3.4 Topic 4 - 3.4.5 Species and taxonomy

Question 1

species definition

Answer 1

two organisms that are capable of breeding together to produce living and fertile offspring.

Question 2

what does it mean if two organisms can produce fertile offspring?

Answer 2

they belong to the same species.

Question 3

what naming system is used in classification?

Answer 3

the binomial system.

Question 4

list 3 features of the binomial system used to classify organisms

Answer 4

1) universal system based upon latin or greek names.
2) the first name is called the generic name and denotes the genus to which the organism belongs = equivalent to the surname used to identify people and shared by their close relatives.
3) the second name is called the specific name and denotes the species to which the organism belongs = equivalent to first name used to identify people - never shared by other species within the genus.

Question 5

what are the 3 rules which must be applied to the use of the binomial system in scientific writing?

Answer 5

1) names are printed in italics, if handwritten they are underlined to indicate that they are scientific names.
2) the first letter of the generic name is in upper case, but the specific name is in lower case.
3) if the specific name is not known it can be written as ‘sp’.

Question 6

what do the current names in the binomial system reflect?

Answer 6

they reflect the present state of scientific knowledge and understanding.

Question 7

when are courtship behaviours useful? and why?

Answer 7

when classifying species because they are species specific.

Question 8

courtship behaviours help to ensure mating is successful and that the offspring have the maximum chance of survival. Courtship behaviour helps to achieve this by enabling individuals to:

Answer 8

• recognise members of their own species to ensure that mating only takes place between members of the same species because only members of the same species can produce fertile offspring.
• identify a mate that is capable of breeding because both partners need to be sexually mature, fertile and receptive to mating.
• form a pair bond that will lead to successful mating and raising of offspring.
• synchronise mating so that it takes place when there is the maximum probability of the sperm and egg meeting.
• become able to breed by bringing a member of the opposite sex into a physiological state that allows breeding to occur.

Question 9

How is courtship behaviour used by males?

Answer 9

It is used by males to determine whether the female is at this receptive stage (they are often only receptive to mating for a period around the time when they produce eggs).

Question 10

What do animals use during courtship?

Answer 10

During courtship animals use signals to communicate with a potential mate and with members of their own sex.

Typically there is a chain of actions between a male and female. The chain of actions is the same for all members of a species but differs for members of different species. In this way both individuals recognise that their partner is of the same species and that they may be prepared to mate.

Question 11

what is the grouping of organisms known as?

Answer 11

classification.

Question 12

what is the theory and practice of biological classification called?

Answer 12

taxonomy.

Question 13

name the 2 forms of classification

Answer 13

1 - artificial classification
2 - phylogenetic classification

Question 14

what does artificial classification mean and how does it divide organisms?

Answer 14

divides organisms according to differences that are useful at the time. Features include colour, size, number of legs, leaf shape. These are described as analogous characteristics where they have the same function but do not have the same evolutionary origins.

Question 15

what does phylogenetic classification mean and how does it divide organisms?

Answer 15

is based upon the evolutionary relationships between organisms and their ancestors, classifies species into groups using shared features derived from their ancestors, arranges the groups into a hierarchy in which the groups are contained within larger composite groups with no overlap.

Question 16

what is each group within a phylogenetic biological classification called?

Answer 16

a taxon (plural taxa)

Question 17

taxonomy, what is it?

Answer 17

the study of these groups and their positions in a hierarchical order, where they are known as taxonomic ranks
these are based upon the evolutionary line of descent of the group members

Question 18

what is the highest taxonomic rank? + what are the three recognised?

Answer 18

a domain.
1) bacteria
2) archaea (a group of prokaryotes)
3) eukarya

Question 19

list the order of the taxonomic rank:
+ a way to remember it

Answer 19

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Way to remember -
“Delicious King Prawn Curry Or Fat Greasy Sausage”

Question 20

what are bacteria in relation to a domain and the three recognised?

Answer 20

Bacteria are a group of single-celled prokaryotes with many features:
* the absence of membrane-bounded organelles such as nuclei or mitochondria
* unicellular, although cells may occur in chains or clusters
* ribosomes are smaller (70S) than in eukaryotic cells
* cell walls are present and made of murein (but never chitin or cellulose)
* single loop of naked DNA made up of nucleic acids but no histones

Question 21

what are archaea in relation to a domain and the three recognised?

Answer 21

Archaea are a group of single-celled prokaryotes that were originally classified as bacteria which they resemble in appearance.
They differ from bacteria because:
* their genes and protein synthesis are more similar to eukaryotes
* their membranes contain fatty acid chains attached to glycerol by ester linkages
* there is no murein in their cell walls
* they have a more complex form of RNA polymerase

Question 22

what are eukarya in relation to a domain and the three recognised?

Answer 22

Eukarya are a group of organisms made up of one or more eukaryotic
cells. Their features are:
* their cells possess membrane-bounded organelles such as mitochondria and chloroplasts
* they have membranes containing fatty acid chains attached to glycerol by ester linkages
* not all possess cells with a cell wall, but where they do it contains no murein
* ribosomes are larger (80S) than in Bacteria and Archaea

Question 23

How many kingdoms is the eukarya domain divided into?

Answer 23

four

Question 24

list the names of the four kingdoms in which the eukarya domain is divided into :

Answer 24

Protoctista, Fungi, Plantae and Animalia

Question 25

How the taxonomic rank works -

Answer 25

Within each kingdom the largest groups are known as phyla. Organisms in each phylum have a body plan radically different from organisms in any other phylum. Diversity with in each phylum allows it to be divided into classes. Each class is divided into orders of organisms that have additional features in common. Each
order is divided into families and at this level the differences are less obvious. Each family is divided into genera and each genus (singular) into species.

Question 26

the evolutionary relationship between organisms is known as …

Answer 26

… phylogeny

Question 27

state what phylogenies are used to understand

Answer 27

they are used to understand the evolutionary relationships between organisms - based on the fact that all organisms share a common ancestor - the more closely related will share a most recent common ancestor than most distantly related organisms.

Question 28

how are phylogenetic relationships of different species usually represented by? and how does it work?

Answer 28

a tree-like diagram called a phylogenetic tree. In these diagrams, the oldest species is at the base of the tree while the most recent ones are represented by the ends of the branches

Question 29

how does a phylogenetic classification system attempt to arrange species?

Answer 29

into groups based on their evolutionary origins and relationships

Question 30

what have advances in technology led to?

Answer 30

the development of new techniques to help establish evolutionary relationships between species.

Question 31

what are 3 examples of techniques which have been used to help to clarify evolutionary relationships between organisms?

Answer 31

genome sequencing, amino acid sequencing and antibody-antigen interactions.

Question 32

state how genome sequencing has helped to clarify evolutionary relationships between organisms

Answer 32

• base sequence of organisms can be sequenced and compared to other organisms – more similar the base sequences are between organisms = more closely related the two organisms are.

Question 33

state how amino acid sequencing has helped to clarify evolutionary relationships between organisms

Answer 33

• the amino acids that make-up proteins in an organism can be sequenced and compared to another organisms – more similar the amino acid sequences are between organisms = more closely related the two organisms are.

Question 34

state how antibody-antigen interactions have helped to clarify evolutionary relationships between organisms

Answer 34

• species produce specific antibodies that recognise foreign proteins. an organisms antibodies can be isolated & mixed with another organisms proteins to see how many antigen-antibody complexes are formed – more complexes that form = more closely related the two organisms are.