Chapter 5 Quiz

Osmosis is A. a process that requires energy. B. the active transport of water across membranes. C. the unidirectional diffusion of water across membranes. D. the movement of water across selectively permeable membranes. E. a process that is unaffected by solute concentration inside cells.

D. the movement of water across selectively permeable membranes.

Cell membranes are ________ permeable. A. Selectively B. Always C. Completely D. Not

A. Selectively

The rate of transport of a substance into a cell is drastically reduced when the formation of ATP is blocked. The transport system must be a form of A. active transport. B. both simple and facilitated diffusion. C. both active transport and simple diffusion. D. facilitated diffusion. E. simple diffusion.

A. active transport.

Phospholipids have hydrophilic and hydrophobic areas within the same molecule. This dual nature of the molecule is described by the term A. amphipathic. B. polar. C. non-polar. D. electrostatic. E. ionic.

A. amphipathic.

Proteins embedded in a cell membrane never move. A. True B. False

B. False

Which of the following is NOT a characteristic of the plasma membrane? A. It is composed of a phospholipid bilayer B. Maintains cell shape C. Contains different types of proteins D. It is easily crossed by non-polar molecules

B. Maintains cell shape

Which are the primary molecules making up plasma membranes in cells? A. Peptidoglycan B. Phospholipids C. Nucleic Acids D. Proteins

B. Phospholipids

While on a trip to the desert, a friend of yours was bitten by a rattlesnake. He nearly died from hemolysis, or breakage of many of his red blood cells. You have analyzed the snake venom and found three enzymes: phospholipase, which degrades phospholipids; neuraminidase, which removes cell surface carbohydrates; and protease which degrades proteins. Which of these enzymes do you think was responsible for his near fatal red blood cell hemolysis? Why? A. The protease would degrade transmembrane proteins leading to cell lysis. B. The phospholipase would degrade the phospholipids, the component of a membrane creating a barrier. C. The neuraminidase lyses the carbohydrate rich glycocalyx leadint to cell breakage since this layer is responsible for strengthening the cell membrane.

B. The phospholipase would degrade the phospholipids, the component of a membrane creating a barrier.

Placing phospholipids into an aqueous solution immediately results in their forming a lipid bilayer. What is the driving force causing this ordered arrangement? A. The phospholipids are very ordered in water, and gain freedom of movement by forming a bilayer. B. Water, when associated with lipids, is forced into an ordered arrangement with fewer hydrogen bonds. Forcing lipids into a bilayer gains freedom of movement for the water. C. Phospholipids have a strong affinity for other phospholipids, leading to self assembly.

B. Water, when associated with lipids, is forced into an ordered arrangement with fewer hydrogen bonds. Forcing lipids into a bilayer gains freedom of movement for the water (The water can avoid very unfavorable arrangements by "squeezing" phospholipids into a bilayer, sequestering the hydrophobic fatty acid tails inside the membrane. Once formed, the membrane is further stabilized by the other weak forces, including van der Waals contacts between fatty acids, and hydrogen bonding and electrostatic attractions between the hydrophilic part of the phospholipids and the aqueous solution.).

Cell membrane components are synthesized in the endoplasmic reticulum, transported as vesicles to the Golgi apparatus where they are modified, and then are transported to the cell surface where they deliver their contents to the cells exterior and become a part of the cell membrane in a process called ____________. The reverse of this process, bringing nutrient containing particles from out side to the inside of the cell is called _________. A. simple diffusion; facilitated diffusion B. exocytosis; endocytosis C. active transport; passive transport D. osmosis; diffusion

B. exocytosis; endocytosis

Co-transport of nutrients across the intestinal cell membranes is an active process that can move glucose against a concentration gradient. The energy requiring step for co-transport is A. the permease that allows glucose and Na+ into the cell requires ATP. B. the Na+K+ ATPase that pumps Na+ from the cell into the blood, maintaining low Na+ levels in the cell. C. the permease that pumps glucose from the cell into the blood requires ATP. D. the Na+K+ATPase that pumps Na+ from the cell into the lumen of the intestine.

B. the Na+K+ ATPase that pumps Na+ from the cell into the blood, maintaining low Na+ levels in the cell (The Na+K+ ATPase moves Na+ out of the epithelial cells lining the intestine and into the blood. The reduced concentration of Na+ inside the cell coupled with high Na+ inside the lumen of the intestine provides a driving force for the movement of Na+ into the cell. The cotransporters in the membrane of the epithelial cell facing the intestine allow Na+ to enter only when accompanied by either glucose or one of the amino acids (each have their own set of co-transporters). Glucose then moves into the blood through a permease in the membrane between the cell and the blood. Thus, ATP is used as an energy source to drive Na+ out of the cell resulting in glucose transport from the intestine to our blood.).

What are the three types of protein receptors that can be activated by a signal and start a signal transduction pathway? A. DNA polymerase, RNA polymerase I, RNA polymerase II B. Proteases, lipases, nucleases C. Ion channels, protein kinases, G protein-linked receptors

C. Ion channels, protein kinases, G protein-linked receptors

The system used by protozoa to help control the flow of water into the cell is A. the Na+ K+ ATPase of the cell membrane. B. the lysosome, used to secrete water in animal cells. C. a pump in the cytoplasm that squeezes out water. D. turgor pressure against the cell wall.

