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MCAT - AAMC - Biology Q-Pak 1 & 2

Terms in this set (34)

A. No; AP result in an increased permeability of the PM to Na.

While some Na movement does occurs down the length of the axon during the AP (it occurs in the nodes Ranvier, which are unmyelinated), this movement does not depend on the sodium pump nor does it cause APs.
A student postulated that the sodium pump directly causes action potentials along neurons. Is the hypothesis reasonable?

A. No; AP result in an increased permeability of the PM to Na.
B. No; the myelin sheaths of neurons prevent movement of ions across the PM of neurons.
C. Yes; Na is transported out of neurons during APs
D. Yes; AP are accompanied by hydrolysis of ATP
C. conjugation
Which of the following recombinant processes depends on the F factor plasmid?

A. transformation
B. transduction
C. conjugation
D. translocation
D. negative pressure pumping action
Inflation of the lungs in mammals is accomplished by:

A. diffusion of gases
B. active transport of gases
C. positive pressure pumping action
D. negative pressure pumping action
D. infection of an embryo by a virus modified to carry the gene

A = probably die in stomach
B = impractical
C = no guarantees will reach target
An effective and efficient method for the delivery of an antisense gene could be:

A. orally as an emulsified product
B. microinjection into an individual body cells
C. IV as a nonantigenic, blood-stable product
D. infection of an embryo by a virus modified to carry the gene
B. the coordination of cell differentiation during development

cell differentiation during development is very sensitive to timing of mRNA turnover

A & D (your answer) aren't as time sensitive
If oligonucleotides such as mRNA were not degraded rapidly by intracellular agents, which of the following processes would be most affected?

A. the production of tRNA in the nucleus
B. the coordination of cell differentiation during development
C. the diffusion of respiratory gases across the cell membrane
D. the replication of DNA in the nucleus
D. II and III only

Myoglobin = holds oxygen in muscles and organs
Breaking of it could reveal injury.

Kidneys unable to reabsorb the myoglobin also demonstrate injury
After an accident, physician detected the protein myoglobin in her urine. What type of injury is consistent with this observation?

I. broken bone.
II. damaged muscle
III. damaged kidney

A. I only
B. III only
C. I and III only
D. II and III only
B. maintain sufficient oxygenation of cells

Skin blood vessels PROBABLY don't have a huge impact on blood pressure, rather making sure the skin gets enough oxygen has higher priority for this question
Sara noted that her skin blood vessels were usually constricted to conserve body heat in the cold environment of the mountains. However, her skin blood vessels would occasionally dilate for short periods of time. What would be the most probable physiological purpose for this periodic vasodilation?

A. maintain normal skin tone
B. maintain sufficient oxygenation of cells
C. reduce excessive blood pressure
D. maintain normal muscle tone
B. respiration

only about 1% CO2 comes out of the skin; so little.
All of the following are functions of mammalian skin EXCEPT:

A. sensation
B. respiration
C. protection from disease
D. protection against internal injury
C. a decrease, because the decreased rate of urine output will allow more reabsorption by the kidney

There is no suggestion from this particular passage saying that ADH would be affected.

If the heart stopped and the blood in the glomerular capillaries had no hydrostatic pressure, fluid in the space around the glomerulus would flow back into the capillary bloodstream. This would occur because the protein rich blood would be hypertonic with respect to their protein-poor fluid in the capsular space so that the fluid would down the osmotic gradient into the blood.
Some question about a substance A and it's clearance...

A lower-than-normal blood pressure will cause which of the following effects on the rate of plasma clearance of Substance A?

A. an increase, because the concentration of Substance A i the urine will increase
B. an increase, because the ADH levels will be very low
C. a decrease, because the decreased rate of urine output will allow more reabsorption by the kidney
D. a decrease, because ADH levels will be very high
A. glomerular filtrate rate

Increasing blood pressure should increase flow of fluid through the kidney system and DECREASE (rather than increase) water reabsorption, so C is wrong. C and D are basically the same thing, so that's wrong. B was within the passage demonstrating independency from blood pressure.
The increased BP resulting from the higher-than-normal concentration of ADH most likely affected the urinary output of X by increase the :

