ASTR5: Wk 1 - 5

Consider the following statement. Surface habitability of a planet (or exoplanet) can be determined remotely by studying reflected solar (or stellar) light from the planet's surface and atmosphere, while the determination of subsurface habitability would require exploration by a robotic space probe. Is this statement true or false?

True

Due to variations in its orbit and spin, combined with plate tectonics, Earth has experienced periods of drastically low global temperatures called Ice Ages. We are currently in a long-lasting (10,000 years) inter-glacial period. The end of the last "snowball" phase in which glaciers may have reached the Equator roughly coincides with a dramatic increase in the diversity of life on Earth 540 million years ago. (T/F?)

True

Watch the recommended video. As it leaves the solar system, the Voyager spacecraft is traveling at 17 km/s (11 miles/s). Is this true or false?

True

What discovery made by Luis and Walter Alvarez in 1978 led to the conclusion that a massive impact event occurred about 65 million years ago in which 75% of all the existing plant and animal species at that time were driven to extinction? a. A stratum of rock rich in iridium found world-wide b. A stratum of rock rich in charcoal found world-wide c. A stratum of rock depleted in iridium found world-wide d. A stratum of rock depleted in charcoal found worldwide

a. A stratum of rock rich in iridium found world-wide

Which one of the following statements about the Solar System is NOT correct? a. Comets are relatively large rocks that orbit our planet, and sometimes collide with Earth causing extinction events. b. The Sun is an ordinary star. It is a very large ball of hot, glowing, gas (mostly hydrogen) that generates energy from nuclear fusion reactions deep in its core. c. A planet is a relatively large rocky, icy or gaseous object that orbits a star, and a planet shines only by reflected light from its parent star. d. The solar nebula was a huge interstellar cloud composed mostly of hydrogen gas and some small solid particles that astronomers call dust; the Sun formed by gravitational collapse of this cloud.

a. Comets are relatively large rocks that orbit our planet, and sometimes collide with Earth causing extinction events.

Isolated sequences of the four bases (A, T, G, and C) in DNA represent instructions (code) for a variety of cell functions. The set for one function is called a a. gene b. genome c. genetic mutation d. chromosome

a. gene

Why are clay surfaces potentially good at promoting the formation and replication of biological polymers such as RNA? [Note: A monomer is a long strand.] a. Clays are made of biological polymers. b. They are very common surfaces on Earth. c. They are the only types of material the monomers will stick to. d. They bring monomers close together, allowing them to react with each other.

d. They bring monomers close together, allowing them to react with each other.

Space is well named because it is mostly empty! We might think of Earth as a large place, but our star, the Sun, is much bigger. How many planets the size of Earth can fit into the Sun? (a) 1 million (1.0 x 10E6) (b) ten (1.0 x 10E1) (c) 1 hundred (1.0 x 10E2) (d) 1 thousand (1.0 x 10E3)

(a) 1 million (1.0 x 10E6)

Our Sun is a normal star. It belongs to a huge "spiral" galaxy called the Milky Way, which contains well over 100 billion stars, and probably more like 400 billion stars, that lie mostly in a flattened plane or disk shape. How long would it take to travel across the diameter of the spiral disk of the Milky Way at the speed of light? (a) 100,000 years (b) 2.3 million years (c) 50,000 years (d) 26,000 years

(a) 100,000 years

The Space Age began on October 4, 1957 with the launch of the first artificial satellite called Sputnik 1. By December 1972, 12 men had walked on the Moon's surface. With the International Space Station (ISS), humans have maintained a continuous presence in space for just over (a) 20 years (b) 30 years (c) 50 years (d) 10 years

(a) 20 years

Radio waves also travel at the speed of light. Suppose a strange radio signal is suddenly received tomorrow, that is, in the year 2022, from a star that is known to be 22 light-years away. What Earth year was the signal actually transmitted? (a) 2000 (b) 2200 (c) 2044 (d) 2022

(a) 2000

Dinosaurs were the dominant species for over 250 million years. Which of the following is the most compelling evidence that dinosaurs were made extinct by the impact of a massive asteroid 65 million years ago? (a) A layer of sediment laid down at that time is rich in iridium, which is an element that is rare on Earth but more common in asteroids (b) Layers of sediment laid down at that time are littered with dinosaur fossils (c) The crater formed by this impact is still visible in northern Arizona (d) Dinosaur fossils are not found in rock layers younger than 65 million years

(a) A layer of sediment laid down at that time is rich in iridium, which is an element that is rare on Earth but more common in asteroids

The Mitochondria and chloroplasts of animal and plant cells respectively may have evolved as small bacteria invaded a larger host cell, forming a symbiotic relationship. Reasons for believing this scenario are (a) All of these (b) Both have their own bacteria-like DNA (c) Mitochondria had adapted to use oxygen and sugar to produce ATP (energy) (d) Both reproduce within the cell

(a) All of these

There must have been an intermediate step to go from chemistry to biology, a chemical pathway with a relatively high probability. Early life must replicate, but DNA is complex. The obvious choice is RNA. Today, we know that RNA can catalyze like enzymes, and experiments show that ________ is an ideal mineral to facilitate the formation of strands of RNA that are a few dozen bases long. (a) Clay (b) Limestone (c) Sand (d) Calcium carbonate

(a) Clay

Using the laws of physics, the Nebular Theory of star formation explains that a giant interstellar cloud of gas and tiny particles (dust) will... (a) Contract, heat up, and spin faster. (b) Expand, cool down, and spin faster. (c) Expand, cool down, and spin slower. (d) Contract, heat up, and spin slower.

