Ques: Q: Most, if not all, of the extant animal phyla today evolved during the cambrian period, yet many of what devastating events have taken place since then? Choices: - life extinctions - earthquakes - starvations - mass extinctions A:
Ans: mass extinctions

Ques: Q: What are the newest, outer layers of secondary xylem called? Choices: - bark - fibrous - vascular - sapwood A:
Ans: sapwood

Ques: Q: Each silicon atom shares how many valence electrons with other silicon atoms in a crystal? Choices: - five - ten - three - four A:
Ans: four

Ques: Q: The symbol for each what is usually the first letter or two of its name? Choices: - state - property - material - element A:
Ans:
element