Question 1

The movement of a substance from an area of high concentration to an area of less concentration is called

Accepted Answer

The movement of a substance from an area of high concentration to an area of less concentration is called diffusion. Endocytosis and active transport involve the movement of substances against a concentration gradient, while osmosis and facilitated diffusion involve the movement of specific substances, such as water or ions, across a selectively permeable membrane.

Question 2

A person suffered burns over a large part of his body.Evaporation of fluid from the surface of burned areas occurs.As a result of the evaporation process,cells will tend to

Accepted Answer

Evaporation of fluid causes water loss from the cells, leading to dehydration and a decrease in cell size or shrinkage. This can lead to cell damage, especially in burned areas where the cells are already weakened.

Question 3

The movement of oxygen from the alveoli of the lungs into the bloodstream is an example of

Accepted Answer

The movement of oxygen from the alveoli of the lungs into the bloodstream is an example of diffusion, as it occurs down a concentration gradient - from an area of high concentration (the alveoli) to an area of lower concentration (the blood). Osmosis involves the movement of water across a selectively permeable membrane, while active transport and facilitated diffusion both require the input of energy to move substances across a membrane. Bulk transport involves the movement of larger molecules or particles, such as through endocytosis or exocytosis.

Question 4

Salt was added to a beaker of distilled water (the water was not stirred).A sample taken from the bottom of the beaker was found to be 20% salt.At the same time,a sample taken from the top of the beaker was found to be 2% salt.After 24 hours

Accepted Answer

Since the water was not stirred, a concentration gradient was formed with higher concentration at the bottom and lower concentration at the top. However, given enough time, the concentration gradient would eventually even out and the salt concentration would be approximately equal throughout the beaker. Therefore, the percentage of salt in the top and bottom samples would be approximately equal after 24 hours.

Question 5

The aroma of cookies baking in the kitchen reaches you in the living room.The distribution of this odor throughout the house is an example of

Accepted Answer

Diffusion is the movement of molecules from an area of high concentration to an area of low concentration. In this case, the aroma of the cookies is diffusing from the kitchen (where the concentration of cookie scent is high) to the living room (where the concentration of cookie scent is lower).

Question 6

Solution A contains 5 grams of sugar per liter while solution B contains 2 grams of sugar per liter.The solutions are separated by a selectively permeable membrane.If the solvent in both solutions is water,predict in which direction most of the water molecules will move.

Accepted Answer

Water molecules will move from a region of low solute concentration (solution B) to a region of high solute concentration (solution A) in order to reach equilibrium. This process is known as osmosis. Therefore, most of the water molecules will move from solution B to solution A.

Question 7

Osmosis is the diffusion of _____ across a selectively permeable membrane.

Accepted Answer

Osmosis is the diffusion of water across a selectively permeable membrane from an area of higher concentration to an area of lower concentration. This is a key process in regulating water balance in all living organisms.

Question 8

The plasma membrane is selectively permeable.This means

Accepted Answer

Selectively permeable means that only certain substances can pass through the membrane. This is based on the size and polarity of the molecule, as well as the presence of transport proteins. ATP is not always required, and not all substances require carrier molecules to pass through the membrane. Gases and water are not the only substances that can pass through, as many other molecules can as well.

Question 9

In the process of diffusion,net movement of substances is always from a region

Accepted Answer

In the process of diffusion, substances move from a region of higher concentration to a region of lower concentration until they reach equilibrium. This is known as the principle of concentration gradient. Therefore, the net movement of substances is always from a region of higher concentration (lower gradient) to a region of lower concentration (higher gradient), which is option D.

Question 10

Which of the following will increase the rate of diffusion?

Accepted Answer

An increase in temperature will increase the kinetic energy of the molecules, resulting in them moving faster and increasing the rate of diffusion. The other options will all decrease the rate of diffusion.

Question 11

If 0.9% NaCl (saline)solution is isotonic to a cell,then a 0.5% saline solution

Accepted Answer

A 0.5% saline solution is hypotonic compared to the isotonic 0.9% saline solution, meaning it has a lower concentration of solutes, which can cause the cell to swell as water moves into the cell.

Question 12

A group of cells was treated with a proteolytic (protein-digesting)enzyme.Which of the following processes would be least affected by this treatment?

Accepted Answer

Proteolytic enzymes specifically break down proteins, but do not affect lipid molecules. Therefore, the diffusion of lipid-soluble molecules through the plasma membrane would be the least affected process by this treatment.

Question 13

A red blood cell that is placed in a hypertonic solution

Accepted Answer

A hypertonic solution has a higher concentration of solutes (e.g. salts, sugars) than the red blood cell. As a result, water will leave the cell to try to balance out the concentration of solutes on either side of the cell membrane. This leads to the red blood cell losing water and potentially shriveling up (known as crenation).

Question 14

Vitamin A,a fat-soluble vitamin,would move across the plasma membrane into the cell

Accepted Answer

Vitamin A is fat-soluble, which means it can dissolve in the fatty acid tails of the lipid bilayer of the plasma membrane and pass directly through, without requiring a specific channel or carrier molecule. Therefore, it would move across the membrane by simple diffusion.

Question 15

In _______,ions or molecules move in opposite directions.

Accepted Answer

In antiport, ions or molecules move in opposite directions, whereas in uniport, only one type of ion or molecule is transported in one direction, in symport, ions or molecules move in the same direction, and there is no concept of ionport or comport in biology.

Question 16

If a 0.9% NaCl (saline)solution is isotonic to a cell,then a solution of 3.5% NaCl would be

Accepted Answer

A solution of 3.5% NaCl is hypertonic to the cell because it has a higher concentration of solutes than the 0.9% NaCl solution which is isotonic to the cell. When a cell is placed in a hypertonic solution, water molecules will move out of the cell to try to balance the concentration of solutes, causing the cell to shrink or even die.

Question 17

A runner produced hypotonic sweat while running a marathon in hot weather.After the race,he drank large volumes of water.As a result of the water intake,his body cells will

Accepted Answer

Hypotonic sweat means that the concentration of solutes (such as salt) in the sweat is lower than inside the cells of the body. When the runner drank large volumes of water, it would have diluted the concentration of solutes in the body even more. This would create a hypotonic environment in the cells, causing them to absorb water and swell.

Question 18

Which of the following statements concerning membrane transport across the plasma membrane is true?

Accepted Answer

Lipid-soluble substances can pass through the plasma membrane by dissolving in the lipid bilayer due to the nonpolar nature of the membrane. This allows for the passive diffusion of small nonpolar substances such as oxygen and carbon dioxide across the membrane. Polar molecules and ions, on the other hand, cannot pass through the membrane easily and require the assistance of transport proteins. Active transport is also used to move molecules against their concentration gradient. Water can also pass through the plasma membrane through specialized channels called aquaporins. The ease of passage for cations and anions depends on various factors such as their size, charge, and concentration gradient.

Question 19

In general,water-soluble molecules diffuse through the ______ ______; and lipid-soluble molecules diffuse through the ______ ______.

Accepted Answer

Water-soluble molecules diffuse through membrane channels, while lipid-soluble molecules diffuse through the lipid bilayer.

Question 20

The greater the concentration of a solution,the greater the

Accepted Answer

The greater the concentration of solute particles in a solution, the higher the osmotic pressure. This is because there are more particles that are able to exert a pressure on the membrane trying to balance out the concentration gradient.

Quiz 3: Cell Biology