Download Multiple Choice: Choose the one best answer to each question

Name:____________Practice Test______________ Cell Biology Unit Test #3: 50 points
Multiple Choice (1 pt each): Choose the one best answer for each question on the scantron (double check
for smears) and put “written” answers on the back of the scantron.
---------------------------------------------------------------------------------1) Which of the following is a voltage gated channel that you would expect to find at a pre-synaptic end
of an axon (nerve ending) that is specifically responsible for causing exocytosis of vesicles contianing
acetylcholine (neurotransmitter).
a) K+ b) Na+ c) Ca++ d) Cl2) What second messenger activates protein kinase A to phosphorylate specific serines and theronines?
a) Diacylglycerol b) Calmodulin c) Inositol triphosphate d) Cyclic AMP e) Cyclic GMP
3) During the light reactions of photosynthesis the absolute required first step is to excite electrons at
what location?
a) P700 b) P680 c) d) NADPH d) Beta-carotene
4) a)True/b) False: Carbon fixation occurs when the five carbon Ribose-1,5-bisphosphate accepts carbon
dioxide to become two 3-phosphoglycerates.
Simplified GHK Equation Vm=2.303RT/F log Pk(K)o+Pna(Na)o
Pk(K)i+Pna(Na)i
5) If potassium permeability is increased, the cell becomes more:
a) Depolarized b) Hyperpolarized
6) If sodium permeability is increased, the cell becomes more?
a) Depolarized b) Hyperpolarized
7) a)True/b)False: The ATP synthase generates ATP using a proton gradient in mitochondria and
thylakoids.
8) a)True/b)False: Glycolysis produces pyruvate in the mitochondrial matrix.
9) a)True/b)False: Six carbon dioxide molecules are united at the same time to make a single glucose in
the dark reactions of photosynthesis (Calvin Cycle).
8) A _________channel opens when its threshold membrane potential has been reached.
a) Ligand-gated b) Voltage-gated c) Mechanosensitive
9) Which enzyme breaks down the second messenger cyclic GMP (cGMP)? (viagra blocks this process).
a) Phosphodiesterase b) Calmodulin c) Guanylyl cyclase d) Stimulatory α-GTP
10) Pyruvate dehydrogenase oxidizes pyruvate into acetyl-CoA and ______B__.
A
B
C
D
11) For eukaryotic cells glycolysis occurs in the ______and the tricarboxylic acid cycle occurs in the
______.
a) Mitochondria, Chloroplast
b) Cytosol, Golgi apparatus
c) Cytosol, Smooth endoplasmic reticulum d) Cytosol, Mitochondria
12) Which of the following are directly produced by photosynthesis (P-680 and P-700)?
a) FADH2
ATP!
b) NADH c) Glucose d) Pyruvate
e) None are directly produced-NADPH and
13) The insect poison malathion blocks acetylcholinesterase from degrading the neurotransmitter
acetylcholine. If malathion was present….
a) the post synaptic cell would be less likely to depolarize when acetylcholine is released
b) the post synaptic cell would be more likely to depolarize when acetylcholine is released
14) a)True/b)False: Saltatory conduction of an action potentials is fastest because it uses gaps in the
myelin to expose sodium and potassium voltage-gated channels at Nodes of Ranvier.
15) a)True/b)False: After an action potential has depolarized an excitable membrane by opening sodium
channels, the potassium permeability temporarily increases causing sustained depolarization.
16) a)True/b)False: Voltage gated channels have a gate that closes a few milliseconds after the gates
open during depolarization, this limits the duration of membrane potential depolarization.
17) a)True/b)False: During a typical action potential the sodium and potassium voltage-gated channels
open at the exact same time and close at the exact same time.
18) a)True/b)False: Gap junctions create passages that allow sodium entering a cardiac cell to directly
pass into the cytosol of a second cell causing it to depolarize.
19) ________hormones are produced locally and only act on cells in a close proximity to the origin.
a) Autocrine b) Paracrine c) Endocrine d) Neuroendocrine
20) Which subunit of a G-protein dissociates and stimulates adenylyl cyclase when GDP is displaced?
a) Alpha-GTP b) Beta-GTP
c) Gamma-GTP
d) Calmodulin
21) Which second messenger stimulates protein kinase C to phosphorylate target protein serines and
threonines?
a) Acetylcholinesterase(ACH) b) Diacylglycerol(DAG) c) Phosphodiesterase (PDE) d) Na+/K+ATPase
22) Which of the following can increase calcium permeability to cause contraction or exocytosis?
a) Inositol triphosphate b) Voltage-gated channels c) Calcium
d) All of above
23) Hormones like testosterone have a _________charge and must have a carrier to bring them from the
plasma membrane through the watery cytosol to the DNA in the nucleus.
a) polar b) non-polar
24) Which amino acid residue would be the worst choice for phosphorylation by protein kinases?
a) Tyrosine b) Serine c) Threonine
d) Lysine
d) All of above have hydroxyls and are good targets IF the kinase is specific for that protein and residue
25) a) True/b) False: All living cells have a membrane potential (mV) but only excitable cells can create
and send action potentials down their length.
26) a) Trueb) Fa/lse: All cells have silimar receptors for the same hormones on the intracellular side of
their plasma membranes
27) a) True/b)False: Insulin binds its plasma membrane receptor which is a tyrosine kinase that used a Gprotein to autophosphorylate itself, then it phosphorylates amino groups on target proteins in the
cytosol.
28) a)True/b)False: Typically extracellular sodium is 145 mM, intracellular sodium is 10 mM,
extracellular K+ is 5 mM, and intracellular K+ is 125 mM.
Name:________________Written Questions to Test #3
29) How many of the items indicted below would be produced if palmitate (a 16 carbon long fatty acid)
underwent beta-oxidation (BUT NOT TCA) in the mitochondrial matrix? 4 pts
Acetyl-CoA= 8 NADH= 7 FADH2= 7 GTP= 0 .
16 carbons cut 7 times (7 NADH and 7 FADH2) to create 8 acetyl-CoA……GTP would only come
from TCA
30) How many of the items below are produced when a TWO acetyl-CoAs enter the citric acid cycle and
are oxidized? 6 pts
NADH= _6_ FADH2= _2_ GTP= 2 CO2= _4 (2X2=4 CO2)_ Oxaloacetate= 2 Pyruvate= 0
31) 5 points: How do mitochondria produce ATP from ADP, Pi and the NADH and FADH2 generated in
the question above? You will need to indicate/name all enzymes, proton gradients, and enzyme
complexes. A sketch of the mitochondria will also probably be needed to answer this question.
See notes
32) 2 points: Why is intracellular amplification needed for hormones to change cellular functions?
See notes
33) 5 points: Describe how epinephrine could cause calcium to enter a smooth muscle cell
leading to its contraction via an alpha-1 receptor and phospholipase-C?
Name enzymes, proteins, and second messengers making this possible.
See notes
Extra Credit: 2 points-On The Back
Describe how epinephrine could cause a calcium to enter a heart muscle cell leading to its
contraction via an Beta-1 receptor and cyclicAMP?
Name enzymes, proteins, and second messengers making this possible.
See notes