284 ❯ STEP 5. Build Your Test-Taking Confidence
- Homeostasis, or the maintenance of a steady-state
environment, is a characteristic of all living organ-
isms. (maximum 4 points for entire question)
A. Blood glucose levels (maximum 1 1/2 points)- Mentioning insulin/glucagon is released
from the pancreas. (1/2 point) - Mentioning insulin stimulates uptake of
glucose from the blood to the liver. (1/2
point) - Mentioning insulin causes glucose to be
stored as glycogen in the liver. (1/2 point) - Mentioning insulin signals body cells to
take up glucose for energy use. (1/2
point) - Mentioning glucagon stimulates the liver
to release glucose into the bloodstream.
(1/2 point)
B. Body temperature (maximum 1 1/2 points) - Describing how body insulation (hair, fat,
feathers) reduces heat loss. (1/2 point) - Mentioning that vasodilation results in
increased blood flow and increased heat
loss. (1/2 point) - Mentioning that vasoconstriction results
in decreased blood flow and decreased
heat loss. (1/2 point) - Mentioning that sweating results in evap-
orative cooling. (1/2 point) - Mentioning that shivering generates
energy. (1/2 point)
C. Blood calcium levels (maximum 1 1/2
points) - Mentioning that parathyroid hormone
(PTH) is released by the parathyroid
gland. (1/2 point) - Mentioning that PTH increases the
amount of calcium in circulation. (1/2
point) - Mentioning that PTH causes release of
calcium from bones. (1/2 point) - Mentioning that PTH leads to increased
absorption of calcium by the intestines
and kidneys. (1/2 point) - Mentioning that calcitonin is released by
the thyroid gland. (1/2 point) - Mentioning that calcitonin decreases the
amount of calcium in circulation. (1/2
point)- Mentioning that calcitonin promotes
reabsorption of calcium by the bones.
(1/2 point) - Mentioning that calcitonin leads to
decreased absorption of calcium by the
kidneys and intestines. (1/2 point)
- Mentioning that calcitonin promotes
- Mentioning insulin/glucagon is released
- Membranes are vital to the transport of sub-
stances into and out of cells. (maximum 4 points
for entire question)
A. Active transport (maximum 1 1/2 points)
- Describing active transport as the move-
ment of a particle against its concentra-
tion gradient (from low concentration to
high concentration), which requires input
of energy. (1/2 point) - Mentioning that it allows the cell to con-
centrate substances within the cell mem-
brane. (1/2 point) - Mentioning that it is performed by pro-
tein pumps in the membrane. (1/2 point) - Possible example: sodium-potassium pump
moves potassium into the cell and sodium
out of the cell. (1/2 point)
B. Endocytosis and exocytosis (maximum
2 points) - Mentioning that endocytosis brings a sub-
stance into a cell by enclosing it within a
membrane-created vesicle. (1/2 point) - Mentioning that the vesicle then fuses
with lysosome (contains hydrolytic
enzymes). (1/2 point) - Possible example: phagocytes (white
blood cells) of the immune system engulf
foreign invaders. (1/2 point) - Mentioning that receptor-mediated endo-
cytosis uses proteins embedded in a mem-
brane that contains receptors for specific
molecules. (1/2 point) - Mentioning that exocytosis expels waste
substances for export by enclosing these
substances in a vesicle that fuses with the
membrane. (1/2 point) - Possible examples: cells expelling waste or
a pancreatic cell exporting insulin protein
into the bloodstream. (1/2 point)
C. Facilitated diffusion (maximum 1 1/2 points) - Describing facilitated diffusion as the
diffusion of particles with the assistance