Geologic History and Dating Methods Unit 6B

Which of the following best describes a change in Earth’s atmosphere made by early photosynthetic life?

• increased level of oxygen

• increased level of carbon dioxide

• decreased ability to support life

• decreased ability to transmit light

Tags

NGSS.MS-LS1-6

Which provides the oldest evidence for oxygen accumulation in Earth’s atmosphere?

• the earliest fossils of animals

• the earliest sediments of oxidized rock

• impact craters of oxidized-iron asteroids

• extensive volcanic calderas of similar age

The first atmosphere of Earth was primarily hydrogen and helium.

During this time, Earth's core was not differentiated and the magnetosphere had not yet formed.

Think about this... How did the lack of Earths layers affect the atmospheric composition?

Hint: the atmosphere layers are to be considered for this question.

• by releasing water vapor from the core into the atmosphere

• by magnetically attracting freed metallic elements to the surface

• by providing the heat energy that fueled atmospheric chemical reactions

• by allowing the solar wind to blow away much of the lighter elemental gases

Tags

NGSS.HS-ESS1-6

NGSS.HS-ESS2-1

If cyanobacteria had failed to appear on Earth, how would the evolution of Earth's atmosphere most likely be different?

• Earth's atmosphere would lack significant amounts of nitrogen

• Earth's atmosphere would consist of volcanic gases and water vapor

• Earth's atmosphere would contain more oxygen and less carbon dioxide

• Earth's atmosphere would still be composed mainly of hydrogen and helium

Tags

NGSS.HS-ESS2-7

Studies of Venus indicate what can happen if the atmosphere of a planet contains a high percentage of carbon dioxide. The development of photosynthetic life removed much of the carbon dioxide from the atmosphere of Earth. This process released oxygen, which then bonded with iron on the surface to form redbeds. Compared to current conditions, what can be inferred about what Earth was like before the formation of the redbeds?

• Earth was warmer.

• Earth was cooler.

• Earth was more dense.

• Earth was less dense.

Tags

NGSS.HS-ESS1-6

NGSS.HS-ESS2-4

NGSS.HS-ESS2-6

NGSS.HS-LS2-5

Iron-rich deposits that formed about 2 billion years ago have red layers. Layers formed before then were not red. The red layers formed when oxygen made during photosynthesis reacted with iron molecules in the ocean. The oxidized iron formed layers of sedimentary rock. Which BEST summarizes this phenomenon?

• The biosphere changed the lithosphere.

• The lithosphere changed the atmosphere.

• The hydrosphere changed the atmosphere.

• The atmosphere changed the biosphere.

Answer explanation

The biosphere consisted of cyanobacteria at the end of the Precambrian. These created oxygen that would eventually cause oxidation to the rocks in the lithosphere

Tags

NGSS.HS-ESS2-2

NGSS.HS-ESS2-7

Which environmental condition MOST likely existed at the time a fossil formed?

• Organism remains were deposited in an area of open space.

• Organism remains were covered by lava flow.

• Organism remains were buried with little oxygen.

• Organism remains were buried in an area where a lot of erosion occurred.

Answer explanation

No oxygen = no decomposition

Tags

NGSS.HS-LS4-5

When two fish die, one sinks to the bottom of a lake and the other one washes up on the rocky lake shore. Why is a fossil more likely to form from the body of the fish on the lake bottom?

• Soft parts of the fish will decay more quickly in the water.

• Sediments in the water will quickly cover the fish.

• Scavengers in the water will eat the remains of the fish.

• Currents in the water will move the fish.

Tags

NGSS.MS-LS4-1

Radiocarbon dating is used to determine the age of many artifacts. Select the two objects that could be dated by radiocarbon dating techniques.

Hint- look at the word and think: Radiocarbon

• bronze spear point

• ancient human bone found at a burial site

• piece of cloth that wrapped an Egyptian mummy

• stone from a Neolithic monument in Europe

The half-life of a radioactive element, such as carbon-14, is the time it takes for half of the atoms of the element to decay. How many half-life periods have passed if a fossil contains 1/32 of the original amount of carbon-14?

• 3

• 4

• 5

• 6

Tags

NGSS.HS-PS1-8