Biogeography
Define biodiversity
The variety of species, ecosystems, and genes that exist in a particular area.
Name the five mechanisms of evolution
1. Mutation
2. Crossing over (sexual reproduction)
3. Gene flow
4. Genetic drift
5. Natural selection
Define natural selection
Process where organisms become better adapted to a particular enviornment over time, which increases their chances of surviving and reproducing
List three features of all organisms within a species
1. Phenotypically similar
2. Capable of interbreeding
3. Produce fertile and viable offspring
Name the three mains types of fossils
Direct evidence
Indirect evidence
Trace fossils
Why do evolution scientists study embryology and anatomy?
To determine how closely related species are.
Species
a group of organisms than can reproduce with each other to create fertile offspring
Name the supercontinent
Pangea
Define mutation, and identify its effect on variation in a population.
Mutation is a random change in the genetic sequence of an organism’s DNA.
Increases variation.
Name the four steps of natural selection.
1. Variation
2. Selection pressure
3. Selective advantage
4. Heritability
Define speciation
The process where a new species forms via natural selection
Define fossil
Any part of, or impression made by, a plant or animal that survives following the organism's death
Distinguish between comparative embryology and comparative anatomy.
Comparative embryology compares the embryonic development of species, whereas comparative anatomy compares the body parts and structures of species.
Population
a group of the same species in an area
How long ago did Earth form?
4.54 billion years ago
Define crossing over, and identify whether it increases or decreases variation.
Crossing over is the random combination of chromosomes that occur during meiosis (sexual reproduction).
Increases variation.
What does the phrase 'survival of the fittest' mean?
Organisms who are most suited to the situation / environment / selection pressures are more likely to survive, reproduce, and pass on their genes.
Variation exists in the population
Genetic Isolation occurs
Selection
Speciation - no longer interbreed
State the three requirements for fossilisation to occur
Rapid burial
No decomposition
Undisturbed
Name two structures that can be compared to assess relatedness.
Analgous structures
Homologous structures
Variation
the different characteristics of individuals of the same species
Define Biogeography
How species and ecosystems are distributed across the Earth.
Define natural selection, and identify whether it increases or decreases variation.
Natural selection is where one variation provides an organism a higher chance of surviving and reproducing.
This reduces overall variation as those without this adaptation are less likely to survive.
List the three types of selection pressures, and provide ONE example of each.
Resource pressures - food, shelter, mate availability
Environmental pressures - temperature, weather, geography
Biological pressures - predators, diseases
Distinguish between geographic isolation and reproductive isolation.
Geographical isolation: separation of populations due to land barriers.
Reproductive isolation: when two populations of the same species can no longer successfully reproduce with each other to produce fertile offspring.
Provide an example of each of the three types of fossils (direct evidence, indirect evidence, trace fossil).
Direct evidence - bones; teeth; shells
Indirect evidence - burrows; faeces
Trace fossils - foot prints; nests; scratch / bite marks
Distinguish between analogous and homologous structures, and provide an example of each.
Analogous structures: body parts that have the same function, but do not have a common ancestor. Eg. Sharks, penguins, dolphins all have fins for swimming, but they did not come from a common ancestor.
Homologous structures: body parts that have a similar structure but are used for different purposes. Eg. A human arm, a cat’s leg, and a whale’s flipper all have the same bone arrangement but are used for different things.
Define adaptation
a variation that helps an organism survive / reproduce
Why did the splitting of Pangea lead to biodiveristy?
Oceans blocked travel by creatures, meaning they could no longer interact
Distinguish between gene flow and genetic drift. Reference whether each increases or decreases variation
Gene flow occurs when one population interbreeds with another, introducing new alleles therefore increasing variation.
Genetic drift is when a random event occurs that changes the frequency of alleles in a population. This usually reduces variation.
A population of beetles lives on tree trunks. Most beetles are brown, but some are green. Birds can easily see the green beetles against the brown tree trunks and are more likely to eat them.
a) Identify the selective pressure acting on the beetle population.
b) Explain why being brown gives some beetles a selective advantage
a) selective pressure = predation by birds
b) being brown allows the beetles to camouflage against brown tree trunks, reducing the likelihood of being eaten by birds
Distinguish between absolute dating and relative dating.
Absolute dating - provides a specific age of a fossil by analysing the half life of isotopes in the surrounds of the fossil.
Relative dating - provides an approximate age by comparing the fossil to fossils of known age (index fossils).
Define vestigial structure and provide an example of each.
- Vestigial structure: body parts that have become very small because they are no longer useful.
- Example: tailbone (coccyx) in humans OR pelvis in whales
Define evolution
the genetic change in a population over time