USABO Open Complete Exam Study
Questions with Expert Graded A+
Answers | Latest Edition
1. Five sensory receptor categories - ANSWER Mechanoreceptors,
chemoreceptors, electromagnetic receptors, thermoreceptors, and
nociceptors (pain receptors).
2. Four steps of sensory pathways - ANSWER Reception → transduction →
transmission → perception.
3. Hair cell mechanism - ANSWER Bending in one direction depolarizes the
cell; bending the opposite direction hyperpolarizes it.
4. Auditory ossicle sequence - ANSWER Malleus → incus → stapes
(transmits vibration to the oval window).
5. Calcium regulation of muscle contraction - ANSWER Ca²⁺ binds troponin,
moving tropomyosin to expose myosin-binding sites on actin.
6. Neuromuscular junction excitation sequence - ANSWER ACh release →
muscle depolarization → T tubule action potential → Ca²⁺ release from
sarcoplasmic reticulum.
7. Creatine phosphate function - ANSWER Regenerates ATP from ADP for
approximately 15 seconds during initial sustained muscle activity.
,8. Recruitment vs. Summation - ANSWER Recruitment activates more motor
units; summation increases stimulus frequency to increase force.
9. Distinguishing features of cardiac muscle - ANSWER Striated, involuntary,
connected by intercalated disks, self-depolarizing pacemakers, long
refractory period.
10.Smooth muscle Ca²⁺ mechanism - ANSWER Lacks troponin and T tubules;
Ca²⁺ binds calmodulin to trigger contraction.
11.Three animal skeleton types - ANSWER Hydrostatic (pressurized fluid),
Exoskeleton (external cuticle/shell; requires molting), Endoskeleton (internal
support; grows continuously).
12.Joint types and movements - ANSWER Ball-and-socket (multi-plane
rotation), hinge (single-plane flexion/extension), pivot (axis rotation).
13.Which statement is true about enzymes? Enzymes
A. Are made up of a base containing nitrogen, phosphate, and ribose.
B. Have activity that is independent of temperature and pH.
C. Lose some or all of their normal activity when their 3-D structure is
disrupted.
D. Provide the activation energy needed to activate a reaction.
E. Work once only and then are destroyed. - ANSWER C. Lose some or
all of their normal activity when their 3-D structure is disrupted.
14.Pitch vs. volume detection in hearing - ANSWER Volume equals wave
amplitude; pitch depends on which region of the basilar membrane vibrates.
, 15.Basilar membrane tonotopic mapping - ANSWER High frequencies vibrate
the stiff base; low frequencies vibrate the wide, flexible apex.
16.Utricle & saccule function - ANSWER Detect linear position relative to
gravity and linear acceleration using calcium carbonate otoliths.
17.Semicircular canals function - ANSWER Detect rotational and angular
acceleration of the head using hair cells and cupulae.
18.Phototransduction in the dark - ANSWER High cGMP keeps Na⁺ channels
open, depolarizing photoreceptors and continuously releasing glutamate.
19.Phototransduction in the light - ANSWER Light activates transducin and
PDE, breaking down cGMP, closing Na⁺ channels, and hyperpolarizing
photoreceptors.
20.Rods vs. Cones - ANSWER Rods: high sensitivity, night vision, no color.
Cones: lower sensitivity, color vision, fovea-concentrated.
21.Lateral inhibition in the retina - ANSWER Horizontal cells inhibit
neighboring pathways to sharpen visual contrast and edge perception.
22.Optic chiasm processing rule - ANSWER Visual information crosses so
each hemisphere processes the opposite visual field.
23.Taste receptor mechanisms by flavor - ANSWER Sweet, umami, bitter use
GPCRs; sour and salty use direct ion channels.
Questions with Expert Graded A+
Answers | Latest Edition
1. Five sensory receptor categories - ANSWER Mechanoreceptors,
chemoreceptors, electromagnetic receptors, thermoreceptors, and
nociceptors (pain receptors).
2. Four steps of sensory pathways - ANSWER Reception → transduction →
transmission → perception.
3. Hair cell mechanism - ANSWER Bending in one direction depolarizes the
cell; bending the opposite direction hyperpolarizes it.
4. Auditory ossicle sequence - ANSWER Malleus → incus → stapes
(transmits vibration to the oval window).
5. Calcium regulation of muscle contraction - ANSWER Ca²⁺ binds troponin,
moving tropomyosin to expose myosin-binding sites on actin.
6. Neuromuscular junction excitation sequence - ANSWER ACh release →
muscle depolarization → T tubule action potential → Ca²⁺ release from
sarcoplasmic reticulum.
7. Creatine phosphate function - ANSWER Regenerates ATP from ADP for
approximately 15 seconds during initial sustained muscle activity.
,8. Recruitment vs. Summation - ANSWER Recruitment activates more motor
units; summation increases stimulus frequency to increase force.
9. Distinguishing features of cardiac muscle - ANSWER Striated, involuntary,
connected by intercalated disks, self-depolarizing pacemakers, long
refractory period.
10.Smooth muscle Ca²⁺ mechanism - ANSWER Lacks troponin and T tubules;
Ca²⁺ binds calmodulin to trigger contraction.
11.Three animal skeleton types - ANSWER Hydrostatic (pressurized fluid),
Exoskeleton (external cuticle/shell; requires molting), Endoskeleton (internal
support; grows continuously).
12.Joint types and movements - ANSWER Ball-and-socket (multi-plane
rotation), hinge (single-plane flexion/extension), pivot (axis rotation).
13.Which statement is true about enzymes? Enzymes
A. Are made up of a base containing nitrogen, phosphate, and ribose.
B. Have activity that is independent of temperature and pH.
C. Lose some or all of their normal activity when their 3-D structure is
disrupted.
D. Provide the activation energy needed to activate a reaction.
E. Work once only and then are destroyed. - ANSWER C. Lose some or
all of their normal activity when their 3-D structure is disrupted.
14.Pitch vs. volume detection in hearing - ANSWER Volume equals wave
amplitude; pitch depends on which region of the basilar membrane vibrates.
, 15.Basilar membrane tonotopic mapping - ANSWER High frequencies vibrate
the stiff base; low frequencies vibrate the wide, flexible apex.
16.Utricle & saccule function - ANSWER Detect linear position relative to
gravity and linear acceleration using calcium carbonate otoliths.
17.Semicircular canals function - ANSWER Detect rotational and angular
acceleration of the head using hair cells and cupulae.
18.Phototransduction in the dark - ANSWER High cGMP keeps Na⁺ channels
open, depolarizing photoreceptors and continuously releasing glutamate.
19.Phototransduction in the light - ANSWER Light activates transducin and
PDE, breaking down cGMP, closing Na⁺ channels, and hyperpolarizing
photoreceptors.
20.Rods vs. Cones - ANSWER Rods: high sensitivity, night vision, no color.
Cones: lower sensitivity, color vision, fovea-concentrated.
21.Lateral inhibition in the retina - ANSWER Horizontal cells inhibit
neighboring pathways to sharpen visual contrast and edge perception.
22.Optic chiasm processing rule - ANSWER Visual information crosses so
each hemisphere processes the opposite visual field.
23.Taste receptor mechanisms by flavor - ANSWER Sweet, umami, bitter use
GPCRs; sour and salty use direct ion channels.
