4.3 Quantifying biodiversity

Question 1

Biodiversity

Answer 1

The variety in living organisms.
Biodiversity has three main components. These
are: 1) species or organism diversity; many
different species are found in tropical forests and
on coral reefs – these places have high
biodiversities; 2) genetic diversity – diversity
within a species; animals such as tigers which
live in small isolated populations often have
low genetic diversity; 3) ecosystem diversity; a
wide range of different habitats in an area will
result in a much greater species diversity.

Question 2

Binomial system

Answer 2

The system by which each
species of organism is given a unique two-part
Latin name. The first part of the name is the
genus to which the organism belongs. The
second part defines the particular species. For
example, the scientific name of the brown rat is
Rattus norvegicus and the scientific name of the
black rat is Rattus rattus. Both rats belong to the
genus Rattus but their full scientific names tell
us that they belong to different species.

Question 3

Genus, Genera

Answer 3

A level of classification between
family and species. The white-spotted butterfly
fish belongs to the genus Chaetodon. Members
of this genus and members of a number of
closely related genera belong to the family
Chaetodonitae. When scientific names are used,
each species of organism is given a unique twopart
Latin name. The first part of the name is the
genus to which the organism belongs.

Question 4

Dichotomous key

Answer 4

In a dichotomous key, used,
for example, to identify organisms, there are
always two possible answers to each question
about the features of the organism.

Question 5

Taxonomy

Answer 5

The scientific study of classification

of organisms into hierarchical taxa.

Question 6

Family

Answer 6

A level of classification between order
and genus. The white-spotted butterfly fish
belongs to the family Chaetodonitae. The
Chaetodonitae includes several genera of
closely related fish and is put, together with
other related families, in the order Perciformes.

Question 7

Order

Answer 7

The level of classification between class
and family. Humans are a member of the order
Primates. The Primates include several closely
related families including the family Hominidae
which contains humans. The order Primates,
together with other orders, is put in the class
Mammalia.

Question 8

Class

Answer 8

Biologists divide organisms into smaller
and smaller groups, which reflect their
similarities and differences. All living organisms
belong to one of five kingdoms. Each kingdom
is made up of a number of phyla. Each phylum
is made up of a number of classes and so on.
Humans belong to the mammal class and share
features such as the possession of hair and sweat
glands with all other mammals.

Question 9

Phylum, Phyla

Answer 9

The level of classification
between kingdom and class. Each of the five
kingdoms is made up of a number of phyla. The
animal kingdom, for example, has nine phyla.
These include the Mollusca, the Arthropoda and
the Chordata. All members of a phylum share
common features, for example all members of
the Arthropoda have segmented bodies and
exoskeletons made of chitin.

Question 10

Kingdom

Answer 10

One of the five main groups into which
all organisms are classified. These kingdoms
are: Prokaryotae, Protoctista, Fungi,
Animalia, and Planta.

Question 11

Animalia

Answer 11

The kingdom containing animals.
Animals share the following characteristics.
1) They are multicellular eukaryotic organisms.
They have different sorts of cells which are
specialised to form different organs. 2) Their
cells do not have cell walls or large vacuoles.
3) Their nutrition is heterotrophic and they are
unable to photosynthesise. 4) Most animals can move from one place to another and these
movements are coordinated by a nervous
system.

Question 12

Taxon, Taxa

Answer 12

Organisms are placed in groups in
which the members all share one or more
common features. These groups are known as
taxa (singular taxon). Thus kingdoms, phyla,
classes, orders, families, genera and species
are all taxa. Organisms that are in the same
group in the lower levels of the classification
system (e.g. different species within a genus) are
more closely related than those in the higher
taxa.

Question 13

Homology, Homologies

Answer 13

A common feature
shared by all members of a particular taxonomic
group of organisms.

Question 14

Hierarchy of groups

Answer 14

Kingdom > phylum > class > order > family > genus > species

Question 15

Plantae

Answer 15

The kingdom containing plants. Plants
are all multicellular eukaryotic organisms. They
have different sorts of cells which are
specialised to form different organs. Their cells
have large vacuoles and cell walls containing
cellulose. Most plants have chloroplasts. Their
nutrition is autotrophic and they are able to
photosynthesise.

Question 16

Fungi, Fungus

Answer 16

A kingdom consisting of
organisms such as mushrooms and toadstools,
moulds and yeasts. Fungi do not possess
chlorophyll. They feed by extracellular
digestion, secreting enzymes onto their food and
digesting it outside their cells. They are made up
of a mass of thread-like structures called hyphae
and reproduce by spores. Fungi have cell walls
but these are made of a substance called chitin,
not cellulose.

Question 17

Protoctista, Protoctist

Answer 17

The kingdom Protoctista
contains various Protozoa, single-celled eukaryotic organisms such as amoebae, as well
as the multi-celled seaweeds.

Question 18

Prokaryotae

Answer 18

The kingdom containing bacteria.
Members of the Prokaryotae share the following
characteristics. They are prokaryotes. They have
small cells, typically less than 10 micrometres
across. These cells have no nucleus or other organelles, such as mitochondria or
chloroplasts, which are surrounded by a
membrane.

Question 19

Phylogenetic tree

Answer 19

Shows the evolutionary relationships between organisms based on molecular differences, the result of mutations accumulated over time

Question 20

Domain

Answer 20

a domain is a taxon in the highest rank of organisms, higher than a kingdom.

Question 21

Convergent evolution

Answer 21

Unrelated organisms
which live in similar habits and occupy similar
niches often look very similar. This is because
they experience the same selection pressures.
Dolphins are mammals and sharks are fish, but
they both have the same streamlined shape. This
is an adaptation for swimming rapidly and
catching fish.

Question 22

Genetic diversity

Answer 22

A measure of the genetic
variation found in a particular species. Species
whose members show a lot of genetic variation
have a high genetic diversity. Species where all
the individuals are genetically very similar have
a low genetic diversity. Many cultivated plants
and domesticated animals have been bred for
specific purposes and, as a result, are genetically
very similar. Their low genetic diversity means that they may be unable to adapt if their
environment changes.

Question 23

Independent assortment, Random assortment

Answer 23

During the first stage of meiosis the arrangement
of the pairs of homologous chromosomes on the
spindle is at random with each chromosome
acting independently. When these chromosomes
are drawn to the poles of the cell during
anaphase, this leads to many different
combinations of paternal and maternal
chromosomes. Independent assortment is an
important source of genetic variation.

Question 24

Species richness

Answer 24

A simple measure of

biodiversity, the number of species in a habitat.

Question 25

Dominant species, Dominant organism

Answer 25

A
species which has an important effect on the
other organisms in a community. In many
British woods, for example, the dominant tree is
oak. Its size determines such factors as how
much light falls on the ground and the water
content of the soil. These factors determine the
other organisms able to grow in an oak wood.

Question 26

Endemic

Answer 26

A species which is endemic is native to
a particular region and found nowhere else. The
Galapagos Islands have a very high proportion
of endemic species such as the marine iguana.
These species are found only on the Galapagos
Islands.

Question 27

Biodiversity hotspot

Answer 27

An area with a particularly

high plant biodiversity.