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? Read this paragraph and choose the correct option from the provided answers: Describe at least two major changes to the animal phylogenetic tree that have come about due to molecular or genetic findings. How is it that morphological data alone might lead scientists to group animals into erroneous evolutionary relationships? 26. Briefly describe at least two theories that attempt to explain the cause of the Cambrian explosion. How is it that most, if not all, of the extant animal phyla today evolved during the Cambrian period if so many massive extinction 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? Read this paragraph and choose the correct option from the provided answers: 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? Read this paragraph and choose the correct option from the provided answers: Each silicon atom has four valence electrons it shares with other silicon atoms in a crystal. A semiconductor is formed by replacing a few silicon atoms with other atoms that have more or less valence electrons than silicon. 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? Read this paragraph and choose the correct option from the provided answers: Choices: - state - property - material - element A:
Ans:
element