MSCI 102 Exam 1 2024-2025 | MSCI 102
Exam Update 2024 -2025 Questions and
Correct Answers Rated A+
What caused partial melting of early Earth? -ANSWER-heat and
gravitational condensation
How was the Earth's core formed? -ANSWER-gravity moved iron and
denser materials toward the center (iron, nickel)
How was the Earth's crust formed? -ANSWER-lighter materials
migrated to surface
What caused the Earth's layers to form? -ANSWER-density
stratification
How was the moon formed? -ANSWER-a planetesimal colliding with
the Earth; piece broke off and began orbiting the planet
What are the 2 theories of how water came to Earth ? -ANSWER-
Earth's interior - mantle, extraterrestrial - by comet
How did the mantle bring water to the surface? -ANSWER-contains a
small amount of water (~0.5% wt) that was emitted to the atmosphere
as water vapor during eruptions
How would comets have brought water to Earth? -ANSWER-comets
contain ice and would enter atmosphere on a daily basis
What elements is the modern day atmosphere made of? -ANSWER-
Nitrogen (78%), Oxygen (21%), Argon (<1%), Carbon Dioxide
(<0.04% - rapidly increasing)
What elements made up the ancient atmosphere? -ANSWER-
nitrogen, carbon dioxide, water, methane, ammonia
,When did oxygen enter the atmosphere? -ANSWER-~2.5 bya
How did oxygen first enter the atmosphere? -ANSWER-by
photosynthesis; evidence of early life on Earth
What were the first life forms to carry out photosynthesis and produce
oxygen? -ANSWER-cyanobacteria
When did the great oxidation event occur? -ANSWER-2.5-2.0 bya
When was the second oxygen spike? -ANSWER-around 0.5 bya (500
mya)
What shows that oxygen was present in the Archean eon? -ANSWER-
banded iron formations
Most nitrogen on Earth is in the form of -ANSWER-N2 (triple bonded
N atoms)
What is the most abundant element in the ocean? -ANSWER-nacl
(salt)
What do shell fish use to form their shells? -ANSWER-calcium
Other abundant elements in the ocean -ANSWER-potassium,
magnesium, calcium
What is the average depth of the ocean? -ANSWER-3,800 - 4,000
meters
How is salt brought to the ocean? -ANSWER-rivers and runoff
The northern hemisphere is -ANSWER-60.7% sea, 39.3% land
The southern hemisphere is -ANSWER-80.9% sea, 19.1% land
, Precipitation (wet) includes -ANSWER-snow and rain
Evaporation includes -ANSWER-transpiration and sublimation
Runoff includes -ANSWER-surface and underground flow
Definition of life -ANSWER-a minimal cell can be thought of as
compromising informational, compartment-forming and metabolic
subsystems
Living organisms have -ANSWER-- ways of capturing and using
energy and raw materials
- ways of sensing and responding to the environment
- the capacity to reproduce
- the capacity to evolve
Cells are composed of -ANSWER-proteins, carbohydrates, lipids,
nucleic acids
Cell components are assembled from -ANSWER-simple sugars, fatty
acids, amino acids, nucleotides
Energy is available from -ANSWER-the Sun, lightning, heat vented
from crust
The precursor molecules are present in -ANSWER-Mars rocks,
meteorites, moon rocks
Two conditions critical to the development of life -ANSWER-lack of
oxygen, presence of water
Lack of O2 in early atmosphere allowed for -ANSWER-the
spontaneous formation of organic compounds
What would have happened if oxygen was present in the early
atmosphere? -ANSWER-it would react with other elements
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