What is an ecosystem?

All the organisms in a habitat together with the abiotic environment

What does the niche of a species describe?

Its role, the resources it uses, its interactions and the conditions it tolerates

Intraspecific (within the same species)

An organism whose presence or absence shows environmental conditions

To avoid bias and give a representative sample

carbon dioxide + water produces glucose + oxygen

Water is split, releasing oxygen

Energy is always lost between levels, so each level has less than the one below

Heat, movement and undigested material

Their nitrates let plants make more amino acids and proteins

Light is blocked, plants die and bacteria use up the oxygen

The build-up of a non-biodegradable pesticide up a food chain

Isolation of populations by a barrier

16questions. Pick an answer and you'll see why right away.

What is an ecosystem?
What does the niche of a species describe?
Which type of competition is usually more intense?
What is an indicator species?
Why must quadrats be placed randomly?
What is the word equation for photosynthesis?
In the light reactions of photosynthesis, what is split, and what gas is released?
Which is a limiting factor of photosynthesis?
In a food chain, the arrows show:
Why is a pyramid of energy always pyramid-shaped?
Most energy lost between levels of a food chain is lost as:
How do fertilisers increase crop yield?
What happens after fertiliser leaches into a loch and causes an algal bloom?
What is bioaccumulation?
What is the only source of new alleles in a population?
Which is a required stage of speciation?