Biology 121 - Test 1, UL Dr. Povinelli
UPDATED ACTUAL Exam Questions and
CORRECT Answers
When (roughly) did the first oxygen-producing bacteria evolve on earth? - CORRECT
ANSWER - As long as 3.5 billion years ago and certainly by 2.7 billion years ago.
How do scientists today measure the CO2 in the earth's atmosphere over the most recent million
years or so? - CORRECT ANSWER - Ice-core data before 1958. Mauna Loa data after
1958.
What structure of fossil plants can be measured by scientists to estimate the C02 in the earth's
atmosphere prior to a million of years ago? Why is this feature of plants a good way of
estimating how much CO2 was in the Earth's atmosphere? - CORRECT ANSWER -
Carbon Structures. Stoma. Plants breathe through tiny pores called stomata on the underside of
their leaves, which are surrounded by a pair of guard cells that expand or contract depending on
environmental conditions, allowing more or less gas to flow in and out of the pores. Plants need
CO2 to enter and O2 to exit. Stomata close when it is dark and dry, unless carbon dioxide levels
inside the leaf start to fall. The early earth's atmosphere had almost no free oxygen (O2). Now it
is almost 20%. It came from the evolution of single-celled photosynthetic organisms that could
turn sunlight + CO2 + H2O into sugar then output oxygen as waste.
Roughly speaking, how many HUMAN cells are in the human body? How many other cells are
present in the human body? What are they? - CORRECT ANSWER - 37.2 Trillion cells in
the human body. 200 different types of cells. Red blood cells, skin cells, neurons, fat cells, bone
cells, and white blood cells. 50 Trillion bacterial cells.
The formation of the earth - CORRECT ANSWER - The formation of the earth around 4.6
billion years ago, approximately one-third the age of the universe, by accretion from the solar
nebula.
The appearance of earliest life. - CORRECT ANSWER - 3.5 billion years ago
, Stages that led up to current levels of O2 in the earth's atmosphere. (What happened to the O2
that was produced by the first photosynthetic organisms on earth? What is cyanobacteria how did
it lead to the Great Oxidation Event, or GOE, about 2.5 billion years ago? What is the GOE? -
CORRECT ANSWER - Cyanobacteria are the first organisms to conduct photosynthesis.
The used sunshine, water and carbon dioxide to produce carbohydrates and oxygen. Because the
cyanobacteria produce oxygen it helped the GOE. The GOE is event that happened around 2.45
billion years ago during the beginning of the Proterozoic eon. This is when the cyanobacteria
first appeared which caused the oxygen to start producing. The early earth's atmosphere had
almost no free oxygen (O2). Now it is almost 20%. It came from the evolution of single-celled
photosynthetic organisms that could turn sunlight + CO2 + H2O into sugar then output oxygen
as waste.
The Cambrian explosion. - CORRECT ANSWER - The Cambrian explosion was an event
approximately 541 million years ago in the Cambrian period when most major animal phyla
appeared in the fossil record. It lasted for about 20-25 million years. It resulted in the divergence
of most modern metazoan phyla. The event was accompanied by major diversification of other
organisms. 500 MYA (542). Cambri = whales - occurred during Paleozic Era-gave rise to all the
plants and animals we know today- marked by dramatic evolutionary change- all life was
aquatic- - 1st Fossils indicate complex predator/prey relationship. Burgess Shale fossil.
A condensed history of the whole history of the earth from its formation to right now to a single
hour (60 minutes). About when did humans first appear on this clock? - CORRECT
ANSWER - If the formation of earth was a clock it would be around 11:58:43.
Where we are in right now the complete history (including the future) of the earth? - CORRECT
ANSWER - We are about half way through the history of earth. We are currently in the
Phanerozoic eon.
What will happen to the Earth in approximately 5 billion years? Why? - CORRECT
ANSWER - In a few billion years the sun will become a red giant so large that it will
engulf our planet. The Earth will become uninhabitable much sooner than that. After about a
billion years the sun will become hot enough to boil our oceans.
When did modern humans appear on Earth? - CORRECT ANSWER - The first human
ancestors appeared between five million and seven million years ago, probably when some
apelike creatures in Africa began to walk habitually on two legs.
