ACARA v9 CONTENT DESCRIPTION “investigate the physical conditions of a habitat and analyse how the growth and survival of living things is affected by changing physical conditions”
Builds on matching the features of living things to their habitats. Here we look at the physical conditions of a habitat, such as temperature, water, light and shelter, and at how the growth and survival of living things is affected when those conditions change.
The physical conditions of a habitat
A habitat is the place where a living thing makes its home, such as a pond, a meadow, a desert or a rainforest. Every habitat has physical conditions: the temperature of the air and ground, how much water there is, how much light reaches it, and the shelter it offers. These are the parts of a place a scientist can investigate and measure. The plants and animals that live there depend on these conditions to grow and stay alive.
The physical conditions of a habitat
A pond and meadow have physical conditions that living things depend on. Pick one to see it in the scene.
A habitat is the place where a living thing makes its home. It has physical conditions, such as temperature, water, light and shelter. These are the parts of the place a scientist can measure. The plants and animals that live there depend on these conditions to grow and stay alive.
Changing one condition
To find out what one condition does, a scientist changes only that condition and keeps the others the same. Give a plant too little water and it wilts. Give it too much and its roots drown. Give it just the right amount and it grows tall and healthy. The growth of the plant is affected straight away by how much water the place provides, so a careful change shows exactly what that condition controls.
Change one condition: water
Keep light, warmth and soil the same and change only the water. Step the water up and down.
When a scientist changes only one condition, they can see what that condition does. With too little water the plant wilts. With too much water the roots drown. With just the right amount it grows tall and healthy. The growth of the plant is affected here and now by how much water the place gives it.
A range it can survive in
A living thing does not need one exact condition, but a range. For a pond fish there is a band of temperatures that is just right. Below that band the water is too cold, and above it the water is too hot. Inside the band the fish stays healthy and grows. Outside the band the same fish cannot survive. Every living thing has a range like this for the conditions it depends on.
A range it can survive in
A fish survives only in a band of temperatures. Step the temperature and find the safe range.
A living thing survives only within a range of conditions. For this fish there is a band of temperatures that is just right. Below it the water is too cold and above it the water is too hot. Inside the green band the fish stays healthy. Outside it, the same fish cannot survive.
Matching living things to conditions
Different living things need different conditions, so they grow and survive in different places. A desert plant needs little water, bright light and heat, and does well on dry ground. A rainforest fern needs lots of water, shade and steady warmth, and does well in a damp shady place. When you analyse a habitat, you can predict which living things will grow there by matching the conditions of the place to what each living thing needs.
Match the plant to the place it needs
Different plants need different conditions. Pick a plant and see the habitat that suits it.
Different living things need different conditions. A desert plant needs little water, bright light and heat, and grows well in a dry place. A rainforest fern needs lots of water, shade and steady warmth, and grows well in a damp place. Each plant grows and survives where the conditions match what it needs.
When conditions change too far
Conditions can change so far that they pass beyond the range a living thing can cope with. In a long dry spell, with no rain and a hot sun, a pond shrinks day by day. While there is enough water the fish stays healthy, but once the pond dries up the fish has nowhere to live and cannot survive. A large change in the physical conditions affects the growth and survival of living things straight away.
When conditions change too far
A hot dry spell shrinks a pond day by day. Step the days and watch what happens to the fish.
Conditions can change so far that a living thing can no longer survive. In a long dry spell, with no rain and a hot sun, the pond shrinks each day. While there is enough water the fish stays healthy. Once the pond dries up, the water leaves the fish nowhere to live, and it cannot survive. A big change in conditions affects survival straight away.
Why this matters
Investigating the physical conditions of a habitat helps you explain why living things grow where they do and what threatens them. When you can measure temperature, water, light and shelter, and analyse how a change affects growth and survival, you can care for a garden, protect a pond or understand a drought. This way of thinking prepares you for more science about ecosystems and how living things depend on their environment.
Quick self-check
1. Which of these is a physical condition of a habitat?
2. A plant is given far too little water while everything else stays the same. What happens?
3. A fish survives only in a band of temperatures. What is this band called?
4. Which conditions does a rainforest fern need to grow well?
5. In a long dry spell the pond a fish lives in dries up completely. What happens to the fish?