Scientists Think That the Life We Have on Earth Today

question 18

Multiple Choice

Scientists think that the life we have on Earth today originated some time between 3.5 and 3.8 billion years ago. Yet the solar system and the Earth are known to be at least 4.5 billion years old. Which of the following is one reason life as we know it had to wait until 3.5 to 3.8 billion years ago to get going?

• A) supernovae were exploding near the Sun's location every year back then
• B) the Sun was so much cooler when the Earth formed, that the Earth's oceans (and even Mars' oceans) were frozen over for billions of years
• C) before 3.8 billion years ago, the Earth was experiencing a period of heavy bombardment, when giant chunks of rock and ice left over from planet formation kept hitting our planet and making it uninhabitable
• D) experiments like the one done by Miller and Urey show that life on Earth could not form until plants produced a lot of oxygen for our atmosphere
• E) the early solar system was filled with dark matter, and life could not form with so much dark matter around

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Definitions:

Encoded

The process of converting information into a particular form for efficient communication, storage, or processing.

Short-Term Memory

A capacity for holding a small amount of information in mind in an active, readily available state for a short period of time.

Stimulus Decays

The gradual weakening of a stimulus's impact over time, leading to a decrease in the response it evokes.

Maintenance Rehearsal

A cognitive process involving the repeated review of information to retain it in short-term memory.