CH 3 MAP questions

If cells are placed in a hypertonic solution containing a solute to which the membrane is impermeable, what could happen? 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. The cells will show no change due to diffusion of both solute and solvent.

The cells will lose water and shrink.

Interstitial fluid represents one type of extracellular material. True False

true

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

true

What is the role of membrane proteins in transporting molecules across the plasma membrane

work as enzymes,transport proteins, receptors, cell-to-cell connections and for shape change during cell division

Describe the different kinds of vesicular transport

• Endocytosis: transport into cell -Phagocytosis, pinocytosis, receptor-mediated endocytosis • Exocytosis: transport out of cell enclosed in secretory vesicles

Describe the different types of extracellular materials

• Extracellular fluids,:such as, interstitial fluid, blood plasma, cerebrospinal fluid • Cellular secretions: (e.g., saliva, mucus) • Extracellular matrix: substance that acts as glue to hold cells together

Explain the concept of tonicity and the effect it can have on water volume within a cell

• Isotonic solutions: equal amount of water inside the cell; cells retain normal size and shape • Hypertonic solutions: more water outside cell; cells shrink • Hypotonic solution: more water inside of cell; cells become bloated and burst (lyse)

Describe the structure and functions of the plasma membrane

• It consists of a phospholipid bilayer with embedded proteins. • The basic function is to protect the cell from its surroundings.

Describe the different types of diffusion that can occur across a plasma membrane

• Simple diffusion : Nonpolar lipid soluble (hydrophobic) substances diffuse directly through PM ex. O2, CO2 • Carrier-and-channel-mediated facilitated diffusion: Selectively transport ions or water (via leakage channels) Transport specific molecules too large for channels (via leakage channels) • Osmosis: Movement of water through PM (via aquaporins)

Describe the different types of cell junctions

• Tight junctions: impermeable junctions that form continuous seals around cell • Gap junction: communicating junctions that allow ions and small molecules to pass through channels • Desmosomes: anchoring junctions that bind cells together. Acts like molecular "velcro"

Whats the role of the sodium-potassium pump in maintaining differences in ion concentrations on either side of the plasma membrane

• Works as a symporter that allows slow leakage down concen. gradients; Na+ into and K+ out of the cell • Works as antiporter that pumps Na+ out of cell and K+ back into cell against their concentration gradients

What are the different types of active transport processes?

• sodium-potassium pump • endocytosis (phagocytosis, pinocytosis) • exocytosis

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

cellular energy rationale: Osmosis is a special type of diffusion, which is always a passive process.

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

swell and burst

What is the difference between active and passive transport 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. 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 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 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. rationale: In active transport, the cell provides the metabolic energy (ATP) needed to move substances across the plasma membrane (against their concentration gradient). In passive transport, substances cross the plasma membrane (down their concentration gradient) using kinetic energy, without any energy input from the cell.

Which of the following statements about cells is FALSE? Cells join together to form organelles, which then form our organs and organ systems. Although human cells are diverse in size, shape, and function, they have essentially the same organelles and general structure. The cells in our bodies collectively carry out all of the functions necessary for us to stay alive. Cells are the most basic units of life.

Cells join together to form organelles, which then form our organs and organ systems. rationale: Organelles are the functional parts of cells—they are inside the cells, in the cytoplasm. Cells join to form tissues, and the tissues then join to form the organs that work together in organ systems.

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. During exocytosis, substances from inside the cell are moved outside. Endocytosis and exocytosis are passive transport mechanisms.

During exocytosis, substances from inside the cell are moved outside. rationale: Vesicular transport processes that eject substances from the cell interior into the extracellular fluid are called exocytosis. Exocytosis is a form of active transport; thus, it requires energy, usually in the form of ATP.

Why is it necessary for glucose to be pumped into the cell rather than diffusing in? Two types of membrane active transport processes. Glucose cannot pass through a phospholipid bilayer by simple diffusion. Glucose is too big for a facilitated diffusion protein channel. Glucose is repelled by the polar heads of the membrane phospholipid molecules. Glucose may have to be moved against a concentration gradient.

Glucose may have to be moved against a concentration gradient.

Drinking alcohol makes the blood hypertonic. Which option best describes the consequences of this hypertonic blood? Hypertonic blood draws water out of the interstitial fluid, which makes the interstitial fluid hypertonic. This, in turn, draws water out of the cells. Hypertonic blood will lose water to the interstitial fluid, which makes the interstitial fluid hypertonic. This, in turn, causes water to move into the cell. Hypertonic blood forces water into the interstitial fluid, which makes the interstitial fluid hypotonic. This, in turn, makes the interstitial fluid lose water to the cells. Hypertonic blood draws water out of the interstitial fluid, which makes the interstitial fluid hypotonic. This, in turn, makes the interstitial fluid lose water to the cells.

