. Sources of water.
6. Conservation of water. 

About three fourth of Earth’s surface is covered with water. Water is found in rivers, seas, oceans, soil, air, plants and animals. Man is dependent on plants and animals which are in turn dependent on air, water and soil etc. All such substances which are used by man for sustenance of life and his welfare are called resources and those that are found in nature are called natural resources.

Importance of water : Water is the most important substances required by us. Without water, we cannot live. Water is used in agriculture, industries, for washing, bathing, drinking, cooking, cleaning and several other purposes. Our body has 70% water by weight while water melon is 99% water.

Percentage of water in food and animals
1. Several life processes like digestion, excretion, absorption of nutrients and distribution required large quantity of water.
2. Water is the natural habitat for marine life.
3. Water is a universal solvent as it can dissolve may substances.
4. It is used in bathing, cleaning, washing, dyeing and other household purposes.
5. Water helps in dispersal of seeds and fruits.
6. It is used for generating steam in factories.
7. It is used in sports and recreation.
8. It is also used to generate hydroelectricity.
9. It is essential for germination of seeds and for photosynthesis.
10. Crops cannot grow without water.
11. Our body temperature is controlled by water.
12. It is also used as a mode of transportation.

STATES OF WATER
Water can exist in three states: solid, liquid and gas.
→ Ice is the solid form of water.
→ Water that we drink is the liquid state.
→ Steam is the gaseous state.
In nature, water is found in solid state as snow on high mountains. Most of water on earth is in liquid form found in rivers, seas, oceans and lakes. Water vapour in air is the gaseous state of water.
We can change the state of water by changing the temperature; either by heating or cooling.
Water can be changed to ice by cooling. This is called freezing.
When ice is heated it will melt to form water. This is called melting of ice. Similarly when water is heated, it forms steam. This is called evaporation.
Evaporation occurs at all temperature. Water from wet clothes evaporates and then clothes become dry. Wet clothes dry faster in the sun and water evaporates faster if the surface area is increased.
Water vapour condenses to form water on cooling. This is called condensation.

Water circulates in nature. The circulation of water from the surface of earth to the atmosphere and back to earth is called water cycle.
Water from water bodies like rivers, seas, oceans and lakes evaporates because of the heat of sun. Plants also give out water from their leaves during transpiration. Water vapour rises and as they reach higher up in the atmosphere they cool and condenses to form water droplets. These water droplets coalesce to from clouds. The clouds cool further and when they become too heavy, they fall down on earth as rain. This is called precipitation.
The rainwater falls on seas, rivers and other water bodies. Water from land also flows into rivers through streets. Some rainwater may seep underground as groundwater. This water is used in houses; agriculture and industries. Finally this water too goes into rivers and seas. Snow from mountains also melt and flows into rivers. The water in oceans, seas, rivers and lakes evaporate again.
This cycle goes on and in this way water cycle goes on in nature.

Fog : During winter, sometimes, condensation of water vapours start near the surface of earth. These condensed vapour do not form rain clouds. Instead they appear near the earth surface as fog.

Hail or snow : Sometimes when rain falls on high mountains or when it is too cold, the water becomes solid and becomes snow. When snow falls it is called hail.

Dew : During winter nights, when air becomes very cool, the vapours near the earth’s surface condense and form water droplets. These appear as dew on leaves, flowers, railings etc.

Sources of Water

Rainwater : Rain is the main source of water. It is free from germs but may contain dust particles. There are some dissolved gases such as carbondioxide and sometimes acids may also pollute rain water causing acid rain.

Groundwater : When rain falls on the ground, some water penetrate the soil and accumulate on the non-porous rocky layer. This is called underground water and the level of water is called water table.
Sometimes the groundwater may come out at the surface to form a natural spring. It may also form a lake.
Groundwater passes through several layers of sand and rocks. It gets filtered through these layers and is free from suspended impurities. However, it may be contaminated with germs and some dissolved salts of calcium and magnesium.
We can obtain groundwater by digging wells and tube

Surface water : Rainwater that runs off the surface of earth to form streams, lakes and rivers is called surface water. Snow melts and the water flows down
to rivers and lakes. Surface water is highly contaminated with germs, suspended impurities and dissolved salts. Sewage water from houses and industries are also discharged into rivers. River water needs to be cleaned before being supplied to cities and towns for drinking. If uncleaned water is consumed, it may cause dangerous diseases like jaundice, cholera and typhoid.

Sea Water
Rivers and streams finally flow into sea and so they are the largest reservoirs of natural water. Sea water is the most impure water. It contains dissolved common salt. Due to this sea water is salty and is called saline water. It is unfit for drinking, cannot be used in irrigation and in industries. People must use water judiciously otherwise there will be a severe water crisis.

Disadvantage of no rainfall at all : Rain is the main source of water. Less or no rainfall can convert an area into a desert. If there is no rainfall for a long period, in continuation, it may lead to drought. There will be no crop, no food for humans and animals. There will be loss of life. An economic crisis will occur in the region and this will become a natural calamity.

Problem due to heavy rain : If there is heavy rainfall, then also problem will rise. The fields will get flooded and crops will be damaged. Again there will be shortage of food and fodder. Collection of rain water will also disrupt the normal life of peoples. Many roads and bridges will get damaged and there will be loss to life and property. Low lying areas will be flooded and people have to be shifted.

Factors affecting shortage of water
(i) Increase in population has increased the demand for water.
(ii) Change in lifestyle of people has increased the consumption of water.
(iii) Urbanisation has decreased the groundwater reserves as concrete roads do not allow seepage of water.
(iv) Industrial demand for water is increasing many times.

