Deck 3: Cell Structure and Function

Question 1

Ion channels open and close in response to all the following except

A) mechanical pressure.
B) ligand binding.
C) voltage changes.
D) temperature changes.

Answer 1

temperature changes.

Question 2

Gap junctions are connecting channels that allow passage of small molecules from one cell to the next and are especially important for

A) distance signaling.
B) tissues requiring synchronized function.
C) communication within a cell.
D) passage of large molecules.

Answer 2

tissues requiring synchronized function.

Question 3

GTP-binding proteins (G-proteins)function to

A) activate receptors on the extracellular surface.
B) degrade second-messenger molecules.
C) activate intracellular enzyme systems.
D) synthesize ATP.

Answer 3

activate intracellular enzyme systems.

Question 4

Phospholipids spontaneously form lipid bilayers,because they are

A) polar.
B) charged.
C) insoluble.
D) amphipathic.

Question 5

The benefit of glycolysis is that this second stage of catabolism supplies

A) ATP to meet energy needs of the body.
B) pyruvate to the citric acid cycle.
C) energy for oxidative phosphorylation.
D) lactate during anaerobic conditions.

Question 6

The organelle that contains enzymes necessary for oxidative phosphorylation to produce ATP is the

A) mitochondria.
B) ribosome.
C) lysosome.
D) nucleus.

Question 7

The phase of cellular metabolism in which energy is released during breakdown of nutrient sources is anabolism.

Question 8

An increase in extracellular potassium ion from 4.0 to 6.0 mEq/L would

A) hyperpolarize the resting membrane potential.
B) make it more difficult to reach threshold and produce an action potential.
C) hypopolarize the resting membrane potential.
D) alter the threshold potential.

Question 9

Cell-to-cell communication through secretion of chemical signals into the bloodstream to target cells throughout the body is called _____ signaling.

A) synaptic
B) paracrine
C) endocrine
D) autocrine

Question 10

The resting membrane potential in nerve and skeletal muscle is determined primarily by

A) extracellular sodium ion concentration.
B) the ratio of intracellular to extracellular potassium ions.
C) activation of voltage-gated sodium channels.
D) activity of energy-dependent membrane pumps.

Question 11

During conditions of prolonged insufficient oxygen availability (e.g.,respiratory or cardiovascular disease)anaerobic glycolysis accumulated pyruvate can lead to lactic acidosis.

Question 12

Excitable cells are able to conduct action potentials because they have

A) receptors for neurotransmitters.
B) tight junctions.
C) ligand-gated channels.
D) voltage-gated channels.

Question 13

The cardiac drug digitalis enhances myocardial contraction,because it

A) increases intracellular calcium level in cardiac cells.
B) inhibits sodium from entering cardiac cells.
C) enhances the sodium-potassium pump.
D) increases the sodium gradient across the cell membrane.

Question 14

Ribosomes are very important organelles within the cell that have the function of

A) detoxifying substances.
B) synthesizing proteins.
C) converting energy to forms that can be used.
D) coding for protein synthesis.

Question 15

Some individuals inherit a gene that results in dangerously high blood cholesterol caused by impaired endocytosis of low-density lipoproteins (LDLs).

Question 16

Glycolysis is the metabolic process of breaking down a glucose molecule to form

A) CO₂ and H₂O.
B) 2 ATP and 2 pyruvate.
C) 30 ATP.
D) oxygen.

Question 17

Repolarization of a neuron after a depolarizing action potential is because of

A) activation of the Na⁺-K⁺ pump.
B) influx of calcium.
C) efflux of potassium.
D) influx of sodium.