Question 1

How much of the Earth's water is found in the ocean?

Accepted Answer

Approximately 97% of the Earth's water is contained in the ocean. An ocean, in general, is a term used to describe a vast body of saline water that occupies depressions on Earth's surface. Information can be found in the section Earth is an Ocean World.

Question 2

How long did the process of density stratification of Earth last?

Accepted Answer

The density stratification of Earth lasted approximately 100 million years. Then the Earth began to cool down. Information can be found in the section Earth, Ocean, and Atmosphere Accumulated in Layers Sorted by Density.

Question 3

A(n) ____ is a test involving manipulations made on conditions of a particular observation.

Accepted Answer

The simplification of an observation in nature or in a laboratory is conducted by manipulating conditions. Often times, one aspect is manipulated at a time to narrow possible reasons for an observation. Information can be found in the section Marine Scientists Use the Logic of Science to Study the Ocean.

Question 4

The composition of the Milky Way does not include:

Accepted Answer

The Milky Way galaxy is made up of stars, gas, dust, and debris. As with any galaxy, it is held in place by gravity. The Milky Way galaxy is named after the Greek galaktos, which means "milk". Information can be found in the section Stars and Seas.

Question 5

What key characteristic marks the beginning stages of the collapse of a star?

Accepted Answer

The lack of hydrogen in a star marks its death. The rapid compression of the core then causes the internal temperature to increase. In turn, this allows for the formation of heavy metal atoms. Information can be found in the section Stars and Seas.

Question 6

What had the most influence in irreversibly changing the Earth's atmosphere?

Accepted Answer

Although all these factors did occur, the addition of oxygen to the atmosphere changed the atmosphere forever. It was called the oxygen revolution. As more and more photosynthetic organisms evolved, more oxygen was added into the atmosphere. Information can be found in the section Earth, Ocean, and Atmosphere Accumulated in Layers Sorted by Density.

Question 7

Why is biosynthesis unlikely to occur today as it did in Earth's youth?

Accepted Answer

Living organisms have altered the ocean and atmosphere, and those changes are not consistent with any new origin of life. Plants are now producing oxygen which is then added to the atmosphere. Oxygen, in the form of Ozone, also blocks the most dangerous wavelengths of light from reaching the surface of the ocean. Additionally, the many tiny organisms present today would gladly scavenge on any large organic molecules. Information can be found in the section Life Probably Originated in the Ocean.

Question 8

The life history of a star is dependent upon what?

Accepted Answer

The life history of a star is based on its initial mass. Stars convert hydrogen atoms into larger carbon and oxygen atoms. Once the star begins to consume the carbon and oxygen it produced, it increases its energy output. The rate of this is determined by temperature and size. Information can be found in the section Stars and Seas.

Question 9

What process accounts for the layers found in Earth?

Accepted Answer

Heavy elements like iron and nickel pulled inward towards the core while lighter materials like oxygen and silicon rose toward the surface. The Earth now has distinct interior layers separated by their density. Information can be found in the section Earth, Ocean, and Atmosphere Accumulated in Layers Sorted by Density.

Question 10

Since the formation of our ocean, Earth has made approximately ____ orbits around the galaxy.

Accepted Answer

The Earth has only made about 20 orbits around the galaxy since the ocean's formation. One orbit takes approximately 230 million years, despite our speed of 200 kilometers per second. This puts into perspective the sheer magnitude of our galaxy. Information can be found in the section Stars and Seas.

Question 11

A(n) ____ is an explanation that can be tested by additional observations or controlled experiments.

Accepted Answer

In general, a hypothesis is a tentative explanation for a particular observation or measurement. It can be supported or refuted based on further observations and controlled experiments. Information can be found in the section Marine Scientists Use the Logic of Science to Study the Ocean.

Question 12

There were multiple sources of water that contributed to the ocean. How was the majority of the ocean's water formed?

Accepted Answer

Although the Earth (and other planets in our solar system) was formed via the condensation of a dust and gas ridden cloud, this was not the direct cause of the formation of the ocean. Water vapor began escaping from Earth's interior. Over time this vapor condensed and cooled. Additional water was brought to Earth by comets. Information can be found in the section Stars and Seas.

Question 13

How old are fossils that indicate the first life forms on Earth?

Accepted Answer

Bacteria-like fossils have been found in northwest Australia. These are the oldest fossils found to date. There is additional evidence found near Greenland in the form of carbon residue in some of the rocks which could represent life as far back as 3.85 billion years ago. Information can be found in the section Life Probably Originated in the Ocean.

Question 14

____ is a critical aspect of science.

Accepted Answer

Science is a dynamic process. Scientific theories have the ability to change or be refined as new information is obtained. Science can even operate in reverse by using laws and theories to predict what could happen. Information can be found in the section Marine Scientists Use the Logic of Science to Study the Ocean.

Question 15

What caused Earth to partially melt when being formed?

Accepted Answer

Asteroids, comets, and debris heated the surface of Earth. Combined with gravitational compression and decaying radioactive elements, this caused Earth to partially melt. Information can be found in the section Earth, Ocean, and Atmosphere Accumulated in Layers Sorted by Density.

Question 16

Which is not necessarily a characteristic of a red giant?

Accepted Answer

Not all red giants are large enough to become a supernova. When our sun begins to die, it likely will not become a supernova. It will engulf planets and expand its radius. The pieces sent into space are to be recycled. Information can be found in the section What Will be the Future of Earth.

Question 17

A marine scientist is studying the amount of dissolved oxygen in a particular area. They are attempting to connect the data with the type of organisms found in that area. What kind of marine scientist might they be classified as?

Accepted Answer

Chemical oceanographers study dissolved gases and solids in the ocean. They then apply these measurements to the geology and biology of the ocean as a whole. Information can be found in the section Marine Scientists Use the Logic of Science to Study the Ocean.

Question 18

What was the main requirement for the development of life on Earth?

Accepted Answer

In laboratory experiments, gases and compounds thought to be similar to Earth's early atmosphere were exposed to light, heat, and electrical sparks; the result was the production of simple sugars, small proteins, and nucleotides. The absence of free oxygen seemed to be the key factor. Information can be found in the section Life Probably Originated in the Ocean.

Question 19

What created Earth's moon?

Accepted Answer

The moon orbiting Earth resulted from the initial collision with another planetary body about the size of Mars. The collision ejected some rocky mantle while the metallic core of that body fell into Earth's core. The rocky mantle began to condense to form the moon we know today. Information can be found in the section Earth, Ocean, and Atmosphere Accumulated in Layers Sorted by Density.

Question 20

What planet is an example that others planets besides Earth have a plethora of water?

Accepted Answer

Water is a common resource throughout our solar system. Although Jupiter has hundreds of times more water than Earth, it is in a solid state of ice. Information can be found in the section Are There Other Ocean Worlds.

Quiz 1: The Origin of the Ocean