Question

13 a researcher hypothesizes that water will move out of the cell more quickly when the concentration of salt in the water outside the cell is greater. which experiment would best test this hypothesis?
a a researcher places three cells of the same type in varying concentrations of salt water. then the researcher measures the size of each cell every minute during a 5 - minute period of time.
b a researcher places three cells of the same type in the same concentration of salt water. then the researcher measures the size of each cell every minute during a 5 - minute period of time.
c a researcher places cells from three different fish in varying concentrations of salt water. then the researcher measures the size of each cell at the end of a 5 - minute period of time.
d a researcher places cells from three different fish in the same concentration of salt water. then the researcher measures the size of each cell at the end of a 5 - minute period of time.

14 based on the food web (figure 2), what effect will a decrease in the algae population have on the finger mullet population in the estuary?
a the finger mullet population will increase because the zooplankton population will decrease.
b the finger mullet population will decrease because the zooplankton population will increase.
c the finger mullet population will decrease because the zooplankton population will decrease.
d the finger mullet population will stay the same because algae is not a direct food source for the mullets.

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Explanation:

For question 13: The hypothesis tests how external salt concentration affects water movement (cell size change). A valid experiment needs the independent variable (salt concentration) to vary, while other factors (cell type, measurement frequency) stay controlled. Option A varies salt concentration and uses same-type cells with regular measurements, which tests the hypothesis.
For question 14: Algae are typically a food source for zooplankton in food webs. A decrease in algae would reduce zooplankton (their food source). If finger mullet eat zooplankton, a decrease in zooplankton would then reduce the finger mullet population.

Answer:

1. A. A researcher places three cells of the same type in varying concentrations of salt water. Then the researcher measures the size of each cell every minute during a 5-minute period of time.
2. C. The finger mullet population will decrease because the zooplankton population will decrease.