biology midterm

Many viruses enter host cells through receptor-mediated endocytosis. What is an advantage of this
entry strategy?

•  

  The virus directly enters the cytoplasm of the cell.

•  

  The virus is protected from recognition by white blood cells.

•  

  The virus only enters its target host cell type.

•  

  The virus can directly inject its genome into the cell’s nucleus.

Active transport must function continuously because __________.

• Active transport must function continuously because __________.

•  

  plasma membranes wear out

•  

  not all membranes are amphiphilic

•  

  facilitated transport opposes active transport

In which situation would passive transport not use a transport protein for entry into a cell?

•  

  an ion flowing into a nerve cell to create an electrical potential

•  

  oxygen moving into a cell after oxygen deprivation

•  

  glucose being absorbed from the blood

•  

  water flowing into a hypertonic environment

Imagine a cell can perform exocytosis, but only minimal endocytosis. What would happen to the cell?

•  

  The cell would lyse.

•  

  The cell would secrete all its intracellular proteins.

•  

  The plasma membrane would increase in size over time.

•  

  The cell would stop expressing integral receptor proteins in its plasma membrane.

Which plasma membrane component can be either found on its surface or embedded in the membrane
structure?

•  

  carbohydrate

• protein

• phospholipid

• cholesterol

What is the primary function of carbohydrates attached to the exterior of cell membranes?

•  

  channels through membrane

•  

  flexibility of the membrane

•  

  strengthening the membrane

•  

  identification of the cell

In what important way does receptor-mediated endocytosis differ from phagocytosis?

•  

  It transports only small amounts of fluid.

•  

  It brings in only a specifically targeted substance.

•  

  It does not involve the pinching off of membrane.

•  

  It brings substances into the cell, while phagocytosis removes substances.

How does the sodium-potassium pump make the interior of the cell negatively charged?

•  

  by pulling in anions

•  

  by expelling anions

•  

  by expelling more cations than are taken in

•  

  by taking in and expelling an equal number of cations

Cells have only a small amount of ATP on hand at any given time. Why is this true?

•  

  it's not true. ATP is stored by cells for easy access to energy when needed.

•  

  Cells use ADP, not ATP for cell energy.

•  

  it's not true. Cells don't use ATP.

•  

  ATP is not efficient for long-term storage of energy

Which of the following organelles relies on exocytosis to complete its function?

•  

  mitochondria

•  

  endoplasmic reticulum

•  

  vacuole

• golgi apparatus