Lecture Three - The tree of life

Question 1

Define phylogeny.

Answer 1

A phylogeny is a hypothesis about the evolutionary relationships among various taxa.

Question 2

Define convergence and divergence (analogy and homology).

Answer 2

Convergence, or analogy is where two organisms have no common ancestor, but have similar structures due to having a similar use/function for these structures.

Divergence, or homology is when two organisms have similar structures due to evolving from a common ancestor.

Question 3

Did the impact that wiped out the dinosaurs cause the diversification of mammals?

Answer 3

Not necessarily.

The mammals were already fairly diversified before the impact, and continued to diversify afterwards.

Question 4

Despite diversity, what are the five things that almost all organisms share?

Answer 4

ATP
DNA 
RNA 
Genetic code 
Molecular machinery for transcribing genetic information.

Question 5

How do prokaryotes and eukaryotes metabolise?

Answer 5

Eukaryotes:
Autotrophs.
Heterotrophs.
Some anaerobic metabolism - Yeast.

Prokaryotes:
Many respire using oxygen.
Others use NO2, SO2, or metallic oxides of Fe and Mg.
Or chemoautotrophy, usually occurs by oxidising H or methane etc.

Question 6

What kinds of organisms are usually found in the arches taxon?

Answer 6

Commonly represented by extremophiles.

I.e. organisms which can live in high/low pH, temperature, pressure etc.

Question 7

Which group of organisms are mitochondria and chloroplasts classified in?

Answer 7

Bacteria.