Conservation of water : In summers people face shortage of water because the level of groundwater goes down and so there is no water in wells and tube wells. If there is low rainfall the situation becomes even more grim. There is scarcity of drinking water. Therefore, management of water resources is very important and in this water conservation plays an important role

Measures for conservation of water
1. Development of watershed plan for drinking, irrigation and industrial areas.
2. Carrying out surveys to identify over exploited areas.
3. Artificial recharging of ground water.
4. Adoption of flood control methods.
5. Transfer of excess water to deficit areas by interlinking of rivers.
6. Adopting water harvesting methods.
7. Avoiding misuse of water.
8. Organising people awareness programmes.

Rain water Harvesting : Rain water simply flows into drains and is lost.
Instead this rain water can be collected and used later. This is called harvesting of rain water.
Rain water from roof tops and kitchen weather can be collected in underground tanks. Water from these tanks percolate underground and recharge the aquifers.

Preventing water pollution : We can also conserve water by protecting the water bodies from pollution. We should not dump garbage and harmful chemicals from factor in water bodies. Dirty water is bad for marine line. Even plants and animals die around polluted water. If humans consume polluted water they may suffer from many diseases.

Keywords
• Condensation : Process by which water vapour in air changes into liquid water.
• Evaporation : Process by which liquid water turns into vapour.
• Transpiration : Process by which plants lose water in the form of water vapour into the atmosphere.
• Water cycle : The cyclic movement of water from the atmosphere to the Earth and back to the atmosphere through various processes is called water cycle.
• Drought : Abnormally long period of insufficient or no rainfall is called drought.
• Famine : Lack of food in a region for a long period is called famine.
• Rain water harvesting : The process of collecting and storing rainwater from roofs or a surface catchment is called rainwater harvesting

Match the Column

DIRECTIONS : Match Column-I with Column-II and select the correct answer using the codes given below the columns.

Question.
Column-I                              Column-II
(A) Ground water           (p) Excess rains
(B) Ocean                      (q) Aquifiers
(C) Clouds                     (r) Water containing dissolved salts
(D) Floods                     (s) Water vapour and dirt
(a) A → (p); B → (q); C → (r); D → (s)
(b) A → (q); B → (r); C → (s); D → (p)
(c) A → (r); B → (s); C → (p); D → (q)
(d) A → (s); B → (p); C → (q); D → (r)
Answer : B

Question.
Column-I                        Column-II
(A) Drought                (p) Slow process
(B) Surface water       (q) Rivers, ponds etc.
(C) Evaporation          (r) Loss of water by plants
(D) Transpiration        (s) Absence of rains for a long time
(a) A → (s); B → (q); C → (p); D → (r)
(b) A → (s); B → (r); C → (q); D → (p)
(c) A → (s); B → (p); C → (q); D → (r)
(d) A → (p); B → (s); C → (r); D → (q)
Answer : A

Question.
Column-I                                                       Column-II
(A) Water cycle                                 (p) Solid state of water
(B) Hail, snow                                   (q) Condensation
(C) Water vapour changes to           (r) Circulation of water between ocean liquid water and land
(D) Water enters air                         (s) Transpiration
(a) A → (p); B → (q); C → (r); D → (s)
(b) A → (q); B → (r); C → (s); D → (p)
(c) A → (r); B → (p); C → (q); D → (s)
(d) A → (s); B → (q); C → (p); D → (r)
Answer : C

Passage Based Questions

DIRECTIONS : Read the passage (s) given below and answer the questions that follow.

Passage-1
Apart from drinking, there are so many activities for which we use water.
Most of the water is in oceans and seas.
We draw drinking water from taps which is further drawn from a well or a lake etc.

Question. We need water for which of the following?
(a) Baking
(b) Brushing
(c) Cooking
(d) All of these
Answer : D

Question. We need water for
(a) industries
(b) producing many things
(c) Both the above
(d) None of these
Answer : C

Question. Choose the correct option?
(a) All of us (i.e., Indians) get drinking water from taps.
(b) The water that we get from taps is also drawn from a lake, or a river or a well.
(c) Both the above
(d) None of these
Answer : B

Passage-2
If we put some water in a plate and allow the plate to lie in open in sunlight we find that the water from the plate disappears.
Moreover even if we keep the plate in shade the water still disappears.

Question. The process by which the water disappears from the plate is
(a) Evaporation
(b) Condensation
(c) Transpiration
(d) Precipitation
Answer : A

Question. The process of disappearance of water from the plate occurs
(a) rapidly in sunlight
(b) rapidly in shade
(c) with same speed in day and night
(d) occurs only in day time
Answer : A

Question. If we take sea water in plate and allow it to stand in sunlight till whole of the water disappears, we find that
(a) nothing is left in the plate
(b) some solid is left behind
(c) some liquid is left behind
(d) None of the above is correct
Answer : B

Passage-3

Only a small fraction of water available on the earth is fit for use of plants, animals and humans. The total amount of water on earth remains the same, but the water available for use is very limited and is decreasing with over usage.

