How much of Earth's history had passed before multicellular life evolved? 20% 80% 10% 50% Multiple Choice 1 point What was Laurasia? mass extinction at end of Cenozoic Era southern portion of supercontinent northern section of supercontinent supercontinent during Permian

Question 1:<br />How much of Earth's history had passed before multicellular life evolved?<br /><br />Answer:<br />【Explanation】: Multicellular life evolved approximately 600 million years ago, during the Ediacaran period. The Earth is estimated to be about 4.54 billion years old. To determine the percentage of Earth's history that had passed before multicellular life evolved, we need to calculate the ratio of the time elapsed to the total age of the Earth and then multiply by 100 to get the percentage.<br /><br />The time elapsed before multicellular life evolved is 600 million years, and the total age of the Earth is 4.54 billion years. Converting these values to the same unit (million years), we have 600 million years and 4,540 million years. <br /><br />The percentage of Earth's history that had passed before multicellular life evolved is calculated as follows:<br />\[ \text{Percentage} = \left( \frac{600}{4,540} \right) \times 100 \]<br /><br />Calculating this gives us approximately 13.19%. However, since this value is not among the given options, we need to choose the closest option, which is 10%.<br /><br />【Answer】: 10%<br /><br />Question 2:<br />What was Laurasia?<br /><br />Answer:<br />【Explanation】: Laurasia was the northern section of the supercontinent Pangaea. It existed during the late Paleozoic and early Mesozoic eras and eventually separated into the continents of North America, Europe, and Asia.<br /><br />【Answer】: northern section of supercontinent