The Environment

The pond outside your school is not just water and mud. Look more carefully and you will find pond plants, small fish, insects hovering over the surface, and maybe even a frog or two. Now look even further — the sunlight shining in, the temperature of the water, the soil at the bottom, the air above. All of these together make up the environment. Take any single piece away and the whole picture changes. That is what this note is about.

Parents: each section has a prediction step — let your child guess first before tapping to reveal the answer. The blue dotted words open a quick definition, and the Teacher Tip boxes flag the exact keywords the PSLE marker rewards. Ten minutes together here is worth more than reading a textbook summary alone.

By the end you will be able to describe what an environment is, name the five non-living factors, explain how living things depend on them, and predict what happens when one factor changes. The four ideas we will master: biotic and abiotic, non-living factors, interdependence, and factor changes.

Biotic and Abiotic: Two Parts of Every Environment

Your school garden has caterpillars munching on leaves, birds hopping across the grass, bacteria in the soil doing their invisible work. These are all living things — scientists call them the biotic parts.

But the garden also has sunlight, rain, warm afternoon air, and the soil those plants grow in. These have never been alive. Scientists call them the abiotic parts. Every single environment — a park, a pond, a void-deck pot plant, a Singapore nature reserve — is made up of both parts together.

The Five Non-Living Factors

Non-living things in an environment are not all equal. Five of them are especially important because living things cannot survive without the right amount of each one. Scientists call these the non-living factors.

• Light — plants capture light energy to make food. Too little light and they cannot photosynthesise. Too much direct heat from light can also scorch leaves.
• Temperature — most organisms live within a narrow band. A tropical fish kept in cold water will slow down and eventually die.
• Water — every living thing needs water for its life processes. A pond plant in a dried-up pond wilts and dies.
• Air — land animals and most plants need oxygen from air to respire.
• Soil — plants anchor their roots in soil and absorb water and minerals from it. No soil means no foothold and no nutrients.

Living Things Depend on Non-Living Factors — and on Each Other

Here is the key idea that PSLE questions love to test: living things do not just exist inside an environment, they depend on it. Take water away and the pond plant dies. Take the pond plant away and the herbivorous fish that eats it has no food. Take that fish away and the heron that eats the fish goes hungry. Everything is connected.

This is called interdependence. The living things depend on the non-living factors, and they depend on each other through food chains and other relationships.

Try the habitat experiment below. Set the non-living factors yourself and see whether the organism thrives, struggles or dies.

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Tune the Habitat

🤔 Predict first: What happens to a pond plant if all the water dries up?

Wilts and diesKeeps growing fine

Changes in Factors Affect Which Organisms Can Live There

Now think about what happens when a non-living factor changes. Heavy rainfall floods the void deck. A heatwave warms the pond. A tree is cut down and the forest floor suddenly gets a lot more sunlight. Each change creates winners and losers.

Organisms that can cope with the new conditions survive. Organisms that cannot cope have to move away or they die. Over time the community of living things in that habitat shifts. This is why protecting non-living factors — keeping a river clean, keeping a forest shaded — is the same as protecting the organisms that live there.

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What happens when a factor changes?

🤔 Predict first: If a pond dries up completely, which organism is most directly affected first?

The heron hunting beside itThe pond plant rooted in the mud

Watch out — easily mixed up

Quick recap

🎯 Mastery check

Answer all 8 — your progress is saved on this device.

1. A pond contains water, sunlight, soil, pond plants, fish and frogs. Which of these are the abiotic (non-living) parts?

   Pond plants, fish and frogsWater, sunlight and soilSunlight, fish and soil

2. Name two non-living factors that affect whether a plant can grow in a habitat.

   Light and temperatureFrogs and insectsBirds and wind direction

3. A pond dried up during a long dry season. What happened to the pond plants?

   They thrived because there was less competitionThey wilted and died because water is a non-living factor they depend onThey moved to a drier habitat nearby

4. A factory releases warm water into a river, raising the river temperature. How does this affect the fish in the river?

   The fish grow larger because warm water has more foodThe fish struggle because warm water holds less oxygen for them to breatheThe fish are unaffected because temperature is not a non-living factor

5. A student says fire is a living (biotic) thing because it moves, grows and needs air. Is the student correct?

   Yes, fire moves and grows so it is bioticNo, fire is abiotic — it does not carry out all life processes such as reproduction and growth from withinYes, fire needs air, which proves it is alive

6. You want to grow a cactus and a pond fern in the same pot. Why is this a bad idea?

   Because they are both plants and cannot share soilBecause a cactus needs little water and high light while a pond fern needs lots of water and shade — the same habitat cannot suit bothBecause cacti are poisonous to ferns

7. Trees in a forest are cut down. Predict what happens to the ferns on the forest floor that normally grow in shade.

   The ferns thrive because they now get more lightThe ferns struggle or die because too much light now reaches themNothing changes for the ferns

8. Which of these is the best example of an organism depending on a non-living factor?

   A bird eating a worm from the soilA plant absorbing water through its roots to carry out photosynthesisA frog eating a dragonfly beside the pond

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