MCAT Practice Biology Exam
2026/2027 Updated Verified
Questions and Solutions A+
Pass Guaranteed
Why are triacylglycerols used in the human body for energy
storage?
A) They are highly hydrated, and therefore can store lots of
energy.
B) They always have short fatty acid chains, for easy access by
metabolic enzymes.
C) The carbon atoms of the fatty acid chains are highly
reduced, and therefore yield more energy upon oxidation.
D) Polysaccharides, which would actually be a better energy
storage form, would dissolve in the body.
- ANS - C
Triacylglycerols are highly hydrophobic and therefore not
highly hydrated (which would add extra weight from the water
of hydration, taking away from the energy density of these
molecules), eliminating choice (A). The fatty acid chains
, produce twice as much energy as polysaccharides during
oxidation because they are highly reduced. The fatty acid
chains vary in length and saturation.
Action potentials travel down neural axons that resist the flow
of current. In considering a theoretical circuit, one normally
assumes that the wire has no resistivity. In the real world,
however, wire resistivity is an important consideration. Which
of the following is a way to increase resistance?
A) Lengthen the wire
B) Widen the wire
C) Lower the temperature
D) Change from tungsten to copper wire
- ANS - A
This question tests your knowledge of resistance in wires. An
electrical wire's resistance is directly proportional to its length
and inversely proportional to its cross-sectional area. Think of
it as gravel in a pipe—the wider the pipe and the shorter the
pipe, the easier it is for water to go through it.
B is incorrect because when a wire's cross-sectional area is
increased, its resistivity is decreased.
2026/2027 Updated Verified
Questions and Solutions A+
Pass Guaranteed
Why are triacylglycerols used in the human body for energy
storage?
A) They are highly hydrated, and therefore can store lots of
energy.
B) They always have short fatty acid chains, for easy access by
metabolic enzymes.
C) The carbon atoms of the fatty acid chains are highly
reduced, and therefore yield more energy upon oxidation.
D) Polysaccharides, which would actually be a better energy
storage form, would dissolve in the body.
- ANS - C
Triacylglycerols are highly hydrophobic and therefore not
highly hydrated (which would add extra weight from the water
of hydration, taking away from the energy density of these
molecules), eliminating choice (A). The fatty acid chains
, produce twice as much energy as polysaccharides during
oxidation because they are highly reduced. The fatty acid
chains vary in length and saturation.
Action potentials travel down neural axons that resist the flow
of current. In considering a theoretical circuit, one normally
assumes that the wire has no resistivity. In the real world,
however, wire resistivity is an important consideration. Which
of the following is a way to increase resistance?
A) Lengthen the wire
B) Widen the wire
C) Lower the temperature
D) Change from tungsten to copper wire
- ANS - A
This question tests your knowledge of resistance in wires. An
electrical wire's resistance is directly proportional to its length
and inversely proportional to its cross-sectional area. Think of
it as gravel in a pipe—the wider the pipe and the shorter the
pipe, the easier it is for water to go through it.
B is incorrect because when a wire's cross-sectional area is
increased, its resistivity is decreased.
