biology unit 3 topic 1 - ecosystems and biodiversity

Define an ecosystem.

All the living and non-living in an area where they interact with each other. 

composed on various habitat. these can be microhabitats, or massive eco-regions.

What is an ecological niche.

the specific role a species plays within its environment. 

give examples of biotic and abiotic factors.

biotic:

• plants, animals, decompers, pathogens (specific)

abiotic:

• temperature, soil pH, shelter/nesting site, pollutants, mineral content

Define abundance.

how many of a particular organism is present.

measured by frequency, percentage cover, biomass etc.

Define distribution.

refer to the total area inhabited by a particular species (the organism’s range). 

can also refer to the density pattern of their range.

Define a microhabitat.

a small, localised habitat within a larger ecosystem that sustain a limited range of animals and plants. These may form sub-communities.

Define ecoregions (bonus: name some examples)

Geographical units with characteristic flora, fauna and climate. BIG divisions of biographic regions. E.g. tropical rainforests, grasslands, deserts, coral reefs, tundras.

Contrast a closed and open ecosystem.

Closed: exchanges energy but not matter with its surroundings.

Open: exchanged both energy and matter with surrounding environments (most ecosystems on earth)

What are the two important measures of population?

1. Population size: the number of individuals.

2. Population density: individuals/unit area or volume

What are the three distribution patterns and describe them.

1. Uniform dispersion: individuals spaced more or less evenly (e.g. toxic plants that need to take up own space)

2. Random dispersion: spaced randomly without a predictable pattern.

3. Clumped dispersion: clustered in groups (e.g. schools of fish)