HOTS Questions: Water-The Essence of Life | Our Wondrous World Class 5 - New NCERT PDF Download

Q1: If the water cycle suddenly stopped due to a lack of solar heat, what would be the most immediate impact on Earth's freshwater availability?
(a) Ice caps would melt, increasing surface water
(b) Groundwater would recharge faster without evaporation
(c) Oceans would expand, providing more freshwater
(d) Rivers and lakes would dry up as no rain would replenish them
Ans: (d)
Explanation: The water cycle needs the sun's heat to make water evaporate and turn into rain.
If it stops, no more rain falls to fill up rivers and lakes, so they would dry up quickly because nothing replenishes them.
That's why the most immediate impact would be rivers and lakes drying up as no rain replenishes them.

Q2: In a scenario where urban areas replace natural soil with concrete, how would this primarily affect groundwater recharge compared to rural forested areas?
(a) It would increase recharge due to faster water flow
(b) It would improve water quality by filtering pollutants
(c) It would decrease recharge as water cannot seep into the soil
(d) It would have no effect since groundwater comes from rivers
Ans: (c)
Explanation: Concrete in cities covers the ground like a hard blanket, so rain can't soak into the soil to reach underground water.
In forests, soil lets water seep down slowly to recharge groundwater, but cities make water run off fast into drains instead. 
Urban areas with concrete would have decreased groundwater recharge compared to rural forested areas.

Q3: Why might aquatic plants like lotus have waxy leaves, and how does this adaptation benefit them in a flooded environment?
(a) To store extra nutrients from the water
(b) To prevent excess water absorption and damage
(c) To increase buoyancy for floating higher
(d) To attract more insects for pollination
Ans: (b)
Explanation: Lotus plants live in watery places that can flood a lot, and their leaves have a waxy coating like a raincoat.
This stops too much water from getting in and hurting the plant, keeping the leaves dry and healthy on top.
Without it, the leaves might rot or get damaged easily, so the waxy leaves prevent excess water absorption and damage in a flooded environment.

Q4: If global warming causes more ice to melt into oceans, how would this indirectly affect freshwater availability for human use?
(a) It would have no impact since ice is not freshwater
(b) It would improve groundwater recharge worldwide
(c) It would decrease freshwater by raising sea levels and salinising coastal aquifers
(d) It would increase freshwater as the oceans desalinate
Ans: (c)
Explanation: Global warming melts ice from the poles into the oceans.
This makes sea levels rise and pushes salty water onto land.
It hurts our freshwater supply without adding more usable water, so this indirectly decreases freshwater availability by raising sea levels and salinising coastal aquifers.

Q5: Evaluate why groundwater is often more reliable than surface water in drought-prone areas, considering the water cycle.
(a) It evaporates more slowly due to being underground
(b) It flows faster, replenishing rivers quickly
(c) It is stored deep and is less affected by short-term weather changes
(d) It is saltwater, making it abundant
Ans: (c)
Explanation: Groundwater is like hidden water stored deep in the earth, and it doesn't dry up fast during short droughts.
Surface water in rivers can evaporate or stop flowing quickly, but groundwater stays put and is safer from quick weather changes.
That's why it's more reliable than surface water in drought-prone areas, as it's stored deep and less affected by short-term weather changes in the water cycle.

Q6: In a city with heavy concretisation, propose a solution to improve groundwater recharge and explain its mechanism.
(a) Create permeable pavements that allow water infiltration
(b) Increase air conditioning to cool the atmosphere
(c) Divert rivers to urban areas
(d) Build more dams to store surface water
Ans: (a)
Explanation: Cities with lots of concrete don't let rain soak into the ground, but permeable pavements are like special roads with tiny holes.
They let water seep through slowly into the soil below, helping refill the underground water instead of it running away.
It's a smart way to save more fresh water for everyone, which is why creating permeable pavements would improve groundwater recharge by allowing water infiltration.

Q7: Why do animals like the fishing cat have webbed paws, and how does this relate to their survival in freshwater habitats?
(a) To fly short distances over water
(b) To climb trees to escape predators
(c) To swim efficiently and catch prey in water
(d) To dig burrows in dry land
Ans: (c)
Explanation: Fishing cats live near rivers and wetlands full of water, and their webbed paws are like built-in flippers for swimming.
This helps them move fast in water to catch fish and frogs, and without it, hunting for food would be much harder.
Webbed paws help them swim efficiently and catch prey in freshwater habitats.