(a) Contract, heat up, and spin faster. This is a result of the Law of Gravity and Conservation of Angular Momentum.

To emphasize the vastness and emptiness of space consider the following scale model of the solar system. If the Sun is reduced in size by a factor of 10 billion then it becomes the size of a grapefruit. Which statement describes Earth's size, and its orbit, on this scale? (a) Earth is the size of the ball point tip of a pen, moving in a large circle with a radius of 15 m. (b) Earth is the size of the ball point tip of a pen, moving in a circle 50 m in radius. (c) Earth is the size of a marble, moving in a large circle about 15 m in radius. (d) Earth is the size of a marble, moving in a large circle about 50 m in radius.

(a) Earth is the size of the ball point tip of a pen, moving in a large circle with a radius of 15 m.

Why do all the Galilean moons of Jupiter keep the same face towards the giant planet, just like our Moon keeps the same face pointed at Earth? (a) Gravitational tidal friction has locked the rotation to the revolution (b) All moons do this and therefore it is nothing special (c) No reason, it is just a coincidence (d) Jupiter's magnetic field creates a drag force on the moons which stops them turning

(a) Gravitational tidal friction has locked the rotation to the revolution

In what way can isotopes of carbon (specifically C12 and C13) be used to discover the presence of past biological activity in ancient rocks? [Read the Lecture Slide on Isotopic Evidence carefully.] (a) Living organisms absorb certain carbon isotopes more easily than others (b) Living organisms remove all carbon from rocks (c) Carbon isotopes are found only in living organisms and not rocks (d) Living organisms absorb only the most common carbon isotope

(a) Living organisms absorb certain carbon isotopes more easily than others

Which of the following is not one of the hallmarks of science? (a) Modern science relies on the opinion of experts, and/or acceptance of supernatural phenomena to explain nature. (b) Science progresses through the creation and testing of models of nature that explain the observations as simply as possible. (c) Modern science seeks explanations for observed phenomena that rely solely on natural causes (d) A scientific model must make testable predictions about natural phenomena that would force us to revise or abandon the model if the predictions do not agree with observations.

(a) Modern science relies on the opinion of experts, and/or acceptance of supernatural phenomena to explain nature.

From the list below, identify the process that was most likely to have been an important source of Earth's early atmosphere. (a) Outgassing by volcanoes on Earth's surface (b) Gases trapped from the Solar Nebula (c) Charged particles captured from the Solar Wind (d) Material blasted from the surface of the Moon

(a) Outgassing by volcanoes on Earth's surface

Which of the following statements about Mars is NOT true? (a) The atmospheric pressure on Mars is the same as that on Earth. (b) Mars has an axial tilt and a rotation period quite similar to Earth. (c) Seasonal variations occur in polar ice caps on Mars. (d) At 1.52 AU from the Sun, Mars gets about 43% of the sunlight received by Earth.

(a) The atmospheric pressure on Mars is the same as that on Earth. No. Mars has a very thin atmosphere of CO2

The fossil record is part of the larger Geological Record of Earth. Suppose a fossil is found in a layer of rock strata between two other layers. The upper layer is dated at 5 million years using radioactive dating, while the lower layer is found to be 10 million years old. What does this tell us about the age of the fossil? (a) The fossil is between 5 and 10 million years old (b) The fossil is younger than 5 million years (c) The fossil is older than 10 million years (d) Nothing, because we don't know the age of the stratum containing the fossil

(a) The fossil is between 5 and 10 million years old

There are many reasons to support the idea that Europa has a subsurface ocean. Which of the following is NOT one of those reasons? (a) The surface of Europa is covered in rivers flowing from mountains into underground caves. (b) Space probes have detected a magnetic field from Europa itself, most likely caused by the interaction of Jupiter's magnetic field with a salty subsurface ocean (c) There are very few impact craters, demonstrating the surface is geologically young. (d) Spacecraft show a frozen surface crisscrossed with cracks in the ice that resemble arctic ice packs in Earth

(a) The surface of Europa is covered in rivers flowing from mountains into underground caves. The surface is frozen. There is no "flowing rivers"

Venus is almost the same size and mass as Earth. It is closer to the Sun at 0.7 AU compared to Earth at 1 AU, which means that it receives about twice as much light and heat from the Sun. However, Venus is much hotter than this distance would imply. Why? (a) Venus is suffering from a "runaway" Greenhouse Effect due to its dense atmosphere of carbon dioxide. (b) Venus is suffering from a "runaway" Greenhouse Effect due to its thin atmosphere of carbon dioxide. (c) Venus, unlike Earth, does not have an atmosphere. (D) Venus, unlike Earth, does not have any oceans to reflect sunlight back to space.

(a) Venus is suffering from a "runaway" Greenhouse Effect due to its dense atmosphere of carbon dioxide.

