Question 1

Which of the following best explains why potassium permanganate diffuses faster than Janus Green in agar at the same temperature?

Accepted Answer

Potassium permanganate has a lower molecular mass, allowing it to move more rapidly through the agar matrix.

Question 2

A dialysis bag containing 10 ml of 10% sucrose is placed in a beaker of distilled water. After 40 minutes, the mass of the bag increases. Which process is responsible for this change, and what is the direction of water movement?

Accepted Answer

Osmosis; water moves from the beaker into the bag.

Question 3

In the experiment testing the effect of temperature on diffusion, which plate would you expect to have the largest diameter of dye after 30 minutes, and why?

Accepted Answer

The plate at $$37^\circ \mathrm{C}$$, because increased temperature increases the kinetic energy and movement of molecules.

Question 4

A dialysis bag containing distilled water is placed in a beaker of 10% sucrose. What will happen to the mass of the bag after 40 minutes, and why?

Accepted Answer

The mass will decrease because water will move out of the bag into the beaker.

Question 5

Which of the following best describes the property of the dialysis bag that allows some molecules to pass through but not others?

Accepted Answer

Selective permeability

Question 6

In the selective permeability experiment, which molecule is least likely to diffuse out of the dialysis bag into the beaker, and why?

Accepted Answer

Starch, because it has a large molecular size that cannot pass through the pores of the dialysis membrane.

Question 7

A red blood cell is placed in a 10% NaCl solution. What will happen to the cell, and what is the underlying reason?

Accepted Answer

The cell will shrink (crenate) because water moves out of the cell into the hypertonic solution.

Question 8

Which of the following equations best represents the relationship between the rate of diffusion ($$R) $$and temperature ($$T$$), assuming all other factors are constant?

Accepted Answer

$$R \propto T$$

Question 9

If a plant cell is placed in a 20% NaCl solution, what will you observe under the microscope, and what is the process called?

Accepted Answer

The cell membrane will pull away from the cell wall (plasmolysis) due to water loss.

Question 10

In the experiment with three dialysis bags, which bag is in an isotonic environment, and what is the expected net movement of water?

Accepted Answer

Bag 3 (10% sucrose in 10% sucrose); no net movement of water.

Question 11

Which of the following statements about osmosis in plant cells is correct?

Accepted Answer

Osmosis occurs in plant cells, and the presence of a cell wall allows the cell to become turgid without bursting.

Question 12

A student adds Benedict’s reagent to a test tube containing solution from the beaker after dialysis. The solution turns orange after boiling. What does this indicate?

Accepted Answer

Reducing sugars have diffused out of the dialysis bag into the beaker.

Question 13

If the molecular mass of a solute is increased, what is the expected effect on its rate of diffusion through agar, assuming temperature is constant?

Accepted Answer

The rate of diffusion will decrease because larger molecules move more slowly.

Question 14

Which of the following best describes the tonicity of a 0.45% NaCl solution relative to sheep’s blood, and what is the expected effect on the red blood cells?

Accepted Answer

Hypotonic; cells will swell and may burst due to water influx.

Question 15

Which hazardous chemical is used to test for the presence of sulfate ions in the selective permeability experiment?

Accepted Answer

Barium chloride

Question 16

A dialysis bag containing a mixture of sodium chloride, sodium sulfate, glucose, starch, and protein is placed in distilled water. After 40 minutes, which molecules are most likely to be detected in the beaker solution, and why?

Accepted Answer

Sodium chloride, sodium sulfate, and glucose, because they are small enough to pass through the dialysis membrane.

Question 17

Which of the following best describes the independent and dependent variables in the osmosis experiment with dialysis bags?

Accepted Answer

Independent variable: solute concentration; Dependent variable: change in mass of the bag

Question 18

If the temperature of the agar is decreased to $$0^\circ \mathrm{C}$$, what is the expected effect on the rate of diffusion of both Janus Green and potassium permanganate?

Accepted Answer

The rate of diffusion will decrease for both dyes because molecular motion is reduced at lower temperatures.

Question 19

Which of the following best explains why plant cells do not burst when placed in a hypotonic solution, unlike animal cells?

Accepted Answer

The rigid cell wall provides structural support and prevents excessive expansion.

Diffusion and Osmosis: Principles, Experiments, and Cellular Effects

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