11. Classification

Question 1

What does classification mean

Answer 1

The way in which organisms are divided into groups

Question 2

What does Taxonomy mean

Answer 2

The scientific practice of grouping organisms based on shared characteristics

Question 3

How is the modern classification system group organisms

Answer 3

Hierarchial
Phylogenetic

Question 4

What does Hierarchical mean

Answer 4

Consists of
-Smaller groups within larger groups
-No overlap between groups

Question 5

What does phylogenetic mean

Answer 5

Its based on the evolutionary history of organisms i.e their common ancestry

Question 6

What is the hierarchial taxonomic rank

Answer 6

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Each group is a taxon

Question 7

Where does the biological name of each species come from

Answer 7

Derived from its genus and species names
A binomial naming system

Question 8

How is a phylogenetic system usually represented

Answer 8

By a phylogenetic tree
The oldest species at the base of the tree and most recent species at the ends of the tree
Each branch represents where a divergence occured (ancestor evolves to become a new species)
The closer the branches, the closer the evolutionary relationship, the more recently they shared a common ancestor

Question 9

How do you clarify evolutionary relationships

Answer 9

Observable characteristics or DNA and molecular technology

Question 10

What technologies have been useful for clarifying evolutionary relationships

Answer 10

-Genome sequencing
-Comparing amino acid sequences
-Immunological comparisons

Question 11

What is the definition of a species

Answer 11

A group of organisms with similar characteristics that can interbreed to produce fertile offspring

Question 12

Two organsims can belong to the same species if

Answer 12

-They have the potential to breed with eachother
-Their offspring are fertile

Question 13

Why are offspring of different species unable to undergo meiosis and unavle to produce gametes

Answer 13

In meiosis gametes are formed which contain half the chromosomes found in a normal body cell
With an odd number of chromosomes, meiosis cannot be completed and no gametes form.

Question 14

What are problems in classifying organisms as distinct species

Answer 14

-Life evolved 3.5 billion y/a and the extinct species outnumber the living ones
-Most didnt leave fossils. Fossils often incomplete and not all features can be observed
-If organism is only known from fossil records, cant test weather they can interbreed
-Considerable variation between any one species
-Organisms that are isolated may be classified as different species but could turn ut to be same species
-Ability to interbreed cant be tested on organisms that use asexual reproduction

Question 15

What is courtship behaviour

Answer 15

Innate - genetically determined
All members of same species are genertically programmed to show same courtship behaviour as they share same genes
Necessary for successful mating

Question 16

What are the different functions of courtship behaviour

Answer 16

-Species recognition
-Synchronising reproductive behaviour
-Identifying a mate that is capable of breeding
-Formation of a pair bond
-Becoming able to breed

Question 17

What is the function of species recognition

Answer 17

Allows one species to recognise other members of the same species
Important for producing fertile offspring

Question 18

What is the function of synchronising reproductive behaviour

Answer 18

Behaviour of one individual stimulates a response from the other
Ensures mating only occurs when there is a maximum probability of the sperm and egg meeting
E.g when theyre at correct stage in reproductive cycle

Question 19

Why is identifying a mate tha is capable of breeding an important courtship behaviour

Answer 19

Both partners need to be sexually mature and receptive to breeding

Question 20

Why is formation of a pair bond an important courtship behavior

Answer 20

Keeps male and female together
Increases the survival chances of the offspring

Question 21

Why is becoming able to breed an important courtship behavior

Answer 21

Bringing a member of the opposite sex into a physiological state that allows breeding to occur

Question 22

What are forms courtship behaviour can take

Answer 22

Display of breeding colours
Dance
Song
Depends on the habitat

Question 23

What are the 5 ways of investigating genetic diversity and looking at evolutionary relationship between species

Answer 23

-Frequency of measurable or observable characteristics
-Base sequence of DNA
-Base sequence of mRNA
-Amino acid sequence of the proteins encoded by DNA and mRNA
-Immunological techniques

Question 24

How do you investiagte genetic diversity by comapry the frequency of measurable or obervable characteristics

Answer 24

Careful detailed observations of the anatomy and physiology of different individuals
But they are often coded for by more than one gene
Environmet can also influence some characteristics so doesnt show differences in DNA

Question 25

How do you comapre the base sequence of DNA

Answer 25

Mmebers of same species have similar DNA base sequences Random mutations cause genetic variation Species that have closer evolutionary relationships will have more similar sequences of DNA in a particular gene

Question 26

How do you compair the base sequence of mRNA to see genetic diversity

Answer 26

More useful to compare organisms by looking which parts of their genome are expressed Base sequence of mRNA can be studied and compared in different organisms. Similarities and differences can be used to determine evolutionary relationships and genetic diversity.

Question 27

How does comparing amino acid sequence of the proteins encoded by DNA and mRNA help to see genetic diversity

Answer 27

DNA base sequence codes for sequence of amino acids in proteins Organisms that share a more recent common ancestor will have more similar amino acid sequences in a specific protein.

Question 28

Why should any conclusions about evolutionary relationships from a study of amino acid sequences be treated with caution

Answer 28

· Only a short section of polypeptide has been analysed · Amino acid sequences may be the same but DNA/RNA base sequence may be different, due to degenerate nature of the genetic code.

Question 29

How are immunological techniques used to see genetic diversity

Answer 29

Antibodies that are specific to antigens from a particular species can be mixed with antigens from a different species to see if they are also complementary. If the antigens of the two species are similar there will be a large number of antigen-antibody complexes formed, suggesting they are closely related

Question 30

How do you measure variation

Answer 30

Collect data that is quantitative and analyse it mathematically. Allows features such as the mean and standard deviation to be calculated which allow valid comparisons to be made.

Question 31

What kind of samples are more representative

Answer 31

Large samples are more representative of the population than small samples, and minimise the influence of chance on the results size of the sample is often determined by the time available to collect the sample

Question 32

How do you ensure a representative smaple is used

Answer 32

Random sampling used, to ensure that every member of the population has an equal chance of being included in the sample. This avoids sampling bias.

Question 33

When can the standard deviation be calculated

Answer 33

Whenever replicates have been taken in an investigation

Question 34

What is standard deviation and what does in show

Answer 34

-A measure of the spread of values about the mean and thus indicates the extent of variation a population shows. -Data is more similar if the standard deviation is smaller -SD can be indicative of the reliability of the data – the smaller the SD the more precise the data -SD is not the same as the range. Using SD is more valid because involves use of all values but will reduce impact of extreme data points

Question 35

When is SD useful

Answer 35

Comparing two or more sets of data. SD is calculated for both sets If SD overlap then there is no significant difference If no overlap then theres asignificant difference

Question 36

What happens when SD is doubled

Answer 36

It gives a spread about the mean in which 95% of the data lies If used to compare sets and theres no overlap, you can be confindent that there is a significant difference between the means