11. Classification Flashcards
What does classification mean
The way in which organisms are divided into groups
What does Taxonomy mean
The scientific practice of grouping organisms based on shared characteristics
How is the modern classification system group organisms
Hierarchial
Phylogenetic
What does Hierarchical mean
Consists of
-Smaller groups within larger groups
-No overlap between groups
What does phylogenetic mean
Its based on the evolutionary history of organisms i.e their common ancestry
What is the hierarchial taxonomic rank
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Each group is a taxon
Where does the biological name of each species come from
Derived from its genus and species names
A binomial naming system
How is a phylogenetic system usually represented
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
How do you clarify evolutionary relationships
Observable characteristics or DNA and molecular technology
What technologies have been useful for clarifying evolutionary relationships
-Genome sequencing
-Comparing amino acid sequences
-Immunological comparisons
What is the definition of a species
A group of organisms with similar characteristics that can interbreed to produce fertile offspring
Two organsims can belong to the same species if
-They have the potential to breed with eachother
-Their offspring are fertile
Why are offspring of different species unable to undergo meiosis and unavle to produce gametes
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.
What are problems in classifying organisms as distinct species
-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
What is courtship behaviour
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
What are the different functions of courtship behaviour
-Species recognition
-Synchronising reproductive behaviour
-Identifying a mate that is capable of breeding
-Formation of a pair bond
-Becoming able to breed
What is the function of species recognition
Allows one species to recognise other members of the same species
Important for producing fertile offspring
What is the function of synchronising reproductive behaviour
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
Why is identifying a mate tha is capable of breeding an important courtship behaviour
Both partners need to be sexually mature and receptive to breeding
Why is formation of a pair bond an important courtship behavior
Keeps male and female together
Increases the survival chances of the offspring
Why is becoming able to breed an important courtship behavior
Bringing a member of the opposite sex into a physiological state that allows breeding to occur
What are forms courtship behaviour can take
Display of breeding colours
Dance
Song
Depends on the habitat
What are the 5 ways of investigating genetic diversity and looking at evolutionary relationship between species
-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
How do you investiagte genetic diversity by comapry the frequency of measurable or obervable characteristics
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
How do you comapre the base sequence of DNA
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
How do you compair the base sequence of mRNA to see genetic diversity
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.
How does comparing amino acid sequence of the proteins encoded by DNA and mRNA help to see genetic diversity
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.
Why should any conclusions about evolutionary relationships from a study of amino acid sequences be treated with caution
· 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.
How are immunological techniques used to see genetic diversity
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
How do you measure variation
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.
What kind of samples are more representative
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
How do you ensure a representative smaple is used
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.
When can the standard deviation be calculated
Whenever replicates have been taken in an investigation
What is standard deviation and what does in show
-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
When is SD useful
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
What happens when SD is doubled
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
