📌 How to Use
First read the questions carefully using the Read section. Use the Details button to understand concepts clearly. After completing reading, click Practice Quiz to test yourself.
📘 Study MCQs
Q1. what should you do to prevent bread from getting mouldy quickly?
• keep it in a warm, moist place
• store it in a clean, dry, airtight container
• leave the packet open
• put it in a plastic bag with water
Answer: store it in a clean, dry, airtight container
mould spores from the air cause spoilage. a dry environment slows mould growth, and an airtight container prevents new spores from landing on the bread.
Q2. how can you safely preserve leftover cooked rice?
• leave it in the pot on the stove
• cover it and let it cool to room temperature before putting it in the fridge
• keep it near a window
• add more water to it
Answer: cover it and let it cool to room temperature before putting it in the fridge
covering prevents contamination. cooling it quickly and refrigerating slows bacterial growth. leaving it at warm temperatures allows dangerous bacteria like bacillus cereus to multiply.
Q3. what is the most important step before canning fruits or vegetables at home?
• use beautiful jars
• sterilize the jars and lids in boiling water
• use cold jars
• wipe jars with a dry cloth
Answer: sterilize the jars and lids in boiling water
sterilizing kills any microbes present on the jars and lids. this prevents them from spoiling the preserved food inside the sealed container.
Q4. why are lemons or vinegar often added to homemade pickles?
• only for taste
• their acidity prevents the growth of harmful bacteria
• to add color
• to make them juicy
Answer: their acidity prevents the growth of harmful bacteria
most bacteria cannot grow in an acidic environment (low ph). the acid from lemons or vinegar acts as a natural preservative.
Q5. what should you do with a jar of pickle if you see a white layer of fungus on top?
• mix it in, it is safe
• remove the top layer carefully and use the rest
• throw away the entire contents of the jar
• add more oil
Answer: throw away the entire contents of the jar
visible mould on the surface often means its roots (hyphae) and toxins have spread throughout the food, even if not visible. it is not safe to eat.
Q6. how does freezing food help in its preservation?
• it kills all microbes
• it makes food taste better
• it turns microbes into ice
• it drastically slows down microbial growth and enzyme activity
Answer: it drastically slows down microbial growth and enzyme activity
freezing does not kill all microbes, but it puts them in a dormant state. their metabolic activities stop, so they cannot spoil the food.
Q7. what is a simple way to preserve fresh herbs like coriander for a longer time?
• leave them on the kitchen counter
• wash, dry completely, and store in an airtight box in the fridge
• soak them in water
• keep them in a wet cloth
Answer: wash, dry completely, and store in an airtight box in the fridge
moisture promotes microbial decay and wilting. drying the leaves removes water, and cold storage slows down any remaining microbial action.
Q8. why is it important to store raw meat separately from cooked food in the fridge?
• to save space
• to prevent juices from raw meat (which may contain bacteria) from dripping onto cooked food
• raw meat looks different
• cooked food smells more
Answer: to prevent juices from raw meat (which may contain bacteria) from dripping onto cooked food
this is to avoid cross-contamination. harmful bacteria like salmonella from raw meat can transfer to ready-to-eat food and cause illness.
Q9. what should you do if a canned food item (like beans or tuna) has a bulging lid?
• open it and smell it
• cool it in the fridge
• do not eat it; dispose of the can safely
• press the lid down
Answer: do not eat it; dispose of the can safely
a bulging lid can indicate gas production by dangerous bacteria like clostridium botulinum inside the sealed can. the toxin they produce can cause severe food poisoning (botulism).
Q10. how does adding sugar in high amounts help in making jams and preserves?
• it adds sweetness only
• it binds with water, making it unavailable for microbes
• it changes the color
• it makes the fruit soft
Answer: it binds with water, making it unavailable for microbes
sugar is hygroscopic. in high concentration, it draws water out of microbial cells through osmosis, causing them to dehydrate and die or become inactive.
