A103 Lecture & Reading Quiz Questions Unit 2

Why are the polar caps larger during the Martian winter?

Carbon dioxide in the atmosphere condenses into dry ice on the poles.

What was needed in the Miller-Urey experiment to form complex organic molecules in the 2nd iteration of the experiment?

Clay mineral catalyst

Why do we think gas giants formed preferentially in the outer Solar System?

Colder temperatures allowed larger amounts of molecular hydrogen to condense on their surfaces.

Why do we think the liquid metallic hydrogen layer inside Saturn is thinner than Jupiter's?

Saturn has a lower mass than Jupiter. - Saturn's lower mass and thus lower gravity means it compresses fewer hydrogen compounds into a liquid metallic hydrogen phase. You can see a comparison of giant planet interiors in Figure 11.5.

What must be true if Mars was warmer and wetter in the past?

Mars once had a thicker atmosphere.

How can we recognize the oldest surface regions of Mars?

Regions with the most impact craters.

What best describes the likely origin of the asteroid belt between Mars and Jupiter?

A planet was prevented from forming by tidal forces from Jupiter.

Briefly define asteroid, comet, dwarf planet, and meteor.

- An asteroid is a small rock that orbits the Sun. They mostly reside in the asteroid belt, found between the planets, Mars and Jupiter. - Comets are rocks that come from the outer solar system. They enter the inner solar system, but it moves much quicker while in the outer solar system. A comet has a tail, a coma, and a nucleus. - A meteor comes from a meteoroid. A meteoroid is another small rock that resides in space, and it becomes a meteor when it hits Earth's atmosphere. - A dwarf planet has the same three criteria as a planet, except a dwarf planet is NOT the most massive object in its orbital zone.

What pieces of evidence from Mars exploration suggest that water once flowed on Mars? (select all that apply)

- Hydrated minerals - Eroded rims of craters - Dry river beds and dry river deltas - Stone pebbles rounded by flowing water

Why are membranes important for the formation of the first organisms?

- Membranes concentrate organic molecules - Membranes increase the speed of chemical reactions - Membranes store electricity that can be used by the cell - Membranes protect the interior of the cell from the outside environment

What are the three most likely reasons that life is not silicon-based?

1. Bonds formed by silicon are weaker than equivalent bonds formed by carbon. 2. Silicon does not normally form double-bonds. 3. Silicon is not mobile in the environment like carbon.

What two factors cause colored bands to form in Jupiter's atmosphere? (choose two)

1. Convection in the atmosphere 2. Planet Rotation

Jupiter rotates once every 10 hours, more than twice as fast as the Earth. Along with rapid rotation, what other property of Jupiter leads to it having a very strong magnetic field (20,000x Earth)?

A convecting liquid metallic hydrogen layer

What is the primary molecule used in metabolism and energy storage in all life on Earth?

ATP

Protoplanets formed by accumulating planetesimals (smaller asteroid sized rocks) through what process?

Accretion

The Miller-Urey experiment attempted to replicate the conditions of early Earth to then watch for the production of organic molecules. What molecules formed as a result of the first experiment?

Amino acids

What do we mean when we say liquid water is unstable on Mars?

Any liquid water on the surface would quickly freeze or evaporate.

What evidence do we have that Jupiter has a strong magnetic field?

Aurora activity near its magnetic poles.

What evidence do we have that Saturn's magnetic field is about as strong as Earth's?

Aurora activity near the planet's poles. - Aurora activity on all giant planets gives us an idea of the strength of their magnetic fields. For example, look at Jupiter's aurorae in Figure 11.12. A comparison of planetary magnetic fields let's us compare the size of their magnetospheres (see Figure 11.13).

What is the origin of meteor showers?

Debris trails left by comets.

What is the main difference between planets and dwarf planets?

Dwarf planets are not the most massive body in their orbital zones.

There are several potential liquids in our solar system that could be solvents for lifeforms (see Table 7.1). Which of these substances remains liquid at the lowest temperatures?

Ethane

What energy sources might be available for life on Europa? Overall, what can we say about the likelihood and abundance of life on Europa? Briefly explain.

Europa looks to be more promising than Jupiter's other moon Io because it's tidal heating isn't as extreme and could contain a better amount to sustain life. It is also possible that Europa has a subsurface ocean - another factor that can sustain life. Evidence from the Galileo spacecraft shows that it is a possibility that Europa contains a liquid water ocean underneath its icy crust. Therefore, if there is life, it would probably be buried beneath the surface. Europa also might have a magnetic field, which supports the notion that Europa has liquid water. In terms of energy sources available on Europa, the textbook mentions how Europa plausibly has "a rocky ocean floor, tidal heating, decay of radioactive elements, and large undersea volcanoes" (315). While these can be energy sources life could pull from, a stronger case is the magnetic field near Europa. Since Europa meets the three requirements discussed in section 7.1, we can say that there is a good likelihood of some form of life on Europa; however, it is probably tiny.

Unlike Earth, the orbit of Mars has a more significant impact on its climate. Why is this?

Mars' orbit has a higher eccentricity than Earth's.

Mars has many ancient dry river beds on its surface. Craters interrupt and erase some of the dry river bed patterns. What does this imply about Mars?

Martian rivers dried up before the bombardment stage of Mars' formation.

What are extremophiles? Give some examples. What are the implications of the existence of extremophiles for the search for extraterrestrial life?

Extremophiles are simply organisms that can live in extreme environments. One example of an extremophile is Deinococcus radiodurans, which can survive radiation that is 1000x stronger than a level humans can survive. A more common example is tardigrades, which are small animals found in water. The implication of the existence of extremophiles for the search for extraterrestrial life is we can look to more areas in the world for living organisms. Extremophiles can survive such extreme - hot, cold, below ground, above ground, the vacuum of space- conditions and environments that life may be possible in more areas than initially thought. Also, to be noted, extremophiles have lived for a lot longer than humans and have been in conditions more closely related to the early stages of Earth's history.