Q8: If deforestation occurs upstream of a river, analyse the potential long-term effects on downstream freshwater ecosystems.
(a) Higher groundwater levels from exposed soil
(b) Soil erosion leading to sedimentation and habitat loss
(c) Cleaner water from reduced plant debris
(d) Increased fish populations due to warmer water
Ans: (b) 
Explanation: Deforestation means cutting down trees upstream by a river, and without trees, soil washes away easily into the water.
This mud clogs the river, making it dirty and shallow, so fish and plants downstream lose their homes and can't survive.
This leads to soil erosion, sedimentation, and habitat loss in downstream freshwater ecosystems.

Q9: Compare the adaptability of free-floating plants like water hyacinth to rooted plants like lotus in changing water levels.
(a) Rooted plants spread faster in floods
(b) Free-floating plants are less adaptable as they sink
(c) Both are equally affected by droughts
(d) Free-floating plants can move with water, while rooted ones are fixed
Ans: (d)
Explanation: Water hyacinth floats freely on top of the water, so it can drift with rising or falling water levels easily.
Lotus plants have roots stuck in the mud at the bottom, so they stay in one spot and might dry out if the water drops.
Free-floaters adapt better to changes without getting stuck, which is why free-floating plants like water hyacinth can move with water, while rooted ones like lotus are fixed.

Q10: Propose why conserving wetlands is crucial for maintaining the water cycle's balance.
(a) They increase flooding in urban areas
(b) They prevent evaporation entirely
(c) They act as natural filters and recharge groundwater
(d) They store excess saltwater
Ans: (c)
Explanation: Wetlands are like squishy, wet lands with plants and ponds, and they clean dirty water by trapping bad stuff like a sponge.
Saving them helps us have clean water for a long time, which is why conserving wetlands is crucial, as they act as natural filters and recharge groundwater.

Q11: If plastic pollution increases in rivers, evaluate its impact on aquatic food chains.
(a) It disrupts chains as animals ingest plastics, leading to starvation
(b) It does not affect non-marine species
(c) It purifies water by absorbing toxins
(d) It provides new habitats for fish
Ans: (a)
Explanation: Plastic trash in rivers doesn't break down and floats around, so animals like fish mistake it for food and eat it.
This fills their tummies with junk, so they can't eat real food, and they get sick or starve, hurting the whole food chain.
This disrupts the chains as animals ingest plastics, leading to starvation.

Q12: Why might cities face more water scarcity than rural areas, linked to the water cycle?
(a) Cities use less water per person
(b) Rural evaporation is higher
(c) Urban concretisation reduces infiltration and recharge
(d) Rural areas have more oceans
Ans: (c)
Explanation: Cities have lots of concrete covering the ground, so rain can't soak in to refill underground water, and it runs off fast, wasting the chance for storage.
Rural areas have soil that lets water seep down slowly, making cities run out of water quickly during dry times.
That's why cities face more water scarcity, linked to urban concretisation, reducing infiltration and recharge in the water cycle.

Q13: Analyse how the water cycle influences seasonal changes in freshwater availability.
(a) It stops during monsoons
(b) Evaporation and precipitation vary, affecting river flows
(c) It causes permanent droughts in winter
(d) It increases salinity in lakes
Ans: (b)
Explanation: The water cycle changes with seasons, like more rain in some months, and in summer, more sun makes water evaporate faster from rivers.
In rainy seasons, more precipitation fills them up again.
It keeps rivers flowing differently throughout the year, so evaporation and precipitation vary, affecting river flows and seasonal freshwater availability.

Q14: If groundwater extraction exceeds recharge rates, predict the consequences for local ecosystems.
(a) Drying of wells, rivers, and loss of habitats
(b) Enhanced soil fertility
(c) Increased biodiversity from new wells
(d) Cooler temperatures from exposed aquifers
Ans: (a)
Explanation: Pulling out too much groundwater is like emptying a hidden tank fast, and if it doesn't refill enough, wells and springs dry up.
Rivers and lakes lose water, hurting plants and animals, so habitats vanish, and creatures have nowhere to live.
The whole area gets drier and less lively over time, leading to drying of wells, rivers, and loss of habitats.

Q15: Design a community initiative to promote water conservation, explaining its expected impact on the water cycle.
(a) Increasing plastic use for storage
(b) Building more concrete dams
(c) Rainwater harvesting to boost local recharge
(d) Diverting rivers to deserts
Ans: (c)
Explanation: Rainwater harvesting means collecting rain in tanks or pits, and people can do it at home or in neighbourhoods together.
It lets water soak into the ground to refill underground stores, helping the water cycle by saving water for dry days.
Less waste means more fresh water for everyone long-term, which boosts local recharge through this community initiative.