Section 1:  Short answers;  (2 marks each)  answer non-mulitple choice questions in only one, or at most 2 sentences or phrases.

1.1   A single, Europa-sized exomoon is discovered in orbit around an exo-Jupiter that itself orbits a Sun-like star.  This planet orbits at 10 AU from its star and the moon’s orbit is at      about the same distance as Europa is around our Jupiter.   Is this Moon habitable?  (yes or no).  If so, by what mechanism?  If not, why not?

1.2   Circle one:  The carbon in your bodies is a consequence of

a) carbon synthesis in Sun-like stars   b) planetary nebulae   c) supernova explosions

d) helium flashes

1.3  For Earth- like planets,  what is the scaling relation between the radius of a planet in terms of its mass?  Give the simple derivation stating your assumption.

1.4  Circle one:  The source of the nitrogen atoms in nucleotides is

a) molecular nitrogen    b) ammonia   c) methane   d)  hydrogen cyanide   e) formaldehyde

1.5   What is the streaming instability?  How does it work and what kinds of objects (name, approximate sizes) are produced?

1.6  During the post main-sequence evolution of the Sun, at what solar luminosity will     Jupiter’s orbit (5AU) lie in the middle of the Habitable Zone (ie Earth-like flux)?  Give your answer in units of current solar luminosity.

1.7  What kind of energy drives the formation of RNA, or peptides, in pre-biotic environments?  State the bonding mechanism and give name of the bond.

1.8.  What role does a certain mineral (name it) play in the formation of important biological sugars, such as ribose?

1.9  What are two major types of evidence that suggest that early Mars had warm and wet conditions?

1.10  Suppose that a microbe is discovered within the top meter of the surface of Mars . Given that the planet’s surface temperature is -55C, why could life be present at these temperatures (explain)?

Section 2. (3 marks each)  Medium Questions – respond with no more than 3 – 4 bullet points. Answers requiring diagrams need to be hand drawn, and very clearly labelled.

2.1 Draw the Lewis diagram for phosphate molecule, PO4 .  Clearly state whether it is nucleo- or electro-philic, give the reason why, and state what molecule it bonds to in RNA.

2.2  Why does water freeze?   Sketch a small piece of ice (4 water molecules, say) showing the atoms, and indicating any bonds that is part of your answer, with dashed lines.

2.3  i) Draw a portion of a  lipid bilayer, containing 10 schematic lipid molecules, derived from meteorites.  Label the orientation of hydrophobic and hydrophilic structures.  ii) How does      such a structure limit the flow-through of molecules in protocells? (indicate this region in your diagram).   Iii) Assuming that non-living protocells have no proteins, what properties of          membranes could give rise to good transport of nutrients across their membranes?

2.4.   In early oxygenic photosynthesis used by the first cyanobacteria: i) what is meant by “reducing power”?  ii) what is the energy source,  reactants, and products?  Iii) what         molecule is the electron donor?

3.  Longer Questions (6 marks each).  All drawings hand drawn, and clearly labelled.

3.1. A planet is discovered that orbits around a sun-like star.  (a) It is concluded that the planet has a radius that is 1% the radius of its star.   What observation has been done to deduce this?   Give a sketch of the data and clearly labelled axes.   What is the fractional change of the light from the star?

(b) What method can be used to measure this planet’s mass?  What measurements need to be made?  Sketch the data expected with a clearly labelled graph .

(c )   For a Jupiter-mass planet described above, if the star’s period is a year, what is the observed orbital velocity of the star expected to be?

3.2.  Life on Titan?   (a) Give the main pieces of evidence for the existence of a liquid on the surface of Titan.  What liquid is it?

(b) Compare the ability of this liquid with that of water, to dissolve materials.  In your    explanation, draw a Lewis diagram for this molecule.   What makes water such a good solvent in comparison (give physical or chemical reason).

(c) The Cassini probe found abundant HCN in Titan’s atmosphere.   How is this molecule synthesized (main reactants and reactions, energy source).

3.3 (a) In your OoL experiment, you saw that it is likely that 150 nucleotides may have been polymerized into RNA strands.  If such RNAs could successfully self-replicate, what value   does the fidelity of RNA nucleation reactions need to be in order to ensure that such a         molecule – having a superiority of just 3 – is able to emerge from a random pool?

(b) Describe how molecular evolution could produce long RNA strands with high fidelity  starting from a very large pool of short chains and low fidelity.  Focus on an example of a selection pressure on RNA that has been carried out in a well-known laboratory study.