B4 Community Level Systems

habitat

a place where plants animals and microorganisms live

abiotic

non-living elements of an ecosystem such as climate temperature water and soil type

population

all the numbers of a single species that live in a particular habitat

Community

all the organisms that live in a habitat (plants and animals)

Ecosystem

the living organisms in a particular area together with the non-living components of the environment

biotic

living elements of an ecosystem such as plants and animals

biotic factors x4

food availability
disease
competitors
predators

abiotic factors x7

climate
non-living things
sunlight
temperature
nutrient enrichment
humidity
soil

temperature

in low temperatures Chemical Reactions Happen too slowly and so all metabolic reaction slow down

nutrients and soil

plants and microorganisms need nutrients to make other chemicals they need to grow

light

plants need light for photosynthesis

water

needed by organisms for living processes

Oxygen

needed by all organisms for aerobic respiration

carbon dioxide

needed by plants for photosynthesis

predation

a biological interaction where predator (an organism that is hunting) feeds on its prey (the organism that in attacked)

Interdependence

all organisms that live in an ecosystem depend upon each other for food protection shelter ETC in order to survive

trophic levels

describe the feeding positions in the food chains. energy is transferred from one trophic level to the next along the food chain

parasitism

where one organism benefits but the other is harmed by that relationship EG tapeworms

mutualism

why do organisms of different species exist in a relationship in which each species benefits from the activities of others

disadvantages of pyramids of biomass

- organisms need to be collected and killed to measure dry mass
- it is difficult to catch and weigh the organisms
- Biomass varies. A tree in the summer has more Biomass than it does in the winter
- Some organism are omnivores and feed at more than one level

why is biomass lost

- lost in faeces
- lost as energy from respiration is transferred to surroundings
- lost in urine

efficiency of energy transfer

energy transferred to the next level output/ energy in the previous level input x 100

decomposers

organisms that gain the energy by feeding on dead or decaying material

detritivore

small organisms which help break down organic matter into smaller parts. they can help speed up decomposition

examples of decomposers x4

- maggots
- mould
- bacteria/fungi
- insects/snails

how do decomposers release nutrients

Bacteria and fungi release enzymes which break down substances into organic matter. They can then absorb the soluble nutrients into their bodies and use them for growth and as an energy store. Many of the bacteria and fungi can be eaten by other organisms resulting in the nutrients being passed on. Some nutrients are released directly into the soil or the environment

factors affecting the rate of decomposition

- Water content
- temperature.
- oxygen availability

calculating rate of decomposition

rate of Decay = change in mass ÷ time

what percent of the atmosphere is carbon dioxide

0.04%

carbon

- photosynthesis occurs
- animals eat plants and absorb carbon
- returned to the atmosphere by respiration and combustion of fossil fuels and wood

what percent of the atmosphere is nitrogen

78.09%

Nitrogen

- also found in soil
- plants take in nitrogen and store it
- animals need it for proteins
- bacteria can decompose plants and animals

denitrifying bacteria

Bacteria that convert the nitrates in soil or water to gaseous nitrogen and release it back into the atmosphere.

nitrogen fixing bacteria

bacteria that convert nitrogen in the air into forms that can be used by plants and animals

nitrifying bacteria

Convert the ammonium ion into nitrates

evaporation

the process that turns a liquid into water vapour

Transpiration

the loss of water vapour through the stomata

condensation

the conversion of water vapour or gas to a liquid

precipitation

rain snow Sleet or hail that falls or condenses on the ground

percolation

water filters through soil until it reaches the underground Reservoir