It has been argued that hydrogen-powered automobiles can solve our energy problems because we can get all of the hydrogen that we need from sea water. Which of the following comments about the energy needed to separate the hydrogen and oxygen in water is correct?
Yes. It is the same as the energy released when the hydrogen is burned, so we get no net gain of energy.
The chlorophyll in plants uses sunlight to
Yes. It also produces the hydrogen in an ionized form that can power other chemical reactions.
The original source of energy for life forms that live near a black smoker is
Yes. Bacteria using chemosynthesis are the base of this alternate food chain.
A DNA molecule consists of
Yes. Then a special enzyme can separate the amino acid pairs and unzip the DNA molecule into two single-sided ladders.
A pair of sugar phosphate chains connected by pairs of amino acids describes a molecule of
Yes. It is essentially a ladder that is twisted to form a double helix. The sugar phosphate chains are the sides of the ladder. The amino acid pairs are the rungs.
The role of the DNA molecule in current Earth life is to
Yes. Each sequence of three amino acid pairs in the DNA encodes one of the 20 basic amino acids and those are the building blocks for enzymes and proteins..
Which of the following systems is closest to the plan of most current Earth life-forms?
Yes. That is the current system.
The strongest evidence that Earth life is all descended from a single self-copying molecule is that all Earth life
Yes. There are other possible choices, particularly the mirror image molecules, that would serve the same purpose. Since we only find one choice, it suggests a single ancestor of all life
The strongest evidence that Earth life is all descended from a single self-copying molecule is that all Earth life
Yes. The mirror-image molecules would be able to carry out exactly the same reactions among themselves. If life arose more than once we would expect to find some life forms using the mirror-image molecules.
Which of the following models for the formation of life on Earth would most likely apply if it turns out that the first step of forming a self-copying molecule is extremely difficult and improbable?
Yes. In that model, life only needs to start once in universe and does not arise whenever conditions are right.
Yes. In that model, life develops just once and spreads from planet to planet so it would have identical DNA systems.
Yes. They have the lowest frequency of any type of electromagnetic radiation.
radiation has the from highest to lowest frequency?
Yes. About 74% of all matter in the universe.
Yes. It is number four after hydrogen, helium, and oxygen.
The key advantage of Carbon over Silicon as the basic element for life is that
Yes. That limits the kinds of structures and processes that are possible.
Yes. That is the way the Solar Wind blows.
After a comet's closest approach to the Sun, its tail points
Yes. It points away from the Sun and, after its closest approach to the Sun, its direction of motion is away from the Sun.
The ion tail of a comet
Yes. It consists of electrically charged gas, which responds to the solar wind much more strongly than the Sun's gravity, so it is pushed straight away from the Sun.
The dust tail of a comet
Yes. Each dust particle is in its own separate orbit in the Sun's gravity and not much affected by the solar wind.
You hear a loud noise outside and go outside to find a smoking rock embedded in your driveway underneath your wrecked car. The object is probably a
Yes. Since it is now on the ground.
A meteoroid is a medium-sized rock that is
Yes. Before it hits the Earth's atmosphere. A really big rock would be called an asteroid.
An annual meteor shower occurs when
Yes. The dust left from the comet provides the meteors.
During a meteor shower, shooting stars seem to be coming from
Yes. That is defined to be where the meteors seem to be coming from.
The radiant of a meteor shower is the
Yes. It is actually the point that the Earth is moving towards when it hits the cloud of comet debris.
Yes. REALLY far.
Yes. Between 20,000au and 50,000au is considered to be the Outer Oort Cloud.
The Outer Oort Cloud is
Yes. We know that from the way long period comets come in from all directions.
Comets that originate in the Outer Oort Cloud have orbits that are
Yes. Those are the long period comets.
The Kuiper Belt is mostly located
beyond the orbit of Neptune.
Yes. From the orbit of Neptune at 30au out to about 55au.
The Inner Oort Cloud is located
Yes. It starts where the Kuiper Belt ends.
The Inner Oort Cloud is
Yes. It is much thicker than the Kuiper Belt but not a sphere around the Sun.
Yes. Not quite as close as comets from the Kuiper Belt, but closer than comets from the Outer Oort Cloud.
The Oort cloud of our Sun reaches
Yes. It is about one light year in radius and the distance to the nearest star is about 4 light years.
