Cell and Molecular Biology Exam 2 Multiple Choice

The site on an enzyme that will bind the substrate is called the

a. activation site

b. active site

c. catalyst

d. metastable site

b. active site

which of the following is an enzyme?

a. histidine

b. iron

c. carboxypeptidase A

d. N-acetylmuramic acid

e. ATP

c. carboxypeptidase A

An enzyme is active in the stomach of an animal but quickly loses its activity when it leaves the stomach. This example illustrates that enzymes are?

a. sensative to changes in pH

b. consumed by the quantities of substrate in the small intestine

c. inactivated by movement

d. specific to the organs in which they are produced

a. sensative to the changes in pH

saturation can be defined as?

a. denaturation of an enzyme

b. the inability to increase reaction velocity beyond a finite upper limit

c. the substrate concentration at which velocity reaches one-half maximum velocity

d. a characteristic of all uncatalyzed reactions

e. inhibition of enzyme function by blocking the active site

b. the inability to increase reaction velocity beyond a finite upper limit

the induced fit model?

a. proposed that very strong covalent bonds are formed upon substrate binding.

b. states that enzyme-substrate interactions are rigid

c. involves a conformational change in the shape of an enzyme

d. is also called the lock and key model

c. involves a conformational change in the shape of an enzyme

a linear relationship between initial reaction velocity and substrate concentration would be expected when?

a. [S]>> Km

b. [S]<< Km

c. [S] = Km

d. both choices A and B

e. both choices B and C

b. [S] << Km

An allosteric inhibitor?

a. binds at the regulatory site

b. increases the rate of substrate binding

c. is converted to an activator by the enzyme

d. binds and activates the high-affinity state of the enzymes

e. is identical to the active site

a. binds at the regulatory site

a competitive inhibitor?

a. cannot be processed as a substrate by the enzyme

b. bind at a site other than the active site

c. binds to and inactivates the substrate

d. does not inhibit enzyme activity but does lower substrate concentration

a. cannot be processed as a substrate by the enzyme

an increase in temperature actives chemical reaction by?

a. increasing number of molecules in the reaction center

b. increasing activation energy

c. increasing the number of molecules with energy high enough to undergo the reaction

d. decreasing free energy

c. increasing the number of molecules with energy high enough to undergo the reaction

Aspirin binds to prostaglandin synthetase and permanently stops its ability to produce prostaglandin. This is an example of?

a. allosteric inhibition

b. reversible competitive inhibition

c. irreversible inhibition

d. noncompetitive inhibition

c. irreversible inhibition

Which of the following types of work involves a change in position of the cell or a cell structure?

a. electrical

b. synthetic

c. mechanical

d. concentration

e. bioluminescent

c. mechanical

Fireflies have the ability to convert the energy in ATP to light. Which of the following types of work is performed by the firefly?

a. concentration

b. mechanical

c. heat

d. bioluminescent

e. electrical

d. bioluminescent

A student drops his notes, and his papers scatter. The fact that the papers scatter and do not remain neatly stacked is an illustration of

a. the first law of thermodynamics.

b. an increase in entropy.

the second law of thermodynamics.

c. both the first law and the second law of thermodynamics

d. the second law of thermodynamics; an increase in entropy.

d. the second law of thermodynamics; an increase of entropy

Aerobic refers to what property of chemotrophs?

a. chemotrophs remove carbon dioxide from the air

b. chemotrophs require oxygen to produce energy

c. fermentation releases great amounts of gas but only in chemotrophs

d. heat losses occur in the presence of oxygen

b. chemotrophs require oxygen to produce energy

Carbon Dioxide generally enters the plant through pores called?

a. connexons

b. mesophyll

c. stomata

d. the cuticle

e. bacteriochlorophylls

c. stomata

in the chloroplast, the stroma is the?

a. connection between the grana

b. stack of thylakoids

c. cytochromes associated with the thylakoids

d. region between in the the inner and outer membranes

e. central semifluid region

e. central semifluid region

A house plant seems to be growing slowly and lacks its normal bright green color. You call a botanist for advice. She suggests that the plant may be deficient in magnesium (Mg++). Why are these symptoms are associated with Mg++ deficiency?

a. cytochromes require Mg2+ to function properly

b. Mg2+ is important in the structure of many amino acids

c. Mg2+ is required before NADPH can function

d. lack of Mg2+ in the soil allows pathogenic bacteria to grow

e. Mg2+ is an important component in chlorophyll

e. Mg2+ is an important component in chlorophyll

Which of the following minerals are directly involved with light absorption in photosynthesis?

a. Fe

b. Zn.

c. Ca.

d. Na.

e. Mg

e. Mg

The calvin cycle occurs in the ____ region of the chloroplast?