Question. Why is the demand for water increasing day by day?
(a) The quantity of water used per person is increasing day by day
(b) The number of persons using water is increasing
(c) More and more water is being used by industries
(d) Only (b) and (c) are correct
Answer : D

Question. We have a lot of water in oceans, then how is it said that the amount of usable water is limited?
(a) Sea water is not fit for all our uses
(b) Sea water can not be used directly by us for drinking
(c) Sea water can not be used directly for plant production
(d) All of the above
Answer : D

Question. How is it that total amount of water on earth remains same though it is consumed by us for various activities on a large scale?
(a) Because of water cycle
(b) Because of transpiration
(c) Because of condensation
(d) Because of water harvesting
Answer : A

Assertion/ Reason Based Questions

DIRECTIONS : The questions in this segment consists of two statements, one labelled as “assertion A” and the other labelled as “reason R”. You are to examine these two statements carefully and decide if the assertion A and reason R are individually true and if so, whether the reason is a correct explanation of the assertion. Select your answers to these items using codes given below.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

Question. Assertion (A) : The sea water is saline.
Reason (R) : The sea water contains many dissolved salts.
Answer : A

Question. Assertion (A) : Role of oceans in supplying usable water is quite important.
Reason (R) : When the sea water reaches us, in various other forms of sources of water, it is no more saline.
Answer : B

Question. Assertion (A) : Sea water changes to water vapours by the process of transpiration in the presence of sunlight.
Reason (R) : When sea water changes into water vapour it leaves the dissolved salts behind.
Answer : D

Question. Assertion (A) : In such areas where there is no vegetation the rain water flows quickly and has no effect on the top layer of soil of that area.
Reason (R) : When water level rises in rivers, ponds etc. Due to excessive rains it causes floods.
Answer : D

Question. Assertion (A) : During drought there is a shortage of food and fodder.
Reason (R) : Droughts result in conservation of water.
Answer : C

Question. Assertion A : Level of ground water below the surface of Earth at a given place is known as water table.
Reason R : Excess use of groundwater in cities is resulting in lowering of water table.
Answer : B

Figure Based Questions

Question. Identify the process represented by the part ‘A’ of the diagram.

(a) Evaporation
(b) Transpiration
(c) Condensation
(d) None of these
Answer : C

Water

I. Fill in the blanks:

Question 1. The process by which plants evaporate water is called _________________.
Answer: transpiration
In simple words: Plants release excess water as water vapor through tiny pores in their leaves called stomata.

Exam Tip: Remember that transpiration is specific to plants, whereas evaporation is a general process.

Question 2. The major natural source of water is _________________.
Answer: oceans (or rain/precipitation)
In simple words: Oceans cover most of the earth and hold the largest amount of water.

Exam Tip: Oceans contain saline water, while precipitation is the source of fresh water.

Question 3. Water vapour gets added to the atmosphere by _________________ and ___________________.
Answer: evaporation, transpiration
In simple words: Water enters the air from water bodies through evaporation and from plants through transpiration.

Exam Tip: Both processes together contribute to atmospheric moisture and the water cycle.

Question 4. Water disappears from wet clothes by the process of ___________________.
Answer: evaporation
In simple words: Liquid water turns into invisible water vapor and mixes with the air when clothes dry.

Exam Tip: Evaporation happens at temperatures below the boiling point of water.

Question 5. The source of water below the ground such as wells, tubewells, lakes etc. is known as _______.
Answer: groundwater
In simple words: Rainwater that seeps deep into the earth gets collected underground.

Exam Tip: Groundwater is a major source of drinking water.

Question 6. In winter mornings , __________is formed due to condensation of water vapour near the ground.
Answer: fog
In simple words: Tiny water droplets hang close to the ground on cold winter mornings when water vapor cools down.

Exam Tip: Do not confuse fog with dew; fog floats in the air near the ground.

Question 7. Many tiny water droplets high up in the air, come together and fall down as _____________,
Answer: rain (or precipitation)
In simple words: When cloud droplets grow too heavy to stay afloat, they fall down as rain.

Exam Tip: Precipitation includes rain, snow, hail, and sleet.

Question 8. The release of water vapour into air by the leaves of plants is called ___________________.
Answer: transpiration
In simple words: Plants continuously lose water vapor through tiny openings in their leaves.

Exam Tip: Transpiration helps cool the plant and pulls water up from roots.

Question 9. _______________________ are made of droplets of water, ice crystals, particles of dust and air.
Answer: Clouds
In simple words: Clouds are visible masses of condensed water vapor floating high in the atmosphere.

Exam Tip: Clouds form when warm air rises, cools, and water vapor condenses on dust particles.

Question 10. Any natural phenomenon which repeats itself after some time is said to constitute _________________________.
Answer: a water cycle (or periodic phenomenon)
In simple words: Events that occur in a regular repeating sequence are cyclic.

Exam Tip: The water cycle has no fixed beginning or end; it is continuous.

Question 11. Continued absence of rain causes _________________________.
Answer: drought
In simple words: A long period without rain leads to severe water shortage and dry soil.

Exam Tip: Drought affects crops, drinking water supply, and animal life.

Question 12. Drought and floods are called _________________________.
Answer: natural calamities (or natural disasters)
In simple words: Extreme natural events that cause widespread damage and suffering.

Exam Tip: Both excess water and lack of water cause extreme hardship.

II. Name the following:

Question 1. Two natural sources of water.
Answer: Oceans, rivers (or rain, lakes, springs)
In simple words: Sources of water provided by nature without human intervention.

Exam Tip: Mention oceans as the primary source and rivers or rain as fresh water sources.

Question 2. Two fresh water bodies.
Answer: Rivers, lakes (or ponds, glaciers)
In simple words: Natural water bodies containing water with very low salt content.

Exam Tip: Fresh water is essential for drinking and agriculture.

Question 3. Two rainwater harvesting techniques.
Answer: Rooftop rainwater harvesting, storage in underground tanks (or percolation pits)
In simple words: Methods used to collect and store rainwater for future use rather than letting it run off.

Exam Tip: Rooftop rainwater harvesting is the most common method in residential areas.

Question 4. Four uses of water at home.
Answer: Drinking, cooking, bathing, washing clothes
In simple words: Daily domestic activities that require clean water.

Exam Tip: Keep answers precise and direct.

Question 5. The two processes through which water vapour enters the air.
Answer: Evaporation and transpiration
In simple words: Water turns into vapor from land/water bodies and from plants.

