AQA GCSE Geography A - Living World Notes

Revision notes for Paper 1 (physical geog), Living World

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MOCK EXAM 14 Nov 2012 [PHYSICAL GEOGRAPHY REVISION NOTES]
Living World
Ecosystems
An ecosystem is a living community of plants and
animals, which is linked to the natural environment
where they live.
Each element depends on and influences others,
meaning they are interrelated.
A hedgerow is a small scale ecosystem
o UK's temperate maritime temperate allows certain plants to grow, e.g. deciduous.
o Rich vegetation due to fertile soils (brown earths) found in lowland Britain.
o Soils benefit from decomposition or organic material such as leaves which returns
nutrients to the soil.
o Varied vegetation provides habitats for wildlife, for food, shelter and breeding.
Animals help to fertilise soil and spread seeds.
o People may also help, for example farmers trim hedges to encourage bushy growth.
The flow of energy and nutrient cycle needs to be constant in an ecosystem, to maintain
balance between elements.
Plants are primary producers ­ they make living matter (glucose) through photosynthesis.
The nutrients and energy are passed along the food chain, however 90% of energy is lost so
only 10% can be used for growth.
Bacteria and fungi in the soil are decomposers, so they break down dead remains of plants
animals and release nutrients into the soil.
o These nutrients can be used by plants again, hence creating the nutrient cycle.
The largest and fastest nutrient cycle occurs in the tropical rainforest.
o Leaf fall and falling branches provide continuous supply of litter to forest floor.
o High temperatures and rainfall allow intensive biotic activity, which leads to rapid
decomposition of organic material.
o All-year plant growth means quick reuse of nutrients released.
Changes to the ecosystem can trigger a chain reaction to the whole system, e.g. climate
change (natural), plant and animal diseases, or human activity.
o For example, rainforest clearance damages the nutrient cycle, as nutrients are
washed out with nothing to replace them.

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MOCK EXAM 14 Nov 2012 [PHYSICAL GEOGRAPHY REVISION NOTES]
Global distribution of large-scale ecosystems
Climate is the main factor affecting characteristics of natural vegetation cover.
o Tropical rainforests are located close to the Equator, and are located down the
wet eastern sides of the continents in the tropics.
o Hot deserts are closer to Tropics of Cancer and Capricorn. Greatest extent is in
Sahara, around Egypt and Northern Africa.…read more

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MOCK EXAM 14 Nov 2012 [PHYSICAL GEOGRAPHY REVISION NOTES]
Structure reflects availability and competition for light, as small plants on the ground layer
flower early in spring before leaves grow back on canopy trees and block the light.
Plants and trees in the deciduous forest have many adaptations to the temperate climate.
o Trees shed leaves in winter due to reduced light and heat; as water is lost through
their large and fleshy leaves (soil is not readily available in cold winter soils).…read more

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MOCK EXAM 14 Nov 2012 [PHYSICAL GEOGRAPHY REVISION NOTES]
o Ferns have large leaves containing plenty of chlorophyll, allows them to absorb
sunlight for photosynthesis even in lower layer of rainforest.
Latosol is the name given to the soil of a tropical rainforest.
o Red or yellow-ish red in colour throughout.
o Usually very deep, around 20-30m.
o Layer of organic material in the black humus layer at the top of the latosol.…read more

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