Question

1) Imagine that a simulated cell is made using dialysis tubing as the membrane and water mixed with glucose, salt, and protein as the cytosol. Imagine that this 16 gram cell is placed in a beaker of distilled water for 1 hour. After 1 hour the cell has gained 3 grams of weight. The beaker solution tests positive for glucose and salt, but tests negative for protein. Which of the following CANNOT be correctly concluded?

a. Glucose and salt diffused out of the cell.

b. The cell membrane was not permeable to protein.

c. Water osmosed into the cell.

d. The membrane is selectively permeable.

e. The cell contents would test negative for glucose and salt.

2) Cells are protein factories. Cells that line the inside of the nose and respiratory system called goblet cells make the protein mucin made by fixed ribosomes. The mucin is mixed with water and exported out of the cells onto the surface of the nasal cavity as mucus by secretory vesicles. Which of the following is FALSE?

a. Goblet cells use exocytosis.

b. Mucin and water are moved by vesicular transport.

c. Motor proteins use ATP to move membranous sacs full of water and mucin.

d. Vesicular transport is passive.

Answer 1

Answer for the question no 1 : Option (e) - The cell contents would test negative for glucose and salt.

Explanation - After the 1 hour experiment the beaker solution was tested for the presence of glucose, salt and protein where it showed positive result for glucose and salt but negative for protein.Whereas, the cell content was not tested for glucose, salt and protein after 1 hour of experiment.

So, it can't be clearly concluded that whether the cell content would test negative (as it is not clear that if all the glucose and salts has come out from the cell to the beaker or not) for glucose and salt. So, Option e is the right answer.

Option (a) is not the right answer as the beaker solution contained only distilled water (absence of glucose and salt). But after the 1 hour experiment the beaker shows positive result for glucose and salt. So, from this information we can clearly conclude that glucose and salt diffused out of the cell.

Option (b) is not the right answer as the cell initially has glucose, salt and protein but after the 1 hour experiment the beaker solution tested negative for protein, so it is confirmed that the cell membrane was not permeable to protein that's why it could not diffused out from the cell to the beaker.

Option (c) is not the right answer as after the experiment the cell gained 3 grams of weight so it can be concluded that water osmosed in to the cell and contributed to this weight gain.

Option (d) is not the right answer as it is also explained for Option (b) that after the experiment the beaker solution showed positive result for glucose and salt but negative for protein so, from this observation it can be correctly concluded that the membrane is selectively permeable.

Answer for question no 2:

Option (a) is true as ' mucin mixed with water' is exported out of the goblet cell.So, it is a process of exocytosis.

Option (b) is true as it is clearly explained in the question the mucin mixed with water, what become mucus are exported out of the cell by secretory vesicles. So, it is a vesicular transport mechanism.

Option (c) is true as in vesicular transport the vesicle needs to be passed through the hydrophobic region of the plasma membrane using energy, so it is a form of active transport.So, it requires ATP to drive this process( move the membranous sac full of water and mucin).

Option (d) is false as explained above this is not a passive transport,this is a active transport system.

So, this option (option d) is the right answer.