On the 10 billion to 1 scale model of the Solar System the Sun is like a grapefruit. If the model Sun was placed on the UCLA campus, the nearest star system, Alpha Centauri, would be located 2,500 miles away in... (a) Washington, D.C. (b) London, UK (c) Denver, Co. (d) San Francisco, Ca.

(a) Washington, D.C.

All living cells on Earth depend on liquid water, and none can survive indefinitely without it. Which of the following is NOT one of the three roles of water? (a) Water molecules are both necessary and sufficient to create the mutations in base pairs that lead to species evolution (b) Water molecules are necessary for the reactions that store and release energy in ATP (c) Liquid water allows organic chemicals to float inside cells (d) Liquid water allows the transport of chemicals into the cell and waster products out

(a) Water molecules are both necessary and sufficient to create the mutations in base pairs that lead to species evolution

NASA's latest Martian lander/rover - Perseverance - is unique because (a) it deployed the first helicopter on the red planet (b) it was lowered to the ground using a "sky crane" (c) it has six wheels instead of four (d) it took the first "selfie" on Mars

(a) it deployed the first helicopter on the red planet

Liquid ethane (C2H6) has a temperature range almost as wide as that of water. However, ethane is not as good a biological solvent as water because it is only a liquid at (a) much lower temperatures, which means metabolic processes would be very slow (b) very high pressures that are unlikely to be found in nature (c) very low pressures that are unlikely to be found on other worlds (d) much higher temperatures, which means fragile biological molecules would break down

(a) much lower temperatures, which means metabolic processes would be very slow

Strong winds on Mars associated with seasonal freezing and evaporation of carbon dioxide at the poles cause (a) severe, planet-wide dust storms (b) freezing fog that can damage landers and rovers on the surface (c) thunderstorms and acid rain (d) ice storms in the polar regions

(a) severe, planet-wide dust storms

If the speed of light is 300,000 km/s, how far does light travel in 500 seconds? Use correct Scientific Notation to express your answer. [You can use a simple calculator to multiply the numbers first, then convert to powers of ten. FYI: this is the distance from Earth to the Sun, and it is also known as 1 Astronomical Unit.] (a) 15.0 x 10E7 km (b) 1.5 x 10E8 km (c) 0.15 x 10E9 km (d) 150 x 10E6 km

(b) 1.5 x 10E8 km

One of the constraints on life elsewhere in the solar system is the amount of light and radiant (heat) energy received from the Sun. Because of the inverse square law, at the 10 AU distance of Saturn and its moon Titan, energy from the Sun is ______ than that received by Earth. (a) 9 times less (b) 100 times less (c) 110 times less (d) 10 times less

(b) 100 times less

Radioactive dating is a powerful scientific tool for determining how old rocks and fossils are. Suppose a rock sample contains 1 microgram of the radioactive isotope U-235 and also 1 microgram of its "daughter" isotope Pb-207. This means that half of the original quantity of uranium has become lead. If the half-life of this decay is 700 million years, how old is this rock? [Make sure you understand the definition of half-life.] (a) 350 million years (b) 700 million years (c) 1,400 million years (d) 2,100 million years

(b) 700 million years

Study the Cosmic Calendar, in which the history of the almost 14 billion years old universe is compressed into one Earth year of 12 months, or 365 days. If the Big Bang begins January 1 on this calendar, when did modern humans invent the telescope? [Galileo's first use of the telescope was in 1609.] (a) Three weeks before midnight on December 31. (b) A few seconds before midnight on December 31. (c) A few minutes before midnight on December 31. (d) Three days before midnight on December 31.

(b) A few seconds before midnight on December 31.

Fill in the blanks. The basic molecular building blocks of proteins are ________. A section of DNA that corresponds to a particular protein is known as a ______. (a) Amino acids; genome (b) Amino acids; gene (c) Nucleotides; gene (d) Nucleotides; genome

(b) Amino acids; gene

On Earth, life has been discovered under conditions that humans would consider extreme. For example, microbes are found around volcanic vents on the ocean floor known as _________ and in the airspace between tiny mineral grains in cold environments like _________. (a) Hot Springs; Antarctica (b) Black Smokers; Antarctica (c) Endospores; Arctica (d) Blue-green algae; Arctica

(b) Black Smokers; Antarctica

Plants get energy directly from the Sun via photosynthesis, and they can absorb carbon (food) directly from the atmosphere in the form of carbon dioxide, releasing oxygen as a by-product. The Metabolic Classification of plants is Photoautotroph. Humans obtain energy from chemical reactions and absorb carbon from other organisms. Consequently, humans have a metabolic classification of (a) Photoautotroph (b) Chemoheterotroph (c) Photoheterotroph (d) Chemoautotroph

(b) Chemoheterotroph

Could Jupiter's moon Europa have life? Life is found around hot, deep sea volcanic vents on Earth, and may even have arisen there. We have three requirements for life: organic molecules, energy for metabolism, and a liquid medium. Which of these three would be hardest to account for on Europa? (a) Organic molecules (b) Energy for metabolism (c) It is impossible to choose. (d) Liquid medium

(b) Energy for metabolism Weak energy sources exist, but the very low temperatures would imply an extremely slow metabolism.

