1. The spectrum of an extrasolar planet peaks in the:
a. infrared.
b. optical.
c. gamma rays.
d. X-ray.
e. ultraviolet.

2. Which of the following are called `Greenhouse Gases', since they contribute the most to the Greenhouse Effect?
a) CO₂, H₂O, and methane.
b) H₂.
c) Ozone.
d) O₂ and N₂.
e) Argon.

3. What does the first term in the Drake Equation R_* stand for?
a) The distance from the Earth to the Sun.
b) The radius of the Earth.
c) The rate of evolution of a star.
d) The rate of star formation in the Milky Way.
e) The lifetime of a star, as a main sequence star.

4. Which of the following is most important in protecting us from the solar wind?
a) the Earth's magnetic field.
b) the ozone layer.
c) the greenhouse gases.
d) N₂ in our atmosphere.
e) the solar wind is not dangerous.

5. The reason the core of the Earth is very iron-rich compared to the crust of the Earth is:
a) the iron was attracted by the strong magnetic field of the Earth.
b) tidal forces from the Moon pushed iron to the center of the Earth.
c) differentiation in the young molten Earth.
d) plate tectonics.
e) the Earth's core is not iron-rich.

6. Which of the following objects has no global magnetic field?
a) Earth.
b) Mars.
c) Venus.
d) Mars and Venus.
e) All of them have strong global magnetic fields.

7. The magnetic field of the Earth is caused by:
a) The solid inner core of the Earth, which is a strong magnet.
b) The solar wind.
c) A magnetic dynamo caused by the motion of charged particles in the liquid outer core.
d) The rotation of the Earth creating an electric current in the semi-liquid upper layer of the Earth's mantle.
e) Plate tectonics.

8. In the Greenhouse Effect, what type of radiation is trapped by the Earth's atmosphere?
a) Ultraviolet.
b) Infrared.
c) Visible.
d) Radio.
e) The solar wind.

9. Which of the following molecules contributes significantly to the Greenhouse effect?
a) Nitrogen.
b) Oxygen.
c) Carbon dioxide.
d) Ozone.
e) Hydrogen.

10. The Greenhouse Effect is caused by:
a) X-rays from the Sun being trapped by the ozone layer.
b) Infrared light from the Sun being trapped by the Earth's magnetic field.
c) Infrared light from the Earth being trapped by the Earth's lower atmosphere.
d) X-rays being absorbed and re-emitted by the Earth's atmosphere.
e) Ultraviolet light from the Sun being absorbed by the ozone layer.

11. In a DNA molecule, the base cytosine connects to:
a) adenine.
b) guanine.
c) thymine.
d) cytosine.
e) all of the above.

12. Which of the following planets has the least Greenhouse Effect?
a) Venus.
b) Earth.
c) Mars.
d) They are all about the same.
e) The Earth and Mars have about the same Greenhouse Effect; Venus's is larger.

13. The albedo of a planet is:
a) The density of the planet.
b) The color of the planet.
c) The type of atmosphere the planet has.
d) The reflectivity of the planet.
e) The temperature of the planet.

14. In a DNA molecule, the bonds that connect the bases to each other are:
a) hydrogen bonds.
b) carbon-carbon single bonds.
c) carbon-carbon double bonds.
d) phosphodiester bonds.
e) CORN bonds.

15. A fragment of a DNA molecule is shown to the right. The molecule marked by an `A' is adenine; the molecule marked by `T' is thymine, and the molecules marked by `G' are guanine. What is the molecule marked by an `X'?
a) phosphate.
b) deoxyribose sugar.
c) cytosine.
d) guanine.
e) adenine.

16. In the figure to the right, what type of molecule is marked by a `Y'?
a) phosphate.
b) deoxyribose sugar.
c) cytosine.
d) guanine.
e) adenine.

17. In the figure to the right, what type of molecule is marked by a `Z'?
a) phosphate.
b) deoxyribose sugar.
c) cytosine.
d) guanine.
e) adenine.

18. In the figure to the right, what type of bonds connect adenine and thymine?
a) hydrogen bonds.
b) phosphodiester bonds.
c) peptide bonds.
d) carbon-carbon double bonds.
e) nitrogen-nitrogen double bonds.

19. In chemistry, the term `hydrogen bond' refers to:
a) the hydrogen-hydrogen bond in a molecule of H₂.
b) The bonds between hydrogen and carbon in a methane molecule.
c) When hydrogen shares a pair of electrons with another atom.
d) A weak attraction between a hydrogen atom in a molecule and an unshared pair of electrons in an atom in another molecule.
e) When two hydrogen nuclei fuse together to form helium.

