Self-study
Scientists removed all viruses from a seawater sample and then measured the growth rate of the plankton population in the water. ████ ████████ ███ ████ ██ ████████ █████████████ ███ ███ ██████████ ████████ ███ ████████
"Surprising" Phenomenon
The plankton population in a seawater sample didn't grow as expected once viruses were removed from the environment, but instead shrank.
Objective
The correct answer will be a hypothesis that explains why the plankton population shrank. The explanation must explain why plankton do better in an environment with viruses rather than one without viruses, even though the viruses may threaten the plankton.
7.
Which one of the following, ██ █████ ████ █████ ██ ███████ ███ ██████████ ██████ █████████ ██████
a
Viruses in seawater ████ ██ ████ ███ ████████ ██████████ █████ ███ ███████ █████ ████ ███ █████████ ██ ███ █████ ████ ████████
Even without viruses, plankton still would’t be able to expand beyond the maximum level water resources support. We need to know why the plankton population actually shrank.
b
Plankton and viruses ██ ████████ ███████ ███ ████ ██ ███ ████ ██████████
If plankton and viruses are competitors, then the plankton population should’ve grown without the viruses. Instead, it shrank, and this doesn't tell us why.
c
Plankton utilize the █████████ ████████ ██ ███ █████ ██ █████████ ██████ ██ ████████
Viruses kill organisms which in turn feed plankton. Without viruses, the plankton population simply had fewer nutrients available. This explains why the plankton population shrank.
d
The absence of ███████ ███ ██████████ ███ ███████████ ██ ████████ ████ █████████ ██████ █████ ██████████
The language here is very weak. We don’t know if bacteria in fact flourished without the viruses, or if plankton are one of the organisms those bacteria can damage.
e
At any given █████ █ ████████████ ███████ ██ ███ ████████ ██ ████████ ███ ███████ ████████ ██ ████████
This doesn’t explain why the plankton population shrank without the viruses. Whether or not many plankton were already infected, we need some other reason why the plankton population shrank further once the viruses were gone.