Formation of Mature Active rRNA
Part A Multiple Choice
1. In the formation of mature, active rRNA, which of the following is false?
a. Precursor rRNA is formed by transcription from ribosomal DNA in the chromosomes.
b. The self-splicing intron contains the non-coding region.
c. When a self-splicing intron is excised from the precursor rRNA, no other components are involved.
d. The mature spliced rRNA consists of exons joined together to form a continuous coding sequence.
2. Which of the following statements concerning condensation reactions is false?
a. A condensation reaction occurs when 2 molecules are joined together by removing
a molecule of water between them.
b. When two amino acids join together by means of a condensation reaction they form a dipeptide.
c. Water is produced as a bi-product when acetic acid reacts with a phosphate molecule.
d. When a new DNA strand is made, the two halves of the ‘rung’ are bonded together by a condensation reaction between the bases A=T or G=C.
3. Which of the following is true regarding the role of ozone in relation with life?
a. Ozone is more opaque to ultraviolet radiation than oxygen and absorbs radiation that could harm biological systems.
b. Ozone is created independently of oxygen in the upper levels of the atmosphere.
c. Ozone is needed along with oxygen for breathing organisms.
d. Ozone is produced as a by-product of the breathing process of living organisms.
4. Which of the following concerning chiral properties is true?
a. Enantiomers can be superimposed on to one another.
b. The plane of polarization of light when passed through enantiomers is always to the right.
c. All amino acids found on Earth are of the left-handed form.
d. The biological form of glucose is levorotatory
5. Communication delays between the Earth and astronauts can lead to:-
a. A decrease in reported communication and teamwork between astronauts.
b. A decrease in well-being.
c. An increase in self-reported performance.
d. A decrease in self-reported performance.
6. Which sense did researchers experiment with in order to try to reduce homesickness?
a. Smell.
b. Taste.
c. Touch.
d. Sound.
7. Which of these is false in presence of microgravity?
a. There is a slight decrease in mammalian cell size.
b. Synthesis of mRNA in live animals is reduced.
c. Growth rate of cells decreases 2-3 fold.
d. Rat cells contain less growth hormone.
8. Which of the following atmospheres is in the breathable zone?
a. 100% oxygen at 1.0 atmosphere pressure.
b. 20% oxygen, 80% nitrogen at 0.5 atmospheres.
c. 10% oxygen, 90% nitrogen at 5 atmospheres.
d. 5% oxygen, 95% nitrogen at 1.0 atmosphere.
9. Consider an exoplanet with albedo A=0.35 and effective temperature Teff = 270 K in orbit
about its host star. Which of the following is false?
a. The insolation, S, at the top of the atmosphere is 1854 Wm-2.
b. If the exoplanet were at the same distance from its star, but with albedo A = 0.8, the effective temperature would be 170 K.
c. If the exoplanet with A = 0.35 were located at twice the distance from its star, its Teff would be 191 K.
d. Taking the greenhouse effect into consideration, Tsurf the temperature at the
planetary surface will be higher than Teff for any given insolation and albedo.
10. Which of the following is true?
a. An organism with a small genome can cope well with genetic damage.
b. Retrotransposition leads to a second copy of a gene but it is nonfunctional.
c. The J. Craig Venter Institute has successfully constructed a synthetic genome for a bacterium.
d. Retroviruses have DNA as their genetic material and therefore have an advantage
over organisms using the less stable RNA.
Part B Conventional questions
1. What are the proposals of Oparin and Haldane on how life began on the early Earth?
Discuss how it might be possible to test this hypothesis in part or in full. Summarise any tests together with the main results. Your answer should include a relevant diagram.
2. Alternative chemistry.
a. How does the mass of the silicon atom and its bond length affect the element’s ability to emulate carbon?
b. Give two reasons why silicon life is not a choice favoured by astrobiologists.
c. Give two reasons why biochemists might consider silicon life a possibility.
3. Designers can control the internal temperature of a satellite by carefully selecting the properties of the external surfaces. The absorption co-efficient for solar radiation, a, and the emissivity, e, enable the equilibrium temperature to be calculated.
a. Consider a spherical satellite with an outer shell of polished aluminium in high Earth orbit. The values of a and e are 0.19 and 0.038, respectively, giving a ratio a/e, of 5. Calculate the equilibrium temperature of the satellite (neglecting the effects of the Earth).
b. If the emissivity of the satellite shell is increased by using clear, anodised aluminium, with a = 0.19 and e = 0.625, what is the new equilibrium temperature? Which one of two materials (polished aluminium vs anodised aluminium) would you use if you need to place electronic equipment in orbit?
c. Make the same equilibrium temperature estimate for the Earth (a = 0.6 and e = 0.9). Comment how this compares with the Earth’s observed mean surface temperature.
4. Describe Earth-based studies which have explored the psychological implications of space
exploration (up to ~500 words).
5. Describe three important physiological changes that could occur during a manned mission
to Mars. Explain why you think these are the most important and suggest strategies for
reducing their effect. (up to ~500 words)