BIOL 171 Chapter 5 Mastering Biology

endocytosis

-forms vesicles from inward folding of the plasma membrane -decreases the surface area of the plasma membrane

exocytosis

-requires fusion of vesicles with the plasma membrane -secretes large molecules out of the cell -increases the surface area of the plasma membrane

both

-transported substances never physically cross the plasma membrane -requires cellular energy

Which of these is a single molecule?

A

Which of these is a receptor molecule?

B

A semipermeable membrane is placed between the following solutions. Which solution will decrease in volume? Solution A: 1.4% (m/v) starch Solution B: 7.62% (m/v) starch

Solution A

A semipermeable membrane is placed between the following solutions. Which solution will increase in volume? Solution C: 9% (m/v) NaCl Solution D: 12.4% (m/v) NaCl

Solution B

Which of the following statements correctly describe(s) the driving forces for diffusion of Na+ and K+ ions through their respective channels? Select all that apply.

The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane. The diffusion of K+ ions out of the cell is impeded by the electrical gradient across the plasma membrane. The electrochemical gradient is larger for Na+ than for K+.

Identify Structure A.

glycoprotein

A signal molecule is also known as a (n) _____.

ligand

Facilitated diffusion via channels and carrier proteins

only channels: allow water molecules and small ions to flow quickly across the membrane, provide a continuous path across the membrane only carriers: undergo a change in shape to transport solutes across the membrane, transport primarily small polar organic molecules both: provide a hydrophilic path across the membrane, transport solutes down a concentration or electrochemical gradient, are integral membrane proteins

Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism? Select all that apply. sucrose oxygen proteins water lipids ions carbon dioxide

oxygen water lipids carbon dioxide

Identify Structure D.

phospholipid bilayer of membrane

A signal transduction pathway is initiated when a _____ binds to a receptor.

signal molecule

What is the function of Structure E?

stabilization of the phospholipids

Which of these is the second of the three stages of cell signaling?

transduction

isotonic

water flows into the cell to the same extent that it flows out of the cell

hypotonic

water flows into the cell, which causes it to swell and potentially burst

hypertonic

water flows out of the cell, which causes it to shrink