Question 6. Two adverse effects of floods.
Answer: Destruction of crops, displacement of people and animals (or spread of waterborne diseases, damage to property)
In simple words: Floods submerge land and cause heavy loss of life and property.

Exam Tip: Floods occur due to excessive and continuous rainfall.

Question 7. Two adverse effects of drought.
Answer: Scarcity of drinking water, failure of crops leading to famine
In simple words: Lack of water causes soil to dry up and plants to wither.

Exam Tip: Drought severely impacts farmers and livestock.

Question 8. Two factors leading to shortage of usable water on the earth.
Answer: Increasing population, rapid industrialization and deforestation (or water pollution)
In simple words: Growing demand and misuse of water reduce available fresh water.

Exam Tip: Conservation is key to overcoming water shortages.

Question 9. The process by which water changes into water vapour on heating.
Answer: Evaporation (or vaporization)
In simple words: Heating turns liquid water into gas.

Exam Tip: Boiling is rapid evaporation at the boiling point.

Question 10. The process by which water vapour change into liquid water on cooling.
Answer: Condensation
In simple words: Cooling turns water vapor back into liquid droplets.

Exam Tip: Condensation is responsible for cloud formation and dew.

Question 11. The falling of drops of water from the clouds.
Answer: Precipitation (or rainfall)
In simple words: Water falling down from clouds onto the earth.

Exam Tip: Rain is the most common form of precipitation.

Question 12. The journey of water from the oceans to the atmosphere and back to the oceans again.
Answer: The water cycle (or hydrological cycle)
In simple words: Continuous circulation of water on Earth.

Question 13. Two methods of rainwater harvesting.
Answer: Rooftop rainwater harvesting, collecting rainwater in underground storage tanks
In simple words: Capturing rain where it falls for future use.

Exam Tip: Helps recharge groundwater tables.

III. Write true or false:

Question 1. Open wells are fed by ground water:
Answer: True
In simple words: Water seeps into the ground and fills up open wells.

Exam Tip: Groundwater feeds wells, borewells, and springs.

Question 2. Life is possible on earth without water:
Answer: False
In simple words: All living organisms need water to survive.

Exam Tip: Water is essential for all cellular and metabolic processes.

Question 3. Saline water is fit for drinking and other domestic, agricultural and industrial needs:
Answer: False
In simple words: Saline water contains high salt and cannot be used directly.

Exam Tip: Saline water requires desalination before use.

Question 4. Evaporation of water takes place at all times:
Answer: True
In simple words: Water evaporates from oceans, rivers, and soil continuously at all temperatures.

Question 5. Concrete land surfaces increases the seepage of rainwater into the ground:
Answer: False
In simple words: Concrete surfaces are impermeable and prevent water from seeping into the soil.

Exam Tip: Concrete roads decrease groundwater levels by preventing infiltration.

Question 6. About two-thirds of the earth is covered with water.
Answer: True
In simple words: Most of the Earth's surface is covered by oceans and seas.

Exam Tip: Out of this, only a very small fraction is usable fresh water.

Question 7. When water is heated, it changes into ice.
Answer: False
In simple words: Heating water changes it into water vapor, whereas cooling changes it into ice.

Exam Tip: Freezing occurs when water is cooled below zero degrees Celsius.

Question 8. The water cycle is powered by the heat of the sun and the force of gravity.
Answer: True
In simple words: Sunlight causes evaporation, and gravity pulls precipitation down to Earth.

Exam Tip: Solar energy and gravity are the two main driving forces of the water cycle.

Question 9. The main reason of precipitation is that clouds cool off.
Answer: True
In simple words: As warm moisture-laden air rises and cools, water droplets coalesce and fall as precipitation.

Exam Tip: Cooling is essential for condensation and droplet growth.

IV. Define the following:

Question 1. Water cycle
Answer: The continuous circulation of water from the Earth's surface to the atmosphere (through evaporation and transpiration) and back to the Earth (through precipitation and condensation) is called the water cycle.
In simple words: The endless recycling of water between land, air, and oceans.

Exam Tip: Mention the four main stages: evaporation, condensation, precipitation, and collection.

Question 2. Rainwater harvesting
Answer: The collection and storage of rainwater from rooftops or open spaces for future domestic or agricultural use, or for recharging groundwater, is known as rainwater harvesting.
In simple words: Saving rainwater instead of letting it wastefully flow away.

Exam Tip: Highlight both storage and groundwater recharge benefits.

Question 3. Precipitation
Answer: The process by which condensed water droplets in clouds become too heavy to remain suspended in the air and fall back to the earth in the form of rain, snow, hail, or sleet is called precipitation.
In simple words: Water falling from clouds to the ground.

Exam Tip: Rain is the most common form of precipitation.

V. Distinguish between: Evaporation and condensation.

Question 1. Evaporation and condensation
Answer:
- Evaporation: The process in which liquid water changes into water vapor on heating. It takes place at all temperatures.
- Condensation: The process in which water vapor changes into liquid water on cooling. It takes place when warm air comes in contact with cooler surfaces or layers.
In simple words: Evaporation turns water into gas, while condensation turns gas back into liquid.

Exam Tip: Use a comparative table format for clear distinction in exams.

VI. Draw, colour and label the water cycle.

Question 1. Draw, colour and label the water cycle.
Answer:
Steps to draw:
1. Draw oceans/water bodies at the bottom with arrows pointing upwards showing evaporation.
2. Draw mountains, trees with arrows showing transpiration.
3. Draw clouds in the sky.
4. Draw arrows pointing down from clouds showing rainfall (precipitation).
5. Label: Evaporation, Transpiration, Condensation (clouds), Precipitation (rain), and Groundwater collection.
In simple words: A diagram showing water rising into the sky as vapor, forming clouds, and falling back as rain.

