Chapter 3 transport

What is the difference between active and passive transport across the plasma membrane? Active transport means that the cell is actively going after substances that it wants to bring into the cell, whereas passive transport means that the cell just waits for the substance to cross the membrane. Active transport is used to move substances down their concentration gradient, whereas passive transport is used to move substances against their concentration gradient. Active transport implies that the cell is working with other cells, whereas passive transport implies that the cell does not cooperate with other cells. Active transport is ATP dependent, whereas passive transport uses only the kinetic energy of the particles for movement across the plasma membrane.

Active transport is ATP dependent, whereas passive transport uses only the kinetic energy of the particles for movement across the plasma membrane.

Gap Junctions

Allows ions and small molecules to pass through from one cell to another. Present in electrically excitable tissues.

Which of the following statements is true? Unlike endocytosis, exocytosis does not rely on protein interactions with the plasma membranes. Exocytosis involves infolding of the plasma membrane. Endocytosis and exocytosis are passive transport mechanisms. During exocytosis, substances from inside the cell are moved outside.

During exocytosis, substances from inside the cell are moved outside.

Which of the following is most likely to move through the cell membrane by facilitated diffusion? CO2 Na+ O2 small lipids

Na+

True or false: A resting membrane potential is a sign of a depolarized membrane.

False

True or false: Aquaporins are believed to be present in red blood cells and kidney tubules, but not in any other cells in the body.

False

True or false: Channel-mediated diffusion is a form of active transport.

False

True or false: Osmosis is the passive movement of water but it follows almost completely opposite laws of physics when compared to the diffusion of ions or other small particles.

False

Tight Junctions

Help prevent molecules from passing through the extracellular space between adjacent cells.

What is the basic difference between simple diffusion and facilitated diffusion across a cell membrane? Simple diffusion is passive but facilitated diffusion is an active process that uses energy. In facilitated diffusion, molecules only move with the aid of a protein in the membrane. In simple diffusion, molecules move down the concentration gradient but in facilitated diffusion molecules move up the concentration gradient. Simple diffusion requires molecules to move through special doorways in the cell membrane.

In facilitated diffusion, molecules only move with the aid of a protein in the membrane.

Which of the following is a difference between primary and secondary active transport? Primary active transport is used to transport sugars and amino acids across the plasma membrane, while secondary active transport includes the sodium-potassium pump. Energy is required for primary active transport, but energy is not required for secondary active transport. Primary active transport is driven by secondary active transport. In primary active transport, the transport protein gets phosphorylated; in secondary active transport, the transport protein is not phosphorylated.

In primary active transport, the transport protein gets phosphorylated; in secondary active transport, the transport protein is not phosphorylated.

If a person is severely dehydrated, their extracellular fluids will become hypertonic to the intracellular fluid. What do you predict will happen to the person's cells? The cells will lose water and shrink. Extracellular fluids do not impact cell size, because cells contain intracellular fluid. The cells will rupture. The cells will swell.

The cells will lose water and shrink.

If cells are placed in a hypertonic solution containing a solute to which the membrane is impermeable, what could happen? The cells will lose water and shrink. The cells will show no change due to diffusion of both solute and solvent. The cells will shrink at first, but will later reach equilibrium with the surrounding solution and return to their original condition. The cells will swell and ultimately burst.

The cells will lose water and shrink.

Which of the following statements is correct regarding net diffusion? Molecular weight of a substance does not affect the rate. The rate is independent of temperature. The greater the concentration gradient, the faster the rate. The lower the temperature, the faster the rate.

The greater the concentration gradient, the faster the rate.

True or False: In their resting state, all body cells exhibit a resting membrane potential; therefore, all cells are polarized.

True

True or False: The speed of individual particle diffusion is influenced by temperature and particle size, not by concentration.

True

True or false: Concentration differences cause ionic imbalances that polarize the cell membrane.

True

Desmosomes

Type of anchoring junction. Abundant in tissues subjected to great mechanical stress.