What is meant by a light-year? (a) A light-year is the time it takes light to travel from the Sun to Earth. (b) A light-year is the time it takes for light to travel from the nearest star to Earth. (c) A light-year is the distance traveled by light in one year in space. (d) A light-year is the average distance between Earth and the nearest star.

(c) A light-year is the distance traveled by light in one year in space. Light travels about 9.45 trill km in one year

Venus might be considered our sister planet because it is the closest planet to us, and it is essentially the same size and mass as Earth; it even has an atmosphere. But Venus is not likely to support life mainly because... (a) Extreme low surface temperatures of almost -480 C (-880 F) and crushing atmospheric pressure make the planet inhospitable to life as we know it. (b) Extreme high surface temperatures of almost 480 C (944 F) and crushing atmospheric pressure make the planet inhospitable to life as we know it. (c) It rotates very slowly and therefore has no magnetic field, despite having an iron core. (d) The atmosphere is mostly carbon dioxide and nitrogen, with clouds of sulfuric acid droplets.

(b) Extreme high surface temperatures of almost 480 C (944 F) and crushing atmospheric pressure make the planet inhospitable to life as we know it. There is no getting around the exceptionally hot temperatures which would certainly destroy surface life!

The main chemical building blocks of life: carbon, nitrogen, oxygen, and iron were formed... (a) Inside interstellar gas clouds during star formation. (b) In nuclear reactions at the cores of ancient stars and then ejected into space when those stars died. (c) At the center of Earth, and then brought to the surface by volcanic eruptions. (d) All together in the Big Bang that created the universe.

(b) In nuclear reactions at the cores of ancient stars and then ejected into space when those stars died.

Which object is the most volcanically active body in the solar system? (a) Triton (b) Io (c) Europa (d) Enceladus

(b) Io

What can be said about the presence of Order in living organisms? [Hint: make sure you understand the logic. Consider what is meant by necessary and sufficient.] (a) It is neither a necessary nor a sufficient condition for life (b) It is a necessary but not a sufficient condition for life (c) It is a sufficient but not a necessary condition for life (d) It is both a necessary and a sufficient condition for life

(b) It is a necessary but not a sufficient condition for life

Mars is well known as the "red" planet, but why? (a) The reddish appearance of Mars is a visual illusion caused by refraction of light in Earth's turbulent atmosphere. (b) Martian soil contains iron that has long ago been oxidized into rust, which produces the reddish colors. (c) The Martian atmosphere is so thick that it dims and reddens the light reflected from the surface, like a red sunset on Earth. (d) Martian soil contains tiny red plants that give the planet its distinguishing color.

(b) Martian soil contains iron that has long ago been oxidized into rust, which produces the reddish colors.

Later experiments carried out by the Phoenix and Curiosity missions in 2007 and 2012 offered an explanation for the conflicting and confusing results of the Viking mission. It turns out that a toxic salt called ________ in the Martian soil can release oxygen and destroy organic molecules when heated. (a) Potassium Chloride (b) Percholate (c) Sodium Chloride (d) Chlorox

(b) Percholate

Einstein's General Theory of Relativity is an extension of Newton's Theory of Gravity that explains new phenomena, such as black holes in space, and the distortion of space and time due to the presence of a large mass. Which modern utility depends on Einstein's equations for accuracy? (a) The global system of weather satellites (b) The Global Positioning Satellite system (c) The Internet (d) The International Space Station

(b) The Global Positioning Satellite system Without correcting for General Relativity, GPS would be "off" by ~ 1 mile.

Based on extensive fossil evidence, what happened at the start of Earth's Cambrian Period about 540 million years ago? (a) The first oxygen-producing bacteria appeared (b) There was a marked increase in genetic diversity, with many new phyla (body shapes) appearing, including the first animals (c) The first early humans appeared (d) There was a rapid decrease in genetic diversity, with many phyla (body shapes) disappearing, including many animals

(b) There was a marked increase in genetic diversity, with many new phyla (body shapes) appearing, including the first animals

Why are scientists confident that early microbial life (3.5 billion years ago) had a much higher probability of developing in the oceans than on the land surface? (a) Organic materials (carbon, nitrogen, oxygen, hydrogen) were not present on the land (b) There was no ozone (O3) layer in the upper atmosphere to protect life on the land from extremely harmful ultraviolet rays from the Sun (c) Meteoric impacts from space would have destroyed any life on the land (d) Life needs water and there was no water on the land surface

(b) There was no ozone (O3) layer in the upper atmosphere to protect life on the land from extremely harmful ultraviolet rays from the Sun

If we take a "biological" tour of the solar system looking for possible sources of water, now or in the past, and subsurface and/or in frozen form, we see that _____ is not attractive because it is too hot, but the large ______ of Jupiter and Saturn are actually more interesting than the planets themselves. The best choice is ______. (a) Mercury; rings; Mars (b) Venus; moons; Mars (c) Mars; moons; Venus (d) Mercury; rings; Europa

(b) Venus; moons; Mars

Why do the Martian volcanoes of the Tharsis Bulge dwarf any on Earth? (a) More internal heat because the planet is smaller (b) Weaker gravity and no plate tectonics so mantle plumes are stationary (c) Stronger gravity and no plate tectonics so mantle plumes are stationary (d) Mars is much older than Earth so has had more time to build large volcanoes

(b) Weaker gravity and no plate tectonics so mantle plumes are stationary

There is considerable evidence that Mars once had oceans and rivers. Today, even when daytime temperatures exceed the freezing point, there is no chance of liquid water remaining on the surface. Any liquid water would (a) refreeze due to the low atmospheric pressure (b) evaporate due to the low atmospheric pressure (c) refreeze due to the high atmospheric pressure (d) evaporate due to the high atmospheric pressure

(b) evaporate due to the low atmospheric pressure There are two conditions for liquid water on the surface — a temperature above freezing point, and sufficient atmospheric pressure.

