chapter 18

Question 1

Define the biological species concept.

Answer 1

In this concept, a species is defined as a
group of individuals that interbreed to
produce fertile offspring. It is not based on
their similarities in appearance.

Question 2

Define the morphological species

concept.

Answer 2

The morphological species concept
classifies species by their morphological
similarities (how they look), not by their
ability to reproduce or their DNA.

Question 3

Define the ecological species concept.

Answer 3

In this concept, a species is a group of
organisms that are adapted to a particular
niche in an ecosystem.

Question 4

Outline the main features of the domains

Archaea, Bacteria and Eukarya.

Answer 4

https://ibb.co/0r97y3j

Question 5

List the levels of taxonomic classification.

Answer 5

domain, kingdom, phylum, class,
order, family, genus, species

Question 6

Outline the main features of the kingdoms Protoctista, Fungi, Plantae and Animalia.

Answer 6

https://ibb.co/52QW3rr

Question 7

Why are viruses not included in any of the three domains?

Answer 7

Viruses are acellular and do not share
any characteristic features with cells in
the domains.

Question 8

How are viruses classified?

Answer 8

Viruses are grouped according to their nucleic
acids e.g. RNA or DNA, double-stranded or single-stranded.

Question 9

What is meant by the term ecosystem?

Answer 9

The community of organisms (biotic) and
non-living (abiotic) components of an area
and their interactions.

Question 10

What is meant by the term niche?

Answer 10

Describes how an organism ‘fits’ into an
ecosystem and its role in that
environment.

Question 11

What is biodiversity?

Answer 11

Biodiversity refers to the variation of
living organisms.

Question 12

List the three levels at which biodiversity can be considered.

Answer 12

● Variation of ecosystems or habitats

● Number and abundance of species

● Genetic variation within a species

Question 13

Why is random sampling important for
investigating biodiversity in an area?

Answer 13

It avoids bias, which makes the results
more reliable.

Question 14

Describe how random sampling and frame quadrats can be used to assess the abundance of a species.

Answer 14

The study area is divided into a grid. A random
number generator is used to obtain coordinates.
At the coordinates, the frame quadrat is placed
on the ground and the abundance of the species
within the quadrat is recorded.

Question 15

How can the abundance of a species
within a quadrat be estimated?

Answer 15

● The number of organisms within the quadrat can
be counted (species richness).

● The percentage cover can be estimated. This is
useful for species that are very abundant.

Question 16

When is it appropriate to use transects
rather than random sampling of an area?

Answer 16

Transects are used to measure the change in
abundance and distribution of a species across a
habitat, rather than within the habitat only. A
gradual change in an abiotic factor often causes
the change in species abundance.

Question 17

Describe how systematic sampling and a
belt transect can be used to assess the
abundance and distribution of a species.

Answer 17

A belt transect is drawn from one part of a
habitat to another. The frame quadrat is placed
at regular intervals along the belt transect and
the abundance of a species is measured.

Question 18

Describe the difference between a line transect and a belt transect.

Answer 18

● Line transect - all organisms touching the line
are recorded

● Belt transect - only organisms in the frame
quadrat at each interval are recorded

Question 19

What method is used to investigate populations of
motile organisms?

Answer 19

Mark-release-recapture

Question 20

Outline the mark-release-recapture method.

Answer 20

● A group of organisms of the target population are caught, counted and marked
● The marked organisms are released back into their habitat
● After a period of time, organisms of the same population are captured again
● The proportion of marked to unmarked organisms in the captured group is assumed to
be the same as the proportion of marked to unmarked in the whole population

Question 21

How is Spearman’s rank correlation coefficient used in investigations of species populations?

Answer 21

Spearman’s rank tests whether there is a
correlation between two data sets e.g. to see
if there is a correlation between distribution of
organisms and an abiotic factor like soil pH.

Question 22

Outline the difference between Pearson’s and Spearman’s correlation coefficients.

Answer 22

Pearson’s correlation coefficient is used for
linear correlations between two data sets.

Spearman’s correlation coefficient works for
linear correlations and monotonic relationships
(does not increase/decrease by the same
amount each time).

Question 23

Explain what the values of D mean forSimpson’s Index of Diversity.

Answer 23

D is the index of diversity. A high value
for D means there is a lot of diversity, so
species richness and species evenness
is high.

Question 24

Outline the threats to biodiversity in ecosystems.

Answer 24

Some of the threats include climate change,
deforestation and destruction of habitats,
pollution, introduction of new species, and
hunting by humans.

Question 25

Why does biodiversity need to be maintained?

Answer 25

● To maintain stable ecosystems
● Ethical reasons
● Aesthetic reasons
● Many plant species are yet to be discovered and may
contain chemicals that could be used in future
medicines

Question 26

List methods of protecting endangered species.

Answer 26

● National parks
● Zoos
● Botanic gardens
● Frozen zoos
● Seed banks

Question 27

Give examples of methods of assisted reproduction for conservation efforts.

Answer 27

● In vitro fertilisation (IVF)
● Embryo transfer
● Surrogacy

Question 28

State what is meant by an ‘alien species’.

Answer 28

An alien species (also known as an introduced
species) is one which is living in a habitat it is
not native to. The species may arrive there
intentionally or unintentionally.

Question 29

What effects can an alien species have on a habitat?

Answer 29

● An alien species represents a new competitor for
resources. They may outcompete the native species,
resulting in extinction
● The alien species may be predators of a native species
● The alien species may bring new diseases into the habitat

Question 30

What is the role of the World Wide Fund for Nature (WWF)?

Answer 30

WWF is a non-governmental organisation. It aims
to conserve biodiversity on a global level, protect
and restore ecosystems, promote the use of
sustainable resources and reduce pollution and
waste.

Question 31

What is the role of the Convention on
International Trade in Endangered
Species of Wild Fauna and Flora (CITES)?

Answer 31

CITES is an agreements between governments.
It regulates wildlife trade to ensure it is not a
threat to their survival. It prevents
overexploitation of resources, particularly of
endangered species.