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Question:
Two identical plants are watered equally. Plant A is placed near a sunny window, while Plant B is kept in a dark cupboard. After one week, Plant B is yellow and much shorter. Explain why.
Answer:
Plant B did not receive enough light for photosynthesis, so it could not make enough food. It became weak, yellow, and grew poorly.
Question:
Why do frogs lay hundreds of eggs instead of just a few?
Answer:
Many eggs are eaten or do not survive, so producing many eggs increases the chance that some grow into adult frogs.
Question:
Clothes dry faster on a windy day than on a calm day. Explain why.
Answer:
The wind carries away water vapour, allowing more water to evaporate.
Question:
A feather and a stone are dropped in a vacuum. Which reaches the ground first?
Answer:
They reach the ground at the same time because there is no air resistance.
Question:
A magnet attracts one end of a steel nail but not a plastic ruler. Explain why.
Answer:
Steel contains magnetic materials, while plastic is non-magnetic.
Question:
A gardener removes many leaves from a plant before transplanting it. Explain why this helps the plant survive.
Answer:
Fewer leaves reduce transpiration, so the plant loses less water while its roots recover.
Question:
Why do your heartbeat and breathing rate remain high for a short time after you stop running?
Answer:
Your muscles still need oxygen to recover and remove carbon dioxide produced during respiration.
Question:
A mirror becomes foggy after a hot shower. Explain why.
Answer:
Water vapour cools when it touches the cold mirror and condenses into tiny water droplets.
Question:
Why do athletes wear shoes with rough soles during a race?
Answer:
Rough soles increase friction, giving better grip and preventing slipping.
Question:
How can throwing rubbish into rivers affect fish?
Answer:
It pollutes the water, reduces oxygen, and may poison or trap fish.
Question:
Polar bears have thick fur and a thick layer of fat. Explain how both adaptations help them survive.
Answer:
The thick fur traps air to reduce heat loss, while the fat layer insulates the body and stores energy.
Question:
A student swallows food without chewing it properly. Explain why this may slow digestion.
Answer:
Large pieces of food have less surface area, making it harder for digestive juices to break them down.
Question:
A balloon becomes bigger after being left in the sun. Explain why.
Answer:
The air inside is heated, causing its particles to move faster and spread out, increasing the balloon's volume. It expands.
Question:
A flashlight becomes dim after many hours of use. Explain why.
Answer:
The battery's stored chemical energy is being used up, so less electrical energy is available.
Question:
A forest is cleared to build houses. Explain two effects on wildlife.
Answer:
Animals lose their habitat and food sources, causing populations to decrease or move elsewhere.
Question:
A disease kills most of the frogs in a pond. Predict two changes that may happen in the food web.
Answer:
Question:
Why is blood important even though it looks like just a red liquid?
Answer:
Blood transports oxygen, nutrients, hormones and wastes. It also helps fight infections and clot wounds.
Question:
Explain how the digestive, respiratory, and circulatory systems work together during exercise.
Answer:
The digestive system provides nutrients, the respiratory system supplies oxygen, and the circulatory system transports both to muscles for respiration.
Question:
Why does a metal spoon feel colder than a wooden spoon in the same room?
Answer:
Metal conducts heat away from your hand faster than wood, making it feel colder.
Question:
Why is the Sun considered the main source of energy in most food chains?
Answer:
Plants use sunlight to make food through photosynthesis, and this energy is passed to other organisms.
Question:
A whale lives in the sea but is classified as a mammal instead of a fish. Give two reasons.
Answer:
It breathes using lungs and gives birth to live young (also feeds milk to its young).
A metal bench and a wooden bench are left under the hot sun. A cat chooses to lie on the wooden bench instead of the metal one. Explain why.
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Answer:
A farmer sprays pesticide to kill insects that damage his crops. After several months, he notices fewer birds in the area. Explain why this may happen.
Answer:
Question:
Melting ice and burning paper are both changes. Explain why only one is reversible.
Answer:
Melting is reversible because water can freeze again. Burning forms new substances and cannot be reversed.
Question:
A young plant is watered every day but still grows poorly. Suggest three possible scientific reasons.
Answer (any three):