a. thylakoid membrane

b. stroma

c. grana

d. thylakoid lumen

e. outer membrane

b. stroma

In the Calvin Cycle the enzyme that catalyzes the capture of Carbon Dioxide and the formation of 3-phosphoglycerate is?

a. glyceraldehyde-3-phosphate dehydrogenase

b. Ribulose Bisphosphate Carboxylase/Oxygenase (Rubisco)

c. phosphohlycerokinase

d. phosphoribulokinase

e. triose phosphate insomerase

b. Ribulose Bisphosphate Carboxylase/Oxygenase (Rubisco)

Carbon Assimilation and synthesis of starch and sucrose occur?

a. only in the light

b. only in the dark

c. both in the light and in the dark

d. in the roots

c both in the light and in the dark

The breakdown of glucose to pyruvate by a cell is an example of reaction?

a. anabolic

b. synthesis

c. catabolic

d. amphibolic

e. aerobic

c. catabolic

An energy-liberating pathway is considered to be?

a. anabolic.

b. catabolic.

c. metabolic.

d. hydrogenation.

e. all of the above

b. catabolic

The negatively charged phosphate of ATP influence one another by?

a. charge repulsion

b. dehydrogenation

c. relative hydration

d. all of the above

a. charge repulsion

The ​gross​ output of ATP from glycolysis is __________, whereas the net​ output of ATP is __________. ?

a. 2;1

b. 4;1

c. 4;2

d. 2;4

e. 6;4

c. 4;2

During strenuous exercise, you may notice that your muscles burn. Which of the following statements best explains this phenomenon?

a. without oxygen, pyruvate is being converted to lactic acid

b. carbon dioxide is building up in muscle and changing the pH

c. pyruvic acid causes muscle pain

d. ADP is accumulating, which produces a burning sensation

e. proteins are being digested to provide energy

a. without oxygen, pyruvate is being converted to lactic acid

the process of glucose synthesis is called

a. glucogenesis

b. glycolysis

c. aglycolysis

d. gluconeogenesis

e. both choices b and c

d. gluconeogenesis

Why are mitochondria so prevalent in skeletal muscle?

a. bones and muscles require a great deal of energy to prevent them from separating

b. they are needed to provide energy for muscle contraction

c. they are needed to repair damages tissue that accumulates during exercise

d. they give the muscle enough elasticity to contract

e. the flow of blood is greatest in skeletal muscle

b. they are needed to provide energy for muscle contraction

energy in the cell can be stored by accumulating reduced compounds because?

a. reduction reaction are exergonic

b. reduction reactions are endergonic

c. oxidation reactions are exergonic

d. oxidation reactions are endergonic

e. choices b and c

e. choices b and c (Reduction reactions are endergonic and

Oxidation reactions are exergonic)

Gluconeogenesis occurs in the ?

a. muscles

b. stomach

c. liver

d. brain

c. liver

electron transport and oxidative phosphorylation occur?

a. in the outer mitochondrial membrane

b. in the mitochondrial matrix

c. in the inner mitochondrial membrane

d. in the cytoplasm

c. in the inner mitochondrial membrane

Male newborn mammals, including human infants, have a special type of adipose tissue called brown fat, in which a naturally occurring uncoupling protein called thermogenin is present in the inner mitochondrial membrane. Thermogenin uncouples ATP synthesis from electron transport so that the energy released as electrons flow through the electron transport chain is lost as heat instead. In which of the following animals would you expect to have more brown fat tissue?

a. an adult bear hunting in the summer

b. an adult bear in the summer having a nap

c. an adult hibernating bear

d. an adult walrus

c. an adult hibernating bear

Which of the following is not a product of the TCA cycle?

a. ATP

b. FADH2

c. acetyl CoA

d. CO2

e. NADH

c. acetyl CoA

Which of the following would not be used as a final electron acceptor in anaerobic respiration?

a. nitrogen

b. oxygen

c. sulfur

d. iron

e. protons

b. oxygen

In the graph above, the point at which the sodium channels begin to open is indicated by the letter?

a. a

b. b

c. c

d. d

e. e

a (circle a at the bottom)

36. In the graph above, at what point in the action potential does the repolarization end?

a. a

b. b

c. c

d. d

e. e

d (cirlce d at the bottom)

The part of the graph between points D and E represents?

Hyperpolarization

(Refer to the graph above.) At the same time that the stimulus was introduced, a drug that specifically inhibits sodium channels was added to the system. The effect this would have is that the membrane would 

A) not depolarize. 

B) depolarize, but would not for a second impulse. 

C) not be able to repolarize. 

D) repolarize, but would not for a second impulse. 