Q11. what is the benefit of storing potatoes and onions in a mesh bag or open basket?
• it looks decorative
• it allows air circulation, preventing moisture buildup and fungal growth
• it keeps them warm
• it makes them easy to carry
Answer: it allows air circulation, preventing moisture buildup and fungal growth
good ventilation keeps the surface dry. dampness encourages mould and bacteria to grow, causing the vegetables to rot.
Q12. why should you avoid refreezing thawed meat or fish?
• it becomes too hard
• it loses all its protein
• each freeze-thaw cycle allows microbial growth during thawing, increasing spoilage risk
• it changes shape
Answer: each freeze-thaw cycle allows microbial growth during thawing, increasing spoilage risk
when food thaws, microbes present can multiply. refreezing doesn’t kill these increased numbers, leading to faster spoilage and higher risk when thawed again.
Q13. what is the purpose of the wax coating on some cheeses?
• for decoration
• to make it shiny
• to create a protective barrier against mould and bacteria
• to add weight
Answer: to create a protective barrier against mould and bacteria
the wax seal prevents air and contaminants from reaching the cheese, allowing it to age without spoiling from surface microbes.
Q14. how can you tell if honey has gone bad?
• it crystallizes (becomes sugary)
• it changes color
• it grows mould or smells fermented
• it becomes watery
Answer: it grows mould or smells fermented
pure honey has very low water content and natural preservatives, so it rarely spoils. if it is diluted with water, yeast can ferment it, or mould can grow.
Q15. why are some dried foods like papads and spices sun-dried?
• to cook them
• sunlight kills some surface microbes and removes moisture
• to make them black
• to attract insects
Answer: sunlight kills some surface microbes and removes moisture
the uv rays in sunlight have a mild germicidal effect. the heat also evaporates water, creating an environment where microbes cannot thrive.
Q16. what should you do to prevent spoilage of a large sack of wheat or rice at home?
• keep it in a damp corner
• store it in a cool, dry place and check for insects
• leave the sack open
• pour water on it occasionally
Answer: store it in a cool, dry place and check for insects
moisture leads to fungal growth (aflatoxins). dry conditions prevent this. insects can also introduce microbes and cause damage.
Q17. why is it advised to use clean, dry spoons to take out pickles or jam from a jar?
• to avoid breaking the jar
• a wet or used spoon can introduce water and new microbes, leading to spoilage
• to take the correct amount
• dry spoons are lighter
Answer: a wet or used spoon can introduce water and new microbes, leading to spoilage
introducing moisture dilutes the high sugar/salt/acid environment. introducing new microbes from your mouth or other food can start fermentation or mould growth.
Q18. how does smoking fish or meat help preserve it?
• it only adds a smoky flavor
• the smoke contains chemicals that inhibit bacterial growth, and the process dries the food
• it makes the food soft
• it is a cheap method
Answer: the smoke contains chemicals that inhibit bacterial growth, and the process dries the food
compounds in smoke like phenols have antimicrobial properties. the heat during smoking also removes moisture, combining two preservation methods.
Q19. what is the safest way to preserve eggs for a longer duration?
• wash them and keep them at room temperature
• store them unwashed in a cool place or the refrigerator
• paint them
• bury them in soil
Answer: store them unwashed in a cool place or the refrigerator
eggs have a natural protective coating. washing removes it, making pores susceptible to bacteria. cold storage slows bacterial growth inside the egg.
Q20. why does fermenting vegetables, like making sauerkraut or kimchi, preserve them?
• the salt kills all microbes
• the lactic acid bacteria produced during fermentation create an acidic environment that prevents spoilage
• it makes them spicy
• it removes all water
Answer: the lactic acid bacteria produced during fermentation create an acidic environment that prevents spoilage
good bacteria (lactobacilli) outcompete harmful ones and produce lactic acid. the resulting low ph prevents the growth of spoilage-causing microbes.
