B5.2 Flashcards
What is evolution?
Change in inherited characteristics of a population over time via natural selection.
What can evolution result in?
Formation of a new species.
Who proposed the Theory of Evolution?
Darwin and Wallace.
What did the Theory of Evolution suggest?
All species evolved from simple life forms over 3 billion years ago.
What causes evolution?
Natural selection.
What provides variation between organisms?
Mutations
What happens if a mutation provides a survival advantage?
Organism is more likely to survive to breeding age.
What happens to advantageous mutations?
Passed on to offspring.
What happens to the frequency of mutations over generations?
It increases in the population.
Why is there usually a lot of variation in a population?
Due to random mutations in genes.
What can variation within species lead to?
Speciation (formation of new species).
What is speciation?
When populations become so different they can no longer interbreed to produce fertile offspring.
What is artificial classification?
Classification based only on observations.
Who invented the artificial classification system?
Carl Linnaeus.
What system did Linnaeus invent?
The Linnaean system.
What groups are in the Linnaean system?
Kingdom, phylum, class, order, family, genus, species.
What was Linnaeus’ system based on?
Human judgement.
What is natural classification based on?
Advances in biology like microscopes, biochemistry, DNA.
What is phylogenetics?
Study of how closely related organisms are via evolutionary history.
What is DNA sequencing used for in classification?
Comparing protein structures between species.
Who added the three domains above kingdoms?
Carl Woese.
What are the three domains Woese added?
Archaea, Bacteria, Eukaryota.
What are Archaea?
Primitive bacteria in extreme environments (e.g. hot springs).
What are Bacteria?
True bacteria (despite some similarities to archaea).
What are Eukaryota?
Organisms with nuclei in membranes (includes fungi, protists, plants, animals).
What is the binomial system?
A two-part name for organisms: genus and species.
Why is the binomial system useful?
Overcomes language barriers, used worldwide.
Example of binomial name?
Harmonia axyridis (ladybug).
What are fossils?
Remains of organisms from millions of years ago.
How are fossils formed - three ways?
1) Hard parts not decaying, 2) Replacement by minerals, 3) Casts of traces like footprints
What is the first way of fossils being formed?
- Parts of organisms not decayed - oxygen & moisture not present meaning microbes that cause decay cannot survive
What is the second way of fossils being formed?
- Parts of organisms such as teeth, bones etc are replaced by minerals as they decay - forming a rock structure of original part
What is the third way of fossils being formed?
- Preserved traces eg footprints, burrows etc remain due to ground hardening around them & forming a cast
What do fossils show us?
How anatomy has changed over time.
What can fossil comparison reveal?
How closely related organisms are (used in evolutionary trees).
What is antibiotic resistance in bacteria?
Bacteria evolve to survive antibiotics and reproduce resistant offspring - pass on advantageous gene
What causes antibiotic resistance to spread?
Selection pressure from antibiotics.
What is an example of resistant bacteria?
MRSA – resistant to many antibiotics.
What was Darwin’s book called?
On the Origin of Species.
What did Darwin’s theory state?
Variation occurs due to mutations, survival of the fittest - more likely to survive w wanted characteristics
What happens to beneficial traits?
Passed to next generation.
Over generations, what increases?
Frequency of advantageous alleles.
Why was Darwin’s theory controversial?
1) Contradicted religion, 2) Little evidence then, 3) Inheritance mechanism unknown.
What was Wallace known for?
Supporting evolution and developing theory of speciation.
What causes speciation? (Step 1)
Variation from mutations.
Step 2 in speciation?
Advantageous alleles selected.
Step 3 in speciation?
Isolation (e.g. by barriers like rock falls).
Step 4 in speciation?
Different alleles selected in new environment.
Step 5 in speciation?
Genetic differences build up.
Step 6 in speciation?
Reproductive isolation → new species.
