Q: What is the upper most level of earth's layers called? Choices: - surface - volcanic - mantle - crust A:
crust

(Question)
Q: What two ways may catalyst be classified? Choices: - oxygenated or heterogenous - reactive or nonreactive - fast or slow - homogeneous or heterogeneous A:
(Answer)
homogeneous or heterogeneous

Ques: Q: Embryos usually don't survive if they have extra or too few of these genetic units? Choices: - phenotypes - genes - ribosomes - chromosomes A:
Ans: chromosomes

(Q).
Q: What is secreted by the cells surrounding spermatogonia to help sperm production? Choices: - estrogen - dihydrotestosterone - follicle stimulating hormone - testosterone A:
(A).
testosterone

Ques:Q: When a species always migrates, what is this type of migration called? Choices: - emigration - genus migration - mass migration - obligate migration A:

Ans:obligate migration

Q: What are the two main types of air pollutants? Choices: - a and b - new and old - good and bad - primary and secondary A:
primary and secondary