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The most common isotope of carbon is


A) carbon-14
B) carbon-13
C) carbon-12
D) carbon-11

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Which of the following are possible causes for mass extinctions on Earth?


A) episodes of widespread volcanism
B) impacts of asteroids
C) snowball Earth episodes
D) all of these can be responsible for mass extinctions

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The LEAST significant evolutionary changes in human beings over the past 40,000 years have been


A) biological
B) political
C) technological
D) cultural

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The layered colonies of microbes found in western Australia that resemble some of the Earth's earliest living organisms are called


A) living stromatolites
B) microfossils
C) zircons
D) protocorals

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What is the main potential concern regarding the creation of artificial life?


A) that they would rapidly evolve and replace existing life on Earth
B) that they would be used by hostile nations to build clone armies
C) that they might be the source of new diseases or toxins for which terrestrial life would have little resistance
D) that they would travel on our robotic space probes and contaminate other planets

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One theory for the origin of life suggests that life formed spontaneously from increasingly complex chemical reactions on the Earth. This is referred to as


A) intelligent design
B) naturism
C) panspermia
D) chemical evolution

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The study of 2-3 billion year old banded iron formations shows that


A) the amount of oxygen in the Earth's atmosphere has remained constant throughout its history
B) Earth's atmosphere contained much more oxygen in the past compared to today
C) there was no oxygen in the Earth's atmosphere at that time
D) Earth's atmosphere contained much less oxygen in the past compared to today

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The probability of Earth being hit by a large asteroid in the next few hundred million years is


A) almost certain
B) impossible to predict
C) zero
D) small but not zero

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Which approach is currently proving to be the most promising way of determining how life on Earth originated?


A) studies of Martian meteorites
B) studies of organisms living around deep-sea ocean vents
C) studies of the fossil record
D) laboratory simulations of conditions present on the early Earth

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Impacts of large asteroids on the Earth's surface generally result in


A) localized destruction close to the impact area
B) the destruction of most but not all life on Earth
C) the formation of Moons
D) total destruction of all life on Earth

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The oldest hominid so far discovered dates back to


A) 540 million years ago
B) 65 million years ago
C) a few thousand years ago
D) 6 to 7 million years ago

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A sample of an ancient sedimentary rock contains slightly less of the isotope carbon-13 than normal. One possible explanation for this is that


A) it was a meteorite that fell from the sky
B) some kind of radioactive decay occurred in it in the past
C) it used to be at the bottom of an ancient ocean
D) some kind of biological activity occurred in it in the past

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The first living organisms probably resembled


A) single-celled eukaryotes
B) multicellular eukaryotes
C) single-celled prokaryotes
D) multicellular prokaryotes

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What is one reason that early life formed cells?


A) only cells can replicate
B) cell walls prevent heat from escaping
C) cells help to protect fragile biological molecules from the outside environment
D) biological reactions can occur only within cells

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Why is the claim of the discovery of microfossils controversial?


A) they are found in rocks from the Hadean Eon
B) it is not clear whether they are of biological or non-biological origin
C) the rocks they are found in are probably contaminated by terrestrial bacteria
D) they are too small to be of biological origin

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A large piece of debris that only partially burns up in the atmosphere, leaving a fragment to hit the surface, is called a


A) meteor
B) hail stone
C) meteorite
D) meteoroid

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The earliest Homo sapiens appeared about


A) 25 million years ago
B) 6 to 8 million years ago
C) 100,000 years ago
D) 545 million years ago

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The Carboniferous Period began about


A) 475 million years ago
B) 65 million years ago
C) 360 million years ago
D) 545 million years ago

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In 2010, scientists discovered an RNA strand capable of catalyzing biochemical reactions made of


A) 165 bases
B) only 5 bases
C) only 2 bases
D) 1967 bases

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How long did it take for oxygen to build up in the Earth's atmosphere to its present levels?


A) 545 million years
B) 360 million years
C) 2 billion years
D) 3.5 billion years

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