According to our current (very tentative) estimates, a spaceship travelling from our Sun to one of the nearest stars such as Alpha Centauri A would probably be traveling through the Oort cloud of our Sun and that of Alpha Centauri A for a distance that is
Yes. One light year in each cloud and the trip is 4 light years.
According to current theories it seems likely that "rogue planets" or planetary mass objects that are not in orbit around any particular star
Yes. That seems to be a possibility.
According to our current (very tentative) estimates, a spaceship travelling from our Sun to one of the nearest stars such as Alpha Centauri A probably
Yes. For example, escaped Oort Cloud objects would make ideal permanent bases along the way.
When a large interstellar cloud collapses, it usually
Yes. That is why stars usually form in clusters.
Stars usually come in clusters, all born at about the same time, because
As seen from far above the Earth's North Pole, the Earth orbits the Sun counter clockwise and
Yes. They all orbit counter-clockwise.
As seen from far above the Earth's North Pole,
The Earth orbits nearly in the plane of the Sun's equator as do
Yes. They all orbit in the same plane. Note that Pluto, which orbits way out of the plane, is no longer considered to be a planet
The plane that contains the Earth's orbit around the Sun is also called the plane of the ecliptic. When you look for the planets in the sky, you expect to find
Yes. They all orbit in about the same plane that the Earth does. Note that Pluto, which is no longer considered to be a planet, orbits out of the plane and can be quite far from the ecliptic.
The photosphere of a protostar
Yes. As a result, that is where we see the light coming from.
Yes. Literally "sphere of light."
Yes. Note that the extra brightness is mostly in infrared light, with wavelengths too long for our unaided eyes to see.
The number of protostars that can be seen right now is
Yes. They stand out in infra-red images.
In the original Solar Nebula, objects that condensed near the protoSun tended to be mostly rock and iron rather than volatile gases and water because, in that part of the nebula
Yes. At those high temperatures, those materials stayed in gas form.
In the original Solar Nebula, objects that condensed far from the protoSun tended to include large amounts of frozen gas and water ice because, in that part of the nebula
Yes. Since there was a lot of those materials, when they could condense they formed a large fraction of the condensed objects.
Jupiter failed to become a star because
Yes. A new protostar creates a Tau Tauri wind that blows away the nebula that it formed from.
The Tau-Tauri wind from the Sun's final collapse toward ignition
Yes. Otherwise Jupiter might have continued to grow by sweeping up gas from the Solar Nebula.
Had Jupiter ignited, we would be living in a multiple star system. Such systems
Yes. About half of all stars are in multiple-star systems.
The most likely candidate for a second star in our Solar system was
Yes. As the largest of the gas giant planets, it had the best chance.
Icy objects were ejected outward from the neighborhood of the Jovian planets to form
Yes. They were ejected at high speed and went right past the Kuiper Belt.
The Oort Cloud is thought to have originated when
Yes. There were no stable orbits in that region. Icy objects were ejected by the same gravitational slingshot process that our space probes use to reach the outer Solar System.
Icy objects were ejected inward from the neighborhood of the Jovian planets to form
Yes. Along with the polar caps of Mars and the atmosphere of Venus.
The oceans and atmosphere of Earth are thought to have originated when
Yes. That is how all of the volatile substances got to the Terrestrial planets.
Icy objects condensed from the outskirts of the Solar Nebula to form
Yes. We think that those objects formed right where they are now.
The Kuiper Belt is thought to have originated when
Yes. They stayed there because there were no giant planets out there to disperse them.
According to the current definition of a planet, Pluto is not regarded as a planet because
Yes. In addition to being spherical and orbiting the Sun, a planet must have enough gravitational influence to rule out any stable orbits near it.
The Kuiper Belt was named after Gerard Kuiper, who said that
Yes. Kuiper thought that Pluto was 500 times as massive as it really is, so he figured that it would not allow any stable orbits near it.
Which of the following substances is the smallest fraction of our atmosphere?
Yes. For such an imporant gas, it makes up only 1/2500 of our atmosphere.
In the Earth's atmosphere, the amount of carbon dioxide is
Yes. About 1/25 as much.
Which of the following substances is the largest fraction of our atmosphere?
Yes. Almost 80%.
In the Earth's atmosphere, the percentage that is Nitrogen is roughly
Warmer air always.
Yes. Like smoke from a chimney.
Colder air always
Yes. It is heavier than warm air.
