The Environment and Change Over Time

6Why is it difficult for scientists to absolute-age date sedimentary rock formations using isotopes?

• Sedimentary rocks are composed of particles from other rocks, making it hard to date them directly.

• Isotopes are not present in sedimentary rocks.

• Sedimentary rocks are too young to be dated using isotopes.

• The isotopes in sedimentary rocks decay too quickly.

7. The geologic time scale is:

• a system of chronological dating that relates geological strata to time

• a method to measure the depth of the ocean

• a scale to measure the height of mountains

• a tool to predict weather patterns

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NGSS.MS-ESS1-4

8. Name: Scientists use _______ to mark boundaries in the geologic time scale.

• fossils

• radiometric dating

• stratigraphy

• magnetic reversals

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NGSS.MS-ESS1-4

Visual Check: List the following living organisms in the order in which they first appeared on Earth: humans, insects, single cells, dinosaurs.

• Single cells, insects, dinosaurs, humans

• Dinosaurs, single cells, insects, humans

• Insects, single cells, humans, dinosaurs

• Humans, dinosaurs, insects, single cells

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NGSS.MS-ESS1-4

Use Scientific Notation: The first vertebrates appeared on Earth about 490,000,000 years ago. Express this time in scientific notation.

• 4.9 x 10^8 years ago

• 49 x 10^7 years ago

• 490 x 10^6 years ago

• 0.49 x 10^9 years ago

Visual Check: Analyze when did the most recent mass extinction happen? Circle the name of the time period on the graph. About how long ago did it happen?

• Cretaceous-Paleogene, 66 million years ago

• Permian-Triassic, 252 million years ago

• Triassic-Jurassic, 201 million years ago

• Ordovician-Silurian, 444 million years ago

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Reading Check: Relate what is the relationship between extinction and environmental change?

• Environmental change can lead to extinction by altering habitats and resources.

• Extinction causes environmental change by removing species from ecosystems.

• There is no relationship between extinction and environmental change.

• Environmental change and extinction are unrelated phenomena.

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The fossil record has obvious clues about the extinction of species over time. What patterns did scientists find in the fossil record?

• Scientists found patterns of gradual extinction over time.

• Scientists found patterns of sudden mass extinction events.

• Scientists found no discernible patterns in the fossil record.

• Scientists found patterns of both gradual and sudden extinction events.

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Fossils are evidence of biological evolution because they show:

• the existence of ancient life forms and their changes over time

• the current biodiversity on Earth

• the impact of human activity on the environment

• the daily life of ancient humans

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In what ways did the horse change over time?

• The horse grew larger and developed hooves.

• The horse developed wings and could fly.

• The horse became smaller and lost its tail.

• The horse turned into a marine animal.

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NGSS.MS-LS4-2