Exam Tip: Always draw directional arrows to show the continuous circular path of water.

I. Fill in the blanks:

Question 1. Fish have ____________shaped body that help them to move inside water.
Answer: streamlined
In simple words: A pointed body shape reduces water resistance during swimming.
Exam Tip: Streamlined shape helps both fish and birds move smoothly through water and air.

Question 2. Small changes that take place in the body of a living organism over a short period to overcome to some problems due to changes in the surrounding are called ________________.
Answer: acclimatization
In simple words: Short-term adjustment to sudden environmental changes like high altitude.

Exam Tip: Do not confuse acclimatization with long-term evolutionary adaptation.

Question 3. In the mountain regions, the trees are normally ______________ shaped.
Answer: cone (or pyramidal)
In simple words: Cone-shaped trees allow snow and rain to slide off easily.

Exam Tip: Coniferous trees are common in high-altitude mountain ranges.

Question 4. The process of producing more of their own kind by the living organisms is called ________________.
Answer: reproduction
In simple words: Producing offspring to ensure the survival of a species.

Exam Tip: Reproduction can be sexual or asexual.

Question 5. Frogs have ____________feet that help them to swim in water.
Answer: webbed
In simple words: Skin between toes helps push against water while swimming.

Exam Tip: Webbed feet also help frogs leap on land.

Question 6. Dolphins and whales breathe through _______________.
Answer: blowholes
In simple words: Being mammals, they come to the water surface to breathe air through blowholes on their heads.

Exam Tip: Whales and dolphins do not have gills; they have lungs.

Question 7. The process of getting rid of wastes by the living organisms is called ________________.
Answer: excretion
In simple words: Removal of metabolic waste products from the body.

Exam Tip: Plants also excrete wastes in the form of gums, resins, and oxygen.

Question 8. The stems of aquatic plants are long, ______________ and _____________.
Answer: hollow, light (or flexible)
In simple words: Hollow stems help plants float and remain upright in water.

Question 9. During respiration, organisms take in _____________ and give out ___________.
Answer: oxygen, carbon dioxide
In simple words: Breathing in oxygen helps release energy from food, producing carbon dioxide.
Exam Tip: Respiration is vital for energy generation in all living beings.

Question 10. Exchange of gases in plants take place through the tiny pores on the leaves called ___________________.
Answer: stomata
In simple words: Microscopic openings on leaves that let gases enter and leave.
Exam Tip: Stomata are also responsible for transpiration.

Question 11. Organisms in oceans are surrounded by _______________ water.
Answer: saline (or salty)
In simple words: Ocean water contains high concentration of dissolved salts.
Exam Tip: Marine organisms are specially adapted to survive in saline environments.

Question 12. Gills help fishes to use ______________ dissolved in water.
Answer: oxygen
In simple words: Gills absorb oxygen mixed in water as it flows over them.
Exam Tip: Fish cannot breathe atmospheric air directly.

Question 13. Plants and animals living on land belong to ______________ habitat.
Answer: terrestrial
In simple words: Land-based environments like forests, deserts, and grasslands.

Exam Tip: Terrestrial habitats include deserts, mountains, and grasslands.

Question 14. Photosynthesis in desert plants is carried out by the _______________.
Answer: stem
In simple words: Since leaves are reduced to spines to prevent water loss, green stems make food.

Exam Tip: Cacti have fleshy green stems that store water and perform photosynthesis.

Question 15. Exchange of gases in plants takes place through ________________.
Answer: stomata (and lenticels)
In simple words: Pores on leaves and bark allow gas exchange.

Question 16. In mountain regions trees are normally ______________ shaped and have ______________ branches.
Answer: cone, sloping (or needle-like leaves)
In simple words: Cone shape and sloping branches prevent snow accumulation.
Exam Tip: Pine and fir are common mountain trees.

Question 17. Changes in our surroundings that make us respond are called _______________.
Answer: stimuli
In simple words: External triggers like heat, light, or touch that prompt a reaction.

Exam Tip: Response to stimuli is a fundamental characteristic of living things.

Question 18. Animals like rats and snake live in ______________ during day to stay away from heat.
Answer: burrows
In simple words: Deep underground holes remain cool during hot daytime hours in deserts.

Exam Tip: Desert animals are often nocturnal to escape the extreme heat.

Question 19. Breathing is a part of the process of ______________.
Answer: respiration
In simple words: Inhaling oxygen and exhaling carbon dioxide is part of cellular respiration.

Question 20. ________________ protect the fishes and help in easy movement through water.
Answer: Scales
In simple words: Slippery overlapping plates cover a fish's body for protection and smooth swimming.
Exam Tip: Scales also prevent water entry into the fish body.

II. Write true or false:

Question 1. Several kinds of plants and animals share the same habitat:
Answer: True
In simple words: A single habitat supports many different species of plants and animals.

Exam Tip: Biodiversity refers to the variety of life in a habitat.

Question 2. The light brown skin of the lion helps it to become a predator in the grassland:
Answer: True
In simple words: Light brown color helps lions camouflage in dry grassland to hunt prey.

Exam Tip: Camouflage helps predators hunt and prey hide.

Question 3. Desert animals like snakes and rats come during the day:
Answer: False
In simple words: Desert animals usually stay in burrows during the day and come out at night when it is cool.

Exam Tip: They are nocturnal to avoid daytime desert heat.

Question 4. The animals which cannot adapt to changing abiotic factors of a region die out and only adapted ones survive:
Answer: True
In simple words: Organisms must adapt to environmental changes to survive.