In a region of the atmosphere in which the temperature rises with increasing altitude
Yes. The warm air is on the top, where it wants to be, so nothing changes.
In a region of the atmosphere in which the temperature falls with increasing altitude
Yes. The warm air on the bottom wants to rise to the top.
The layer of the atmosphere where one would find hurricanes is the
Yes. Think of a "tropical storm" to help remember it
The layer of the atmosphere that tends to retain dust and smoke for long periods of time is the
Yes. With no vertical circulation, it is "stratified" so that dust and smoke stay there.
The stratosphere is where one finds
Yes. With no vertical circulation, dust and smoke stay there for a long time.
The layer of the atmosphere that absorbs most of the ultraviolet radiation from the Sun is the
Yes. That absorbs most of the UV radiation
The ozone layer is where one finds
Yes. That is where most of the UV is absorbed.
The highest altitude layer of the atmosphere is the
Yes. That is the highest on this list. Sometimes a higher layer, the 'Exosphere' is defined.
Relative to the other layers of the atmosphere, the Ionosphere is
Yes. At least for the layers that we defined. Sometimes one more layer, the Exosphere, is added above the Ionosphere
The term 'greenhouse effect' refers to
Yes. Specifically by carbon dioxide, methane, and water vapor.
The absorbtion and re-radiation of infrared light by gases such as carbon dioxide is the key process in the
Yes. It keeps heat from escaping.
The Greenhouse Effect is important because it suggests an effect on
Yes. Specifically, it is a cause of global warming.
The possibility that increasing the amount of carbon dioxide in the air will raise the average temperature of the Earth is referred to as the
Yes. Kind of dumb name for it since actual greenhouses work a bit differently.
The thickness of the Earth's crust is about
Yes. It varies a lot from place to place, but that is the closest answer here.
Which layer of the Earth has a thickness of only about ten miles?
Yes. It is thicker in some places and thinner in others.
The Earth's mantle is made of
Yes. It flows under steady pressure and moves the tectonic plates around.
Yes. It flows under pressure and the crust rides on top of it as it moves.
The Earth's core consists of
Yes. The higher pressure at the center is enough to make the iron solid there.
The portion of the Earth that is liquid iron and nickel is the
Yes. The outer core is where liquid iron currents generate the magnetic field.
Information about the structure of the Earth's interior comes mainly from
Yes. As they propagate through the interior, they are affected by the material that they pass through.
Seismic waves are used to determine the Earth's
Yes. They provide the equivalent of an ultrasound image of the interior.
Pressure waves are transmitted through
Yes. Pressure waves go through most things.
Shear waves are transmitted through
Yes. Liquids do not spring back from shearing strains. They just flow.
Europe and North America are
Yes. That corresponds to new ocean floor being created along the Mid-Atlantic Ridge.
The first generally accepted example of Sea-floor spreading was under the
Yes. At the Mid-Atlantic Ridge.
The motion of tectonic plates is driven by
Yes. The mantle carries the plates along with it.
Convection currents in the Earth's Mantle
Yes. The plates are carried along with the mantle.
Underneath a place where the sea floor is spreading, one expects there to be
Yes. That is where the new sea floor is coming from.
Underneath a place where the sea floor is disappearing into a deep ocean trench, one expects there to be
Yes. Pulling the vanished sea floor into the mantle.
The edges of the moving plates on the Earth's surface are often where
The epicenters of earthquakes are located
Yes. The majority of earthquakes happen there
When tectonic plates move past each other, they usually cause
Yes. Earthquakes can be caused in other ways but most of them are the result of plates grinding past or over or under each other.
Earthquakes are often caused by
Yes. They can be caused in other ways as well, but slipping plates definitely cause earthquakes.
All of the following elements occur in living things. Which one is essential for forming complex compounds?
Yes. It forms a far larger variety of compounds than any other element. With four chemical bonds and the ability to bond to other carbon atoms, it can form complex branching structures.
Carbon is essential for all life we know about because it
Yes. It has four chemical bonds and can bond to other carbon atoms, which permits complex branching structures.
On a world with liquid water but no life, carbon dioxide in the atmosphere would
Yes. It would form lots and lots of limestone.
Liquid water tends to permanently remove carbon dioxide from the atmosphere of a planet by
Yes. Once the carbon dioxide has combined to form limestone, only tremendous heat can reverse the reaction, so the loss is permanent.
