4.2.1 Biodiversity
(a) How biodiversity may be considered at different levels
Types of biodiversity
Biodiversity: a measure of the variation found in the living world
Habitat biodiversity
Habitat biodiversity is the range of places in which different species live, such as sand dunes,
woodland, streams. Each habitat will be occupied by many different organisms.
Species biodiversity
A species is a group of organisms that have a very similar appearance, anatomy and physiology
and can interbreed freely to produce fertile offspring. Species biodiversity is composed of how
many different species are in a habitat, however the more evenly represented each species is,
the more biodiverse the area is.
Genetic biodiversity
Genetic biodiversity is the variation of alleles between individuals of the same species e.g.
between different breeds of dog.
(b) (i) how sampling is used in measuring the biodiversity of a habitat and
the importance of sampling
Sampling
To measure the diversity of a habitat, you need to identify all the species present and count how
many of each species there are. For some organisms, this is impossible e.g. fungi and bacteria
although estimates can be gained from culturing samples in a lab. To make the numbers
manageable, a small area is sampled and then multiplied to represent the area of the whole
habitat.
Type of sampling Description Advantages Disadvantages
Random Random sites are Not biased May not cover all areas
selected using random equally and miss key
number generators as species
coordinates.
Opportunistic Sites are chosen based Quick and easy and Biased may lead to an
on prior knowledge to doesn’t miss key overestimation of
choose sites of interest features species and hence
that shouldn’t be biodiversity
missed.
Stratified Dividing the habitat into Ensures all variations May lead to
different types of area within the habitat are overrepresentation of
and sampling each sampled and species a small area i.e. too
separately. aren’t under- many samples taken of
represented a tiny different area
Systematic Samples are taken at Good at showing a Only species on the
fixed intervals e.g. trend across an area transect can be
across a transect. and no bias recorded so some may
be missed
(a) How biodiversity may be considered at different levels
Types of biodiversity
Biodiversity: a measure of the variation found in the living world
Habitat biodiversity
Habitat biodiversity is the range of places in which different species live, such as sand dunes,
woodland, streams. Each habitat will be occupied by many different organisms.
Species biodiversity
A species is a group of organisms that have a very similar appearance, anatomy and physiology
and can interbreed freely to produce fertile offspring. Species biodiversity is composed of how
many different species are in a habitat, however the more evenly represented each species is,
the more biodiverse the area is.
Genetic biodiversity
Genetic biodiversity is the variation of alleles between individuals of the same species e.g.
between different breeds of dog.
(b) (i) how sampling is used in measuring the biodiversity of a habitat and
the importance of sampling
Sampling
To measure the diversity of a habitat, you need to identify all the species present and count how
many of each species there are. For some organisms, this is impossible e.g. fungi and bacteria
although estimates can be gained from culturing samples in a lab. To make the numbers
manageable, a small area is sampled and then multiplied to represent the area of the whole
habitat.
Type of sampling Description Advantages Disadvantages
Random Random sites are Not biased May not cover all areas
selected using random equally and miss key
number generators as species
coordinates.
Opportunistic Sites are chosen based Quick and easy and Biased may lead to an
on prior knowledge to doesn’t miss key overestimation of
choose sites of interest features species and hence
that shouldn’t be biodiversity
missed.
Stratified Dividing the habitat into Ensures all variations May lead to
different types of area within the habitat are overrepresentation of
and sampling each sampled and species a small area i.e. too
separately. aren’t under- many samples taken of
represented a tiny different area
Systematic Samples are taken at Good at showing a Only species on the
fixed intervals e.g. trend across an area transect can be
across a transect. and no bias recorded so some may
be missed