E) none of the above

a. not depolarize

The technique that allows one to record ion currents passing through individual channels is known as?

a. patch- clamping

b. voltage-gating

c. ionophores

d. ligand-gating

e. ion sensors

a. patch clamping

In the structure of ion channel, the gate and selectivity filter?

a. are the same thing

b. can be different parts of the channel molecule

c. are always intracellular

d. are always extracellular

b. can be different parts of the channel molecule

Major ion concentrations inside and outside mammalian cells are approximately (in mM)

a. 140 Na+ outside, 10 Na+ inside, 140 K+ inside, 5 K+ outside

b. 10 Na+ outside, 140 Na+ inside, 140 K+ inside 5 K+ outside

c. 140 Na+ outside, 10 Na+ inside, 5 K+ inside, 140 K+ outside

d. 140 Na+ outside, 140 Na+ inside, 5 K+ inside, 10 K+outside

A. ​140 Na+ outside, 10 Na+ inside, 140K+inside, 5K+ outside

The factors that influence a cell's membrane potential are?

a. the amounts of sodium and potassium in the cytoplasm

b. the concentration gradients of different ions across the membrane

c. the permeability of the membrane to the ions

d. and c

e. b and c

e. b and c (the concentration gradients of different ions across the membrane and the permeability of the membrane to the ions)

In a single channel experiment amplitude histogram, what peaks would you expect from two channels with amplitudes of 3 and 5 pA?

a. 3 pA and 5 pA

b. 3 pA, 5 pA, and 8 pA

c. 3 pA, 6 pA, 5 pA, and 10 pA

d. 0 pA, 3 pA, 5 pA, and 8 pA

d. 0 pA, 3 pA, 5 pA, and 8 pA

The signaling distance is increasing in the following order?

a. synaptic- paracrine- endocrine signaling

b. paracrine- synaptic- endocrine signaling

c. endocrine- synaptic- paracrine signaling

d. endocrine- paracrine- synaptic signaling

a. synaptic-paracrine-endocrine signaling

Metabotropic and ionotropic receptors differ in the following?

a. metabotropic receptor has a built in ion channel

b. ionotropic receptor has a built in ion channel

c. metabotropic receptor is always intracellular

d. ionotropic receptor is always intracellular

b. ionotropic receptor has a built in ion channel

The transport systems involved in maintaining low calcium ion concentration in the cytoplasm are?

a. store operated calcium channels, ER calcium pump, and plasma membrane calcium pump

b. ER calcium pump, plasma membrane calcium pump, and calcium/sodium exchanger

c. plasma membrane calcium pump, calcium/sodium exchanger, and voltage-gated calcium channels

d. ER calcium pump, ryanodine receptors, and plasma membrane calcium pump

b. ER calcium pump, plasma membrane calcium pump, and calcium/sodium exchanger

Which of the following is not a function of the cytoskeleton?

A) cell movement

B) cell division

C) moving organelles

D) passive transport

d. passive transport

What is largely responsible for the negative resting membrane potential (around -70 mV) in a neuron?

a. axonal insulation by Schwann cells

b. voltage-gated sodium channels opening

c. action potential

d. potassium leak currents

d. pottasium leak currents

According to the current model, which of the following is the correct sequence of microtubule assembly?

A) dimers, oligomers, sheets of protofilaments, protofilaments, closing of microtubule, elongating microtubule

B) dimers, sheets of protofilaments, closing of microtubule, oligomers, protofilaments, elongating microtubule

C) dimers, oligomers, protofilaments, sheets of protofilaments, closing of microtubule, elongating microtubule

D) protofilaments, sheets of protofilaments, closing of microtubule, elongating microtubule, dimers, oligomers

c. dimers, oligomers, protofilaments, sheets of protofilaments, closing of microtubule, elongating microtubule

Capping proteins?

a. stabilize microtubules

b. connect microtubules to microfilaments

c. cause microtubules branching

d. destabilize microtubules

a stabilize microtubules

In relaxed muscle, calcium is found in high concentration in the?

a. myofibril

b. sarcolemma

c. T tubules

d. neuromuscular junction

e. sacroplasmic reticulum

e. sacroplasmic reticulum

when glucose is converted to glucose 6 phosphate by hexokinase, the accumulation of glucose 6 phosphate inhibits the reaction.

a. non-competitive

b. competitive

c. feedback inhibition

d. covalent modification

e. allosteric regulation

c. feedback inhibition

A foreign substance is added to the reaction in part A above. This substance binds to hexokinase and prevents its ability to catalyze the reaction

a. non-competitive

b. competitive

c. feedback inhibition

d. covalent modification

e. allosteric regulation

a. non- competitive

an inactive form of an enzyme becomes active after being phosphorylated

a. non-competitive

b. competitive

c. feedback inhibition

d. covalent modification

e. allosteric regulation

d. covalent modification