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52 Cards in this Set
- Front
- Back
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What is a species? |
A group of similar organisms able to reproduce to give fertile offspring. |
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What must happen before animals can mate? |
They have to recognise one another as being from the same species. |
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How do they do this? |
There are complicated rituals whereby one of the pair carries out a stereotypical behaviour which is seen and recognised by the other. The other then performs its own stereotypical behaviour. |
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What does this courtship behaviour result in? |
Mating |
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How does this allow different species to identify each other? |
Each species has its own different courtship behaviour so males and females don't accidentally mate with the wrong species, resulting in no offspring. |
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What causes the male three spine stickle back to start building the nest? |
The presence of the female |
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What is step 1 of the three spine stickle back's courtship behaviour? |
The male recognises a female with a swollen belly, showing she has many eggs. He attracts her to his nest with a zig zag dance recognised only by female stickle backs. The female responds to this, especially if he has a strong red colouring, showing he's in good breeding condition. |
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What is step 2 of the three spine stickle back's courtship behaviour?
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The male encourages the female to enter the nest. |
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What is step 3 of the three spine stickle back's courtship behaviour? |
The male quivers against the female's sides to encourage her to spawn (release her eggs) |
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What is step 4 of the three spine stickle back's courtship behaviour?
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The male enters the nest and chases her out. He then releases sperm to fertilise the eggs. The female swims away, leaving the the eggs to the care of their father. |
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What are other examples of courtship behaviour? |
Birds and insects |
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What courtship behaviour do birds show? |
They perform dances and build nests. Males display brightly coloured feathers and females select those with the most impressive tail display as these males have more offspring and pass on the allele for impressive tail feathers. Males sing specific songs to attract mates and intimidate other males. |
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Give an example of a bird which performs a dance. |
Great crested grebes run across the surface of lakes. |
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Give an example of a bird with an impressive tail display. |
Peacocks |
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Give an example of a bird which builds a nest. |
Male bowerbirds build decorated nests |
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What courtship behaviour do insects display? |
Many female insects secrete pheromones which attract males of their own species only. |
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What are pheromones? |
Chemicals |
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What can these species specific behaviours be used for? |
They can be used by scientists to classify organisms. The more similar the behaviour, the more closely related the species are. |
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What is taxonomy? |
The study of the classification of organisms into a series of categories called taxa. |
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What is the singular version of taxa? |
Taxon |
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What can the categories be defined as? |
Hierarchical |
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What does this mean? |
Each organism is classified into a series of smaller and smaller taxa with no overlap between taxa. |
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What is the first taxa? |
The domain |
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What is the domain followed by? |
Kingdom Phylum Class Order Family Genus Species |
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What are the domains? |
Eukarya Archaea Bacteria |
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What domain do prokaryota belong to? |
Archaea or bacteria |
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What are kingdoms? |
Animalia Plantae Fungi Protoctista Prokayota |
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What happens with each taxa as you progress? |
Each taxa contains fewer and fewer species until the final taxa which contains just one. |
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Which taxa are humans classified into? |
Domain-Eukarya Kingdom-Animalia Phylum-Chordata Class-Mammalia Order-Primates Family-Hominidae Genus-Homo Species-sapiens |
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What are the final 2 taxa and what are they used for? |
They are genus and species. They're used to give the binomial name to an organism. |
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What is the binomial (scientific) name in and how is it identified? |
It's in Latin and in italics. If it's hand written, it's often underlined. |
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How are the genus and species written differently? |
The genus always starts with a capital letter, but there's no capital letter at the start of the species |
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What word can be used to describe the classification system? |
Phylogenetic |
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What is phylogeny? |
The study of the evolutionary history of organisms, all species have evolved from a common ancestor. |
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How are different species and their common ancestor connected? |
The more recently 2 species have shared an ancestor, the more closely related they are and the more taxa they share. |
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What are phylogenetic trees? |
Diagrams that show relationships between species
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What happens when taxonomists are faced with a species they've never seen before? |
They have to decide which taxa to classify the organism into. Several techniques can be used. |
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What is the debate around these techniques? |
There are often debates as to whether 2 populations are sufficiently different to be classified as separate species or not. There are many examples of 2 populations that are considered to be 2 separate species but they can hybridise to produce fertile offspring. |
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What is an example of this hybridisation? |
Dogs (Canis familiaris) and wolves (Canis lupus) |
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What are the techniques used to classify organisms? |
Physical appearance
Comparison of amino acid sequences in proteins Immunological comparisons Comparing DNA sequences/genome sequencing Comparing mRNA sequencing |
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How can physical appearance be used to classify organisms? |
The taxonomist looks at the general physical features of the organisms. This is a relatively easy way to decide which of the higher taxa to place an organism into. |
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Why can physical appearance by used to classify organisms? |
Physical appearance is largely determined by genes and the more closely related 2 organisms are, the more similar there gene sequences are
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How can comparison of amino acid sequences in proteins be used to classify organisms? |
The sequence of amino acids in a protein of an organism is determined by its DNA gene sequence. Closely related species have similar DNA sequences and hence, have similar amino acid sequences. |
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Which protein do scientists often use for this process? |
A proteins called cytochrome C which is found in the majority of organisms. Taxonomists compare amino acid sequences to see how closely related species are. |
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What other proteins is commonly used for this technique? |
Haemoglobin |
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How are immunological comparisons used to help classifying organisms? |
Antibodies bind to proteins of a specific shape only. When antibodies from one animal are added to proteins from another, antibodies will bind if the proteins are similar in shape. |
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What does this tell us? |
The more closely related the 2 organisms are, the more similar the shape of their proteins will be and the more likely the antibodies will be to bind. When antibodies bind the proteins usually precipitate out- the more precipitate, the more similar the proteins are. |
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How can comparing DNA sequences/ genome sequencing help us to classify animals? |
The process of finding the sequence of bases in the DNA of an organism has become quicker and cheaper in recent years.The entire genome of and organism can be sequenced in hours. Computer programmes are also able to make quick comparisons between the sequences of 2 organisms. |
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What can this tell us? |
The more similar sequences are, the more recently the two species shared a common ancestor with the same sequences. |
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How can comparing mRNA sequences help us classify organisms? |
They can be comparing between species. There are large databases scientists can access, and add to, to compare mRNA and DNA sequences. mRNA is easier to extract from a cell than DNA as it's found in the cytoplasm and many more copies are present. |
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What has happened over the past few years in terms of classification techniques? |
The development of next generation gene technologies like DNA and RNA sequencing has replaced more traditional methods of inferring diversity by observation of observable characteristics. |
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Why are offspring from 2 different species usually infertile? |
They have a different number of maternal and paternal chromosomes. This means they can't form homologous pairs, so they can't produce gametes and are infertile. |
