28. Good experiments have 2 key characteristics; they are

a. an experimental group and a confirmed hypothesis
b. analysis of the control group and an accurate prediction of the outcome
c. conducting the actual experiment and reporting the results
d. testing a single variable and using a control
No idea..

32. The 2 primary types of ocean currents are
a. wind and global currents
b. warm and cold water currents
c. ocean floor and gulf currents
d. surface and deep currents
D

38. 2 threats to ocean ecosystems are
a. nutrient runoff and industrial waste discharges
b. overfishing and entanglement of marine mammals in trawl nets
c. sewage and algal blooms
d. all of the above
Not sure..

39. What is the difference between an endangered species and a threatened species?
a. An endangered species has very low numbers while a threatened species' population is in decline
b. An endangered and a threatened species' population are both so low that they face extinction
c. An endangered species no longer exists and threatened species are on the verge of extinction
d. none of the above
D?

47. The composition of the atmosphere include gases, solid particles, and atmospheric dust. -True

Thanks
-MC