Deck 2: Cell Physiology

Question 1

The stronger the stimulus, the greater the frequency of action potentials generated in a neuron.

Answer 1

True

Question 2

Net sodium movement into the cell occurs passively, whereas net sodium movement out of the cell occurs actively.

Answer 2

True

Question 3

A given synapse may produce EPSPs at one time and IPSPs at another time.

Answer 3

False

Question 4

According to the Nernst equation, the equilibrium potential for a given ion decreases as the difference in concentration of the ion outside and inside the cell increases.

Question 5

When equilibrium is achieved and no net diffusion is taking place, there is no movement of molecules.

Question 6

Action potentials can be summed.

Question 7

Presynaptic neurons converging upon a postsynaptic cell will be either all excitatory or all inhibitory.

Question 8

Secretory vesicles are about 200 times larger than transport vesicles.

Question 9

A postsynaptic neuron can either excite or inhibit a presynaptic neuron.

Question 10

Temporal summation occurs when EPSPs from several different excitatory presynaptic inputs occur simultaneously.

Question 11

Carrier molecules always require energy to accomplish transport of a substance across the membrane.

Question 12

Sheets of epithelial cells are joined by gap junctions.

Question 13

All cell organelles are renewable.

Question 14

According to the fluid mosaic model of membrane structure, the plasma membrane consists primarily of a bilayer of mobile phospholipid molecules studded with an ever-changing mosaic pattern of proteins.

Question 15

If a concentration or electrical gradient is present for a given substance, the substance will always passively permeate the membrane.

Question 16

Action potentials are initiated at the axon hillock region because it has the lowest threshold voltage.

Question 17

The only means by which an extracellular chemical messenger can bring about a desired intracellular response is to activate a second messenger system.

Question 18

The period of time following an action potential during which a membrane cannot be restimulated, no matter how strong the stimulus, is known as the subminimal response period.

Question 19

The cytosol is the gel-like mass of the cytoplasm.

Question 20

Pinocytosis, or "cell drinking," refers to the process of a cell engulfing a large, solid particle and bringing it into the contents of the cell.

Question 21

During the relative refractory period, a neuron is completely refractory.

Question 22

Myelinated fibres in both the central and the peripheral nervous systems are capable of regenerating when cut.

Question 23

Lack of aerobic exercise can have negative health implications, such as heart disease and high blood pressure.

Question 24

The rough endoplasmic reticulum is most abundant in cells specialized for protein secretion, whereas smooth endoplasmic reticulum is abundant in cells that specialize in lipid metabolism.

Question 25

Gap junctions play an important role in transmission of impulses for heart contraction.

Question 26

Coated vesicles enclose a representative mixture of proteins present in the Golgi sac before budding off.

Question 27

Dynein is a mitochondrial enzyme.

Question 28

The sodium-potassium pump indirectly offers the energy source for glucose transport across intestinal cells.

Question 29

Phosphorylation of a carrier can alter the affinity of its binding sites, accompanied by a change in its conformation.

Question 30

A high percentage of sodium and potassium ions move during each action potential.

Question 31

The grand postsynaptic potential depends on the sum of activity of the presynaptic inputs.

Question 32

Endocytosis can be accomplished by phagocytosis and pinocytosis.

Question 33

The nucleus indirectly governs most cellular activities by directing the kinds and amounts of various enzymes and other proteins that are produced by the cell.

Question 34

The large protein anion does not leave the cell because there is no concentration or electrical gradient to drive it outward.

Question 35

The equilibrium potential for K⁺ is less than the resting membrane potential.

Question 36

The axon hillock occurs between the cell body and the axon of a neuron.

Question 37

The predominant cation in the intracellular fluid is calcium.

Question 38

Schwann cells promote axonal growth, while oligodendrocytes inhibit it.

Question 39

The endoplasmic reticulum is one continuous organelle consisting of many tubules and cisternae.

Question 40

The refractory period limits the frequency of action potentials.