On Saturn's largest moon Titan, the thick atmosphere and low surface temperature allow what to occur on its surface?

Flowing liquid methane. - The cold surface temperature and thick N2 atmosphere allow liquid methane to stably exist on the surface. See a summary on page 328.

What observations support the idea of a subsurface ocean on Enceladus?

Fountains of ice spray from surface vents. The ice spray tells us there is ongoing geological activity and fractures in the crust from such activity releases subsurface liquid the sublimates (turns to ice) as it erupts into space.

Which of the following is NOT a domain of life?

Fungi

When we take infrared photos of Jupiter we see that it is glowing brightly with heat. In fact, Jupiter emits more energy (in the form of infrared light) than it receives from the Sun in the form of sunlight. What is the source of most of Jupiter's heat?

Gravitational contraction

Why does Saturn emit more heat than it receives from the Sun in the form of sunlight?

Gravitational contraction and the settling of helium droplets. - The settling of helium droplets is essentially ongoing differentiation through gravitational contraction, and is the source of Saturn's internal heat. (See a summary on page 315 and 316 in the textbook).

Which four elements make up most of the mass of living cells on Earth?

Hydrogen Oxygen Carbon Nitrogen

Why is Jupiter's moon Io covered in volcanoes while Jupiter's moon Europa is covered in ice?

Io is subject to stronger tidal heating

What is unusual about Neptune's moon Triton relative to other moons?

It orbits Neptune backwards.

Evidence of dry river beds on the Martian surface suggest that it once had liquid surface water. Presence of surface water in the past suggests that Mars was once warmer; what else does it suggest?

Mars once had a thicker atmosphere.

Why do Uranus and Neptune appear blue to our eye?

Methane in their atmosphere's scatters blue wavelengths from sunlight.

There are several potential liquids in our solar system that could be solvents for lifeforms (see Table 7.1). Which of these substances remains liquid over the widest range of temperatures?

Methanol

What are mutations, and what effects can they have? Briefly explain why mutations represent the molecular mechanism of natural selection.

Mutations are the result of a change in our organism's DNA. The change happens in the base sequence specifically. Mutations can have both positive and negative effects. Harmless consequences involve a change in a code that ends up producing the same protein. Harmful consequences happen when a mutation adds or deletes a base within a given gene. This can occur when a protein is wholly changed (not just the 3rd letter, but the whole base). Mutations represent the molecular mechanism of natural selection because they are the basis for evolution. The reason for this is because mutations are heavily involved with hereditary, and any mutation leads to a permanent, cascading effect for future generations. Some mutations will be more advantageous than others, hence the idea of natural selection applies.

Where is the most likely place life emerged on Earth?

Ocean floor

Mars has two moons, Phobos and Deimos. What makes these moons unique among the moons of the terrestrial planets?

Phobos and Deimos are captured asteroids.

When lipids were added to the Miller-Urey experiment, what important cell feature spontaneously emerged?

Pre-cell structures

What kind of observation lends supporting evidence to the Solar Nebula Theory?

Radio observations of protoplanetary disks.

Why does Saturn appear yellower in color than Jupiter?

The colder temperature means more ammonia ice in Saturn's atmosphere. - Take a look at Figure 11.7 in the textbook which shows the altitude vs. temperature in gas giant atmospheres. You can see how the temperature of gas giant atmospheres (due to their distance from the Sun) gives each gas giant its color.

In the Solar Nebula Theory, as the gas cloud that formed our Solar System gravitationally contracted it began to flatten and began to rotate faster. Why did it do this?

The conservation of angular momentum.

What is the main reason the southern hemisphere of Mars experiences more extreme seasons?

The eccentricity of Mars' orbit.

Compared to the other gas giants, what is unique about Uranus?

The extreme tilt of its rotation axis.

What observation supports the idea that Enceladus remains geologically active?

The icy surface has very few impact craters. As with lava flows resurfacing Venus and removing impact cratering, water and ice resurface Enceladus.

What causes pre-cells, with enclosed self-replicating RNA, to split in two?

The pre-cell becomes unstably large and naturally splits.

Jupiter's moon Io has volcanic activity because we see fresh lava flows and the surface is covered in sulfur. Because Io is roughly the size of Earth's moon, and is about the same age, we would expect Io to have a cold interior and no volcanic activity. How has Io remained hot enough in its interior to have volcanic activity?

Tidal forces from Jupiter releases heat in Io's interior.

Based on recent data, briefly describe the general nature of Titan and describe its prospects for life.

Titan is the second-largest moon and is the only moon that contains a decent atmosphere. Titan appears to be very Earth-like as well due to its clouds and surface oceans. Titan is made up mostly of rock and ice, and the atmosphere consists mainly of nitrogen and methane. Because of Titan's temperatures, its methane and ethane become liquid. If Titan harbored any life, it would likely be under the surface since surface temperatures are too cold, and most things would freeze. Furthermore, because there isn't liquid water but liquid methane and ethane, chemical reactions would occur at a much slower rate than needed to create substantial amounts of life. The textbook mentions that the hope for Titan life would come down to organic molecules from ultraviolet light, chemical reactions due to impacts by comets or asteroids, possible volcanic activity, or bacteria.

There are several potential liquids in our solar system that could be solvents for lifeforms (see Table 7.1). Which of these substances remains liquid at the highest temperature?

Water

Which of the following is NOT an advantage of water as a liquid solvent for life?

Water molecules are not dissociated by ultraviolet radiation.