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What is taxonomy?
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What is taxonomy?
Taxonomy is the science of classifying organisms into groups based on shared characteristics.
State the order of taxonomic ranks from largest to smallest.
The order of taxonomic ranks from largest to smallest is:
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
True or False?
Species with similar observable characteristics always share a recent common ancestor.
False.
Species with similar observable characteristics do not always share a recent common ancestor, as similarities can result from convergent evolution.
Define the term taxon.
A taxon is a group or category in biological classification, such as a genus, family, or phylum.
Why can classifying organisms based on morphology be challenging?
Classifying organisms based on morphology can be challenging because similar physical traits do not always indicate close evolutionary relationships.
True or False?
Genome sequencing can be used for species classification.
True.
Genome sequencing has improved the accuracy of species classification by providing genetic evidence of relationships.
Define the term hierarchical system in biological classification.
A hierarchical system in biological classification is a structure where larger groups contain smaller, non-overlapping groups.
True or False?
The classification system’s taxonomic ranks are fixed and unchangeable.
False.
Taxonomic ranks can change with new evidence, especially from genome sequencing, which may lead to reclassification of species.
Define the term morphology in the context of classification.
Morphology is the study of the form and structure of organisms, used historically in classifying species based on observable characteristics.
Why might fertile hybrids pose a challenge to traditional classification?
Hybrids can complicate classification because they often don't fit neatly into a single taxon and may inherit traits from two different species.
What is a clade?
A clade is a group of organisms that have all descended from a common ancestor.
Define cladistics.
Cladistics is the branch of science that organises organisms into clades based on evolutionary relationships.
True or False?
Morphology alone can accurately determine evolutionary relationships.
False.
Morphology alone can be misleading; DNA sequencing provides a more accurate determination of evolutionary relationships.
What is the molecular clock?
The molecular clock is a concept where the rate of mutations in DNA is used to estimate the time since two species diverged.
What does a node represent on a cladogram?
A node on a cladogram represents a common ancestor of the species or clades that branch from that point.
True or False?
Cladograms are definitive representations of evolutionary relationships.
False.
Cladograms show probable relationships and may change as new evidence emerges.
What is DNA hybridisation used for in classification?
DNA hybridisation is used to compare DNA sequences between species to determine genetic similarities and evolutionary relationships.
What information does sequence similarity provide in evolutionary classification?
Greater sequence similarity indicates a more recent common ancestor, meaning the species are more closely related.
Define a monophyletic group.
A monophyletic group contains all descendants of a single common ancestor, such as a clade.
Define the root of a cladogram.
The root of a cladogram represents the most ancient common ancestor of all organisms within the diagram.
True or False?
Clades can include both extinct and living species.
True.
Clades can include both extinct and living species that share a common ancestor.
Define the principle of parsimony.
The principle of parsimony states that the simplest explanation with the fewest evolutionary changes is most likely correct in constructing cladograms.
True or False?
The development of DNA sequencing has resulted in the reclassification of many organisms.
True.
The use of DNA sequencing to classify organisms has led to discoveries of classification errors and the need to reclassify organisms.
Some species have been reclassified into different groups of organisms
Some groups of organisms have been split
Some groups have been merged
What is convergent evolution?
Convergent evolution is the process where unrelated organisms evolve similar traits independently.
Why was the figwort family reclassified?
The figwort family was reclassified because similarities in morphology were due to convergent evolution, not common ancestry. This was discovered as a result of DNA sequencing which uncovered new evidence about the ancestry of the species.
Define ‘common ancestry’ in the context of cladistics.
Common ancestry refers to an ancestral species from which all members of a clade have descended.
What role does DNA sequencing play in cladistics?
DNA sequencing helps classify organisms by revealing evolutionary relationships based on genetic similarities. More similarities implies a closer evolutionary relationship and a more recent common ancestor.
True or False?
Analysis of chloroplast DNA led to the reclassification of the figwort family.
True.
Original classification of the figwort family was based on flower shape, but analysis of chloroplast DNA showed that the figwort family was not a true clade and the group was split into several different families.
The table shows some data collected about amino acid sequences in different animals. Which animal in the table is most closely related to humans?
Animal | Number of differences in the amino acid sequence compared with human cytochrome c |
|---|---|
Human | 0 |
Dog | 11 |
Duck | 11 |
Turtle | 15 |
Monkey | 1 |
Pig | 10 |
Humans are more closely related to monkeys than to other animals in the sample because there is only one amino acid difference between the human and monkey cytochrome c. Fewer differences indicate a closer ancestral relationship.
What are the three domains in the modern classification system?
The three domains are Bacteria, Archaea, and Eukarya.
True or False?
The three-domain system was proposed in 1877.
False.
The three-domain system was proposed in 1977.
Define domain in biological classification.
A domain is the highest taxonomic rank in the classification of organisms, above the kingdom level.
What evidence supports the three-domain classification system?
Evidence from rRNA base sequences supports the classification of organisms into three domains.
Why was rRNA sequence analysis significant for classification?
rRNA sequence analysis provided a molecular basis for distinguishing domains based on evolutionary relationships.
What distinguishes Archaea from Bacteria?
Archaea have unique rRNA sequences, histones and introns within their DNA, and cell membrane structures, distinguishing them from Bacteria.
True or False?
Eukarya includes only multicellular organisms.
False.
Eukarya includes both unicellular and multicellular organisms.
Define reclassification in taxonomy.
Reclassification is the reassignment of organisms into new taxonomic groups based on new evidence or analysis.