Living World Flashcards
Ecosystem definition
Natural systems that link the living and non-living components of the environment.
What are the living components called?
Biotic elements
What are the non-living components called?
Abiotic elements
Examples of biotic factors
- animals (fauna)
- bacteria
- fungi
- vegetation (flora)
examples of abiotic factors
- air
- climate
- water
- rocks/soil
What scales can ecosystems be identified at?
- a local small-scale ecosystem (can be a pond,hedgerow or woodland)
- a global-scale ecosystem (can be a tropical rainforest or a deciduous woodland. Global ecosystems are called biomes)
producers
They convert energy from the environment (mainly sunlight) into sugar (glucose). The most obvious producers are plants that convert energy from the Sun by photosynthesis.
Consumers
They get energy from the sugars produced by the producers. A pond snail is a good example of a consumer because it eats plants.
Decomposers
They break down plant and animal material and return the nutrients to the soil. Bacteria and fungi are good examples of decomposers.
Food chain
A food chain shows the direct links between producers and consumers in the form of a simple line.
Food web
It shows all the connections between producers and consumers in a rather more complex way
Nutrient cycling
-nutrients are foods that are used by plants or animals to grow. There are two main sources of nutrients:
.rainwater washes chemicals out of the atmosphere
.weathered rock releases nutrients into the soil
Rainforest
- located between the Tropics of Cancer and Capricorn, between 0 and 23.5 degrees N and S of the equator
- high temperatures and heavy rainfall that are associated with the equatorial low pressure belt creates ideal conditions for plants to grow
- The ecosystem covers 6% of the Earth’s land surface
- More than half of the world’s species of plants and animals live in this ecosystem, and 25% of all medicines come from the plants that grow in this ecosystem.
Nutrient cycling
-nutrients are foods that are used by plants or animals to grow. There are two main sources of nutrients:
.rainwater washes chemicals out of the atmosphere
.weathered rock releases nutrients into the soil
Desert
- located up to 30 degrees N and S of the Equator
- the ecosystem covers 20% of the world’s land surface
- this ecosystem is associated with sub-tropical high pressure belts: sinking air stops clouds from forming which results in high daytime temperatures, low night-time temperatures and low rainfall (less than 250 mm a year). Plants and animals have to be very well adapted to survive in these arid conditions.
Polar
-located primarily in the Arctic and Antarctic, but also in the high peaks of mountain systems
- these ecosystems exist because of sinking cold air at the north and South poles
-this results in very low temperatures and dry conditions (these areas are known as cold deserts as their annual precipiration is so low
Antarctica’s precipiration is only 166 mm each year). -The main regions in which this ecosystem exists are Antarctica and Greenland where temperatures can fall below -50 degrees Celsius.
Mediterranean
- this ecosystem is situated between 40 and 45 degrees N of the equator in the Mediterranean region
- there are also some isolated instances of this ecosystem south of the Equator in South Africa and Western Australia.
- This ecosystem is characterised by hot, sunny and dry summers, with mild winters
- this is due to the pressure belts migrating very slightly north and south during the year allowing warm air to circulate in this region.
Temperate grassland
- Situated roughly 30-40 degrees N and South of the Equator, this ecosystem is found inland from coastal areas including vast areas in North America (the prairies) and Eastern Europe (the steppes).
- These areas experience warm, dry summers and cold winters.
- The dominant vegetation in this ecosystem-grass- is able to to tolerate these climactic conditions and so can thrive despite the seasonal extremes
- This land is mainly used for grazing animals
Savanna
- Located between 15 degrees and 30 degrees N and S of the Equator, this ecosystem experiences a tropical climate characterised by distinct wet and dry seasons.
- The dry season can be very hot, leading to the break out of wild fires.
- Violent thunderstorms and torrential rain can occur during the wet season
- Large herds of animals graze on these grasslands, along with predators such as lions and leopards which capitalise on the tall grasses that dominate the ecosystem.
- Precipitation varies from 500 mm to 1300 mm in the dry and wet seasons.
Physical characteristics of hot deserts
- A desert is an area that receives less than 250 mm of rainfall per year
- At these latitudes, air that has risen at the equator descends forming a persistent belt of high pressure. Therefore there is a lack of cloud and rain and very high daytime temperatures and it also explains why temperatures can plummet to below freezing at night during the winter (due to lack of cloud cover).
- desert soils tend to be sandy/stony, with little organic matter due to the general lack of leafy vegetation. They are dry but can soak up water rapidly after rainfall. Evaporation draws salts to the surface, often leaving a white powder on the ground. Desert soils are not very fertile.
Where are hot deserts distributed?
-large areas of desert are found in dry continental interiors, away from coasts, in a belt approximately 30 degrees North and 30 degrees South. There are some coastal deserts too, eg: the Atacama Desert in South America.
Adaptations of cactus
- stores water and reduces water lost to the air though transpiration due to the waxy cuticle
- downward pointing spines make it easier to direct water into depressions of the cactus
- Stored water is protected with spines
- spikes stop predators
