Deck 5: Membrane Structure, Synthesis, and Transport

Question 1

Which of the following organisms is likely to contain biomembranes?

A) plants
B) animals
C) prokaryotes
D) plants and animals
E) All living organisms contain biomembranes.

Answer 1

All living organisms contain biomembranes.

Question 2

Cellular membranes are

A) fluid.
B) solely composed of lipids.
C) composed of a single layer of amphipathic molecules.
D) selective to the transport of gases and small molecules only.
E) characteristic of eukaryotes, but not prokaryotes.

Answer 2

fluid.

Question 3

Which of the following is NOT true of the plasma membrane?

A) It is composed of an extracellular and intracellular layer of phospholipids.
B) The extracellular and intracellular layers or leaflets are highly symmetrical.
C) The membrane contains peripheral proteins.
D) Integral proteins span through the membrane.
E) The membrane contains glycolipids and glycoproteins.

Answer 3

The extracellular and intracellular layers or leaflets are highly symmetrical.

Question 4

Which of the following statements about plasma membranes is INCORRECT?

A) They are composed of phospholipids.
B) They have both integral and peripheral proteins.
C) They are relatively rigid structures.
D) They are composed of two leaflets of phospholipids.
E) They function to separate the extracellular and intracellular environment.

Question 5

Which of the following statements is CORRECT about biomembranes?

A) The phospholipid tails interact with water.
B) The phospholipid head groups are repelled by water.
C) Electron microscopy indicates the membrane looks like train tracks with two light lines of lipids . separated by a dark line containing proteins.
D) The membrane is composed of two protein layers separated by a lipid layer.
E) Membrane proteins are globular, and some span the phospholipid bilayer and project from both sides of the membrane.

Question 6

A scientist produces an artificial membrane from phospholipids and notices that oxygen, but not glucose readily moves through the membrane. What might account for the inability of glucose to move through the artificial membrane?

A) The artificial membrane lacked a protein needed for glucose transport.
B) The artificial membrane lacked the appropriate types of phospholipids for glucose transport.
C) Oxygen readily passes through the membrane, so glucose should have as well.
D) The membrane lacked an adequate amount of amphipathic molecules for glucose transport.
E) Thermodynamics does not allow glucose to pass through membranes produced either artificially or from living organisms.

Question 7

Around what percentage of all genes encode membrane proteins?

A) 0%
B) 10%
C) 25%
D) 50%
E) 75%

Question 8

Which of the following is NOT a function of cellular membranes?

A) selective uptake and export of ions and molecules
B) cell compartmentalization
C) cell signaling
D) maintenance of cell shape
E) cell adhesion

Question 9

Which of the following statements is TRUE of membrane phospholipids?

A) The hydrophilic head groups face the interior portion of the membrane.
B) The hydrophobic tail groups face the exterior portion of the membrane.
C) They spontaneously flip-flop from one side of the membrane to the other.
D) They freely move laterally within the membrane.
E) They rarely flip-flop across or move laterally within the membrane.

Question 10

Phospholipids and ________ are the major components of cell membranes.

A) glycolipids
B) cholesterol
C) glucose transporters
D) glycocalyx
E) proteins

Question 11

The following affect membrane fluidity EXCEPT

A) glycoprotein composition.
B) cholesterol.
C) phospholipid composition.
D) the length of the phospholipid fatty acyl tail.
E) the relative amounts of phospholipids containing saturated or unsaturated fatty acyl tails.

Question 12

Which of the following is TRUE of phospholipids that flip-flop across the lipid bilayer?

A) The process requires energy.
B) The process occurs spontaneously, requiring no energy.
C) The process requires an enzyme called flippase.
D) The process requires energy and the flippase enzyme.
E) The process occurs spontaneously and requires the flippase enzyme.

Question 13

Glycosylated proteins and lipids within the plasma membrane are important for

A) cell recognition.
B) cell protection.
C) cell energy storage.
D) cell recognition and protection.
E) cell protection and energy storage.

Question 14

Placing celery sticks in fresh water will make them more turgid and harder. This is because

A) the celery is hypotonic to fresh water.
B) the celery is hypertonic to fresh water.
C) the celery is isotonic to fresh water.
D) water moves from the celery sticks into fresh water.
E) None of the choices are correct.

Question 15

Of the following molecules, which passes through a lipid bilayer most readily?

A) carbon dioxide
B) glucose
C) K⁺
D) arginine
E) RNA

Question 16

Which of the following molecules would you predict moves through a lipid bilayer most rapidly?

A) C₆H₁₂O₆
B) CH₃OH
C) C₂H₅OH
D) C₄H₁₀
E) NH₂SO₂CH₃

Question 17

Animal cells are permeable to water and urea but NOT to sucrose. The inside of a cell contains 1 M sucrose and 1 M urea and the outside 1 M sucrose and 2 M urea. The solution inside with respect to outside the cell is

A) hypotonic.
B) turgid.
C) isotonic.
D) saturated.
E) hypertonic.

Question 18

Animal cells are permeable to water and urea but NOT to sucrose. Initially, the inside of a cell contains 1 M sucrose and 1 M urea and the outside 1 M sucrose and 2 M urea. After the system reaches equilibrium, what changes are observed?

A) The molarity of urea would be higher outside than inside the cell.
B) The molarity of sucrose would be similar inside and outside the cell.
C) Water would move out of the cell causing the cell to shrivel.
D) The molarity of urea would be higher outside the cell and the molarity of sucrose would be similar inside and outside the cell.
E) The molarity of sucrose would be similar inside and outside the cell and water would move out of the cell causing the cell to shrivel.

Question 19

Which of the following statements is CORRECT about active transport?

A) It requires energy.
B) It is an active process in which molecules move from a region of lower concentration to one of higher concentration.
C) It requires integral proteins.
D) It is necessary to maintain solute gradients across a membrane.
E) All of the choices are correct.

Question 20

The statements about transport of Ca²⁺ from the cytosol (low Ca²⁺ concentration) into the endoplasmic reticulum (high Ca²⁺ concentration) are true EXCEPT which of the following?

A) Calcium movement involves the use of a pump.
B) Calcium movement involves active transport.
C) Calcium movement occurs by facilitated diffusion using a transporter protein.
D) Calcium movement requires energy.
E) Calcium movement occurs through a transmembrane protein.

Question 21

The release of insulin from pancreatic cells occurs by

A) endocytosis.
B) pinocytosis.
C) phagocytosis.
D) exocytosis.
E) receptor-mediated endocytosis.

Question 22

Plant cell membranes contain cholesterol.

Question 23

Membrane proteins are attached to or embedded in the phospholipid bilayer.

Question 24

The current model that best describes biomembranes is the Rigid Mosaic Model.

Question 25

Facilitated diffusion is required for the movement of Na⁺ out of the cell.

Question 26

The Na⁺/K⁺-ATPase pump is a ligand-gated ion channel.

Question 27

A macrophage (immune cell) consuming a bacteria is best described as phagocytosis.