Passive and Active Transport

Small, nonpolar, hydrophobic molecules such as fatty acids, oxygen and carbon dioxide.....

• easily pass through the membrane's bilayer

• very slowly diffuse through the bilayer

• require transport proteins

• enter through endocytosis

Membrane phospholipids

• have hydrophobic heads that face the center of the membrane and are shielded from water

• have hydrophilic tails that face outward

• remain fluid because they are tightly packed

• none of these

Plasma membranes are selectively permeable. This means

• anything can pass in and out

• the membrane regulates the passage of the material in and out of the cell

• glucose cannot enter the cell

• cholesterol cannot enter

Which is NOT a function of the membrane?

• it forms a selective barrier

• it has receptors for chemical messages

• it is the control center of the cell

• it is involved in self recognition

The cholesterol associated with membranes

• is attached to proteins and extends into the environment surrounding the cell

• helps stabilize the membrane at body temperature

• is an abnormality resulting from a diet high in cholesterol

• both a and c

What is the "big idea" of the Fluid Mosaic Model of plasma membranes?

• the plasma membrane creates a specialized FLUID that looks like a MOSAIC.

• the plasma membrane is a MOSAIC.

• the fluid mosaic model is NOT related to the plasma membrane.

• a plasma membrane is a MOSAIC of components that move FREELY and FLUIDLY.

What is the diffusion of water only across a cell or semi-permeable membrane?

• Osmosis
• Diffusion
• Active Transport
• Passive Transport

What type of cellular transport uses energy?

• Passive Transport
• Active Transport

In which case would a cell most likely shrink?

• when placed in a solution containing a high salt concentration
• when placed in a isotonic solution
• when placed in a solution containing a low pH
• when placed in a solution containing distilled water

Tags

NGSS.HS-LS1-3

Active transport requires energy because...

• The cell is moving something against a concentration gradient
• The cell is moving something with a concentration gradient