Crenation (shrinking) is likely to occur in blood cells immersed in ________. a hypotonic solution an isotonic solution blood plasma a hypertonic solution

a hypertonic solution

What is a membrane potential? the possibility of cell activity a voltage or electrical charge across the plasma membrane cooperation between cells the ability of the cells to perform their specialized functions

a voltage or electrical charge across the plasma membrane

Which of the following is not required for osmosis to occur? cellular energy concentration gradient selectively permeable membrane water

cellular energy

What is the force driving all of these transport mechanisms? active transport diffusion down a concentration gradient endocytosis diffusion against a concentration gradient

diffusion down a concentration gradient

A vesicle fuses with the plasma membrane and releases its contents to the extracellular fluid. This statement describes _____. exocytosis active transport simple diffusion endocytosis facilitated diffusion

exocytosis

Some transport processes use transport proteins in the plasma membrane, but do not require ATP. This type of transport is known as _____. simple diffusion exocytosis active transport endocytosis facilitated diffusion

facilitated diffusion

The majority of water molecules moving across plasma membranes by osmosis do so via a process that is most similar to ____. a process that requires energy from the cell active transport simple diffusion cotransport facilitated diffusion

facilitated diffusion

Which of the following would NOT diffuse through the plasma membrane by means of simple diffusion? glucose oxygen a steroid hormone a lipid-soluble vitamin

glucose

Which of the following solutions contains the most solute? isotonic equilibrium hypertonic hypotonic

hypertonic

In general, to maintain homeostasis the relationship between our intracellular and extracellular fluids should be which of the following? intracellular should be hypotonic to extracellular isotonic to each other intracellular should be hypertonic to extracellular intracellular and extracellular should both be hypertonic

isotonic to each other

A primary active transport process is one in which __________. an intracellular vesicle fuses with the plasma membrane and releases its contents to the extracellular fluid molecules move across the plasma membrane without an input of energy the plasma membrane folds inward to form a vesicle containing extracellular material molecules move through transport proteins that have been activated by ATP molecules pass directly through the phospholipid bilayer of the plasma membrane

molecules move through transport proteins that have been activated by ATP

Passive membrane transport processes include ________. movement of a substance down its concentration gradient the use of transport proteins when moving substances from areas of low to high concentration movement of water from an area of high solute concentration to an area of low concentration consumption of ATP

movement of a substance down its concentration gradient

Which of the following best explains diffusion? movement of molecules from an area of high concentration to an area of low concentration exchange of nonpolar molecules for polar molecules movement of molecules from where there are fewer of them to where there are more movement of molecules farther away from equilibrium

movement of molecules from an area of high concentration to an area of low concentration

Which of the following would not be restricted (limited) by low levels of ATP? exocytosis pinocytosis osmosis phagocytosis

osmosis

A cell engulfing a relatively large particle will likely utilize ________. phagocytosis pinocytosis receptor-mediated endocytosis exocytosis

phagocytosis

Which vesicular transport process occurs primarily in some white blood cells and macrophages? intracellular vesicular trafficking pinocytosis phagocytosis exocytosis

phagocytosis

Which of the following is a component of the plasma membrane that creates a chemical barrier between the inside and the outside of the cell? cholesterol phospholipids water proteins

phospholipids

If a cell is non-selectively engulfing samples of extracellular fluid, for example to absorb nutrients, it will likely utilize ________. phagocytosis pinocytosis receptor-mediated endocytosis exocytosis

pinocytosis

If active transport establishes a concentration gradient with the use of ATP, then the concentration gradient can be looked at as ________. an unusable byproduct of active transport that will simply diffuse away unwanted pressure that will be alleviated by channel mediated facilitated diffusion a byproduct of active transport that will be alleviated by pinocytosis potential energy that can be harnessed when molecules passively diffuse down the concentration gradient

potential energy that can be harnessed when molecules passively diffuse down the concentration gradient

The sodium-potassium pump uses ATP to move sodium and potassium ions across the plasma membrane. This statement describes _____. exocytosis facilitated diffusion primary active transport simple diffusion secondary active transport

primary active transport

Some hormones enter cells via ________. primary active transport pinocytosis exocytosis receptor-mediated endocytosis

receptor-mediated endocytosis

Which transport process is the main mechanism for the movement of most macromolecules by body cells? phagocytosis secondary active transport pinocytosis receptor-mediated endocytosis

receptor-mediated endocytosis

You observe a small, nonpolar molecule near a membrane. How would this molecule likely transport across the membrane? simple diffusion carrier-mediated facilitated diffusion channel-mediated facilitated diffusion active transport

simple diffusion

Which of the following is least likely to increase the rate of diffusion? small molecule size small concentration gradient high temperature higher concentration of molecules

small concentration gradient

A red blood cell placed in pure water would ________. neither shrink nor swell swell and burst swell initially, then shrink as equilibrium is reached shrink

swell and burst