BIOL 2160 Graded Quiz 2: Crousillac

T/F: Primary active transport involves one substance moving down its concentration gradient to move another substance against its electrochemical gradient

true

T/F: Endocytosis is the inward movement of a large particle into the cell by means of vesicular transport

true

The transport of amino acids into the cell results when sodium ions move down their electrical gradient and cause amino acids to move into the cell against their electrochemical gradient. This is an example of

secondary active transport

The lipid bilayer portion of the plasma membrane is highly permeable to

nonpolar molecules

If the inside of a cell were to become more positively charged than the outside what would happen to the electrochemical gradient?

it would be in the same direction but larger in magnitude

Which of the following is usually at a higher concentration in the cytosol compared to the extracellular fluid?

potassium

Membrane transport is classified as active when it

requires input of energy

A function of Na+/K+ ATPase is to

maintain low intracellular concentration of Na+

Which of the following CANNOT be considered an active process?

osmosis

Which form of endocytosis is non-specific and used to move fluid into a cell?

pinocytosis

If there is an accumulation of positive charges outside the cell membrane, and fewer positive charges inside, what would you expect to happen to the positive charges if facilitated diffusion occurs?

positive charges will diffuse into the cell

T/F: The term, "Leak channels" implies there is a slow movement of ions through a channel similar to water dripping out of a leaky faucet

true

The solution in the right arm of the tube in the image contains: 5 mM sodium and 150 mM potassium. The left arm of the tube contains 130 mM sodium and 5 mM potassium. If the membrane were equally permeable to both potassium and sodium, which ion would have the greater diffusion rate?

potassium

Nonpolar hydrophobic molecules such as steroids move across cell membranes by

simple diffusion

If the solute concentration is greater inside of the cell than outside the cell, water will move by osmosis __________

into the cell

An extracellular messenger has an effect only on a specific target cell because

the target cell has a receptor for the messenger

Which of the following is the correct order of events for cell to cell communication?

1. binding of messenger to receptor

2. response of cell

3. release of messenger into extracellular space

4. signal transduction

3, 1, 4, 2

What is the functional significance of gap junctions?

they allow for direct communication between cytoplasm of adjacent cells

_______ are extracellular chemical messengers that are carried by the blood to distant target cells

hormones

Which type of signaling involves chemical messengers working on other cells in the immediate neighborhood of a secretory cell?

paracrine

The strength with which a messenger binds to a receptor is called

affinity

T/F: The receptors for water-soluble extracellular messengers are present inside a target cell

false

Receptors for lipid-soluble chemical messengers are primarily located

inside the cell

What are the most significant factors that determine cellular localization of a receptor?

the solubility of the ligand

The decreased number of hormone receptors in the cells in response to long-term high concentrations of the extracellular messengers in blood is called:

receptor down-regulation

In signal transduction pathways, water-soluble hormones often ___________.

bind to a receptor in the plasma membrane that activates a G protein

Why is cAMP referred to as a second messenger?

Because the first messenger, the water soluble hormone, was not able to enter the cell

A signal transduction pathway is started in the cell, and it ends with phosphorylation of an effector protein. Which of the following types of proteins must have been involved in this pathway?

a kinase

G-proteins involved in signaling by plasma membrane receptors are activated by:

the replacement of GDP with GTP

A G-protein is:

OFF when bound to GDP

ON when bound to GTP