Exam Tip: This principle is the basis of natural selection.

Question 5. Animals living in mountain regions have thick skin or fur:
Answer: True
In simple words: Thick fur protects mountain animals like yaks and snow leopards from freezing cold.

Exam Tip: Thick coats insulate against low temperatures.

Question 6. Plants donot show respond to stimuli:
Answer: False
In simple words: Plants do respond to stimuli like light (phototropism) and touch (touch-me-not plant).

Exam Tip: Roots grow towards water and gravity, while shoots grow towards light.

Question 7. Some plants remove some of their waste products as secretions :
Answer: True
In simple words: Plants release waste materials as gums, resins, and latex.

Question 8. Camels excrete large amount of urine and their dung is wet:
Answer: False
In simple words: Camels excrete very little concentrated urine and dry dung to conserve water.
Exam Tip: Desert animals have special physiological adaptations to conserve water.

Question 9. Plants carry out photosynthesis only during the daytime and respiration only at night:
Answer: False
In simple words: Photosynthesis occurs only in daytime (in sunlight), but respiration happens day and night.

Exam Tip: Respiration is a 24-hour continuous process in all living organisms.

Question 10. Animals and plants are abiotic factors.
Answer: False
In simple words: Animals and plants are living components, which make them biotic factors.

Exam Tip: Biotic means living; abiotic means non-living.

Question 11. Dolphins and whales do not have gills.
Answer: True
In simple words: They are marine mammals and breathe air through lungs using blowholes.
Exam Tip: Whales must surface regularly to breathe atmospheric air.

Question 12. Skin of fishes is covered with scales.
Answer: True
In simple words: Scales protect the fish body and reduce friction in water.

Exam Tip: Most bony fish have protective overlapping scales.

Question 13. Leaf like structure in cactus is its stem.
Answer: True
In simple words: The green fleshy part of a cactus that looks like a leaf is actually its modified stem.

Question 14. Yak is adapted to mountain habitat.
Answer: True
In simple words: Yaks have thick long hair to keep warm in cold mountain regions.
Exam Tip: Yaks are common pack animals in high-altitude Himalayas.

III. Give answer in one or two words:

Question 1. Give 2 examples of aquatic habitat.
Answer: Oceans, ponds
In simple words: Water-based environments where aquatic plants and animals live.
Exam Tip: Aquatic habitats can be fresh water or marine.

Question 2. Give 2 examples of terrestrial habitat.
Answer: Forests, deserts
In simple words: Land-based environments.
Exam Tip: Terrestrial habitats include grasslands, deserts, and mountains.

Question 3. Give 2 examples of aquatic plants.
Answer: Hydrilla, lotus
In simple words: Plants that grow fully or partially submerged in water.

Exam Tip: Aquatic plants have special adaptations like hollow stems.

Question 4. Name two animals found on mountains.
Answer: Yak, snow leopard (or mountain goat)
In simple words: Animals adapted to cold and rocky mountain terrain.

Exam Tip: Mountain animals possess thick fur and strong hooves.

Question 5. Two plants of mountain regions
Answer: Pine, fir
In simple words: Coniferous trees found in cold mountain areas.

Exam Tip: They have needle-like leaves and conical shapes.

Question 6. Four important abiotic factors needed for growth of plants
Answer: Sunlight, water, soil, air (temperature)
In simple words: Non-living environmental factors essential for plant life.

Exam Tip: Plants need light and water for photosynthesis.

Question 7. Breathing organs of fish and earthworms.
Answer: Gills (for fish), moist skin (for earthworms)
In simple words: Different animals have different organs to take in oxygen.
Exam Tip: Earthworms breathe through their wet skin directly.

Question 8. Any three modes of reproduction by plants.
Answer: Seeds, stems (vegetative propagation), spores
In simple words: Different ways plants produce new plants.

Exam Tip: Flowering plants mostly reproduce through seeds.

IV. Define the following:

Question 1. Adaptation
Answer: The presence of specific body features or habits that enable a plant or animal to live in a particular surrounding or habitat is called adaptation.
In simple words: Special features that help an organism survive in its environment.

Exam Tip: Adaptations develop over long periods of time.

Question 2. Stimuli
Answer: Changes in our environment or surroundings that make living organisms respond or react are called stimuli.
In simple words: Environmental triggers that cause a reaction.

Exam Tip: Examples include light, heat, cold, and touch.

V. Write four adaptations in each of the following:

Question 1. Deserts
Answer:
1. Animals have thick skin or live in burrows to escape heat.
2. Plants have leaves reduced to spines to prevent water loss.
3. Stems are fleshy and modified to store water and make food.
4. Animals like camels excrete concentrated urine and dry dung to conserve water.
In simple words: Adaptations to survive with very little water and extreme heat.
Exam Tip: Focus on water conservation and heat tolerance.

Question 2. Mountain regions
Answer:
1. Trees are cone-shaped with sloping branches.
2. Leaves are needle-like to prevent snow accumulation.
3. Animals possess thick fur or wool for warmth.
4. Animals have strong hooves for running on rocky slopes.
In simple words: Adaptations to withstand extreme cold, snow, and steep slopes.

Exam Tip: Highlight conical shape of trees and thick fur of animals.

Question 3. Grasslands
Answer:
1. Predators have light brown skin for camouflage in dry grass.
2. Predators have sharp teeth and claws for hunting.
3. Prey animals have strong teeth for chewing grass.
4. Prey animals like deer have eyes on the sides of the head to look for danger in all directions.
In simple words: Adaptations for hunting and escaping in open grassy plains.

Exam Tip: Contrast predator adaptations with prey adaptations.

Question 4. Ponds/lakes
Answer:
1. Aquatic plants have long, hollow, and flexible stems.
2. Leaves float on water surfaces with waxy coatings to prevent rotting.
3. Animals like fish have streamlined bodies for easy swimming.
4. Fish possess gills to utilize oxygen dissolved in water.
In simple words: Features that help plants and animals live successfully in water.

Exam Tip: Mention streamlined body and gills for animals, hollow stems for plants.

Question 5. Camel
Answer:
1. Long legs keep the body away from the hot desert sand.
2. Stores fat in its hump as a food reserve.
3. Excretes little urine and dry dung to save water.
4. Has broad, padded feet that do not sink in loose sand.
In simple words: Special features that make camels the ship of the desert.

Exam Tip: Do not say camels store water in humps; they store fat.

Question 6. Cacti
Answer:
1. Leaves are modified into sharp spines to reduce water loss.
2. Thick fleshy stem stores water.
3. Stem is green and carries out photosynthesis.
4. Roots go very deep into the soil in search of water.
In simple words: Plant adaptations for dry desert survival.

Exam Tip: Spines protect cacti from grazing animals as well.

Question 7. Polar/ Tundra region
Answer:
1. Animals have thick layers of fat (blubber) under the skin.
2. Dense fur coats protect against freezing temperatures.
3. White fur provides camouflage in snow.
4. Animals often huddle together or hibernate during severe cold.
In simple words: Extreme cold-weather survival adaptations.

Exam Tip: Mention polar bears and penguins as classic examples.

VI. Distinguish between:

Question 1. Biotic and abiotic factors.
Answer:
- Biotic factors: The living components of an environment, such as plants, animals, and microorganisms.
- Abiotic factors: The non-living components of an environment, such as sunlight, temperature, water, air, and soil.
In simple words: Biotic means living things, while abiotic means non-living things.

Exam Tip: Both biotic and abiotic factors together make up an ecosystem.

Question 2. Terrestrial organisms and aquatic organisms.
Answer:
- Terrestrial organisms: Animals and plants that live and reproduce on land (e.g., humans, lions, mango trees).
- Aquatic organisms: Animals and plants that live and reproduce in water (e.g., fish, whales, lotus, hydrilla).
In simple words: Land-living organisms versus water-living organisms.

Question 1. The electric energy which is supplied in our home comes from electric ____________________houses.
Answer: generating (or power)
In simple words: Electricity for homes is produced in power stations and supplied through wires.
Exam Tip: Power grids distribute electricity to homes and industries.

Question 2. Diesel __________ is generally used in big factories or at public functions as a standby.
Answer: generator
In simple words: Diesel generators produce backup electricity during power cuts.

Question 3. The battery ____________________ is uses at homes, offices and hospitals.
Answer: inverter (or UPS / dry cell)
In simple words: Inverters store electrical energy in batteries to supply power during power outages.
Exam Tip: Batteries provide direct current (DC).

Question 4. The tiny coiled wire which is supported by two thick wire inside the bulb is called -______
Answer: filament
In simple words: The thin wire inside a bulb that glows white-hot when current passes through it.

Exam Tip: Filaments are made of tungsten metal.

Question 5. Electric cell is a device which converts energy of chemicals ___________________energy.
Answer: into electrical
In simple words: Chemical reactions inside a cell produce electrical energy.

Exam Tip: Electric cells are portable sources of electricity.

Question 6. An electric ______________ is a continuous path along which the current flows.
Answer: circuit
In simple words: A complete unbroken loop through which electricity travels.

Exam Tip: Current flows only in a closed circuit.

Question 7. A circuit in which electricity does not flow is called an ______________ circuit.
Answer: open (or incomplete)
In simple words: A broken path where electricity cannot flow.

Exam Tip: When a switch is OFF, the circuit is open.

Question 8. The source of electricity in an electric cell are the ______________ stored in it.
Answer: chemicals
In simple words: Chemicals react inside the cell to generate electric current.

Exam Tip: When chemicals are exhausted, the cell stops working.

Question 9. Rubber is a good example of electric ______________.
Answer: insulator
In simple words: Materials that do not allow electric current to pass through them.

Exam Tip: Insulators protect us from electric shocks.

Question 10. A device that is used to break of complete an electric circuit is called ______________.
Answer: switch
In simple words: A simple ON/OFF device for controlling electric current.

Exam Tip: Switches make or break electric circuits safely.

Question 11. An electric cell has ______________ terminals.
Answer: two (positive and negative)
In simple words: Every cell has a positive terminal (+ sign) and a negative terminal (- sign).

Exam Tip: The metal cap is positive, and the metal base/plate is negative.

Question 12. If the filament of a bulb breaks, it is said to be ______________.
Answer: fused
In simple words: A damaged bulb that will not glow because the circuit is broken.

Exam Tip: A fused bulb has a broken filament.

Question 13. An electric current is ______________ when no current flows through it.
Answer: stopped (or absent / open circuit)
In simple words: No electricity flows when the circuit is incomplete.

Exam Tip: Current requires a complete conducting path.

Question 14. Electric current flows from ______________ terminal to ____________ terminal of cell in the circuit.
Answer: positive (+), negative (-)
In simple words: Conventional current flows from the positive terminal to the negative terminal of a cell.

Question 1. A combination of two or more cells
Answer: Battery
In simple words: Joining multiple cells together creates a battery.
Exam Tip: In a battery, the positive terminal of one cell is connected to the negative terminal of the next.

Question 2. An electric device which converts electric energy into light energy
Answer: Electric bulb (or LED / tube light)
In simple words: A device that lights up when electricity passes through it.

Exam Tip: Converts electrical energy into light and heat energy.

