UCLA ASTRO 5 Final UPDATED ACTUAL
Exam Questions and CORRECT Answers
What formed the Sun and planets? - CORRECT ANSWER - Cloud of gas & dust
Why is the Solar System flat? - CORRECT ANSWER - Rotational forces in combination
with gravitational forces
What is the habitable zone? What defines it? - CORRECT ANSWER - The habitable zone
of the solar system is where the temperature is right to be able to support life - not too close to
the sun, not too far away. The frost line defines the habitable zone.
Why are the inner planets rocky, while the outer planets are gaseous? - CORRECT
ANSWER - The frost line. The outer planets were formed first, and formed outside the
frost line, so they had more vitreous materials to create their planets from, and hydrogen ice. The
inner planets had less materials to work with and were formed inside the frost line with hydrogen
vapor.
How was the moon formed? How do we know that? - CORRECT ANSWER - Moon was
formed when a competing planet crashed into the Earth during its formation, then got caught in
our orbit. We know this because Earth is the only rocky planet with a large moon and the
materials on the surface of the moon are the same as on Earth.
What was the Late Heavy Bombardment? Why was it both a good and bad thing for life on
Earth? - CORRECT ANSWER - ~4 BYA, period of intense asteroid and comets in the
Solar System. Wiped out any life Earth may have had at that time, but brought water, nitrogen
atmosphere, and possibly life.
When did life on Earth begin? What evidence to scientists use to determine this? - CORRECT
ANSWER - ~3.8 BYA. Microfossils (fossils of anaerobic bacteria before rise of oxygen,
~3.4 BYA), Stromatolites (colony of microbes that used photosynthesis ~3.5 BYA), Zircon
Crystals (Not direct evidence, but since need water could show life ~4.5 BYA)
, Why does it matter exactly when Earth began? - CORRECT ANSWER - Then we can
make determinations and more educated guesses about how life on Earth began - whether it was
created organically here, whether ingredients were brought here, or whether life itself was
delivered here.
What was the Miller-Urey experiment? What did we learn from it? - CORRECT
ANSWER - Miller-Urey experiment was an experiment done to see if molecules could
form organically from scratch in Earth's atmosphere. Although experiment wasn't perfect,
through repeated trials we learned that it could.
How did the first strands of RNA form? - CORRECT ANSWER - Ingredients came
together in the mud of shallow ponds to form RNA.The bases stick to the mud/clay and then find
each other to form strands.
How did the first cells form? - CORRECT ANSWER - The RNA strands were trapped in a
pre-cell/vesicle and go through evolution of self replication. From here, DNA evolves from RNA
to form a true cell.
What are three ways life on Earth could have started? - CORRECT ANSWER - Life was
formed from scratch on Earth, ingredients for life were delivered to Earth by a comet or asteroid,
life itself was delivered here.
What is panspermia? What evidence do we have that panspermia is possible in our Solar
System? - CORRECT ANSWER - Panspermia is the theory that life can spread throughout
the solar system between different planets. Evidence we have is that Mars probably once had
life, and we know that materials from Mars have landed on Earth before. Also, tardigrades and
other extremophiles.
What caused the rapid rise of oxygen in our atmosphere? - CORRECT ANSWER - The
rise of cyanobacteria led to the rise of oxygen. The oxygen levels rose when the oxygen sinks
filled up and could no longer contain the oxygen. It was then released into the atmosphere.
What was the Cambrian Explosion? - CORRECT ANSWER - Fast increase in diversity of
species due to the rapid rise of oxygen. 540 MYA
Exam Questions and CORRECT Answers
What formed the Sun and planets? - CORRECT ANSWER - Cloud of gas & dust
Why is the Solar System flat? - CORRECT ANSWER - Rotational forces in combination
with gravitational forces
What is the habitable zone? What defines it? - CORRECT ANSWER - The habitable zone
of the solar system is where the temperature is right to be able to support life - not too close to
the sun, not too far away. The frost line defines the habitable zone.
Why are the inner planets rocky, while the outer planets are gaseous? - CORRECT
ANSWER - The frost line. The outer planets were formed first, and formed outside the
frost line, so they had more vitreous materials to create their planets from, and hydrogen ice. The
inner planets had less materials to work with and were formed inside the frost line with hydrogen
vapor.
How was the moon formed? How do we know that? - CORRECT ANSWER - Moon was
formed when a competing planet crashed into the Earth during its formation, then got caught in
our orbit. We know this because Earth is the only rocky planet with a large moon and the
materials on the surface of the moon are the same as on Earth.
What was the Late Heavy Bombardment? Why was it both a good and bad thing for life on
Earth? - CORRECT ANSWER - ~4 BYA, period of intense asteroid and comets in the
Solar System. Wiped out any life Earth may have had at that time, but brought water, nitrogen
atmosphere, and possibly life.
When did life on Earth begin? What evidence to scientists use to determine this? - CORRECT
ANSWER - ~3.8 BYA. Microfossils (fossils of anaerobic bacteria before rise of oxygen,
~3.4 BYA), Stromatolites (colony of microbes that used photosynthesis ~3.5 BYA), Zircon
Crystals (Not direct evidence, but since need water could show life ~4.5 BYA)
, Why does it matter exactly when Earth began? - CORRECT ANSWER - Then we can
make determinations and more educated guesses about how life on Earth began - whether it was
created organically here, whether ingredients were brought here, or whether life itself was
delivered here.
What was the Miller-Urey experiment? What did we learn from it? - CORRECT
ANSWER - Miller-Urey experiment was an experiment done to see if molecules could
form organically from scratch in Earth's atmosphere. Although experiment wasn't perfect,
through repeated trials we learned that it could.
How did the first strands of RNA form? - CORRECT ANSWER - Ingredients came
together in the mud of shallow ponds to form RNA.The bases stick to the mud/clay and then find
each other to form strands.
How did the first cells form? - CORRECT ANSWER - The RNA strands were trapped in a
pre-cell/vesicle and go through evolution of self replication. From here, DNA evolves from RNA
to form a true cell.
What are three ways life on Earth could have started? - CORRECT ANSWER - Life was
formed from scratch on Earth, ingredients for life were delivered to Earth by a comet or asteroid,
life itself was delivered here.
What is panspermia? What evidence do we have that panspermia is possible in our Solar
System? - CORRECT ANSWER - Panspermia is the theory that life can spread throughout
the solar system between different planets. Evidence we have is that Mars probably once had
life, and we know that materials from Mars have landed on Earth before. Also, tardigrades and
other extremophiles.
What caused the rapid rise of oxygen in our atmosphere? - CORRECT ANSWER - The
rise of cyanobacteria led to the rise of oxygen. The oxygen levels rose when the oxygen sinks
filled up and could no longer contain the oxygen. It was then released into the atmosphere.
What was the Cambrian Explosion? - CORRECT ANSWER - Fast increase in diversity of
species due to the rapid rise of oxygen. 540 MYA