C. a pump in the cytoplasm that squeezes out water.

Which component of a cell membrane is likely to function as a receptor in cell to cell signaling? A. lipids B. carbohydrates C. proteins D. cholesterol

C. proteins

Cyclic AMP (cAMP) is an important __________ in the signal transduction pathway. It _________ and ________ the signal to trigger a cellular response. A. primary messenger; distributes; amplifies B. secondary messenger; channels, decreases C. secondary messenger; distributes; amplifies D. receptor; distributes; amplifies

C. secondary messenger; distributes; amplifies

Oral rehydration therapy saves the lives of millions of victims of cholera and other diarrhea-producing diseases. This therapy, which requires feeding dilute salts and glucose, is successful because A. the active transport of glucose and sodium from the cell to the intestine is still intact. B. the dilute salts and glucose cause removal of excess water from the body. C. the secondary active transport or cotransport systems of the intestine are still functioning. D. bacterial damage to intestinal transport of ions is reversed by glucose. E. the dilute salts and glucose are hypotonic to the diarrhea-causing bacteria.

C. the secondary active transport or cotransport systems of the intestine are still functioning.

Hormones are chemical signals that A. affect adjacent cells. B. are autocrine signals. C. travel through circulatory systems. D. are paracrine signals. E. work in prokaryotes.

C. travel through circulatory systems.

A universal feature of receptors is that they A. do not undergo structural (shape) changes when the signal molecule is bound. B. are ion channel proteins. C. undergo structural (shape) changes when the signal molecule is bound. D. are present in the plasma membrane. E. are protein kinases.

C. undergo structural (shape) changes when the signal molecule is bound.

Which process allows the transport of sugars and amino acids across the cell membrane? A. Active transport through the Na+/K+ ATPase B. Passive transport through the phospholipid bilayer C. Active transport through peripheral proteins D. Passive transport through carrier proteins

D. Passive transport through carrier proteins

Which statement about membrane proteins is true? A. RNA is found as part of most membrane proteins' structure. B. Hydrophilic regions of integral membrane proteins are in contact with the interior of the bilayer. C. Some membrane proteins may have DNA attached to them. D. Peripheral membrane proteins may be associated with the phospholipid head groups. E. Integral membrane proteins are fixed in place.

D. Peripheral membrane proteins may be associated with the phospholipid head groups.

Which molecule describes a phospholipid bilayer in which proteins can move about within the plane of the cell membrane? A. The fluid musical model B. The fluid musical model C. The rigid mosaic model D. The fluid mosaic model

D. The fluid mosaic model

Active transport moves solutes across the membrane A. following water concentration gradients. B. through facilitated diffusion. C. following their concentration gradients. D. against their concentration gradients.

D. against their concentration gradients.

Cotransport systems of the intestinal epithelial cells include the_________ in the intestine facing membrane, the energy requiring _____________ facing the blood, and the ______________allowing facilitated diffusion of glucose out of the cell. A. Na+K+ ATPase, cotransporters, permeases B. permease, cotransporters, Na+K+ ATPase C. cotransporters, CFTR, permeases D. cotransporters, Na+K+ ATPase, permeases

D. cotransporters, Na+K+ ATPase, permeases

The major driving force for the formation of a lipid bilayer is _____; once formed the membrane is further stabilized by ________. A. repulsion between negative charges of phospholipid fatty acids; hydrogen bonds and van der Waals contacts B. van der Waals contacts between phospholipid charged groups; hydrophobic forces, hydrogen bonding and electrostatic attractions C. electrostatic attractions, hydrogen bonds, and van der Waals contacts; covalent bonds D. hydrophobic forces on the phospholipid fatty acid carbon chains; hydrogen bonds, electrostatic attractions, and van der Waals contacts E. electrostatic attractions between phospholipid head groups; hydrophobic forces and hydrogen bonds

D. hydrophobic forces on the phospholipid fatty acid carbon chains; hydrogen bonds, electrostatic attractions, and van der Waals contacts

A sample of cells is placed in a salt solution. The cells shrink and the membrane is distorted. Relative to the cell, the solution is probably A. osmotic. B. hypotonic. C. isotonic. D. hypertonic

D. hypertonic

Chemical signal transduction pathways A. use nonspecific receptors. B. use receptors that are located only on the cytoplasm. C. all use G proteins. D. involve binding of the signal molecule to receptors. E. use receptors that change the ligands they bind.

D. involve binding of the signal molecule to receptors.

The ____ portion of the cell membrane functions as a barrier while the ____ portion determines specific functions, including pumps, receptors, adhesion, etc. A. nucleic acid, lipid B. carbohydrate, nucleic acid C. lipid, carbohydrate D. lipid, protein

D. lipid, protein

Crossing a membrane by simple diffusion can be distinguished from facilitated diffusion because A. simple diffusion is found only in prokaryotes while facilitated diffusion is found only in eukaryotes. B. simple diffusion can only move material in the direction of a concentration gradient; facilitated diffusion moves materials with and against a concentration gradient. C. simple diffusion does not require energy; facilitated diffusion requires a source of ATP. D. simple diffusion is not saturable; facilitated diffusion rates are limited by the number of functional membrane proteins and can be saturated.

D. simple diffusion is not saturable; facilitated diffusion rates are limited by the number of functional membrane proteins and can be saturated.

Which molecule would diffuse across a phospholipid bilayer fastest, if there are no proteins associated with the bilayer? A. Na+ B. H2O C. CH3COO- D. NH4+ E. NH3

E. NH3

Why do phospholipids spontaneously form bilayer structures, while oils form small droplets? A. The fatty acids in oils preclude bilayer formation. B. Oils and water do not mix. C. Oils are energy reserves of cells. D. Oils are not as hydrophobic as phospholipids are. E. Oils do not have the polar head group that phospholipids have.

E. Oils do not have the polar head group that phospholipids have.

Receptor-mediate endocytosis A. allows small molecules to enter cells. B. directly involves the Golgi apparatus. C. is another name for phagocytosis. D. is nonspecific. E. results in the formation of clathrin-coated vesicles.

E. results in the formation of clathrin-coated vesicles.