Part A Multiple Choice
1. Which of the following has not been demonstrated by scientific means? Life on Earth:
a. has existed for about 4 billion years.
b. originated in comets that subsequently collided with the planet.
c. has evolved to fill some of the most extreme environments on the planet.
d. survived the gradual brightening of the Sun over its history so far.
2. Which of the following concerning Population II stars is false?
a. Population II stars are the oldest stars observed in the universe today.
b. Population II stars are less metal rich than Population I stars.
c. Population II stars are found in globular clusters in the galactic halo.
d. Population II stars formed earlier than Population III stars.
3. Which of the following is false for a prokaryotic cell?
a. contains ribosomes.
b. has a cell wall.
c. is small compared with eukaryotic cells.
d. has an enclosed nucleus.
4. The DNA in a eukaryotic chromosome is:
a. a single linear double-stranded molecule.
b. a single circular double-stranded molecule.
c. a single linear single-stranded molecule.
d. a collection of small linear double-stranded molecules.
5. Which of the following is false?
a. Both the transit and radial velocity methods for detecting exoplanets are more sensitive to massive planets orbiting close to their parent stars.
b. The transit method can be useful only for detecting gas giant planets.
c. Most exoplanets have been discovered with the transit method.
d. It is easier to directly image a planet if it is orbiting close to its parent star.
6. Most of the observed extra-solar planetary systems
a. are very similar to our Solar System.
b. they have Earth-like planets.
c. have been discovered by direct imaging.
d. have gas giant planets. 7. The molecule CO2 can be drawn schematically as O=C=O. Which of the following is false?
a. The molecule contains two double bonds.
b. Each oxygen atom has gained two electrons to form an ion.
c. Each oxygen atom has a share in eight electrons in its outer shell.
d. The carbon atom has a share in eight electrons in its outer shell.
8. A 2.0 solar-mass main sequence star hosts a planet with an orbital period of 3.0 years. Use Kepler’s laws and the main-sequence mass-luminosity relationship, L/LSUN=(M/MSUN) 4, to determine which of the following is false:
a. The orbital radius of the planet is about 2.6 astronomical units.
b. The speed of the planet in its orbit is about 41 km s-1.
c. The flux from the star at the planet is about 3,200 Wm-2.
d. The equilibrium temperature of the planet is about 345 K.
9. Which of the following is true?
a. The Sun’s luminosity remains constant while it is on the main sequence.
b. Volcanic activity may replenish the atmosphere of a planet or satellite.
c. Titan used to have an atmosphere similar to Earth’s early atmosphere but was lost due to tidal interactions with Saturn
d. The main reason that the tidal forces acting upon Io result in volcanic activity is the high mass of Jupiter
10. Which of the following is false?
a. Isomers are molecules with the same compositional formula but different structures.
b. Glucose and sucrose are isomers.
c. Glucose and fructose are isomers.
d. Isobutane and n-butane are isomers.
Part B Conventional questions
1. Efficiency of energy production by aerobic and anaerobic mechanisms
a. Briefly explain what is meant by (i) ‘aerobic metabolism’ and (ii) ‘anaerobic metabolism.’
b. Briefly explain why aerobic metabolism is more productive at producing energy than anaerobic metabolism.
2. Exoplanet detections:
An exoplanet transit survey observes a nearby star that is similar to our Sun (Mstar=MSun, Rstar=RSun). The relative flux of this star shows a modulation as seen on the figurebelow. a. How many exoplanets orbit this star and why?
b. What are the periods of these planets and what are their distances from the central star (assuming circular orbits). What is characteristic about the planets’ orbital periods?
c. Determine the radii of these planets.
d. In order to determine the density of each planet in the system what additional observation could you do? Explain.
3. Habitable zones
a. What is meant by the term “habitable zone” around a star?
b. The data in the table below is taken from the Extra-Solar database at http://exoplanet.eu/catalog.php. Using any appropriate data from this table determine if the exoplanet HD 149026b orbits its host star within the habitable
zone. Comment on your result.
4. Life in the solar system
a. Summarise the characteristics that living systems display.
b. Consequently what conditions are required by the living systems from their environment?
c. Using these conditions make a list of the solar system sites where some or all of them currently exist or might have existed in the past. d. Assuming you are in charge of a national level science programme select two of these sites; put priorities on each, briefly stating your reasons. Your arguments should be based on the science (astrobiology/environment) and the technological challenge in reaching the site.
5. Hot Jupiters may have atmospheric temperatures at the exobase of 5,000 K.
a. If the Earth was close enough to the Sun to be that hot, calculate the particle flux lost due to Jeans escape for molecular hydrogen, atomic helium and atomic carbon.
b. Comment on this in comparison to the Earth as it is, and the likely impact on the atmosphere of a planet such as a hot Jupiter in such conditions.
6. Environment on Mars
a. Calculate the equilibrium temperature for Mars, and compare it with the measured surface temperature.
b. Estimate the temperatures for escape of hydrogen, carbon, oxygen and nitrogen on Mars and compare with the equilibrium and measured temperatures. Hint: you can assume a species is lost from the atmosphere if its root mean square velocity rms v exceeds about 1/6 of the escape velocity.
Part A Multiple Choice