Use these questions to test your understanding. If you get them wrong, you will be linked back to the relevant part of the notes.
Be sure you study them thoroughly (don't just get a quick fix for your mistake) so your overall understanding is improved.
1. The average temperature at the earth has been constant for the 4 billion years over which life has developed because
a. the output of the sun has been extremely constant over this period
b. the distance between earth and sun has changed in a way that canceled the changes in the sun
d. addition of oxygen to the atmosphere by plants has stabilized the temperature
e. the earth is in the habitable zone of the sun
2. The ice ages in the last few hundred thousand years seem to have been triggered by
a. changes in the output of the sun
b. the earth passed through a molecular cloud that absorbed sunlight that normally reaches earth
c. huge volcanic eruptions increased the amount of carbon dioxide in the atmosphere
d. small perturbations in the orbit and polar inclination caused changes in the climate
e. plate motions moved all the continents to the poles
3. To determine when ice ages have occurred in the past, we
a. analyze the isotopes of oxygen in shellfish fossils
b. tunnel deep into the antarctic ice to see how thick it was in the past
c. study tree rings to see when growing conditions were unfavorable
d. study fossils to see when land animals had large amounts of insulating fat
e. survey moraines from ancient glaciers
4. Looking back over hundreds of millions of years, the earth
a. is warmer than average, due to human-induced global warming.
b. is at about an average temperature
d. is in a particularly unsteady state in terms of climate
e. has shown a steady warming trend as the output of the sun has increased
5. Planets in the "habitable zone" will
b. may form life if they are large enough to retain atmospheres
c. may form life if they retain atmospheres and have just the right amount of liquid water
6. Habitable zones are the regions
a. defined by the latitudes on a planet that stay warm during an ice age
b. around a star where water on the surface of a planet is likely to be liquid
c. where the stellar magnetic fields deflect comets and asteroids so they bombard the planets less
d. where the planet orientations cause seasons
e. where only planets about the mass of the earth can form.
7. Life is unlikely to form on planets orbiting stars much more massive than the sun because
a. they burn their nuclear fuels and evolve off the main sequence too quickly
b. their strong gravity causes tidal locking of planets orbiting them
c. their high outputs make any planets around them too hot for life
d. cosmic rays and other radiation emitted by these stars are too intense for life
e. actually, we think life forms preferentially around such stars
8. Long periods when the climate was warmer than average were probably caused by
a. the mantle getting hotter and heating up the continents
b. the orbit of the earth getting smaller, so we were closer to the sun
c. the output of the sun going way up
d. the day being much longer because the earth was spinning more slowly on its axis
e. greenhouse warming due to carbon dioxide released by many volcanoes
9. The weather is difficult to predict because
a. we do not yet gather enough information for weather forecasters
c. weather systems are continually shifted by mountain ranges