We have now sent spacecraft to all the planets of the solar system. The four basic types of robotic space missions are flyby, orbiter, lander/rover, sample return. The New Horizons mission to Pluto in 2015 was which type of mission? (a) orbiter (b) flyby (c) lander (d) sample return

(b) flyby

Astronomical science has shown that the fundamental laws of physics are... (a) random and unpredictable (b) the same everywhere in the observable universe (c) different on different planets in the solar system (d) the same within the solar system but different beyond the solar system

(b) the same everywhere in the observable universe

The Huygens probe released by the Cassini spacecraft landed safely on Titan in January 2005. During the 2.5 hour descent by parachute the probe sent back pictures that showed hills, river valleys and coast lines. We now know that these features are caused by... (a) Liquid ammonia (b) Slow moving glaciers of ammonia ice (c) A mixture of liquid ethane and liquid methane (d) Liquid water

(c) A mixture of liquid ethane and liquid methane

Earth's _________ is shielded from being stripped away by energetic particles in the solar wind because Earth has a global _________. (a) Water; gravitational field (b) Atmosphere; gravitational field (c) Atmosphere; magnetic field (d) Water; magnetic field

(c) Atmosphere; magnetic field

Which of the following is NOT evidence of past water on Mars? (a) Small spheres of the common iron-oxide mineral hematite (Fe2O3) discovered by the Opportunity rover (b) Subsurface ice found near the poles by the Phoenix lander (c) Earth-based observations of canals on Mars. (d) Orbital pictures showing numerous dry river beds, flood plains and erosion

(c) Earth-based observations of canals on Mars. No such features exist on Mars

What is unusual about Saturn's largest moon, Titan? (a) The surface temperature is surprisingly warm at -18 C. (b) It has an atmosphere of carbon dioxide and 0.01x the surface pressure of Earth's. (c) It has an atmosphere of 90% nitrogen and 1.5x the surface pressure of Earth's. (d) It has strange surface markings that are easily seen with telescopes on Earth.

(c) It has an atmosphere of 90% nitrogen and 1.5x the surface pressure of Earth's.

In the struggle for survival of any species, those individuals whose traits best enable them to survive and reproduce will, on average, leave the largest number of offspring that in turn survive to reproduce. This observation led Charles Darwin in 1859 to propose a theory for how evolution works. That theory is known as (a) Creationism (b) Artificial Selection (c) Natural Selection (d) Differential Evolution

(c) Natural Selection

Zircon crystals dating back 4.4 billion years suggest that water might have been present only 100 million years after Earth's formation. Such rocks are rare. Why does the geological record contain far fewer older rocks than younger rocks? (a) Older rocks have been transformed by life processes occurring within them (X) (b) Older rocks get destroyed by more recent meteorite impacts (c) Older rocks get destroyed by geological processes like plate tectonics and erosion (d) Older rocks are mostly found deep within the planet

(c) Older rocks get destroyed by geological processes like plate tectonics and erosion

In our search for a natural explanation for the origin of life, which of the following statements is NOT true? [Read each statement carefully!] (a) Chemical reactions in deep sea volcanic vents should also produce amino acids. (b) Fundamental organic (carbon-based) compounds are found in space, and were certainly delivered to Earth by impacts. (c) Oxygen and water were both available for life to start soon after Earth formed (d) Experiments like that of Miller and Urey demonstrate that amino acids and organic compounds form naturally if the composition of the early atmosphere has a suitable mixture of hydrogen, carbon and nitrogen.

(c) Oxygen and water were both available for life to start soon after Earth formed

Starting in the 1600s, industrialization has added ever increasing amounts of CO2 to the atmosphere from the burning of fossil fuels (coal, oil and gas) as well as wood burning from deforestation. Why can't Earth's natural CO2 cycle compensate for this huge change? (a) Human pollution prevents the natural carbon dioxide cycle from working. (b) The natural CO2 cycle operates much too quickly to correct for short-term changes. (c) The natural CO2 cycle operates much too slowly to correct for short-term changes. (d) The carbon dioxide cycle can only influence CO2 produced by natural sources.

(c) The natural CO2 cycle operates much too slowly to correct for short-term changes.

What is the astronomical definition of a star's Habitable Zone? (a) The range of distances from the star where rocky planets can form. (b) The range of distances from the star where planets with life have been detected. (c) The range of distances from the star where water in the liquid state can be stable on the surface of a suitable planet. (d) The range of distances from the star where organic molecules can be stable on the surface of a suitable planet.

