How was early Earth's atmosphere different from today's atmosphere?

The early Earth was very different from our Earth today.

Explanation:

Earth's first atmosphere had lots of water vapor but had almost no oxygen. Later, frequent volcanic eruptions put several different gases into the air (Figure 12.13). These gases created a new type of atmosphere for Earth.

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c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.