BIOLOGY · Stage 7 · Chapter 4: The Physical Environment and Water Cycle
Biology 4.4 Chapter 4 Review: The Physical Environment — Alhussan International Academy - Biology (Stages 7-9) Revision Notes & Topical Questions
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Lesson summary
4.4 Chapter 4 Review: The Physical Environment — Alhussan International Academy — Biology (Stages 7–9) notes: Revise ecosystems, abiotic and biotic factors, the water cycle and the effects of global warming.Ecosystem — the living community together with the non-living environment…
- Population
- Abiotic factors
- Adaptation
- Measurement
- Sea and air temperature
- Evaporation
Section 1 of 5Ecosystems and habitats
- Ecosystem
- the living community together with the non-living environment.
- Habitat
- the place where an organism lives.
- Population
- all the members of one species in a habitat.
Section 2 of 5Abiotic and biotic factors
- Abiotic factors
- non-living factors such as temperature, light, water, soil pH and oxygen in water.
- Biotic factors
- living factors such as predators, competitors, food and disease.
- Adaptation
- organisms are adapted to the abiotic conditions where they live.
- Cacti store water in deserts.
- Woodland plants flower before the trees shade them.
- Measurement
- a thermometer, light meter and rain gauge measure abiotic factors, and repeated readings are averaged to improve reliability.
- Sampling
- quadrats and transects show how the distribution of a species changes as an abiotic factor changes.
Section 3 of 5Importance and properties of water
- Coverage
- about 71% of the Earth's surface is water, and 96.5% of it is in the oceans.
- Solvent
- water dissolves many substances, and all the chemical reactions of life take place in solution.
- Heat
- water heats up and cools down slowly, so oceans and large lakes have stable temperatures.
- Ice
- it floats and insulates the water beneath, so aquatic life survives.
- Sea and air temperature
- sea temperature changes less through the year than air temperature.
Section 4 of 5The water cycle
- Evaporation
- the Sun's energy turns liquid water from oceans and lakes into vapour.
- Transpiration
- plants lose water vapour from their leaves.
- Condensation
- the vapour cools into liquid droplets that form clouds.
- Precipitation
- water falls as rain, snow, hail or sleet.
- Return
- water returns to the sea by run-off in rivers or by seeping through soil as groundwater.
- Transpiration factors
- it rises with higher temperature, wind and light, and falls with high humidity.
| Process | Change |
|---|---|
| Evaporation | Liquid to vapour |
| Condensation | Vapour to liquid droplets |
| Precipitation | Water falls to the ground |
| Transpiration | Water vapour leaves plant leaves |
Section 5 of 5Global warming
- Greenhouse gases
- carbon dioxide, methane and water vapour trap heat and keep Earth warm enough for life.
- Causes of increase
- burning fossil fuels, deforestation and farming have increased these gases.
- Consequences
- Ice melts and sea level rises as glaciers melt and the oceans expand.
- Rainfall patterns change, causing floods and droughts.
- Coral reefs are damaged and habitats shift.
- Solutions
- use less fossil fuel, use renewable energy, protect forests and save energy.
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