Q21. what should you do if you see a few black spots of mould on a block of hard cheese?
• throw the whole block away
• cut off at least 1 inch around and below the spot; the rest is safe to eat
• scrape off just the spots
• eat it, it is extra flavor
Answer: cut off at least 1 inch around and below the spot; the rest is safe to eat
with dense, hard cheeses, mould threads cannot spread deep and far. cutting well around the mould removes the contaminated part.
Q22. how does vacuum sealing food help preserve it?
• it makes the package small
• it removes air, preventing the growth of aerobic bacteria and fungi
• it cooks the food
• it adds gas to the food
Answer: it removes air, preventing the growth of aerobic bacteria and fungi
many spoilage microbes need oxygen to grow. removing air (creating a vacuum) slows down their growth dramatically, extending shelf life.
Q23. why is it risky to preserve low-acid vegetables (like beans or carrots) by simple home canning without a pressure cooker?
• it takes too long
• the heat may not be enough to kill heat-resistant spores of clostridium botulinum
• it makes them mushy
• jars might break
Answer: the heat may not be enough to kill heat-resistant spores of clostridium botulinum
these spores can survive boiling water (100°c). a pressure cooker achieves higher temperatures (around 116-121°c) needed to destroy them safely.
Q24. what is the role of salt in preserving fish or meat as ‘cure’?
• it adds taste only
• it draws out moisture through osmosis and creates a salty environment where bacteria cannot thrive
• it makes the meat red
• it adds weight
Answer: it draws out moisture through osmosis and creates a salty environment where bacteria cannot thrive
salt dehydrates microbial cells and creates a high-salt concentration that is inhospitable for most bacteria, preventing decomposition.
Q25. how can you prevent cut fruits like watermelon from spoiling quickly?
• leave them uncovered on the table
• cover and refrigerate the cut pieces
• add sugar on top
• keep them in a warm place
Answer: cover and refrigerate the cut pieces
refrigeration slows microbial growth. covering prevents contamination from other foods and microbes in the fridge air.
Q26. why does buttermilk or lassi last longer than fresh milk at room temperature?
• it is white
• it is already fermented and acidic
• it has more fat
• it is always served cold
Answer: it is already fermented and acidic
the lactic acid produced during fermentation lowers the ph. this acidic environment inhibits the growth of many spoilage-causing bacteria.
Q27. what is a simple test to check if yogurt has gone bad?
• check the expiry date
• smell it; a sharp, unpleasant smell indicates spoilage
• see if it is white
• see if it is thick
Answer: smell it; a sharp, unpleasant smell indicates spoilage
good yogurt has a pleasant sour smell. a foul, rancid, or yeasty smell indicates contamination by unwanted bacteria or moulds.
Q28. how does storing tomatoes stem-side down help them last longer?
• it looks neat
• it prevents moisture loss and microbes from entering through the scar at the stem end
• it helps them ripen faster
• it is a tradition
Answer: it prevents moisture loss and microbes from entering through the scar at the stem end
the stem scar is a vulnerable point for moisture loss and microbial entry. placing it down protects this area.
Q29. why should you not store bananas in the fridge?
• they turn black on the skin (though the inside may be fine)
• they become sweeter
• they ripen faster
• they get too hard
Answer: they turn black on the skin (though the inside may be fine)
the cold damages banana skin cells, causing enzymatic browning. this doesn’t mean they are spoiled, but it is unappealing and can affect taste over time.
Q30. what is the best way to store cooking oil to prevent it from turning rancid?
• keep it near the stove for easy access
• store it in a clear bottle in sunlight
• keep it in a cool, dark place in a tightly closed container
• leave the bottle open
Answer: keep it in a cool, dark place in a tightly closed container
heat, light, and air promote oxidation, which makes oil rancid. a cool, dark, airtight environment slows down this chemical and microbial process.
Q31. how can you revive wilted green leafy vegetables temporarily?
