OCR A Level Biology Classification and Evolution

What is the order of classification? (i.e. class, genus etc. in order)

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

What is the name of the groups of classification (i.e. class, genus etc.)?

Taxonomic groups

What were the traditional 5 kingdoms?

Animalia, Fungi, Protoctista, Plantae, Prokaryotae

Who was the first to propose a modern system of classification and when?

Carl Linnaeus in the 18th century, hence it being named Linnaen Classification

What is the binomial naming system?

Where we use the Genus and Species names (in that order) to identify a species

What is an advantage of using the binomial naming system?

It removes the language barrier between two scientists without a common language who wish to talk about the same organism

Can organisms in the same genus reproduce?

Yes, but they only produce infertile offspring

What is the infertile offspring of two organisms of the same genus called?

A hybrid, and has no Latin name

When was the 6-kingdom model of classification with domains first introduced and by whom?

1977 by Carl Woese

What are 3 reasons that scientists classify organisms?

1. To identify species
2. To predict characteristics
3. To find evolutionary links

What is one slight limitation of using a classification system?

The classification is created by humans instead of being defined by nature

What are some features of organisms from the Animalia kingdom?

Multicellular, heterotrophic feeders, no chlorophyll, no cell wall, complex cell structure with nucleus

What are some features of organisms from the Plantae kingdom?

Multicellular, cellulose cell wall, autotrophic feeders using chlorophyll, complex cell structure with nucleus

What are some features of organisms from the Fungi kingdom?

Multicellular, cell walls not made of cellulose, saprophytic feeders so no chlorophyll, complex cell structure with nucleus

What are some features of organisms from the Protoctista kingdom?

Mostly unicellular (a few multicellular), complex cell structure with nucleus

What are the 3 domains?

Eukaryotes, Eubacteria, Archebacteria

Why are some hybrids infertile?

Because they have an odd number of chromosomes

What are some features of Eukarya?

Eukaryotic, bilipid cell membrane, membrane-bound organelles, contain 80S ribosomes, RNA Polymerase has 12 proteins

What are some features of Archaea?

Prokaryotic, monolipid cell membrane, no true organelles, extremophiles, 70S ribosomes, RNA Polymerase has 8-10 proteins

What cellular feature makes Archaea such good extremophiles?

Their monolipid cell membrane is very resistant to being disrupted

What are the main differences between Archaea and Eubacteria?

1. Archaea have no peptidoglycan in their cell wall
2. Different number of proteins in RNA Polymerase
3. Archaea have a monolipid cell membrane, Eubacteria have a bilipid cell membrane
4. Eubacteria are found in all environments whereas Archaea tend to be extremophiles

What are some features of Eubacteria?

Prokarotic, peptidoglycan cell wall, no true organelles, 70S ribosomes, RNA Polymerase contains 5 proteins

Why do scientists think Archaea were some of the earliest life?

They were extermophiles, and conditions on early Earth were very hostile

Are Archaea or Eubacteria more common?

Eubacteria

What is a protein which indicates a shared ancestry between primates?

Haemoglobin- there is only 1 amino acid different between humans and chimpanzees

Where do methanogens live and what do they do?

They live in anaerobic environments such as sewage treatment plants, and make methane

What are some examples of places that extremophilic Archaea live?

Anaerobic conditions, highly acidic environments and hot thermal vents

What does a phylogenetic tree do?

Help us see relationships between organisms and common ancestors

What does it mean when a branch on a phylogenetic tree does not make it to the top of the diagram (i.e. the modern day)?

That the species is extinct

What causes variation within a species?

Random genetic mutations

What is interspecific variation?

Variation which occurs between different species

What is intraspecific variation?

Variation which occurs within a species

What is continuous variation?

Variation which can take any value in a given range

What is discontinuous variation?

Variation which can only take certain values within a given range

How do DNA mutations cause variation?

They can lead do different proteins being coded for, which would give rise to different proteins

What are the 3 genetic causes of variation?

1. Sexual reproduction mixing alleles from the two individuals' gametes
2. Which alleles the gametes contain is down to chance during meiosis (assortment and crossing over)
3. Mutations to the DNA sequence

What is phylogeny?

The evolutionary relationships between organisms

What is phylogenetics?

The study of the evolutionary relationships between organisms

What does the closeness of the branches of a phylogenetic tree mean?

The closer the branches, the more closely related the organisms are

How can classification use phylogeny?

To confirm that classification groups are correct, or that they need to be changed

What are two advantages of phylogeny over classification?

1. Phylogeny allows production of a continuous tree instead of placing organisms into discrete groups like classification
2. Hierarchical nature of classification can be misleading as it implies, for example, that the orchid and cat families are equal, even though there are 35 cat species and 30,000 orchid species. Phylogeny clarifies this.

What shape is a normal distribution?

A 'bell curve'

What percentage of things in a normal distribution are within 1 standard deviation of the mean?

68%

What percentage of things in a normal distribution are within 2 standard deviations of the mean?

95%

What percentage of things in a normal distribution are within 3 standard deviations of the mean?

99.7%

What are the same in a normal distribution?

Mean, median and mode

How would a new species form?

The gradual accruement of enough genetic changes over time

How can intraspecific variations be useful?

They can be beneficial if the environment changes; the better the adaptation, the more likely the organism will be to survive and the more likely the variation will be passed on

In which animals did Darwin first see evidence for evolution?

