4.2.2 - Classification and evolution Flashcards
Define the term ‘classification’ ?
Classification : The process by which living organisms are sorted into groups based on similar characteristics
Define the term ‘species’ ?
Species - A group of organisms with similar characteristics/ features that able to breed together and produce fertile offspring
What is the taxonomic hierarchy ?
- Domain
- Kingdom
- Phylum
- Class
- Order
- Familly
- Genus
- Species
Why do we classify organisms ?
- To identity species
- To predict characteristics
- To find evolutionary links
Explain why we classify organisms to identify species ?
By using a clearly defined system of classification, the species of an organism can easily be identified
Explain why we classify organisms to predict characteristics ?
If several members in a group have a specific characteristic, it is likely another species in the group will have the same features / characteristics
Explain why we classify organisms to find evolutionary links ?
Species in the same group probably share characteristics since they have evolved from a common ancestor
What is the binomial naming system ?
It is a universal naming system where all species are given a scientific name consisting of two parts ( the first part is the genus, the second part is the species )
What are the benefits of the binomial naming system ?
- Different areas use different names
- It is a universal naming system that ensures scientists all over the world can refer to organisms without misunderstanding
What are the five kingdoms ?
- Prokaryotae
- Protoctista
- Fungi
- Plantae
- Animalia
What are the features of Prokaryotae ?
- Unicellular
- No nucleus / membrane-bound organelles
- No visible feeding mechanism ( nutrients absorbed through cell wall and produced internally via photosynthesis )
Features of Protoctista ?
- Unicellular
- A nucleus and other membrane- bound organelles
- Some have chloroplasts
- Some sessile/ some move via cilia, flagella or amaeboid
- Nutrients are acquired by photosynthesis, ingestion of other organisms and some are parasitic
What are autotrophic feeders ?
They are organisms that are self-feeders and produce their food via photosynthesis
What are heterotrophic feeders ?
They are organisms that eats other plants or animals for energy and nutrients
Features of fungi ?
- Unicellular/ multicellular
- A nucleus, other membrane-bound organelles and cell wall made of chitin
- No chloroplasts/ chlorophyll
- No mechanisms for locomotion
- Most have a body or mycelium made. Of threads or hyphae
- Nutrients are acquired by absorption from decaying material
- Most store their food as glycogen
What are saprophytic feeders ?
They are organisms that feed on the dead and the decaying matter in the environment
Features of plantae ?
- Multicellular
- Nucleus, other membrane-bound organelles ( eg. Chloroplasts ) and cell wall made of cellulose
- Contain chloroplasts
- Most don’t move, gametes move via cilia and flagella
- Nutrients are acquired by photosynthesis
- Store food as starch
Features of animalia ?
- Multicellular
- Nucleus, other membrane-bound organelles but no cell wall made of
- No chloroplasts
- Move with aid of cilia, flagella, contractile proteins
- Nutrients are acquired by ingestion
- Food stored as glycogen
How have there been changes in the classification system ?
- Originally, organisms were classified based on observable characteristics/ phenotype ( artificial classification )
- Through study of genetics and other biological molecules, scientists now classify organisms based on their genotype
- By comparing similarities in DNA and proteins of different species, this shows evolutionary relationship
What are the 3 Domains systems ?
- Eukarya
- Archaea
- Bacteria
Features of the Eukarya domain ?
- Have 80s ribosomes
- Nucleus, membrane-bound organelles
- RNA polymerase contains 12 proteins
Features of Archaea domain ?
- Have 70s ribosomes
- RNA polymerase contains 8-10 proteins, similar to eukaryotic ribosome
Features of bacteria domain ?
- Have 70s ribosomes
- RNA polymerase contains 5 proteins
What is the six kingdom classification system ?
What is the difference between Eubacteria and Archaebacteria ?
- They are both single-celled prokaryotes but have a different chemical makeup
- Archaebacteria live in extreme conditions ( ie. hot thermal vents, anaerobic conditions, highly acidic conditions… ) while eubacteria are found in all environments
Define the term ‘phylogenetics’ ?
Phylogenetics : The study of the evolutionary relationships between organisms
What is a phylogenic tree ?
A diagram used to represent the evolutionary relationships between organisms
What are features of a phylogenetic tree ?
- The closer the branches, the closer the evolutionary relationship
- The root is the common ancestor of the tree
- The node shows the common ancestor of those descendants
- The tips represent the descendant taxa/ species
What are the advantages of the phylogenetic system ?
- Uses the study of evolutionary relationships to classify organisms
- Phylogeny produces a continuous tree
- Hierarchal nature of Linnaen classification can be misleading
Explain how using the study of evolutionary relationships to classify organisms is advantageous to phylogenetic system ?
This allows organisms to be classified based on a common ancestor/ genotype instead of observable characteristics/ phenotype which can be inaccurate/ artificial classification
Explain how Phylogeny producing a continuous tree is advantageous to the phylogenetic system ?
Phylogeny produces a continuous tree whereas classification requires discrete taxonomical groups
Explain how the phylogenetic system is advantageous due to the hierarchal nature of linnaen classification being misleading ?
- Hierarchal nature of Linnaen classification can be misleading as it implies different groups within the same rank are equivalent ( cats and orchids )
- Phylogenic system represents different groups in their evolutionary position so can be compared
Define the term ‘ Evolution’ ?