• throw them away
• soak them in ice-cold water for a short time
• cook them immediately
• put them in the sun
Answer: soak them in ice-cold water for a short time
the cold water makes the cells absorb water through osmosis, making the leaves crisp again. this does not kill microbes but improves texture.
Q32. why does commercially packaged juice in tetra packs last for months without refrigeration?
• it contains no nutrients
• it is pasteurized and packed in sterile, airtight conditions
• it is made from artificial flavors
• it has a lot of preservatives
Answer: it is pasteurized and packed in sterile, airtight conditions
pasteurization kills microbes. packaging in a sterile environment without air prevents recontamination, allowing long shelf life without chemicals.
Q33. what should you do to make homemade garlic or herb-infused oil safely?
• store garlic in oil at room temperature for flavor
• use it immediately or refrigerate and use within a week
• keep it in a warm place to ferment
• add water to the oil
Answer: use it immediately or refrigerate and use within a week
garlic can contain botulism spores. in the oxygen-free oil environment at room temperature, they can produce a dangerous toxin. refrigeration inhibits this.
Q34. how does turning a compost pile regularly help?
• makes it look tidy
• introduces air, helping aerobic microbes decompose waste faster with less smell
• makes it dry
• kills all worms
Answer: introduces air, helping aerobic microbes decompose waste faster with less smell
aerobic bacteria work efficiently and produce less foul-smelling gases compared to anaerobic bacteria. turning provides them with oxygen.
Q35. why does a cut lemon last longer in the fridge than a whole one?
• it doesn’t; a whole one lasts longer
• the cold and lower ph of the exposed surface inhibits microbial growth
• it loses its vitamins
• it absorbs smells
Answer: the cold and lower ph of the exposed surface inhibits microbial growth
the acidic juice on the cut surface creates a hostile environment for microbes. combined with cold storage, it slows down spoilage and drying.
Q36. what is the safest way to thaw frozen chicken?
• leave it on the kitchen counter all day
• thaw it in a bowl of hot water
• place it in a container on the bottom shelf of the refrigerator overnight
• cook it directly from frozen
Answer: place it in a container on the bottom shelf of the refrigerator overnight
this keeps the chicken at a safe, cold temperature while it thaws, preventing harmful bacteria from multiplying rapidly in the “danger zone” (5°c-60°c).
Q37. how does keeping ginger in a dry, cool place help preserve it?
• it makes it sprout
• it prevents mould growth caused by moisture
• it makes it more pungent
• it turns it blue
Answer: it prevents mould growth caused by moisture
ginger is prone to fungal mould when damp. a dry environment removes the condition necessary for mould to grow.
Q38. why is it important to clean the refrigerator regularly?
• to make it look new
• to remove spilled food that can harbor and spread microbes to other foods
• to save electricity
• to find lost items
Answer: to remove spilled food that can harbor and spread microbes to other foods
spoiled food residues are sources of mould and bacteria. these can contaminate other foods via air circulation or direct contact in the fridge.
Q39. what does the “danger zone” mean in food safety?
• a place where food is stored
• the temperature range (roughly 5°c to 60°c) where bacteria multiply rapidly
• the area near the stove
• a zone in the supermarket
Answer: the temperature range (roughly 5°c to 60°c) where bacteria multiply rapidly
keeping perishable food (like dairy, meat, cooked rice) in this temperature range for more than 1-2 hours significantly increases the risk of foodborne illness.
Q40. how can you store fresh mushrooms without them becoming slimy quickly?
• wash them and keep them in a sealed plastic bag
• store them in a paper bag in the fridge
• leave them in the plastic wrap from the store
• keep them in a bowl of water
Answer: store them in a paper bag in the fridge
mushrooms release moisture. a paper bag absorbs this excess moisture, preventing a wet environment where bacteria and mould cause slime. plastic traps moisture.
Q41. why does properly made ghee (clarified butter) not need refrigeration?
