Biology · OCR Paper 2
Cycles in Ecosystems
How materials such as carbon, nitrogen and water cycle between the living and non-living parts of an ecosystem, the part that microorganisms play as decomposers, how the carbon cycle and the water cycle work and why they matter to living things, and how temperature, water content and oxygen affect the rate of decay. Matches OCR GCSE Biology A (Gateway Science) B4.1a to B4.1d. The first three lessons are for both Combined Science and separate Biology. The rate of decomposition (B4.1d) is for separate Biology only. Nothing in this chapter is for the Higher tier only.
Lessons
Ticks are remembered on this device only.
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1
Cycling of Materials and Decomposers
The materials that living things are made from are used again and again. This lesson covers how materials such as carbon, nitrogen and water cycle between the…
8 terms -
2
The Carbon Cycle
Every living thing is made of carbon compounds, and the carbon in them is passed round and round. This lesson covers the stages of the carbon cycle, which are…
8 terms -
3
The Water Cycle
Water is needed by every living thing, and it is constantly moving between the sea, the air, the land and living organisms. This lesson covers the stages of…
8 terms -
4
The Rate of Decomposition
Dead material rots quickly in some places and very slowly in others. This lesson is for separate Biology. It explains how temperature, water content and oxygen…
8 terms
Key terms in this chapter
All 32, gathered from every lesson.
- Ecosystem
- All the living things in an area and their non-living surroundings.
- Abiotic
- Non-living, such as air, water and soil.
- Biotic
- Living, such as plants, animals and microorganisms.
- Decomposer
- A microorganism that breaks down dead plants and animals and waste.
- Decomposition
- The breakdown of dead material by microorganisms.
- Mineral ion
- A dissolved substance such as nitrate that plants take up from the soil.
- Nitrogen-fixing bacteria
- Bacteria that turn nitrogen from the air into compounds that plants can use.
- Detritivore
- An animal, such as an earthworm, that feeds on dead material.
- Carbon cycle
- The movement of carbon between the air, living things and fossil fuels.
- Photosynthesis
- The process in which plants take carbon dioxide from the air and make glucose.
- Respiration
- The release of energy from glucose, which releases carbon dioxide.
- Feeding
- The passing of carbon compounds along a food chain when one organism eats another.
- Combustion
- Burning, which releases carbon dioxide into the air.
- Fossil fuel
- A fuel such as coal, oil or gas made from the remains of living things over millions of years.
- Decay
- The breakdown of dead material by decomposers.
- Biomass
- The mass of living material.
- Water cycle
- The movement of water between the sea, the air, the land and living things.
- Evaporation
- The change from liquid water to water vapour.
- Transpiration
- The loss of water vapour from the leaves of plants.
- Condensation
- The change from water vapour to liquid water droplets.
- Precipitation
- Water falling from clouds as rain, snow, sleet or hail.
- Run-off
- Water flowing over the surface of the land.
- Infiltration
- Water soaking into the soil.
- Groundwater
- Water stored in the soil and rocks.
- Rate of decay
- How quickly dead material is broken down.
- Aerobic
- With oxygen.
- Anaerobic
- Without oxygen.
- Optimum temperature
- The temperature at which the rate of decay is fastest.
- Compost
- Decayed plant material that is used to feed plants.
- Waterlogged
- Soaked with water, so there is no air in the spaces.
- Biogas
- A fuel gas, mainly methane, made by the anaerobic breakdown of waste.
- Percentage change
- The change divided by the starting value, multiplied by 100.