Evolution : The gradual change in the characteristics of a species over a great period of time as a result of natural selection
Explain how Charles Darwin produces the theory of evolution ?
- He made observations of finches and noticed different islands had different finches
- Although finches shared similar characteristics, their beaks and claws were different shapes and sizes
- He realised that design of the finches beaks was linked to the food available ( birds with beaks better suited to food available would survive longer than those whose beaks were less suited )
- Concluded organisms/ finches best adapted to their environment are more likely to survive, reproduce and pass on their characteristics to offspring resulting in species characteristics changing over time
How did Russel Wallace contribute to the theory of natural selection ?
- He had similar ideas to Charles Darwin
- They both met and published their paper on natural selection together
- He increased weight of evidence of natural selection
What book did Charles Darwin publish ?
He published ‘On the origin of species’ on the theory of evolution by natural selection
What is the evidence for evolution?
- Palaeontology : The study of fossils and fossil records
- Comparative anatomy : The study of similarities and difference between organisms anatomy
- Comparative biochemistry : Similarities and differences between the chemical makeup of organisms
Explain what are fossil records ?
- Fossils are formed when animal/ plant remains are preserved in rocks
- Different layers of rock correspond to different geological eras, most recent layers being at the to while least recent layers are at the bottom
- This forms a sequence from oldest to youngest and shows how organisms have gradually changed over time
What is the evidence provided by palaeontology ?
- Fossils or simple organisms are found in oldest rock while fossils of more complex organisms found in more recent rock ( supports theory that simple life forms gradually evolved into more complex life forms over long period of time )
- Sequence in which organisms are found match their ecological links to each other
- By studying similarities in the anatomy of fossil organisms, scientists can show how closely related organisms have evolved from the same ancestor
- Fossils allow relationships between extinct and living organisms to be investigated
What is comparative anatomy ?
The study of similarities and he anatomy of different living species
What is the evidence provided by comparative anatomy ?
The presence of homologous structures provides evidence for divergent evolution
What is divergent evolution ?
When different species from a common ancestor have evolved each with a different set of adaptive features
When does divergent evolution occur ?
It occurs when closely related species diversify to adapt to new habitats asa a result of migration/ loss of habitat
What is comparative biochemistry ?
It is the study of similarities and differences in the proteins and other molecules that are central to life processes
What is the evidence provided by comparative biochemistry ?
- Some important molecules are highly conserved among species ( DNA/ RNA, proteins such as haemoglobin and cytochrome C )
- DNA/ RNA sequence or amino acid sequence of molecules between species can be compared
- Similarities imply recent common ancestor/ evolutionary similarities ( allow scientists to determine how closely related they are )
- Differences imply evolutionary distance
Define the term ‘variation’ ?
Variation : The differences in characteristics between organisms
Define the term ‘Interspecific variation’ ?
Interspecific variation : The differences between organisms/ members of different species
Define the term ‘Intraspecific variation’ ?
Intraspecifica variation : The differences between organisms within a species
What are the causes of variation ?
- Genetic variation ( Differences in the genetic material an organisms inherits form its parents )
- Environmental variation ( The environment in which the organisms lives )
What are the causes of genetic variation ?
- Alleles
- Mutations
- Meiosis
- Sexual reproduction
- Chance
Explain how alleles lead to genetic variation ?
Alleles of a gene code for a specific characteristic. Individuals in a species may inherit different alleles of a gene resulting in genetic variation.
Explain how mutations lead to genetic variation ?
Mutations cause changes to the DNA sequence which leads to changes in the proteins that are coded for a gene. These proteins can affect physical/ metabolic characteristics.
Explain how meiosis lead to genetic variation ?
Gametes are produced by the process of meiosis where genetic material inherited from tow parents is ‘mixed up’ by independent assortment and crossing over resulting in genetic variation
Explain how sexual reproduction leads to genetic variation ?
Offspring produced from two parents inherit genes/ alleles from each of the parents. Therefore each individual produced differs from their parents.
Explain how chance leads to genetic variation ?
It is a result of chance that determines which gametes combine, resulting in a unique combination of genetic material resulting in variation
What are the causes of environmental variation ?
All organisms are affected by the environment in which they live in leading to environmental variation
What are the two types of variation that can be portrayed graphically ?
- Discontinuous variation
- Continuous variation
What is discontinuous variation ? Give examples.
A characteristic that can only result in certain categories ( categorical data )
eg. Eye colour, hair colour, blood group
How is discontinuous variation represented ?
Bar charts
What is continuous variation ? Give examples.
A characteristic that can take any value within a range
eg. Height, weight
How is continuous variation represented ?
Typically collected in a frequency table and plotted o a histogram with a bell curve drawn to show the trend
What are the features of a normal distribution curve ?
- Mean, mode and median are the same
- 50% values are less and more than mean
- Most values lie close to mean value, extremities are low
What does standard deviation/ student t-tests and spearman’s rank correlation coefficient show ?
- Standard deviation : The measure of how spread out the data is
- Student t-test : used to compare the means of data values of two populations
- Spearman’s rank : used to show the relationship between two sets of data
Can you calculate the standard deviation ?
Yes
Can you do the student’s t test ?
Yes
Can you calculate Spearman’s rank correlation coefficient ?
Yes