• it is magic
• the process removes water and milk solids, leaving pure fat which is less prone to microbial spoilage
• it is always kept warm
• it contains preservatives
Answer: the process removes water and milk solids, leaving pure fat which is less prone to microbial spoilage
microbes need water to grow. by removing all water and the protein-rich milk solids (which can spoil), ghee becomes shelf-stable.
Q42. what should you do if you accidentally defrosted frozen berries but didn’t use them all?
• refreeze them
• use them to make a jam or cook them, then refrigerate the cooked product
• throw them away
• leave them on the counter
Answer: use them to make a jam or cook them, then refrigerate the cooked product
cooking kills microbes that multiplied during thawing. turning them into jam (with sugar and heat) or cooking them preserves them safely for later use.
Q43. how does keeping dry spices in airtight containers away from light help?
• saves space
• prevents loss of flavor and protects from moisture and insect contamination
• makes them look pretty
• it is a tradition
Answer: prevents loss of flavor and protects from moisture and insect contamination
moisture can lead to clumping and mould. insects can introduce microbes. light and air degrade the oils that give spices their flavor and antimicrobial properties.
Q44. why is it recommended to store flour in a sealed container?
• to keep it soft
• to prevent moisture absorption and infestation by weevils or flour moths
• to make it easy to pour
• to keep it warm
Answer: to prevent moisture absorption and infestation by weevils or flour moths
moisture leads to mould. insects (and their larvae) are common pests in flour; they contaminate it with microbes and waste products.
Q45. what is a sign that sealed packaged food might be compromised even before the expiry date?
• the package is intact
• the package is bloated, leaking, or damaged
• the price is low
• the label is colorful
Answer: the package is bloated, leaking, or damaged
damage can let air and microbes in. bloating indicates gas production by microbes inside. leaking can allow contamination. the food inside may be spoiled.
Q46. how does storing apples separately from other fruits and vegetables help?
• apples need special care
• apples release ethylene gas that speeds up ripening (and spoilage) of others
• other fruits smell bad
• it is just for organization
Answer: apples release ethylene gas that speeds up ripening (and spoilage) of others
ethylene is a plant hormone that triggers ripening. storing apples away from ethylene-sensitive produce (like leafy greens, carrots) keeps them fresh longer.
Q47. why should you not pack a refrigerator too full?
• to save electricity
• to allow cold air to circulate properly, keeping all items evenly cooled
• to show off the food
• it makes noise if full
Answer: to allow cold air to circulate properly, keeping all items evenly cooled
poor air circulation creates warm spots where bacteria can grow faster, leading to uneven cooling and potential spoilage of some items.
Q48. what is the benefit of blanching vegetables before freezing them?
• to cook them completely
• to enhance color and destroy enzymes that cause loss of flavor, color, and texture over time
• to make them soft
• to remove all microbes
Answer: to enhance color and destroy enzymes that cause loss of flavor, color, and texture over time
blanching (brief boiling) stops enzyme activity that leads to spoilage and quality loss during frozen storage, though it doesn’t sterilize the food.
Q49. how can you tell if a sealed jar of homemade pickles is preserved correctly?
• the lid is loosely on
• the lid is concave (pulled in) and makes a “pop” sound when opened
• the lid is rusty
• the pickles are floating
Answer: the lid is concave (pulled in) and makes a “pop” sound when opened
a concave lid indicates a vacuum seal formed during cooling, which means air (and microbes) were forced out. the “pop” confirms the seal was intact.
Q50. why is it important to rotate food items in your pantry and fridge (use older items first)?
• to keep things moving
• to practice “first in, first out” and use items before they spoil or pass their expiry date
• to clean the shelves
• to try new things
Answer: to practice “first in, first out” and use items before they spoil or pass their expiry date
this prevents food waste by ensuring older, more perishable items are used before new ones. it minimizes the chance of finding spoiled food later.