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Biology 121 Test 1 Questions and Correct Answers
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  • BIO 121

When (roughly) did the first oxygen-producing bacteria evolve on earth? 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? Ice-core data before 1958. Mauna Loa data aft...

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  • August 13, 2024
  • 6
  • 2024/2025
  • Exam (elaborations)
  • Questions & answers

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  • biology 121 test 1 questions and correct answers
  • when roughly did the first oxygen producing bact
  • how do scientists today measure the co2 in the ear

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Biology 121 Test 1 Questions and
Correct Answers
When (roughly) did the first oxygen-producing bacteria evolve on earth? ✅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? ✅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? ✅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? ✅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 cells. 50X10 trillion = 500 trillion cells

The formation of the earth ✅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. ✅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? ✅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. ✅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? ✅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?
✅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? ✅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? ✅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.

What does it mean that life is "hierarchically" organized? ✅Hierarchical manner means
that lower levels of organization are progressively integrated to make up higher levels.
The building blocks of matter, called atoms, lie at the base of life's organizational
structure.

Be able to order of the hierarchy of life from smallest to largest (from atoms up to
ecospheres). ✅a. Atoms
b. Molecules
c. Organelles
d. Cells
e. Tissues
f. Organs
g. Systems
h. Organism
i. Population
j. Community

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