Biology Y10

Community

• Group of living interdependent organisms

• Plants produce food by photosynthesis (producers)

• Herbivores eat plants

• Insects pollinate plants

• Animals use plant and animal material to build nests and shelter

• Plants need nutrients from faeces and decay

Abiotic factors

Non-living elements of the environment

Interdependence

When different populations rely on each other to thrive and survive

Biotic factors

Interaction of living things

Habitat

An area where organisms live

Distribution

Where particular types of organisms are found within an environment

Ecosystem

interacting organisms and their environment

Abiotic factors affecting communities

• Light intensity

• Temperature

• Moisture levels

• Soil pH

• Wind intensity

• For aquatic organisms, oxygen availability

• CO² levels

Biotic factors affecting communities

• Food availability

• New pathogens or parasites could wipe out the population

• New predators

• Competition from other species

Trophic levels

• TL 1 - Producers that make their own food via photosynthesis (autotrophs)

• TL 2 - Primary consumers - herbivores that eat plants or algae

• TL 3 - Secondary consumers - carnivores that eat herbivores

• TL 4 - Tertiary consumers - carnivores that eat other carnivores. Apex predators have no predators

Biomass

the total dry mass of living organisms at each level in a food chain

How is biomass lost through TLs?

Biomass is lost through trophic levels due to metabolic processes and excretion. It is also lost as the animal cannot consume all of the dead one ie. bones, claws, hooves etc., and energy is used in respiration. Only a fraction of energy is passed on to the next level.