ACT Science : How to find synthesis of data in biology

Study concepts, example questions & explanations for ACT Science

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Example Questions

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Example Question #511 : Act Science

If a drug is administered intravenously (i.e. injected into a vein), then the concentration of the drug in the blood will rise and then reach a plateau. After some time, the body will begin to eliminate this drug from the bloodstream. During this elimination phase, ion pumps will actively transport some drugs from the blood into the tubules of the kidneys. Organic anion transporters (OAT) transport acids into the tubules of the kidney while organic cation transporters (OCT) transport bases into the tubules of the kidney. This mechanism, known as secretion, depends entirely on transporters and allows both acidic and basic drugs to be eliminated from the body.

Another process known as reabsorption can also occur in the kidneys. During reabsorption, drugs can be transported from the tubules of the kidney back into the blood. This process depends on the pH of the fluid in kidney tubules (e.g. the urine). At a low pH (i.e. acidic environment), acidic drugs are best reabsorbed. Conversely, at high pH (i.e. basic environment), basic drugs are best reabsorbed.

 

Experiment 1

The same drug was administered to various individuals. After some time elapsed, the rate of renal clearance (i.e. the rate of urine elimination from the body) was measured in each of the individuals. Subsequently, the pH of the urine was measured for each individual. The rate of renal clearance versus urinary pH was then plotted in the provided figure (each black dot represents a different individual).

 

Screen shot 2015 11 12 at 9.57.11 pm

 

Experiment 2

A scientist was able to engineer a mouse kidney that lacked organic anion transporters. She administered various drugs to the mouse and measured the rates of secretion. The data collected is located in the provided table.

 

Screen shot 2015 11 13 at 12.39.18 pm   

Suppose an individual who had taken the drug administered in Experiment 1 exhibited the following urinary pH:

Would this drug have stayed in the bloodstream for an extended period of time?

Possible Answers:

Yes, because the rate of clearance was most likely high.

No, because the rate of clearance was most likely high.

No, because the rate of clearance was most likely low.

Yes, because the rate of clearance was most likely low.

Correct answer:

No, because the rate of clearance was most likely high.

Explanation:

From the results of Experiment 1, we see that high urinary pH would have resulted in a high rate of urinary clearance for this drug. As a result, the drug would have been quickly eliminated from this individual's body and would not have stayed in the bloodstream long.

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