Question 3. An electric circuit in which path of electricity is broken at some point is called
Answer: Open circuit (or incomplete circuit)
In simple words: A circuit with a gap where current cannot flow.

Exam Tip: Appliances do not work in an open circuit.

Question 4. The source of electricity
Answer: Electric cell (or generator, power plant)
In simple words: Anything that provides electric current.

Exam Tip: Cells and generators are common sources.

Question 5. Thin wire in a bulb which gives out light
Answer: Filament
In simple words: The glowing wire inside a bulb.

Exam Tip: Made of tungsten.

Question 6. The arrangement of providing a complete path for electricity to pass between two terminals of the electric cell
Answer: Closed circuit
In simple words: A complete unbroken loop for electric current.
Exam Tip: Essential for electrical devices to function.

Question 7. Some times electric bulb does not glow even when electric switch is „ON‟ then we say that bulb is
Answer: Fused
In simple words: The bulb has a broken filament and will not glow.

Exam Tip: Check if the filament is broken inside the glass.

Question 8. An electric appliance which makes or breaks an electric circuit .
Answer: Electric switch
In simple words: Used to turn appliances ON or OFF.
Exam Tip: A switch bridges or creates a gap in the circuit.

III. Mark True (T) or False (F) for following statements :

Question a. Electric current can flow through metals.
Answer: True (T)
In simple words: Metals like copper, iron, and aluminum are good conductors of electricity.

Exam Tip: All metals conduct electricity well.

Question b. Instead of metal wires, a jute string can be used to make a circuit.
Answer: False (F)
In simple words: Jute is an insulator and does not conduct electricity.

Exam Tip: Only conductors can be used as wires in a circuit.

Question c. Electric current can pass through a sheet of thermocol.
Answer: False (F)
In simple words: Thermocol is an insulator.

Exam Tip: Insulators stop the flow of current.

Question d. When current flows through a circuit, the circuit is called open circuit.
Answer: False (F)
In simple words: When current flows, the circuit is closed, not open.

Question e. Electric current can easily flow through Copper.
Answer: True (T)
In simple words: Copper is an excellent conductor of electricity and is used to make wires.
Exam Tip: Copper wires are standard in electrical wiring.

Question f. When an electric circuit is closed, the electric current stops flowing through it.
Answer: False (F)
In simple words: Current flows continuously when a circuit is closed.
Exam Tip: Closed means complete path; current flows freely.

IV. Choose the correct answer :

Question 1. An electric bulb has ( two / one ) terminals.
(a) One
(b) Two
Answer: (b) Two
In simple words: A bulb has two terminals at the base to connect to a circuit.

Exam Tip: One terminal is at the metal tip and the other at the metal casing.

Question 2. The base of an electric cell is its ( negative / positive ) terminals.
(a) Positive
(b) Negative
Answer: (b) Negative
In simple words: The metal disc at the bottom of a cell acts as the negative terminal.

Exam Tip: The raised metal cap is the positive terminal.

Question 3. All metals are ( conductors / Insulators ) of electricity
(a) Conductors
(b) Insulators
Answer: (a) Conductors
In simple words: Metals allow electrical current to pass through them easily.

Exam Tip: Metals are good conductors due to free electrons.

Question 4. Choose a good conductor from the following materials.
(a) Pencil lead
(b) Thermocol
(c) Wooden block
(d) Rubber band
Answer: (a) Pencil lead
In simple words: Pencil lead is made of graphite, which conducts electricity.

Exam Tip: Graphite is a non-metal that conducts electricity.

Question 5. Which of the following is not a good conductor of electricity.
(a) Mercury
(b) Copper
(c) Plastic
(d) Aluminum foil
Answer: (c) Plastic
In simple words: Plastic is an insulator and does not conduct electricity.

Exam Tip: Plastics are used to cover electrical wires for safety.

Question 6. Switch is „OFF‟ when
(a) circuit is complete
(b) Circuit is not complete
(c) Current is flowing in the circuit
(d) Cell is fully charged
Answer: (b) Circuit is not complete
In simple words: An OFF switch creates a break in the circuit stopping current flow.

Exam Tip: OFF means open circuit.

V. Distinguish between :

Question 1. Conductors and Insulators
Answer:
- Conductors: Materials that allow electric current to pass through them easily (e.g., metals, graphite, tap water).
- Insulators: Materials that do not allow electric current to pass through them (e.g., plastic, rubber, wood, thermocol).
In simple words: Conductors let electricity flow; insulators block it.

Exam Tip: Insulators protect us from electric shocks while handling wires.

VI. Name the five transformations of electric energy

Question 1. Name the five transformations of electric energy
Answer:
1. Electrical energy to Light energy (e.g., Electric bulb)
2. Electrical energy to Heat energy (e.g., Electric heater, iron)
3. Electrical energy to Mechanical energy (e.g., Electric motor, fan)
4. Electrical energy to Sound energy (e.g., Electric bell, buzzer)
5. Electrical energy to Chemical energy (e.g., Charging a battery/cell)
In simple words: Electricity can be converted into light, heat, motion, sound, and chemical energy.
Exam Tip: Give practical household examples for each transformation.

VI. Draw an electric circuit & label various symbols used in it.

Question 1. Draw an electric circuit & label various symbols used in it.
Answer:
Steps to draw:
1. Draw a rectangular loop representing connecting wires.
2. Insert a cell symbol (long thin line for positive, short thick line for negative terminal).
3. Insert a switch symbol (open or closed).
4. Insert a bulb symbol (circle with a cross or filament loop inside).
5. Label each symbol clearly.
In simple words: A diagram showing electrical components connected in a loop using standard symbols.
Exam Tip: Always practice standard circuit symbols as they carry direct marks.