Biology Forums - Study Force

1. Water moves from an area of less concentration of solutes to an area of more concentration of solutes. Does
this mean that osmosis is a form of active transport? Explain.

2. Suppose that the concentration of Substance X is higher in the extracellular fluid (ISF) than it is within a neighboring cell. After a period of time, the concentration of Substance X inside the cell increases, and its concentration outside of the cell decreases.  What must you know about Substance X to determine if it is diffusing directly through the cell membrane, or entering through protein channels?

3. A murderer deftly slips cyanide into the tea of his unsuspecting victim. The victim dies, because cyanide inhibits the production of ATP during step 3 of cellular respiration: the electron transport chain.

      a. What types of membrane transport would stop, (passive transport, active transport, facilitated diffusion,
osmosis) and which would still continue to function?

       b. What will happen to the intracellular and extracellular concentrations of Na+ and K+?

4. A surgery patient is mistakenly infused with an I.V. bolus that contains a solution that is hypotonic to normal human plasma. As a result, the patient dies. What might the autopsy reveal about the patient’s blood?

5. Insulin is a protein-based hormone, whereas thyroid hormone primarily made of lipids. Why is it necessary for patients to receive injections of insulin, whereas thyroid patients can take their medications orally

1. Water moves from an area of less concentration of solutes to an area of more concentration of solutes. Does this mean that osmosis is a form of active transport? Explain.

No, because active transport requires a source of cellular energy (i.e. ATP).

2. Suppose that the concentration of Substance X is higher in the extracellular fluid (ISF) than it is within a neighboring cell. After a period of time, the concentration of Substance X inside the cell increases, and its concentration outside of the cell decreases.  What must you know about Substance X to determine if it is diffusing directly through the cell membrane, or entering through protein channels?

You have to know whether the substance is polar/non-polar. Also its size and its charge. Usually only charged molecules that are larger require some kind of transport protein.

4. A surgery patient is mistakenly infused with an I.V. bolus that contains a solution that is hypotonic to normal human plasma. As a result, the patient dies. What might the autopsy reveal about the patient’s blood?

If the solution is hypotonic, it means it lacks solutes, so the cell has more solutes than the solution. To counter this, water would enter the cell, causing it to lyse.

5. Insulin is a protein-based hormone, whereas thyroid hormone primarily made of lipids. Why is it necessary for patients to receive injections of insulin, whereas thyroid patients can take their medications orally

Because insulin would get digested by enzymes and acids found in the stomach - the protein would denature.

Hope that helps...

thanks sooo much!

Anytime :D