Hypertonic blood draws water out of the interstitial fluid, which makes the interstitial fluid hypertonic. This, in turn, draws water out of the cells. rationale: If the blood is hypertonic compared to the interstitial fluid (IF), the IF has a greater concentration of water. This means water will move from the IF toward the blood. As water leaves the IF space, that space would then become hypertonic compared to the cell, causing the same movement to occur.

What is the basic difference between simple diffusion and facilitated diffusion across a cell membrane? In facilitated diffusion, molecules only move with the aid of a protein in the membrane. Simple diffusion requires molecules to move through special doorways in the cell membrane. In simple diffusion, molecules move down the concentration gradient but in facilitated diffusion molecules move up the concentration gradient. 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. rationale: Facilitated diffusion allows molecules that cannot pass through the lipid component of the membrane to pass through via a more compatible protein channel or carrier. This includes ions and polar molecules.

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

Na+ rationale: Ions move easily through water, which is polar, but cannot pass directly through the lipid (nonpolar) part of the cell membrane.

Which of the following is not a passive process? facilitated diffusion of glucose Na+/K+ pump oxygen diffusion osmosis

Na+/K+ pump rationale: This pump is a protein in the membrane that moves these ions only in one direction, and up their concentration gradient. This is active transport, and it requires the use of energy.

Which of the following is a principle of the fluid mosaic model of cell membrane structure? All proteins associated with the cell membrane are contained in a fluid layer on the outside of the cell. Phospholipids form a bilayer that is largely impermeable to water-soluble molecules. Phospholipids consist of a polar head and a nonpolar tail made of three fatty acid chains. The lipid bilayer is a solid at body temperature, thus protecting the cell.

Phospholipids form a bilayer that is largely impermeable to water-soluble molecules.

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? Extracellular fluids do not impact cell size, because cells contain intracellular fluid. The cells will swell. The cells will lose water and shrink. The cells will rupture.

The cells will lose water and shrink. rationale: The hypertonic extracellular fluid will draw water out of the hypotonic intracellular fluid, so the cells will shrink. This is called crenulation.

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

The greater the concentration gradient, the faster the rate.

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

a hypertonic solution

Which of the following is LEAST like the other three? cytoplasm interstitial fluid plasma cerebrospinal fluid

cytoplasm rationale: Cytoplasm is the fluid inside of the cell. It would be least like the extracellular fluids.

Which of the following names the three main parts of a human cell? cytosol, nucleus, and membrane mitochondria, lysosome, and centriole cytoplasm, plasma membrane, and nucleus plasma membrane, mitochondria, and nucleus

cytoplasm, plasma membrane, and nucleus

which cell junction is abundant in tissues subjected to great mechanical stress. gap junctions desmosomes tight junctions

desmosomes

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

exocytosis

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

facilitated diffusion

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

facilitated diffusion rationale: Facilitated diffusion is a passive transport process during which molecules move down their concentration gradients through transport proteins.

Channel-mediated diffusion is a form of active transport. True False

false rationale: Channel-mediated diffusion is a form of passive, not active, transport. Any type of diffusion results from substances moving down their concentration gradient, a form of kinetic energy. In order to move, or actively pump, substances against their concentration gradient, energy must be used. ATP directly, or indirectly, provides the energy for active transport.

Phospholipids provide the specific functions of the plasma membrane. True False

false rationale: Integral and peripheral proteins provide a variety of specific functions at the membrane.

Which of the following is not a major function of proteins in the cell membrane? forming channels acting as receptors anchoring cells to other structures forming the entire glycocalyx

forming the entire glycocalyx rationale: The glycocalyx is composed mostly of carbohydrates.

which cell junction is present in electrically excitable tissues? gap junctions desmosomes tight junctions

gap junctions

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

glucose rationale: Glucose, a small polar solute, uses a membrane transporter (a protein carrier) to cross the plasma membrane via facilitated diffusion. In simple diffusion, small nonpolar and lipid-soluble substances (including gases) diffuse directly through the lipid bilayer.

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

hypertonic rationale: "Hyper" means "high," so a hypertonic solution has a higher solute concentration than the solution to which it is being compared.

Where in a typical eukaryotic cell would you expect to find genes? in chromosomes within the cytosol in the chromatin within the cell's cytoplasm in the nucleolus within the nucleus in the DNA within the cell's nucleus

in the DNA within the cell's nucleus rationale: The nucleus houses the DNA, which contains the genes. Genes determine what proteins the cell can make, which in turn determines what the cell can do.

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

isotonic to each other rationale: In order to prevent the cells from either swelling or shrinking, the body fluids should be isotonic, meaning that they are at equilibrium.