Finches in the Galapagos Islands

What 2 animals did Darwin study in order to provide more evidence for evolution?

Barnacles and Pigeons

Who was the other person, along with Darwin, who helped first propose the theory of evolution?

Alfred Wallace

What is Alfred Wallace better known for his work on?

Warning colouration

How does warning colouration benefit the predator?

It knows not to even try to eat the organism, and so will survive better

Do we have a full fossil record for humans?

No, but we do for some other animals such as horses

What are living fossils?

Species, such as sharks, which are so well adapted to their environment that they have remained largely unchanged for millions of years

What is palaeontology?

The study of fossils and the fossil record

What is comparative anatomy?

The study of similarities and differences between organisms' anatomy

What is comparative biochemistry?

The study of similarities and differences between the chemical makeups of organisms

What 3 main fields of study did scientists use to provide evidence to support evolution?

Palaeontology, comparative anatomy and comparative biochemistry

What types of fossils can be preserved with little decay?

1.Soft tissues found in anaerobic or very cold conditions
2. Hard tissues left behind (i.e. the imprints of bones in rock)

How are bones fossilised?

They are mineralised and turn to rock, before being exposed by the Earth's shifting crust

What is convergent evolution?

Where species from different families or genera evolve similar adaptations to their environment, i.e. bats and birds both evolving wings

What are some reasons that the fossil record is incomplete?

1. Many early organisms were soft-bodied, so left no or very little trace
2. There are many fossils yet to be found
3. Many organisms which died weren't fossilised as the right conditions for fossilisation are rare
4. The majority of early fossils will have been destroyed by geological processes, a factor in why we are unsure how life on Earth began

What is some evidence for evolution provided by the fossil record?

1. Fossils of simple organisms are found in older rocks whilst fossils of more advanced organisms such as vertebrates are found in newer rocks
2. The sequence in which fossils are found match their ecological links to each other
3. Fossils allow relationships between extinct and living organisms to be studied
4. We can study similarities in fossil anatomy to work out how closely related organisms evolved from the same ancestor

What is a homologous structure?

One which appears superficially different in different organisms, but has the same underlying structure

What is divergent evolution?

It describes how organisms have evolved from a common ancestor, each with a different set of adaptations

When does divergent evolution occur?

When closely related organisms diversify to new habitats

What are two proteins which have remained almost unchanged over time, and can be used to compare species?

1. Ribosomal RNA
2. Cytochrome c Oxidase, a protein involved in respiration

What does the theory of neutral evolution state?

That most changes to a molecule's structure don't affect its structure as they occur outside the functional region, so these 'neutral' changes are not affected by natural selection

How can scientists establish a common ancestor using comparative biochemistry?

They can compare the molecular structure of a particular molecule in two species, and the number of differences which exist can be plotted against the rate at which the molecule undergoes neutral substitutions (which has already been established)

What are the two main factors which cause variation and what type of variation does each cause?

1. The environment in which an organism lives, which causes environmental variation
2. An organism's genetic material; differences in genetic material an organism inherits from its parents leads to genetic variation

What is variation caused by in most cases? (genetic or environmental factors)

A combination of both genetic and environmental factors, which is why it is so difficult to determine exactly what causes a characteristic unless you examine identical twins

How many genes are most examples of discontinuous variation caused by?

A single gene

How many genes are most examples of continuous variation caused by?

Multiple genes, as well as being influenced by environmental factors

What is the student T test used for?

Used to compare means from 2 sets of data to see if they are statistically different

What are the three types of adaptations?

1. Anatomical- internal/external features
2. Physiological- internal processes
3. Behavioural- ways of acting, can be innate or learned, usually from parents

What are analogous structures?

Parts of two different organisms' anatomy which have different structures but perform the same function

What are some examples of physiological adaptations?

Poison production, antibiotic production, water holding

What are some examples of behavioural adaptations?

Survival behaviours such as playing dead, courtship, seasonal behaviours such as migration and hibernation

What are some examples of anatomical adaptations?

Camouflage, body covering by fur, scales etc., teeth, mimicry i.e. flies coloured like wasps

Can convergent evolution occur in plants?

Yes

What are selection pressures?

Factors which affect an organism's chances of survival or reproductive success

What are the 5 steps of evolution?

1. Existing genetic variation within a species caused by random genetic mutations and sexual reproduction
2. Organisms whose adaptations allow them to be best survive selection pressures will be more likely to survive, whilst weaker organisms without said adaptations may die
3. Organisms with this advantageous trait will be more likely to pass it onto their children
4. Reproductive success causes a larger proportion of organisms to have this adaptation over time.
5. Over a long period of time this may lead to the formation of a new species

What are 4 examples of organisms which have recently evolved due to a human-caused selection pressure?

1. Flavobacterium
2. Sheep blowflies
3. MRSA
4. Peppered Moths

How and why did Peppered Moths recently evolve?

Most were pale before the industrial revolution, then a greater proportion of black or dark ones during the industrial revolution when trees were covered in soot, now due to cleaner air and trees a higher proportion of pale ones again

How and why did Sheep Blowfly recently evolve?

An organophosphate pesticide was used to kill them in the 1950s, so a very high proportion became resistant to the pesticide used, which was found to be contributed to by a previous resistance to a similar organophosphate pesticide

How and why did Flavobacterium recently evolve?

They live in the waste water of Japanese nylon 6 factories, and have evolved nylonase enzymes to help them digest this nylon to provide a new source of food