On Earth, the carbon that ends up as ocean sediment and limestone is
Yes. The heat of the Earth's interior decomposes everything and frees the carbon dioxide.
On Earth, a stable carbon cycle could not exist without
Yes. That is the critical step that releases carbon dioxide from limestone.
Venus retains a dense carbon dioxide atmosphere because
Yes. Liquid water would dissolve the carbon dioxide and eventually combine it with calcium in surface rocks to make limestone.
An example of a planet with no liquid water at all and a dense carbon dioxide atmosphere is
Yes. About 90 times the atmospheric pressure of Earth.
Mars retains a carbon dioxide atmosphere because
Yes. Whenever the pressure drops below the triple point, there is no liquid water to take carbon dioxide out of the atmosphere. When the pressure rises above the triple point, liquid water appears on the surface and dissolves some of the carbon dioxide until the pressure goes back down.
Yes. Its atmosphere is mostly carbon dioxide and we do see some evidence of liquid water flows there. There appears to be a feed-back mechanism keeping its pressure right at the triple point of water and that would require the occasional presence of some liquid water.
The number of near-Earth asteroids is large because they
Yes. The supply of near-Earth asteroids is constantly replenished.
The gravitational influence of the planets mostly causes asteroids to
Yes. The huge number of asteroids in the belt makes that a frequent occurrence.
There appear to be a bit less than 1000 near-earth asteroids that are more than
Yes. Those are the objects that could cause a global catastrophe.
The number of near-Earth asteroids that are more than one kilometer in diameter appears to be close to
Yes. Right now (Jan 2008) we have found about 850 and the rate of new discoveries is dropping fast.
A very large number of new asteroids have been discovered since 1990 primarily because
Yes. That made it possible to automate the process and use a computer program to subtract images instead of a human watching a mechanical blink comparator.
In the 1990s astronomical telescopes began to switch from recording images on film to recording them digitally using Charge Coupled Devices. This led to the discovery of new asteroids at a rapid rate because
Yes. They could have the computer just subtract two images instead of having a human use a blink comparator. The computer could compare thousands of pairs of images in seconds while a human would need a minute or two for each pair and would probably miss really faint objects.
If an asteroid that is 50 meters in diameter strikes the Earth, the result is likely to be
Yes. Comparable to a few million tons of TNT.
An asteroid impact that leaves a huge crater is probably due to an asteroid that is made of
Yes. That would definitely reach the ground and leave a big crater and asteroids made of iron and nickel are actually fairly common.
An encounter between Earth and an iron asteroid fifty meters in diameter would most likely cause
Yes. An iron asteroid would hold together and hit the ground.
If an asteroid that is one kilometer in diameter strikes the Earth, the result is likely to be
Yes. Not on the same scale as the one that killed off the dinosaurs, but a major and long-lasting climate change.
A large asteroid impact causes the extinction of whole species mainly by the effects of the
Yes. That happens world-wide and for a long time.
The current effort to defend the Earth against space impacts consists of
Yes. That would be near-Earth asteroids larger than 1km in diameter. More than 90% of them have probably been found so far.
Near-Earth asteroids of the sort that caused the Tunguska blast and the Barringer Meteor Crater are
Yes. The next proposed search goal is objects larger than 140m. The Tunguska object was much smaller than that.
Yes. Level 10 would be a certain prediction of a climate-changing impact.
Of the following methods for eliminating an asteroid threat, which one would be affected least by the unknown composition and condition of the asteroid?
Yes. That would deflect any asteroid the same way no matter what its structure.
A disadvantage of the gravitational tractor approach to deflecting an asteroid is that
Yes. It would probably have to be assembled in orbit from many rocket launches, sort of like the International Space Station. Thus, it could not be a rapid response unless we take the costly and very unlikely step of preparing such a thing in orbit against future need.
Light that has been spread out to show the frequencies or colors that are present is called
Yes. The spectrum of a star usually shows that some colors are missing, for example.
Ultraviolet light is sometimes described as either UV-A or UV-B. The UV-A variety is supposed to be less damaging to your skin. You can conclude that of the two types, the UV-A variety has the
Yes. Light is absorbed as individual photons. Lower frequency means lower energy, and thus less damaging photons.
As compared to lower frequency electromagnetic radiation, higher frequency electromagnetic radiation will usually cause
Yes. Higher frequency corresponds to more energetic photons, which can cause more damage.