Question 41

One chemical messenger molecule can ultimately induce the production of millions of molecules of a secretory product by a cell.

Question 42

In the lipid bilayer of the plasma membrane, the hydrophobic tails of the phospholipids orient toward the centre of the membrane, away from water.

Question 43

The lysosomes are one site of protein synthesis.

Question 44

Anions tend to move toward a negatively charged area.

Question 45

Most of the membrane potential of the plasma membrane is established by the active transport of sodium and potassium ions.

Question 46

The Na⁺ and K⁺ channels that open and close during an action potential are voltage-gated channels.

Question 47

The only way in which a neurotransmitter-receptor combination can influence the postsynaptic cell is to directly alter its permeability to specific ions.

Question 48

The myelin on a myelinated fibre in the peripheral nervous system consists of Schwann cells wrapped around the axon.

Question 49

Osmosis does not occur if the concentration gradients for water and solutes are absent in a system.

Question 50

Fibronectin is the extracellular matrix component that provides tensile strength.

Question 51

Facilitated diffusion is passive and does not require energy.

Question 52

At resting membrane potential, no ionic fluxes are taking place across the membrane.

Question 53

Mitochondria are presumed to be descendants of primitive bacterial cells.

Question 54

The carrier molecule actually moves from side to side through the membrane as it transports material across.

Question 55

In a graded potential, the direction of current flow is designated by the movement of positive charges.

Question 56

During conduction by local current flow, current flows locally between the active and the adjacent inactive area of the cell membrane, thereby decreasing the potential in the inactive area to threshold.

Question 57

The passive current flow of a graded potential fades quickly.

Question 58

At resting potential, the outside of the cell is negative compared to the intracellular fluid.

Question 59

The myelin covering the axon promotes the leakage of ions from the neuron.

Question 60

During the resting potential, many potassium channels are open in the plasma membrane.

Question 61

The refractory period prevents action potentials from spreading back over the part of the membrane where the impulse has just passed.

Question 62

After an action potential has occurred, there is more Na⁺ inside the cell than outside the cell (before any Na⁺-K⁺ pump activity has taken place).

Question 63

The synapse is a specialized part of a neuron.

Question 64

A single neuron may be presynaptic to one group of neurons and postsynaptic to another group of neurons.

Question 65

The surface carbohydrates within the plasma membrane serve as cell adhesion molecules (CAMs), which cells use to grip one another and surrounding connective tissue fibres.

Question 66

Spatial summation involves only one neuron influencing one other neuron.

Question 67

DNA's genetic code is transcribed into messenger RNA.

Question 68

Cilia in the respiratory tract beat in the same direction to sweep inspired particles up and out of the airways.

Question 69

Increased permeability of the postsynaptic cell to Cl^- lessens the likelihood that the postsynaptic cell will undergo an action potential because the membrane potential is moved farther away from threshold.

Question 70

Under an electron microscope, the plasma membrane appears as a trilaminar structure consisting of two dark layers separated by a light middle layer.

Question 71

Along a neuron, an action potential normally travels from the dendrites to the cell body to the axon.

Question 72

At the equilibrium potential for K⁺, the concentration and electrical gradients for K⁺ are in opposition to each other and exactly balance each other so there is no net movement of K⁺.

Question 73

The smooth ER specializes in protein metabolism.

Question 74

Cations are attracted to a more positively charged area along an electrical gradient.

Question 75

The protective, waterproof outer layer of skin is formed by the tough skeleton of the microtrabecular lattice that persists after the surface skin cells die.

Question 76

The nerve fibre is another name for the nucleus of a neuron.

Question 77

Neuropeptides are mainly neuromodulators.

Question 78

Rough ER is most abundant in cells specialized for steroid production.

Question 79

Proteins synthesized by the endoplasmic reticulum become permanently separated from the cytosol as soon as they have been synthesized.

Question 80

Glycolysis generates ATP from glucose with high efficiency.