20. Differentiation means:
a) the absorption of infrared light by the Earth's lower atmosphere, and ultraviolet light by Earth's upper atmosphere.
b) the production of a global planetary magnetic field by circulation in a liquid outer core.
c) the fact that moving charged particles create magnetic fields.
d) the tendency of dense material to sink and light material to rise in a gravitational field.
e) the deflection of a moving charged particle by a magnetic field.

21. In a human DNA molecule, how many base-base pairs are there?
a) 1.
b) 10.
c) 100.
d) 3 billion.
e) 10²⁷.

22. The Earth's magnetic field is generated by:
a) The ozone layer.
b) The solar wind.
c) The upper layer of the mantle of the Earth.
d) The liquid outer core of the Earth.
e) The solid inner core of the Earth.

23. Infrared radiation from the Earth is:
a) absorbed by the ozone layer.
b) responsible for the greenhouse effect.
c) responsible for the Earth's magnetic field.
d) responsible for plate tectonics.
e) the Earth does not emit infrared light.

24. In a water molecule, how many pairs of electrons is the oxygen atom sharing with other atoms?
a) none.
b) one.
c) two.
d) three.
e) four.

25. Which of the following planets or moons has the most Greenhouse Effect?
a) Venus.
b) The Moon.
c) Earth.
d) Mars.
e) They are all about the same.

26. Which of the following bonds in a DNA molecule is the weakest?
a) The bonds between the phosphates and the sugars.
b) The bonds between the bases and the sugars.
c) The bonds between two bases.
d) The bonds between the amino acids.
e) The bonds between the amino acids and the sugars.

27. In the double helix structure of DNA, two long strands of molecules are connected by `rungs', like the rungs in a ladder. The strands are sequences of:
a) amino acids.
b) deoxyribose sugar and bases.
c) deoxyribose sugar and amino acids.
d) deoxyribose sugar and phosphates.
e) phosphates and bases.

28. Having a strong magnetic field may be a factor in whether or not a planet is inhabited, because:
a) a magnetic field contributes to the Greenhouse Effect.
b) a magnetic field helps keep a planet warm.
c) a magnetic field protects us from ultraviolet light from the Sun.
d) a magnetic field protects us from tidal forces from the Moon.
e) a magnetic field protects us from the solar wind.

29. The fact that the Earth's core is mainly iron is evidence that:
a) The Earth has an external magnetic field, extending into space.
b) The Earth has an ozone layer.
c) The Earth was molten when it was young.
d) The Earth was not formed with the rest of the solar system, but instead was formed in another solar system and gravitationally captured by the Sun.
e) The Earth was solid throughout its lifetime.

30. In a methane molecule, how many PAIRS of electrons is the carbon atom sharing with other atoms?
a) none.
b) one.
c) two.
d) three.
e) four.

31. What type of radiation from the Earth is primarily responsible for the Greenhouse Effect?
a) X-ray.
b) infrared.
c) ultraviolet.
d) gamma rays.
e) The Earth does not emit any radiation.

32. Interstellar gas clouds are mainly made up of:
a) hydrogen.
b) carbon.
c) dust.
d) iron.
e) nitrogen and oxygen.

33. As an interstellar gas cloud gravitationally contracts in the process of forming into a star and planets:
a) its spin rate stays the same, as does its shape.
b) its spin rate stays the same, and it flattens to a disk.
c) its spin rate decreases, and it flattens to a disk.
d) its spin rate increases, and it flattens to a disk.
e) its spin rate increases, and it expands from a disk into a spherical shape.

34. The figure to the right shows part of a DNA molecule. The section marked by the arrow and dotted ellipse is:
a) Deoxyribose sugar.
b) Adenine.
c) Cytosine.
d) Phosphate.
e) Glycine.

35. As an interstellar cloud gravitational collapses, it spins faster due to the conservation of:
a) angular momentum.
b) linear momentum.
c) energy.
d) mass.
e) luminosity.

36. The interstellar medium is:
a) may not exist; it has never been detected.
b) about 99 percent hydrogen and helium.
c) about half gas, half dust.
d) about 99 percent dust, 1 percent gas.
e) completely ionized.

Answers: 1a, 2a, 3d, 4a, 5c, 6d, 7c, 8b, 9c, 10c, 11b, 12c, 13d, 14a, 15c, 16b, 17a, 18a, 19d, 20d, 21d, 22d, 23b, 24c, 25a, 26c, 27d, 28e, 29c, 30e, 31b, 32a, 33d, 34d, 35a, 36b.