(c) The range of distances from the star where water in the liquid state can be stable on the surface of a suitable planet. As we know from the case of the Moon and Earth, distance alone is not sufficient for liquid water on the surface. The planet must also be "suitable" in having an atmosphere of the appropriate density, pressure and composition.

The total mass of humans is about 300 billion kg, but the total mass of microbes in Earth's oceans is... (a) about the same (b) about 1,000 times greater (c) about 5,000 times greater (d) about 50 times greater

(c) about 5,000 times greater

Over time, as stars (including our Sun) age, the Habitable Zone will (a) suddenly disappear (b) move inwards (c) move outwards (d) remain the same

(c) move outwards

According to the best current astronomical data, what is the approximate age of the universe? [This is the time elapsed since the Big Bang.] (a) 4.6 billion years (b) 6,000 years (c) 65 million years (d) 13.8 billion years

(d) 13.8 billion years

Earth is our spaceship! Our entire planet rotates on its axis once every 24 hours. Given its radius of about 6,370 km, this implies a speed of 1,650 km/s (about 1,000 mph) at the Equator. However, the whole planet moves in its giant orbit around the Sun at about (a) 30 km/s (b) 67,000 mph (c) 108,000 kph (d) All these speeds are equivalent and correct.

(d) All these speeds are equivalent and correct.

What kind of life in the universe does the new science of Astrobiology seek? (a) Large scale intelligent life like us. (b) Large scale life of any kind, such as the plants and animals on Earth. (c) Large scale or microscopic life, similar to the full range of life on Earth. (d) Any kind of life, including the possibility of a lifeless or abiotic universe.

(d) Any kind of life, including the possibility of a lifeless or abiotic universe.

On July 20, 1976 NASA's Viking 1 lander touched down on the Chryse Planitia of Mars. Two months later the companion craft, Viking 2, landed on the other side of the planet. What kind of scientific experiments were carried by both of these probes? (a) Astronomy (b) Meteorology (c) Geology (d) Biology (e) Seismology

(d) Biology

The chemistry of carbon is very rich, as demonstrated by the whole field known as Organic Chemistry. What very important property of the carbon atom makes it ideal as a fundamental building block of biological molecules? (a) Carbon is the only element capable of bonding to itself, i.e. to other carbon atoms (b) Carbon is a very common element (c) Carbon is a very stable element (d) Carbon easily forms chemical bonds with other carbon atoms and other elements to enable a very wide variety of complex molecules

(d) Carbon easily forms chemical bonds with other carbon atoms and other elements to enable a very wide variety of complex molecules

Which statement describes the process of differentiation during Earth's early molten phase? (a) Less dense materials like rock sink to the center while more dense materials like iron rise to the surface (b) Differentiation is the convection process that mixed up materials in Earth's interior (c) Differentiation is the separation of Earth's surface into continents and oceans (d) Denser materials like iron sink to the center while less dense materials such as rock rise to the surface

(d) Denser materials like iron sink to the center while less dense materials such as rock rise to the surface

We take for granted the qualities that make Earth suitable for life, but a comparison with our closest neighboring world, the Moon, reveals that one of the following is NOT a guarantee of habitability. (a) Protective atmosphere (b) Moderate temperature (c) Abundant water (d) Distance from the Sun (e) Stable environment

(d) Distance from the Sun

Which of the following is an accurate scientific statement based on the state of astronomical knowledge? (a) Earth is the only planet in the universe with advanced life. (b) Earth is the only planet in the universe with any kind of life. (c) Earth occupies a special location in the universe so that life elsewhere is unlikely. (d) Earth is just one planet orbiting an ordinary star in a vast universe.

(d) Earth is just one planet orbiting an ordinary star in a vast universe.

At 1 ton, NASA's Perseverance is the heaviest rover to touch down successfully on Mars. It also gave us the first live video of the actual descent and landing. Which of the following were NOT features of this mission? (a) It employed autonomous radar terrain relative navigation to drastically improve landing site accuracy. (b) It used a Sky Crane to lower the rover gently to the surface. (c) It successfully deployed a small helicopter capable of flight in the thin Martian atmosphere. (d) It landed in Gale crater, not far from the Curiosity rover.

(d) It landed in Gale crater, not far from the Curiosity rover. Perseverance landed in Jerezo Crater as planned.

Oxygen in Earth's atmosphere is continually replenished by living things. Why did it take billions of years to build up the oxygen content of Earth's atmosphere to significant levels? (a) Most of the oxygen produced escaped into space. (b) Most of the oxygen produced by cyanobacteria was converted into water by combining with hydrogen in Earth's atmosphere. (c) Most of the oxygen produced by cyanobacteria simply dissolved in the oceans. (d) Oxidation of surface rock and ocean minerals occurred until the geochemical system was saturated.

(d) Oxidation of surface rock and ocean minerals occurred until the geochemical system was saturated.