UPDATED ACTUAL Exam Questions and
CORRECT Answers
When (roughly) did the first oxygen-producing bacteria evolve on earth? - CORRECT
ANSWER - As long as 3.5 billion years ago and certainly by 2.7 billion years ago.
How do scientists today measure the CO2 in the earth's atmosphere over the most recent million
years or so? - CORRECT ANSWER - Ice-core data before 1958. Mauna Loa data after
1958.
What structure of fossil plants can be measured by scientists to estimate the C02 in the earth's
atmosphere prior to a million of years ago? Why is this feature of plants a good way of
estimating how much CO2 was in the Earth's atmosphere? - CORRECT ANSWER -
Carbon Structures. Stoma. Plants breathe through tiny pores called stomata on the underside of
their leaves, which are surrounded by a pair of guard cells that expand or contract depending on
environmental conditions, allowing more or less gas to flow in and out of the pores. Plants need
CO2 to enter and O2 to exit. Stomata close when it is dark and dry, unless carbon dioxide levels
inside the leaf start to fall. The early earth's atmosphere had almost no free oxygen (O2). Now it
is almost 20%. It came from the evolution of single-celled photosynthetic organisms that could
turn sunlight + CO2 + H2O into sugar then output oxygen as waste.
Roughly speaking, how many HUMAN cells are in the human body? How many other cells are
present in the human body? What are they? - CORRECT ANSWER - 37.2 Trillion cells in
the human body. 200 different types of cells. Red blood cells, skin cells, neurons, fat cells, bone
cells, and white blood cells. 50 Trillion bacterial cells.
The formation of the earth - CORRECT ANSWER - The formation of the earth around 4.6
billion years ago, approximately one-third the age of the universe, by accretion from the solar
nebula.
The appearance of earliest life. - CORRECT ANSWER - 3.5 billion years ago
, Stages that led up to current levels of O2 in the earth's atmosphere. (What happened to the O2
that was produced by the first photosynthetic organisms on earth? What is cyanobacteria how did
it lead to the Great Oxidation Event, or GOE, about 2.5 billion years ago? What is the GOE? -
CORRECT ANSWER - Cyanobacteria are the first organisms to conduct photosynthesis.
The used sunshine, water and carbon dioxide to produce carbohydrates and oxygen. Because the
cyanobacteria produce oxygen it helped the GOE. The GOE is event that happened around 2.45
billion years ago during the beginning of the Proterozoic eon. This is when the cyanobacteria
first appeared which caused the oxygen to start producing. The early earth's atmosphere had
almost no free oxygen (O2). Now it is almost 20%. It came from the evolution of single-celled
photosynthetic organisms that could turn sunlight + CO2 + H2O into sugar then output oxygen
as waste.
The Cambrian explosion. - CORRECT ANSWER - The Cambrian explosion was an event
approximately 541 million years ago in the Cambrian period when most major animal phyla
appeared in the fossil record. It lasted for about 20-25 million years. It resulted in the divergence
of most modern metazoan phyla. The event was accompanied by major diversification of other
organisms. 500 MYA (542). Cambri = whales - occurred during Paleozic Era-gave rise to all the
plants and animals we know today- marked by dramatic evolutionary change- all life was
aquatic- - 1st Fossils indicate complex predator/prey relationship. Burgess Shale fossil.
A condensed history of the whole history of the earth from its formation to right now to a single
hour (60 minutes). About when did humans first appear on this clock? - CORRECT
ANSWER - If the formation of earth was a clock it would be around 11:58:43.
Where we are in right now the complete history (including the future) of the earth? - CORRECT
ANSWER - We are about half way through the history of earth. We are currently in the
Phanerozoic eon.
What will happen to the Earth in approximately 5 billion years? Why? - CORRECT
ANSWER - In a few billion years the sun will become a red giant so large that it will
engulf our planet. The Earth will become uninhabitable much sooner than that. After about a
billion years the sun will become hot enough to boil our oceans.
When did modern humans appear on Earth? - CORRECT ANSWER - The first human
ancestors appeared between five million and seven million years ago, probably when some
apelike creatures in Africa began to walk habitually on two legs.
