Test is Thursday, February 26.


1. What is the scientific definition of evolution?

Evolution is a change in allele frequencies in a population over time.

There are two main points in evolution...
  1. Present day organisms are descendants of ancestral species that are different from the modern species.
  2. The main mechanism for this this evolutionary process is Natural Selection.

2. Explain the four processes of natural selection. You need to rewatch the video that was shown in class called "How Does Evolution Really Work" (Video 4) by clicking here.

1. genetic variation - individuals with a genetic advantage will survive and reproduce.
2. overproduction of offspring - individual species produce more than the enviroment can carry, and that is to ensures that a species survives.
3. struggle for existence - overproduction causes a species to struggle and compete for food, space, and mates.
4.differential survival and reproduction - only the ones who are fit to survive will reproduce.

3. Explain how the following lines of evidence support evolution:

a) Fossil evidence - by compairing fossils found in older rock layers to fossils found in younger rock layers, you can begin to see a gradual complex changes in their forms, and compare those to species that currently exist.

b) Biogeography - supports evolution by seeing if the species live in a similar geographic area.

c) Homologous structures (including vestigial, homologous structures) - structures found in a species that are similar that are related by a common ancestor

Vestigal structures - homologous structures that may have had important functions in ancestral species, have no clear function in some modern descendants.

d) Embryology (Evolutionary Development) - You can determine the relatedness between species by comparing the developing fetuses.

e) Molecular Data- you can determine relatedness within a species based on DNA evidence, therefore, you can determine relatedness between species based on the same type of evidence.

4. Define speciation.
Formation of a new species.
5. Explain how allopatric and sympatric speciation lead to new species evolving.
With sympatric speciation, new species evolve from the appearance of new ecological niches or nonrandom mating. This kind of speciation involves no geographic barriers. With allopatric speciation, one or both populations undergo a change, and they can't mate anymore, so they're now two different species. This kind of speciation can involve geographic barriers.

6. How is evolution relevant today? Using examples given in class or available here, be able to explain how understanding evolution helps us:

a) solve crimes - DNA can be taken from the crime scene and compared to a suspect. If those two DNA samples match, then that's the person that committed the crime. Everyone's DNA is different because of evolution; evolution is what causes peoples' alleles to change through generations.

b) understand disease and create new medicines - New treatments and medicines for diseases are always in demand because the diseases evolve through natural selection to become resistant to existing medicines. Scientists try to develop treatments that diseases are not resistant to.

c) trace our family history-

d) conserve endangered species

e) improve agriculture- because we know pests can evolve and become resistant to pestisides farmers are using different farming practices such as disease resistant plants which is healthier for the environment.

7. What is cancer?
Cancer is a loss of cell control. All cancer is due to genetic mutation. Most mutations occur during an individual's lifetime and are not inherited (although some people have inherited a genetic predisposition for a higher likelihood that mutations will occur).
8. Explain the history of HeLa cells.
HeLa cells were, and still are, some of the strongest cells known to science. They reproduce an entire generation every 24 hours. The first sample of her cancer went to George Gey, head of tissue culture research at Hopkins. Her cells were the first cells to survive beyond the 50th generation ad are still growing.