A. glomerular filtrate rate
B. tubular transport of solutes
C. water reabsorption from the tubules
D. concentrating ability of the loop of Henle
C. mitosis
The liver is different from many other organs in that it can at least partially regenerate following illness or damage. This regeneration is accomplished primarily through:

A. fission
B. meiosis
C. mitosis
D. cell growth
C. ulcers could be produced in healthy organisms by infecting them with H. pylori
It is now generally accepted that H. pylori can cause ulcers. Proof of this most likely depended on the demonstration that:

A. people with stomach ulcer have antibodies to H. pylori
B. healthy individuals have antibodies to H. pylori
C. ulcers could be produced in healthy organisms by infecting them with H. pylori
D. the organism can be passed from mother to fetus during pregnancy
A. the ability to produce ATP via ATP synthase

Bacteria --> PM
Humans --> mito

B, although the chemical composition is similar, it's just enough different that some antibiotics can differentiate between the two.
Most bacterial cells and human cells are alike in:

A. the ability to produce ATP via ATP synthase
B. the chemical composition of their ribsomes
C. their enclose within cell walls
D. the shape of self-replicating structures that carry their DNA.
B. decrease, because movement of K+ into the mitochondrial compartments will disrupt proton movement into the intermembrane space

Too much positive in the interspace from K+, so H+ would not want to go into this area. Therefore, H+ would not go through ATP synthetase to form ATP in the matrix. Bummer.
The chemical valinomycin inserts into membranes and causes the movement of K+ in the mitochondria. If mitochondria are a treated with valinomycin, the rate of ATP synthesis in the mitochondria will most likely:

A. decrease, because the K+ will compete with protons at the active site on ATP synthase
B. decrease, because movement of K+ into the mitochondrial compartments will disrupt proton movement into the intermembrane space
C. increase, because the net positive charge i the mitochondria will cause increased movement of protons into the intermembrane space.
D. increase, because the additional positive charge will further activate ATP synthetase.
C. an increase in acetylcholine receptor sites on the motor end plate

This would ENHANCE transmission, and NOT interfere with it!
Which of the following changes would NOT interfere with the repeated transmission of an impulse at the vertebrate neuromuscular junction?

A. addition of a cholinesterase blocker
B. addition of a toxin that blocks the release of acetylcholine
C. an increase in acetylcholine receptor sites on the motor end plate
D. addition of substance that binds to acetylcholine receptor sites
D. bridges between act and myosin form, break, and re-form, leading to a shortening of muscle sarcomeres.

During contraction, neuronal impulses cause the release of calcium from the sarcoplasmic reticulum within muscle cells. Calcium binds troponin, making myosin active site to unveil on actin. Myosin binds to actin. ATP binds to myosin, causing it to detach fro actin and "recharge" (rebend) again. Myosin will keep binding to actin (in different places).
Which statement below most accurately describes the roles of the proteins actin and myosin during muscular contraction?

A. both actin and myosin shorten, causing the muscle tissue to which they are attached to contract.
B. both actin and myosin catalyze the reactions that result in muscle contractions
C. actin molecules are disassembled by myosin, leading to a shortening of muscles sarcomeres
D. bridges between act and myosin form, break, and re-form, leading to a shortening of muscle sarcomeres.
No, in most cases, they progressively differentiate to achieve their final specification.

Cells may induce neighboring cells to differentiate!
In development, is cell differentiation a "all or nothing" phenomenon?
D. LH

A very high increase of estrogen during follicle stimulation causes the LH surge, then estrogen decreases a little.
Which hormone is responsible for triggering ovulation?

A. progesterone
B. estrogen
C. HCG
D. LH
A. inadequate blood volume for effective filtration
Kidney failure during severe dehydration is most likely due to:

A. inadequate blood volume for effective filtration
B. inability to produce sufficient urine
C. buildup of salts in the distal tubules
D. increased body temperature
A. passive H2O diffusion along a concentration gradient

Note: At the venous end of capillaries, reabsorption occurs. At the arterial end of capillaries, filtration occurs. (pressure based)
The osmotic concentration of plasma proteins in the venous side of capillaries helps reduce the amount of interstitial fluid in tissues by inducing:

A. passive H2O diffusion along a concentration gradient
B. passive ion diffusion along an electrochemical gradient
C. facilitated ion transport along an electrochemical gradient
D. active H2O transport mediated by an ATP-department pump
A. net fluid flow in the direction of interstitial spaces will increase

Blood flow: A --> C --> V
Hydrostatic pressure outward into the interstitual fluid
Osmotic pressure inward into the vessels

Backing up V would indicate that MORE flow OUTWARD into the interstitial fluid
Capillaries in the kidney and elsewhere in the body maintain fluid homeostasis by balancing hydrostatic and osmotic pressures. Which of the following is the initial effect of a blood clot forming on the venous side of a capillary bed?