Which of the following components of Earth's geology played a large factor in the long-term climate stability that has allowed life to evolve over billions of years? (a) Erosion and weathering (b) Seismic activity (earthquakes, volcanoes) (c) Global magnetism (d) Plate tectonics

(d) Plate tectonics

Ancient rocks ~3.5 billion years old have been found with a distinctive layered structure that is almost identical to that produced today by living colonies of bacteria. Microbes on the top layer use photosynthesis, whereas those below use organic compounds left as waste. As sediment accumulates on the top layer, the microbes must move up. These ancient rocks are called... (a) Zircons (b) Microfossils (c) Sedimentary inclusions (d) Stromatolites

(d) Stromatolites

There was no oxygen in Earth's early atmosphere, so what is meant by the "Oxygen Crisis" regarding the evolution of life on Earth? [Anaerobic: relating to, involving, or requiring an absence of free oxygen.] (a) The destruction of oxygen in the early atmosphere (b) The period before the development of the ozone layer (c) A time period when evolution accelerated so rapidly that there was insufficient oxygen available (d) The extinction of older anaerobic life as oxygen builds up in the atmosphere

(d) The extinction of older anaerobic life as oxygen builds up in the atmosphere

The Greenhouse Effect is the (a) release of infrared radiation by certain gases in the atmosphere, including carbon dioxide (CO2), methane (CH4) and water vapor (H2O) (b) generation of heat in the ozone layer due to the absorption of ultraviolet radiation (c) release of heat by volcanism along tectonic plate boundaries (d) Trapping of infrared radiation emitted by Earth's surface by certain gases in the atmosphere, including carbon dioxide (CO2), methane (CH4) and water vapor (H2O).

(d) Trapping of infrared radiation emitted by Earth's surface by certain gases in the atmosphere, including carbon dioxide (CO2), methane (CH4) and water vapor (H2O).

Although Venus is a planet almost identical to Earth in size and mass, life is unlikely on Venus because the surface temperatures are __________ because the planet has a __________ of carbon dioxide. (a) Very low; thin atmosphere (b) Very high; thin atmosphere (c) Very low; thick atmosphere (d) Very high; thick atmosphere

(d) Very high; thick atmosphere

Yes, it is true that 98% of the HUMAN GENOME is IDENTICAL to that of a CHIMPANZEE which implies (a) a random chance connection. (b) that DNA is not a useful tool. (c) we are the same species. (d) a common ancestor.

(d) a common ancestor.

Each cell nucleus contains a full complement of DNA. In cell division, an exact copy of DNA is made. The double helix is broken apart by an enzyme, and each strand serves as the template for a new complimentary strand. Two identical "daughter" DNA molecules are produced. When the cell divides, one copy of each daughter DNA goes to each daughter cell. The base pairs (Adenine, Thymine, Guanine and Cytosine) that make up the rungs of the DNA ladder are such that G matches C perfectly, and T matches A. Electrostatic forces enable these bonds to occur. The exact order of the base pairs in a sequence along the DNA molecule is a code for the production of... (a) a specific amino acid (b) a specific animal (c) a specific type of living cell (d) a specific protein

(d) a specific protein

Given that organic molecules need to react in order to produce life, this suggests that we should look for other worlds that have either an atmosphere, or a surface or subsurface liquid medium such as water, or both. Thus the search for life in the solar system is primarily a search for... (a) molecular oxygen (b) organic molecules (c) energy sources (d) liquid water

(d) liquid water

What is the third most abundant element in the universe? (a) helium (b) carbon (c) hydrogen (d) oxygen

(d) oxygen

On Earth, tiny spheres of hematite form in shallow acidic or salty water. What nickname was given to similar tiny spheres of hematite following their discovery on Mars by the Opportunity rover? (a) Opals (b) Strawberries (c) Blackberries (d) Gum balls (e) Blueberries

(e) Blueberries

Defining "life" is quite difficult. Review the properties of living things. Which of the six basic properties of life do biologists consider to be the most fundamental? (a) Response to the environment (b) Growth (c) Order (d) Reproduction (e) Evolutionary adaptation

(e) Evolutionary adaptation

The greenhouse effect is the trapping of infrared electromagnetic radiation (heat) by gases like carbon dioxide, methane and water vapor, but not nitrogen and oxygen. Without a modest greenhouse effect, the global temperature of Earth would be a. well below the freezing point of water b. around the freezing point of water c. well above the freezing point of water d. close to the boiling point of water

a. well below the freezing point of water

Tiny grains of crystal zirconium silicate (zircons) found embedded in sedimentary rocks in Western Australia have been dated using radioactivity to be ________. This is significant because these crystals form in water! a. 3.5 billion years old b. 4.38 billion years old c. 4.02 billion years old d. 3.85 billion years old

b. 4.38 billion years old

In which eon of Earth's history was the surface heavily bombarded from space? a. Phanerozoic b. Hadean c. Archaean d. Proterozoic

b. Hadean

Which of the following is NOT considered a key piece of evidence supporting a common ancestor for all life on Earth? a. The fact that all life on Earth uses the molecule ATP to store and release energy. b. The fact that all life on Earth is carbon based. c. The fact that all life on Earth builds proteins from the same set of left- handed amino acids. d. The fossil record, which clearly shows the diversity of new species that arise from a previous common ancestor.

b. The fact that all life on Earth is carbon based.

