Classification

Question 1

What is a species?

Answer 1

A species is a group of organisms that have similar characteristics and can interbreed to produce fertile offspring

Question 2

What is classification?

Answer 2

The way in which living organisms are divided into groups

Question 3

What is taxonomy?

Answer 3

The scientific practice of grouping organisms based on their shared characteristics

Question 4

What is meant by a heirarchical system?

Answer 4

A system that contains smaller groups within larger groups.
There is no overlap between the groups

Question 5

Describe the heirarchical classification system.

Answer 5

Consists of 8 taxanomic groups, in descending size order
Domain, kingdom, phylum, class, order, family, genus, species.
Each group is called a taxonomic

Question 6

What taxons do all mammals have in common?

Answer 6

All classified into the same kingdom, phylum and class

Question 7

Using classification systems, how are organisms given their biological names?

Answer 7

Devired from the organisms genus and species.
The genus comes first and starts with a capital
Then the species with a lowercase letter

Question 8

Describe the phylogenic classification system

Answer 8

Organisms are classified based on evolutionary history, and it refelcts the evolutionary relationship between different organisms
Shown on a phylogenetic tree

Question 9

How are evolutionary relationships shown on a phylogenetic tree?

Answer 9

Oldest species at base of tree, most recent species at end of branches
Each branch shows where divergence occurs
The closer the branches, the closer the evolutionary relationship, so the more recent common ancestor organisms share

Question 10

State the 4 main ways of investigating genetic diversity between species

Answer 10

Comparing the frequency of measurable characteristics
Comparing the base sequence of DNA
comparing the base sequence of mRNA
comparing the amino acid sequence of proteins encoded by

Question 11

Explain the benefits/problems of investigating diversity of comparing frequency of measurable characterstics.

Answer 11

Diversity can be measured by observing the anatomy and physiology of organisms
HOWEVER not accurate as environments can influence characteristics, and characteristics are often coded for by more than one gene.

Question 12

Explain the benefits of investigating diversity by comparing DNA base sequences

Answer 12

Members of the same species will have similar base sequences
Even is species mutate over time, species that share a more recent common amcestor will still have more similar sequences
Modern technology means DNA based sequences can be compared directly

Question 13

Explain the benefits of investigating diversity by comparing mRNA base sequences

Answer 13

Similar to comparing dna bases (members lf same species will have similar mRNA base sequences), yet more useful to look at which parts of their genome is actually expressed after translation produces proteins

Question 14

Explain the benefits of investigating diversity by comparing the amino acid sequence of proteins encoded by DNA and mRNA

Answer 14

All proteins are coded for by DNA base sequences, so organisms that have more similar amino acid sequences will share a more recent common ancestor

Question 15

Explain how immunological techniques can be used to investigate genetic diversity

Answer 15

Antibodies that are specific to antigens from a particular organism can be mixed with antigens from different organism to see if they are also complimentary.
If the two organisms are genetically similar, a large number of antigen-antibody complexes will be formed. Suggests they have recent common ancestors

Question 16

State five problems with classifying species.

Answer 16

Extinct species outnumber living species.
Most extinct species didnt left no fossils/ incomplete fossils.
There can be lots of variation between any one species.
Species discovered from fossil records cannot be tested to see if they can interbreed to produce fertile offspring.
Ability to interbreed cannot be tested with organisms that reproduce by asexual reproduction

Question 17

Explain how coutship behavior can be used to classify species

Answer 17

Members kf the same species are genetically programmed to show the same courtship behavior, therefore i5 can be used to identify organisms as members kf the same species.m

Question 18

Why is courtship behavior important for species?

Answer 18

It is genetically determined in order to ensure membrrs of the same species mste to produce fertile offspring- to prevent extinction

Question 19

Explain the functions of courtship behavior

Answer 19

• Species recognition- allows organisms to identify others of the same species
• Synchronised reproductive behavior- so mating only occurs when theres max chance of reproduction
• identify a mate capable of breeding
• formation of a pair bond- as keeping male and female together increases survival chance of offspring
• becoming able to breed- bringing member of the opposite sex into a physiological state where they are able to breed

Question 20

Why is courtship song sometimes very important?

Answer 20

Different soecies will produce different songs, so species can identify their own. It is important for nocturnal animals where visual displays are ineffective

Question 21

How is variation measured?

Answer 21

Quantitative data is collected and then analysed mathematically

Question 22

When measuring variation, why are larger samples more accurate?

Answer 22

Minimises the possibility that the results are due to chance.

Question 23

What are the benefits of random sampling when measuring variation?

Answer 23

It ensures a representative sample.
Every member of the population has an equal chance of being included, this avoids sampling bias

Question 24

What is standard deviation and why is it useful when measuring variation?

Answer 24

SD is a measure of the soread of values around the mean. It indicates the extent of variation taht a population has
- if data is more similar than the SD is smaller and there is less variation
- the smaller the SD the more precise the data is
- more valid than the range, as it uses all values yet reduces the impact of anomalies

Question 25

How is standard deviation used to compare two sets of data?

Answer 25

If the SD from both sets of data overlap, there is no significant difference between data.
If i5 doesnt overlap, there is significant difference

Question 26

When would 2x SD be used?

Answer 26

To conclude that the significant difference between two sets of data is more valid (if the 2x SD still doesnt overlap)