A. net fluid flow in the direction of interstitial spaces will increase
B. net fluid flow in the direction of interstitial spaces will decrease
C. capillary osmotic pressure will increase
D. capillary osmotic pressure will decrease
B. ribosomes

Uracil is a component of RNA. You'd expect to it to be on ribosomes because it contains rRNA and proteins
Radioactively labeled uracil is added to a culture of actively dividing mammalian cells. In which of the following cell structures will the uracil be incorporated?

A. chromosomes
B. ribosomes
C. lysosomes
D. nuclear membrane
A. G1

G0 and G1 are nondividing cells that are metabolically active, but not replicating its DNA. Be careful, don't think dividing means DNA synthesis (idk that's what you did and you were wrong and bad for that. Easy Q!)
A stable, differentiated cell that will NOT divide again during its lifetime would most likely be found in which of the following stages of the cell cycle?

A. G1
B. G2
C. M
D. S
In minute blood vessels, it contributes to constriction.

However, in skeletal muscles, it contributes to dilation of blood vessels (increase CO and BP).
How does norepinephrine/epinephrine affect blood vessels?
C. parasympathetic motor

From the vagus nerve (CN X)

Sensory fibers carry information fro the heart to the CNS.
Which autonomic nerve fibers directly innervate the heart to cause it to slow down?

A. sympathetic motor
B. sympathetic sensory
C. parasympathetic motor
D. parasympathetic sensory
More urine output means less ADH.
Less ADH means collecting duct is less permeable, because water is not being reabsorbed.

Rather, you'd expect increased glomerular filtration rate.
Is the collecting duct more/less permeable to water when urine output is increased?
Increased by 1/3

Solving for CO
CO = (P) ÷ (VR)
CO = (2P) ÷ (1.5VR)
CO = 4/3 (P÷VR)

Or, 3/3 + 1/3. Increased by 1/3.
Given: P = (CO) x (VR)
CO = cardiac output, flow rate of blood from the heart
VR = vascular resistance to the flow of blood

Question: If blood pressure double and the resistance of blood flow increased by 50%, the amount of blood pumped by the heart would be increased/decreased by what ratio?
C. absorption of water
What process takes place in the colon?
A. digestion
B. absorption of nutrients
C. absorption of water
D. secretion of digestive enzymes
B. the peritoneal cavity
An ulcer that penetrated the wall of the intestine would allow the contents of the GI tract to enter:

A. the perineum
B. the peritoneal cavity
C. the pleural cavity
D. the lumen of the intestine
when one species adapts to several different environments.
Per Darwin, what is adaption radiation?
nursing cells
FSH
Spermatogenesis
Which hormone is directly related to stimulation of Sertoli cells? What do these cells directly promote?
Phagocytes engulf their prey by changing their shape to engulf large extracellular particles. Cell shape is determined by cytoskeleton, which is predominantly MT's. If colchicine inhibits MT organizations, phagocytes can not disassemble and reorganize; THUS, no phagocytosis.
Colchicine is an inhibitor of MT organization. How is that problematic for phagocytes?
A. dilation of capillary beds in the skin

to compensate for increased body temperature, capillaries dilate to dissipate hear through the skin.
Fever in septic shock lead to which of the following compensation mechanisms?

A. dilation of capillary beds in the skin
B. increased skeletal muscle activity
C. decreased respiration rate
D. decreased fluid loss
D. proteolytic enzymes

I.e. trypsin, chymotrypsin, and carboxypeptidase
The pancreas produces which of the following substances for the digestive system?

A. bile salts
B. emulsifiers
C. gastric juices
D. proteolytic enzymes
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