Species & Taxonomy (AQA A Level Biology): Flashcards
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Define the term species.
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Define the term species.
A group of similar organisms that are able to interbreed to produce fertile offspring.
What is courtship behaviour?
A behaviour carried out by animals that eventually results in mating and reproduction.
Why is courtship behaviour important in species recognition?
It allows an individual to identify a mate of the same species.
This ensures mating occurs only between members of the same species, so that fertile offspring can be produced.
Courtship behaviour allows an individual to identify a suitable mate. What four things can it help an individual to recognise about a potential mate?
That the mate is of the same species.
That the mate is of the opposite sex.
That the mate is sexually mature.
That the mate is receptive to mating.
How does courtship behaviour increase reproductive (mating) success?
It enables individuals to recognise a mate of the same species, opposite sex, that is sexually mature and receptive.
It strengthens the pair bond between mates.
This increases the likelihood of successful mating and the production of fertile offspring.
True or False?
Courtship behaviour is always a complex sequence of acts involving several modes of communication.
False.
Courtship can be a simple process involving only a small number of visual, chemical or auditory stimuli, or a complex sequence of acts by two or more individuals.
Name three types of stimuli that may be involved in a simple form of courtship behaviour.
Visual stimuli.
Chemical stimuli.
Auditory stimuli.
In Drosophila (fruit flies), how does courtship behaviour aid species recognition?
Each species performs a unique, genetically controlled courtship ritual (a species-specific "dance").
Females only respond to the correct sequence of the male's courtship.
This ensures that mating only occurs between members of the same species.
Two organisms belong to the same species if they can interbreed to produce offspring.
Two organisms belong to the same species if they can interbreed to produce fertile offspring.
Courtship behaviour is a necessary precursor to successful and plays a major role in species .
Courtship behaviour is a necessary precursor to successful mating and plays a major role in species recognition.
Courtship behaviour can strengthen the bond between a mating pair, increasing their reproductive success.
Courtship behaviour can strengthen the pair bond between a mating pair, increasing their reproductive success.
What is phylogenetics?
The study of how organisms are evolutionarily related, often shown using a phylogenetic tree.
What is a phylogenetic classification system?
A system that arranges organisms into groups based on their evolutionary origins and relationships.
What is a taxon (plural taxa)?
Each group within the classification hierarchy.
Describe the arrangement of groups in a phylogenetic classification hierarchy.
Smaller groups are placed within larger groups.
There is no overlap between groups.
Each group is called a taxon.
What types of molecular similarity are used to identify evolutionary links in phylogenetic classification?
DNA similarities.
RNA similarities.
Protein similarities.
What does it suggest if two species have very similar DNA sequences?
That they share a more recent common ancestor.
Therefore, they are more closely related.
True or False?
In a phylogenetic classification system, groups can overlap with one another.
False.
In a phylogenetic hierarchy, smaller groups are nested within larger groups with no overlap between groups.
Give three reasons why classifying organisms using a phylogenetic system is useful.
It allows scientists to communicate clearly about different species.
Knowledge about one species can be applied to closely related species (e.g. medicinal properties).
It allows an accurate count of the number of species, which is useful for conservation.
Why does biological classification change over time?
As more molecular analysis is carried out, evolutionary relationships become clearer.
This makes phylogenetic classification more accurate over time.
A phylogenetic classification system groups organisms according to their evolutionary origins and .
A phylogenetic classification system groups organisms according to their evolutionary origins and relationships.
Two species with more similar DNA sequences are assumed to share a more recent common .
Two species with more similar DNA sequences are assumed to share a more recent common ancestor.
Each group within a phylogenetic hierarchy is called a .
Each group within a phylogenetic hierarchy is called a taxon.
List the eight taxa in the taxonomic hierarchy, from largest to smallest.
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Which taxon is the highest rank and which is the lowest rank in the taxonomic hierarchy?
The domain is the highest taxonomic rank.
The species is the lowest taxonomic rank.
What is meant by a hierarchical classification system?
A system in which larger groups contain smaller groups, with no overlap between groups.
Similar species are grouped together into which taxon?
A system in which larger groups contain smaller groups, with no overlap between groups.
True or False?
A phylum is a larger taxon than a class.
True.
The order of taxa from largest to smallest is domain, kingdom, phylum, class, order, family, genus, species, so a phylum contains classes.
In the taxonomic hierarchy, similar classes are grouped into a , and similar phyla are grouped into a .
In the taxonomic hierarchy, similar classes are grouped into a phylum, and similar phyla are grouped into a kingdom.
The eight taxa in order are domain, kingdom, phylum, , order, family, genus and .
The eight taxa in order are domain, kingdom, phylum, class, order, family, genus and species.
What is a binomial?
The scientific name of a species, consisting of its genus and species name in modern Latin.
State the rules for writing a species' binomial name correctly.
The genus name is written first and begins with a capital letter.
The species name is written second and begins with a lowercase letter.
The binomial is written in italics (or underlined when handwritten).
Why is the binomial naming system useful to scientists?
It allows every species to be universally identified.
The binomial for a species is the same across the entire world.
True or False?
In a binomial such as Homo sapiens, the species name is given a capital letter.
False.
The genus name (Homo) begins with a capital letter, but the species name (sapiens) begins with a lowercase letter.
A binomial consists of the organism's name followed by its name.
A binomial consists of the organism's genus name followed by its species name.
Why is using physical features (such as colour, shape and size) unreliable for determining evolutionary relationships?
Physical features have many limitations and can often lead to the wrong classification of species.
Which two scientific advances have allowed scientists to better investigate evolutionary relationships between species?
Genome sequencing.
Immunology.
Which three types of sequence can be compared to determine evolutionary relationships between species?
The DNA base sequence.
The mRNA base sequence.
The amino acid sequence of proteins.
What does it indicate if two species have very similar DNA, mRNA or amino acid sequences?
The more similar the sequences, the more closely related the two species are.
They will have separated into separate species more recently.
Why do species that separated a long time ago have less similar DNA and amino acid sequences?
They have had a greater amount of time to accumulate mutations and changes to their DNA, mRNA and amino acid sequences.
In which situations is genome sequencing especially useful for comparing species?
When comparing with an extinct species (using ancient DNA).
When distinguishing between species that are very physically similar.
Why do scientists compare multiple proteins or regions of the genome between organisms?
It allows for a more accurate estimate of evolutionary relatedness.
What features make a protein suitable for comparing evolutionary relationships between species?
It must be present in a wide range of organisms.
It must show sufficient variation between species.
Describe how immunology can be used to compare the evolutionary relatedness of species using albumin.
Albumin from one species is injected into a rabbit, which produces antibodies against it.
These antibodies are mixed with albumin samples from different species.
The precipitate (antigen-antibody complexes) formed is weighed.
The heavier the precipitate, the greater the similarity and the more closely related the species.
True or False?
Antibodies against human albumin form a heavier precipitate with chimpanzee albumin than with rat albumin.
True.
A heavier precipitate shows greater similarity, reflecting that chimpanzees are more closely related to humans than rats are.
Why can comparing amino acid sequences be more reliable than comparing DNA sequences between species?
DNA sequences can vary due to differences in introns or chromosomal location.
The amino acid sequence of the resulting protein is often more conserved, making it more useful for comparison.
The more similar the DNA, mRNA or amino acid sequences of two species, the more closely they are.
The more similar the DNA, mRNA or amino acid sequences of two species, the more closely related they are.
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