What makes the Galilean moons of Jupiter intriguing in a search for life? a. They are large. b. They experience tidal heating due to Jupiter's gravity. c. Jupiter's light keeps them warm. d. They are made of frozen ice.

b. They experience tidal heating due to Jupiter's gravity.

Scientists use the number of impact craters on a planet, or moon, to estimate the a. habitability of the surfaces b. ages of the surfaces c. temperatures of the surfaces d. chemical compositions of the surfaces

b. ages of the surfaces

In order to have a global magnetic field, a planet must have a. a large core of solid magnetized iron b. an electrically conducting fluid in its interior which is undergoing convection, plus a reasonably rapid rotation c. magnetic rocks in its interior d. magnetic rocks on its surface

b. an electrically conducting fluid in its interior which is undergoing convection, plus a reasonably rapid rotation

Astrobiology, the science of life beyond Earth, is based on the concept that there is no reason to believe that any of the steps in the evolution of the cosmos, the solar system, Earth and life on Earth through its modern manifestations are improbable, and a. therefore we know that life beyond Earth is plentiful b. even if some steps are improbable, nature can wield astronomical numbers to counteract this c. if some steps are improbable, then supernatural forces will overcome such problems d. in any case we have already discovered life beyond Earth

b. even if some steps are improbable, nature can wield astronomical numbers to counteract this

Space is empty. If a grapefruit to represent the Sun is placed on the ground, how many such grapefruits would we need to put down end-to-end with each other before we could place a tiny sphere the size of the tip of a ball point pen to represent Earth? [This is a scale reduction of 10 billion to one.] a. 7 b. 17 c. 107 d. 1,007

c. 107

Based on radioactive dating of meteorites, when did the Solar System form? a. About 6,000 years ago b. About 65 million years ago c. About 4.6 billion years ago d. About 13.8 billion years ago

c. About 4.6 billion years ago

Scientists use the word hypothesis for an educated guess and the word theory for a well-established explanation. Darwin's Theory of Evolution meets all the criteria of a scientific theory because a. Scientific opinion is evenly split as to whether evolution really happened b. Scientific opinion runs about 90% in favor and about 10% opposed c. After more than 100 years, the theory stands stronger than ever, having successfully met every scientific challenge to its validity. d. There is no longer any doubt that the theory of evolution is absolutely true.

c. After more than 100 years, the theory stands stronger than ever, having successfully met every scientific challenge to its validity.

In the swirling cloud or nebula from which the Sun formed, the temperature dropped sharply with distance from the proto-sun. Near the Sun, only small rocky planets can form by accretion of material. However, beyond the _________, the temperature drops low enough for ________ like water, ammonia and methane to freeze out. These "ice" covered fragments can bind together to make much larger objects. a. Oort Cloud; carbon compounds b. Karman Line; hydrogen compounds c. Frost Line; hydrogen compounds d. Frost Line; carbon compounds

c. Frost Line; hydrogen compounds

The true diversity of life on Earth is found among which of the following? a. Insects b. Plants c. Microbes d. Animals

c. Microbes

Individuals whose traits best enable them to survive and reproduce will, on average, leave the largest number of offspring that in turn survive to reproduce. This is the basic idea behind the theory of a. Creationism b. Extinction c. Natural Selection d. Artificial Selection

c. Natural Selection

Plants get their energy directly from sunlight and their carbon from the atmosphere. Given this, they can be classified metabolically as a. Chemoautotrophs b. Chemoheterotrophs c. Photoautotrophs d. Photoheterotrophs

c. Photoautotrophs

Which of the following statements is NOT true? a. The surface of Mars was habitable during a period of its early history. b. The surface of Mars is not habitable now. c. The Viking landers found evidence of life because they had biology experiments on board instead of geology experiments. d. The Viking landers did not find evidence of life because the UV-exposed soil chemistry resulted in false positive results.

c. The Viking landers found evidence of life because they had biology experiments on board instead of geology experiments.

If you could travel back four billion years in time (like Dr. Who in a TARDIS) to visit the early Earth, what is likely to happen to you when you open the door? a. Nothing, it would be like Disneyland b. You would get eaten by dinosaurs almost right away c. You would suffocate because there is no oxygen in the atmosphere yet d. You would freeze to death because the planet would be really cold

c. You would suffocate because there is no oxygen in the atmosphere yet

Evolutionary adaptations are related to changes that occur through time in a. molecules called lipids b. molecules called carbohydrates c. a molecule called deoxyribonucleic acid d. several large molecules called proteins

c. a molecule called deoxyribonucleic acid

The process by which denser materials like iron sank to the center of Earth, while less dense materials like rock rose to the surface is called a. accretion b. convection c. differentiation d. distinction

c. differentiation

The discovery of extremophiles on Earth suggests that a. life elsewhere will only be found under conditions similar to Earth b. life elsewhere will only be possible over a much narrower range of conditions than initially thought c. life elsewhere may be possible over a much wider range of conditions than initially thought d. extraterrestrial life will exist only under extreme conditions

c. life elsewhere may be possible over a much wider range of conditions than initially thought

Which component of Earth's geology is believed to have been largely responsible for the long-term climate stability that has allowed life to evolve? a. global magnetism b. earthquakes c. plate tectonics d. erosion and weathering

c. plate tectonics