Ecology and environment - IGCSE

Question 1

Abiotic factors

Answer 1

The non-living aspects of an ecosystem

Question 2

Biotic factors

Answer 2

The living components of an ecosystem

Question 3

Biodiversity

Answer 3

The variety of living organisms in an ecosystem

Question 4

Community

Answer 4

All the populations of different species living together in a habitat

Question 5

Distribution

Answer 5

The spread of living organisms in an ecosystem. It’s affected by environmental changes which may be seasonal, geographic or man-made

Question 6

Ecosystem

Answer 6

The community of organisms and non-living components of an area and their interactions

Question 7

Habitat

Answer 7

The place where an organism lives

Question 8

Population

Answer 8

All organisms of the same species living with one another in a habitat

Question 9

Decomposers

Answer 9

Organisms that release enzymes which catalyse the breakdown of dead plant and animal material into simpler organic matter

Question 10

Decomposition

Answer 10

The breakdown of dead materials into simpler organic matter. The rate of decomposition is affected by temperature, water and oxygen availability

Question 11

Producers

Answer 11

Photosynthetic organisms at the start of the food chain that provide biomass for all living things

Question 12

Trophic level

Answer 12

The position of an organism in a food chain

Question 13

Carbon cycle

Answer 13

The cycle through which carbon moves between living organisms and the environment, involving respiration, PS and combustion

Question 14

Nitrogen cycle

Answer 14

The cycle through which nitrogen moves between living organisms and the environment

Question 15

Decomposers

Answer 15

Organisms that release enzymes which catalyse the breakdown of dead plant and animal marerial into simpler organic matter, releasing nitrogen-containing compounds into the soil

Question 16

Nitrifying bacteria

Answer 16

Bacteria found in the soil that convert ammonia to nitrates

Question 17

Denitrifying bacteria

Answer 17

Bacteria that converts nitrates in the soil into nitrogen gas

Question 18

Eutrophication

Answer 18

Pollution of water by fertiliser leading to excessive growth of algae at the water surface. This prevents light reaching aquatic plants, causing them to die, and reduces the amount of oxygen available for animal species

Question 19

Evapotranspiration

Answer 19

The loss of water from trees by evaporation and transpiration
The water vapour condenses in the atmosphere, forming clouds, and returns to the trees by rain

Question 20

Leaching

Answer 20

The loss of plant nutrients from the soil when fertilisers run off the land into lakes and rivers
This may be due to rain or irrigation and can lead to eutrophication