Which of the following describes tight junctions? junctions within electrically excitable tissues, such as the heart and smooth muscle junctions where cells are held together by cadherins cell junctions in areas that are subjected to great mechanical stress, such as the skin and heart muscles junctions among epithelial cells lining the digestive tract

junctions among epithelial cells lining the digestive tract rationale: In a tight junction, a series of integral protein molecules (including occludins and claudins) in the plasma membranes of adjacent cells fuse together, forming an impermeable junction that encircles the cell. Tight junctions help prevent molecules from passing through the extracellular space between adjacent cells. For example, tight junctions between epithelial cells lining the digestive tract keep digestive enzymes and microorganisms in the intestine from seeping into the bloodstream.

Which of the following acts as the digestive system of the cell, breaking down materials? endoplasmic reticulum ribosome lysosome nucleus

lysosome rationale: Lysosomes use their enzymes to break down material, much as our digestive system breaks down the foods we consume. The root "lyse" means to loosen or separate, which is what the enzymes in lysosomes do to the chemical bonds in the items they digest.

Which of the following is a function of a plasma membrane protein? molecular transport through the membrane oxygen transport circulating antibody forms a lipid bilayer

molecular transport through the membrane

A primary active transport process is one in which __________. molecules move across the plasma membrane without an input of energy an intracellular vesicle fuses with the plasma membrane and releases its contents to the extracellular fluid 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 rationale: Primary active transporters, such as the sodium-potassium ATPase (or pump), are activated when ATP is hydrolyzed. This activation allows for the transport of solutes across the plasma membrane against concentration gradients.

Passive membrane transport processes include ________. consumption of ATP 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 movement of a substance down its concentration gradient

movement of a substance down its concentration gradient

Which of the following best explains diffusion? movement of molecules farther away from equilibrium 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 from an area of high concentration to an area of low concentration rationale: By diffusion, molecules spread out to maximize their space.

Explain what is meant when we say the plasma membrane is "selectively permeable"

only certain molecules may diffuse through PM

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

phagocytosis

What part of a cell membrane is usually in contact with the interstitial fluid? hydrophobic molecules phosphate heads of phospholipids cholesterol fatty acid tails

phosphate heads of phospholipids rationale: The phosphate heads of the phospholipids are polar, so they are attracted to the polar water molecules.

Which of the following is the main component of the cell membrane? water cholesterol carbohydrates phospholipids

phospholipids rationale: Although phospholipids have a polar head, the long fatty acid tails are nonpolar, making the membrane mostly nonpolar.

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? proteins phospholipids cholesterol water

phospholipids rationale: The plasma (cell) membrane is a phospholipid bilayer, composed of two parallel sheets of phospholipid molecules lying tail to tail, with their polar heads exposed to water on either side of the membrane. Each lollipop-shaped phospholipid molecule has a polar "head" that is charged and is hydrophilic (hydro = water, philic = loving), and an uncharged, nonpolar "tail" that is made of two fatty acid chains and is hydrophobic.

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

primary active transport

Which of the following is NOT one of the three major components of a typical eukaryotic cell? cytoplasm ribosome plasma membrane nucleus

ribosome rationale: Ribosomes are organelles and they are located within one of the major components of the cell.

Which of the following is a characteristic of the cell membrane? impermeable fully permeable not permeable semipermeable

semipermeable rationale: The cell membrane is semipermeable, or selectively permeable, because some things can easily pass through it while others cannot.

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

small concentration gradient rationale: The larger the concentration gradient, the faster the rate of diffusion. Higher concentration means there are more collisions, so the molecules bounce away from each other more rapidly.

Which of the following statements is NOT one of the four major concepts of the cell theory? The cell is the basic structural and functional unit of living organisms. Cells arise from other cells. The function of a cell dictates the structure and organelles of the cells. The activity of an organism emerges from the individual combined activities of the cell.

the function of a cell dictates the structure and organelles of the cells. rationale: this statement is false. The function of cell is instead dictated by the shape of the cell and the organelles inside the cell.

Which of the following describes the plasma membrane? the phospholipid bilayer surrounding the cell a single-layered membrane that surrounds the nucleus of the cell a double layer of protein enclosing the plasma a membrane composed of tiny shelves or cristae

the phospholipid bilayer surrounding the cell

What is the purpose of the energy extracted from ATP in this figure? Two types of membrane active transport processes. to power a chemical reaction between sodium and glucose to transport glucose across the membrane to power a chemical reaction between sodium and potassium to generate a sodium concentration gradient

to generate a sodium concentration gradient rationale: The energy from ATP hydrolysis is used to transport sodium and potassium ions across the membrane and thereby establish concentration gradients for each of those ions.