How Old Is the First Evidence of Life on Earth

Q10: Multicellular organisms first appear<br>A)3.6 billion years ago.<br>B)2

Q11: The sudden appearance of organisms with shells

Q12: Photosynthesis is<br>A)a process found only among modern

Q13: Organic compounds on earth first came from<br>A)processes

Q14: The formation of the "supercontinent" of Pangea<br>A)was

Q16: The earth was formed about<br>A)1 million years

Q17: The heavy elements that now make up

Q18: At the moment,the best guess for the

Q19: An important result of the evolution of

Q20: What is the relationship in time between