1. Question : Current research supports the belief that after heart muscle injury, the damage:
Student Answer:
Remains indefinitely because cardiac cells do not reproduce
Is repaired by newly matured cardiomyocytes
Gradually decreases in size as mitotic cell division occurs
Is replaced by hypertrophy of remaining cells
Instructor Explanation: The recent discovery that cardiac stem cells exist in the heart and
differentiate into various cardiac cell lineages has profoundly changed the understanding of
myocardial biology; it is now believed that bone marrow–derived cardiac stem cells or
progenitor cells that have the ability to mature into cardiomyocytes may populate the heart after
injury. The other options do not accurately describe the process that is believed to occur to
address cardiac muscle damage.
2. Question : The cellular uptake of the nutrient cholesterol depends on which process?
Student Answer:
Receptormediated exocytosis
Antiport system
Receptormediated endocytosis
Passive transport
, Instructor Explanation: The cellular uptake of nutrients, such as cholesterol, for example,
depends on receptormediated
endocytosis. Nutrients
are not transported via the other options.
3. Question : Which statement is true about phagocytosis?
Student Answer:
Phagocytosis is an example of exocytosis.
Phagocytosis is dependent on small vesicles.
Phagocytosis involves the ingestion of bacteria.
Phagocytosis focuses on solute molecules.
Instructor Explanation: In phagocytosis, the large molecular substances are engulfed by the
plasma membrane and enter the cell so that they can be
isolated and destroyed by lysosomal enzymes. Two types of endocytosis are designated, based on
the size of the vesicle
formed. Pinocytosis (cell drinking) involves the ingestion of fluids and solute molecules through
the formation of small
vesicles, and phagocytosis (cell eating) involves the ingestion of large particles, such as
bacteria, through formation of large
vesicles (also called vacuoles). Phagocytosis in an example of endocytosis, not exocytosis.
4. Question : Lead poisoning affects the nervous system by: