Chapter 3.5 - Biology quiz

Describe two ways in which the extracellular surface of plasma membrane differs from the intracellular surface.

1. The extracellular surface has carbohydrates attached to lipids or proteins, but the intracellular surface does not. 2. The extracellular surface has carbohydrate complexes that bind substances to the surface, but the intracellular surface does not.

List the steps involved in facilitated transport.

1. The substance attaches to protein or glycoprotein receptors on the extracellular membrane. 2. The substance is passed to integral proteins specialized to allow its transport into the cell through formation of a channel.

Name four factors that affect the rate at which a substance diffuses through a selectively permeable membrane.

1. the concentration gradient; the higher the concentration gradient, the more rapid the diffusion 2. the mass of the molecules within the substance; the larger the mass, the slower the diffusion 3. temperature; the higher the temperature, the faster the diffusion 4. solvent density; the greater the solvent density, the slower the diffusion

What is a concentration gradient?

A concentration gradient is what occurs when a single substance has different concentrations in neighboring parts.

What is a solute?

A dissolved substance within a solution

Name three types of passive transport.

Diffusion, facilitated transport, and osmosis.

What is another term for facilitated transport?

Facilitated diffusion

T or F An integral protein embedded in the plasma membrane to form a channel or pump allows substances to flow both into and out of the cell.

False. Each integral protein embedded in the plasma membrane to form a channel or pump works only in one direction.

T or F The concentration gradient of one substance in a medium affects the concentration gradient of other substances.

False. Every substance in a medium has its own concentration gradient that is independent of the concentration gradients of all other substances in that medium.

T or F Diffusion occurs only with water.

False. Osmosis occurs only with water; diffusion can occur with water as well as other substances.

T or F Plasma membranes allow substances to travel from the inside of cells to the outside but not in the other direction.

False. Plasma membranes allow for the passage of substances in both directions.

T or F Plasma membranes have nothing to do with preventing substances from travelling into and out of cells.

False. Plasma membranes stop the passage of certain substances and allow the passage of others.

T or F With diffusion, substances move from areas of low concentration to areas of high concentration.

False. With diffusion, substances move from areas of high concentration to areas of low concentration.

What term conveys the fact that plasma membranes allow some substances to pass through them but prevent other substances from doing so.

Selective permeability or selectively permeable.

What does tonicity describe?

The amount of solute dissolved in a solution.

What is osmolarity?

The total amount of solutes dissolved in a specific amount of solution.

T or F Cells would die if their plasma membranes were not selectively permeable.

True

T or F Facilitated transport is used primarily for polar substances that would not otherwise pass through the plasma membrane easily.

True

T or F Moving down the concentration gradient means moving from a region of high concentration to a region of low concentration.

True

T or F Osmosis is a special type of diffusion that occurs with water.

True

T or F Osmosis occurs continuously in living organisms.

True

T or F The major difference between diffusion and osmosis is that diffusion transports a variety of materials across a cell membrane but osmosis transports only water across a membrane.

True

T or F Facilitated transport is an example of passive transport.

True.

Which of the following are true of diffusion? Select all correct answers. a. The end result of diffusion is equal concentration of a substance. b. Substances move up the concentration gradient. c. Substances can move through a cell's plasma membrane via diffusion. d. Diffusion requires the expenditure of energy.

a. The end result of diffusion is equal concentration of a substance. c. Substances can move through a cell's plasma membrane via diffusion.

The end result of osmosis is: a. an equal concentration of a solute on both sides of a membrane but different amounts of water. b. an equal amount of water on both sides of a membrane but different concentrations of a solute. c. unequal amounts both of a solute and of water on two sides of a membrane.

a. an equal concentration of a solute on both sides of a membrane but different amounts of water.

A hypotonic solution may cause cells to: a. burst or lyse b. burst or crenate c. shrivel or crenate d. lyse or crenate

a. burst or lyse

Which of the following increase the rate at which a substance diffuses across a membrane? Select all correct answers. a. high concentration gradient between neighboring regions b. large mass of molecules within the diffusing substance c. low temperature d. high solvent density

a. high concentration gradient between neighboring regions

A lower osmolarity of extracellular fluid corresponds with: a. hypotonicity b. isotonicity c. hypertonicity

a. hypotonicity

Which of the following substances pass easily through the plasma membrane of cells via passive transport? a. lipid-soluble substances b. fat-soluble substances c. ions d. oxygen e. carbon dioxide f. sugars g. amino acids h. water

a. lipid-soluble substances b. fat-soluble substances d. oxygen e. carbon dioxide h. water

Which of the following is an example of a hypertonic solution? Select all correct answers. a. sea water b. carbonated water c. tap water d. cytoplasm in plants

a. sea water d. cytoplasm in plants

The cell wall surrounding the plasma membrane of a plant cell helps prevent: a. cell crenation b cell lysis c. active transport d. cell reproduction

b cell lysis

Diffusion is an example of: a. Active transport b. Passive transport c. Facilitated transport

b. Passive transport

Which of the following are true of passive transport? Select all correct responses. a. Passive transport requires a cell to expend considerable energy. b. Passive transport takes advantage of concentration gradients. c. Passive transport takes advantage of electrochemical gradients. d. If plasma membranes were not selectively permeable, passive transport would not occur.

b. Passive transport takes advantage of concentration gradients. d. If plasma membranes were not selectively permeable, passive transport would not occur.

Plasma membranes allow a. All substances to travel from the inside of cells to the outside. b. Some substances to travel from the inside of cells to the outside. c. No substances to travel from the inside of cells to the outside.

b. Some substances to travel from the inside of cells to the outside.

Which of the following is true of a hypotonic solution? a. the extracellular fluid has a higher concentration of solutes than the cytoplasm. b. the extracellular fluid has a lower concentration of solutes than the cytoplasm. c. the extracellular fluid has an equal concentration of solutes as the cytoplasm.

b. the extracellular fluid has a lower concentration of solutes than the cytoplasm.

Facilitated transport involves which of the following? Select all correct answers. a. osmosis b. expenditure of cell energy c. a concentration gradient d. polar substances e. protein or glycoprotein receptors on the extracellular surface f. integral proteins g. transport vesicles

c. a concentration gradient d. polar substances e. protein or glycoprotein receptors on the extracellular surface f. integral proteins

Osmosis occurs instead of diffusion when: a. a substance found in water is too small to pass through the selectively permeable membrane. b. there is a greater amount of water on one side of a selectively permeable membrane than on the other side. c. a substance found in water is too large to pass through the selectively permeable membrane. d. the active transport system of the cell fails to work properly.

c. a substance found in water is too large to pass through the selectively permeable membrane.

A risk with hypertonicity is that a cell will: a. burst or lyse b. burst or crenate c. shrivel or crenate d. lyse or crenate

c. shrivel or crenate

Which of the following is an example of a hypotonic solution? Select all correct answers. a. sea water b. carbonated water c. tap water d. cytoplasm in plants

c. tap water

What are the three types of tonicity?

hypotonic, isotonic, and hypertonic

T or F With hypertonicity, water flows out of the cell.

true