Question 1

What type of cellular transport involves the cytosolic protein clathrin?

Accepted Answer

Clathrin is a cytosolic protein that plays a key role in receptor-mediated endocytosis, a type of cellular transport in which cells take in specific molecules or particles by binding them to surface receptors and internalizing them through the formation of clathrin-coated vesicles.

Question 2

What will happen if a normal cell is placed in a hyperosmotic solution?

Accepted Answer

The answer of What will happen if a normal cell...

Question 3

During a lab experiment,you forgot to label your solution containers.You see that red blood cells were placed into an unlabeled solution and they shrunk.What can be concluded about the unknown solution?

Accepted Answer

When red blood cells shrink, it indicates that they were placed in a hypertonic solution, where the nonpenetrating solute concentration outside the cell is greater than inside, causing water to move out of the cells to balance the solute concentration.

Question 4

You are examining the data from two time points taken in an experiment.At time 1 there was an extracellular concentration of Na⁺ of 115 mM outside the cell and 8mM inside the cell.An amino acid,lycine,is at 20mM outside and 40mM inside.At the second time measured Na⁺ is 100mM outside the cell and 23 mM inside the cell.Lycine is 15 mM outside the cell and 45mM inside.What is the best explanation?

Accepted Answer

The answer of You are examining the data from two...

Question 5

Once formed inside of the cell,most endocytic vesicles will fuse with which organelle for sorting?

Accepted Answer

Endosomes are organelles responsible for sorting materials that are brought into the cell through endocytosis. Once endocytic vesicles are formed inside of the cell, they will fuse with endosomes for sorting.

Question 6

Why do solutions for injection or infusion into people with low blood volume normally contain 150 mM NaCl?

Accepted Answer

The solution containing 150 mM NaCl is isotonic, meaning it has the same concentration of solutes as the blood. This makes it the best choice for a solution to be infused or injected into people with low blood volume as it can help restore the blood volume without causing damage to the red blood cells. Additionally, the NaCl in the solution will help to retain the added volume in the extracellular fluid compartment.

Question 7

Which of the following statements regarding endocytosis or exocytosis is correct?

Accepted Answer

Exocytosis is the process by which large molecules are secreted from a cell. Endocytosis is the opposite process, by which large molecules are brought into the cell. Pinocytosis and phagocytosis are both types of endocytosis, not exocytosis.

Question 8

Which would be true if substance X was moving into a cell by primary active transport?

Accepted Answer

Primary active transport involves the movement of substances against their concentration gradient using energy directly from ATP. Choice A indicates that substance X is moving from a lower concentration outside the cell to a higher concentration inside the cell, which is characteristic of primary active transport.

Question 9

Regarding the tonicity and osmolarity of solutions,which of the following statements is not true?

Accepted Answer

Isotonic solutions are not always isoosmotic because tonicity depends on the permeability of the solutes across the cell membrane, while osmolarity is a measure of solute concentration regardless of permeability.

Question 10

What will happen if a normal cell is placed in a hypotonic solution?

Accepted Answer

A hypotonic solution has a lower concentration of solutes compared to the inside of the cell. Therefore, water will move into the cell to even out the concentration gradient, causing the cell to swell in size.

Question 11

If the ATP-generating mechanisms in a cell are poisoned and the cell depletes its ATP reserves,which would occur first?

Accepted Answer

Primary active transport involves the energy from ATP directly to move molecules against their concentration gradient. Without a sufficient supply of ATP, primary active transport would cease first. Secondary active transport and facilitated diffusion both rely on existing concentration gradients, so they would continue until those gradients were depleted. The ion concentration gradient across the cell membrane would also be maintained for a short time due to other factors such as the Na+/K+ pump, but eventually would reach equilibrium as ATP is required to maintain this gradient. Therefore, option A is the best choice as it describes the process which would cease first.

Question 12

If all other conditions remain the same and the concentration of a nonpenetrating solute increases inside a cell,which is most likely to occur?

Accepted Answer

Water will tend to enter the cell because the interior has an increased osmolarity, leading to a higher concentration of solute inside the cell compared to outside. This difference in osmolarity causes water to move into the cell to dilute the internal solute concentration, aiming to achieve osmotic balance.

Question 13

Which of these is an example of a hypertonic solution?

Accepted Answer

A hypertonic solution has a higher solute concentration compared to the solution it is being compared to. Out of the given options, option A has the highest concentration of solutes, making it a hypertonic solution.

Question 14

Which form of endocytosis is nonspecific,in that it occurs by the formation of an invagination of the plasma membrane,which then fills with interstitial fluid of the immediate area?

Accepted Answer

Pinocytosis is a nonspecific form of endocytosis that occurs through the invagination of the plasma membrane, which then fills with interstitial fluid of the immediate area. This process is also known as "cell drinking" because it brings in extracellular fluids and any solutes present in the fluid.

Question 15

Cholesterol-containing lipoproteins are cleared from the blood by which process?

Accepted Answer

Cholesterol-containing lipoproteins are cleared from the blood through clathrin-dependent, receptor-mediated endocytosis. This process involves the binding of lipoproteins to specific receptors on the cell surface, followed by the internalization of the lipoprotein-receptor complex into the cell via clathrin-coated pits.

Question 16

"Osmosis" refers to the movement of what substance across semipermeable membranes?

Accepted Answer

Osmosis refers to the movement of water across a semipermeable membrane, from an area of high water concentration (low solute concentration) to an area of low water concentration (high solute concentration).

Question 17

By what transport mechanism does glucose enter most cells?

Accepted Answer

Glucose enters most cells through facilitated diffusion via a protein channel. This process does not require energy and only moves glucose down its concentration gradient, from an area of higher concentration to an area of lower concentration.

Question 18

If pure water and a solution containing a nonpenetrating solute are separated by a membrane that is permeable only to water,what would occur?

Accepted Answer

Water will move by osmosis toward the side with the solute because the solute creates an osmotic gradient, drawing water to that side until the movement is balanced by hydrostatic pressure.

Question 19

Which of the following solutions is not isotonic to human cells?

Accepted Answer

Isotonic solutions have the same concentration of solutes as the interior of human cells, which is around 300 mOsm. Options A, C, and D have a concentration of NaCl that can be converted to mOsm by multiplying by 2. Therefore, options A and D have a concentration of 300 mOsm, which makes them isotonic to human cells. On the other hand, option B has a concentration of urea, which is not an ion and does not contribute significantly to osmotic pressure. Therefore, option B is not isotonic to human cells.

Question 20

Which of the following statements about the Na⁺-K⁺ ATPase pump is false?

Accepted Answer

The Na⁺-K⁺ ATPase pump transports Na⁺ and K⁺ in a 3:2 ratio, not a 1:1 ratio. It moves three sodium ions out of the cell and two potassium ions into the cell for each ATP molecule hydrolyzed.

Quiz 4: Movement of Solutes and Water Across Cell Membranes