NCERT Solutions for Class 5th The World Around Us Chapter 3 Closing questions — Let us reflect

Book page 53–54 Updated on2026-09-19

Q1.

1. Why do some food items last for weeks and others spoil in just a few days?

Answer

Because microbes can grow easily on some foods and not on others. A food spoils fast if it has plenty of moisture, is open to the air and is kept warm. A food lasts for weeks if it is dry, salty, sugary, oily, sealed or cold — because then the microbes cannot get what they need.

Food	How long it lasts	Why
Milk, cooked rice, cut fruit	Less than a day in summer	Full of moisture, kept warm, open to air
Bread, uttapam in a tiffin box	Two to three days	Soft and moist; warmth and air do the rest
Papad, chilli powder, badi	Many months	Sun-dried — almost no moisture left
Pickle	Months, even a year	Salt removes water; a layer of oil keeps out air
Ghee	Many months at room temperature	All the water was evaporated while making it
Canned juice, sealed packets	Months	Airtight — no air, so no microbes
Food in a fridge	Several days to weeks	Too cold for microbes to grow quickly

Moisture + air + warmth = microbes grow = food spoils fast
Remove any one of them = food lasts long

The whole chapter in one idea: Nothing spoils by itself. Microbes spoil it. So how long a food lasts depends on one simple question — can microbes grow on it or not?

Q2.

2. You are going on a field trip for two days. List five food items you will carry. How will you keep them from getting spoiled?

Answer

Choose food that is dry, cooked without much water, whole, or sealed. Leave behind anything with gravy, curd or a lot of water in it — those spoil within hours.

#	Food item I will carry	Why it is safe for two days	How I will pack it
1	Theplas or khakhras (or dry parathas)	Made with very little water and roasted well, so they stay dry	Wrapped in butter paper inside an airtight box
2	Roasted chana and peanuts	Completely dry — microbes cannot grow	In a tight-lidded steel dabba or a sealed pouch
3	Chikki, or a jaggery-and-sesame ladoo	Made with jaggery; sugar keeps microbes away	Wrapped separately so it does not stick
4	Whole fruits — bananas, oranges, apples	The peel is a natural cover; nothing is cut open	Kept whole, never cut in advance; carried in a cloth bag
5	A sealed packet of biscuits or dry poha chivda	Airtight packing keeps out air and moisture	Opened only when it is to be eaten

How I will keep them from spoiling:

Pack everything in clean, dry, airtight boxes. Even one drop of water can start mould.
Keep the bag out of direct sunlight and away from the hot part of the bus.
Carry no curd, no gravy, no cut fruit, no cooked rice — these spoil in a few hours.
Wash my hands before eating, and take food out with a dry spoon or clean hands.
Close every box tightly again after eating from it.
Carry drinking water in my own bottle, boiled or filtered at home.
Eat the softer items first — fruit on day one, dry snacks on day two.
If anything smells odd or looks changed, do not eat it. Throw it away in a dustbin.

Why these choices work: Every item on the list is dry, sealed or protected by its own peel. That takes away moisture and air — two of the three things microbes need. The third, warmth, is taken care of by keeping the bag in the shade.

If your family eats non-vegetarian food and you want to carry some, choose something dry and well-cooked, such as dry-roasted fish or a dry chicken sukka packed in an airtight box, and eat it on the first day itself. Anything with gravy should be left at home.

Q3.

3. What if food cannot be preserved? Imagine a world without food preservation and discuss the consequences.

Answer

A world without food preservation would be a world of daily shortage and enormous waste. Everything would have to be eaten within hours of being grown or cooked, and whatever was left would have to be thrown away.

Where it would show	What would happen	Why
At home	Food would have to be bought and cooked fresh two or three times a day	Nothing could be stored, not even for the evening
Waste	A huge amount of food would be thrown away every day	Whatever is not eaten at once would spoil
Taste and variety	No pickle, papad, jam, murabba, chilli powder, ghee, dried fish or aam papad	All of these are preserved foods
Seasons	Mango only for two months a year; no amla in summer, no peas in June	Nothing could be saved for the rest of the year
Farmers	They would have to sell the whole harvest within days, at any price they were offered	Grain, pulses and chillies are all stored after drying
Travel	No food for a train journey, a pilgrimage, a school trip, a soldier's post or a ship	Nothing would survive the journey
Places far from farms	Cities, deserts, high mountains and islands would struggle for food	Food would spoil on the way there
Hard times	A flood, a drought or a long winter would quickly become a famine	There would be no stored grain to fall back on
Health	More people would fall ill from eating food that had begun to spoil	Fresh food is not always available when hunger is
Price	Food would become dearer and less certain	Nothing could be kept back for the days when there is less

Sample answer for the discussion: “Without preservation we could not keep food even for one day. Every meal would have to be cooked and eaten at once, and the rest thrown away. There would be no pickle, no papad, no chilli powder, no ghee. Farmers would have to sell everything the day they harvested it. We could not carry food on a journey, and a single bad season would leave people hungry. Preserving food is really a way of saving today's food for tomorrow's need.”

Why preservation is not a modern idea: People worked this out long before anyone knew what a microbe was. Drying, salting, pickling and storing in oil are hundreds of years old, and the Do you know? box in your book points out that insects such as solitary hunting wasps were preserving food for their larvae long before humans did.

Q4.

4. Match the following. Which method is used to preserve the following food items (A) to make the final product (B)? — Item (A): Roti, Papad, Mango, Lemon, Butter, Juice, Chillies, Fish. Products (B): Khakhra, Dried papads, Aam papad, Lemon pickle, Ghee, Canned juice, Chilli powder, Dried fish. (The first two methods, ‘Dehydration’ and ‘Dried in sun’, are already filled in.)

Answer

The middle column is what you have to fill in. The first two rows are already given in the book; the rest are filled below.

Item (A)	Method of Preservation	Product (B)	Why that method
Roti	Dehydration (given)	Khakhra	The roti is roasted and pressed thin until all its moisture is gone, so it becomes crisp and keeps for weeks.
Papad	Dried in sun (given)	Dried papads	Rolled dal dough is dried in sunlight until it is hard and brittle.
Mango	Dried in sun (dehydration)	Aam papad	Ripe mango pulp is spread in thin layers and sun-dried until no water is left.
Lemon	Pickling — salt, spices and oil	Lemon pickle	Salt pulls the moisture out of the lemon pieces and keeps microbes away.
Butter	Heating, so that the water evaporates	Ghee	Once the water has gone, nothing is left for microbes to grow in.
Juice	Canning — sealed in airtight cans	Canned juice	The juice is heated and sealed so that no air, and no microbe, can get in.
Chillies	Dried in sun, then ground	Chilli powder	Drying removes the moisture; the powder is then stored in a dry container.
Fish	Salting and drying in the sun	Dried fish	Salt draws out the water and the Sun dries the rest, so the fish keeps for months.

Roti → dehydration → khakhra
Papad → dried in sun → dried papads
Mango → dried in sun → aam papad
Lemon → pickling → lemon pickle
Butter → heating → ghee
Juice → canning → canned juice
Chillies → dried in sun and ground → chilli powder
Fish → salted and sun-dried → dried fish

Notice the pattern: six of the eight rows are really the same idea — take the water out. Only the lemon uses salt and oil to keep air away, and only the juice is sealed in a can. That is the whole science of food preservation, in one small table.

Mystery solved. Disha's last finding is the one to carry home: Eat right, preserve and store right, chew well — and thank the good microbes.

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