Homework Answers
When a molecule moves from an area of low concentration into an area of HIGH concentration, _____ transport is occuring.
active
When a molecule moves from an area of HIGH concentration into an area of low concentration, _____ transport is occurring. passive
Which transport process is used to move water across the plasma membrane?
Osmosis
Which transport process is used to move large polar molecules across the plasma membrane?
Faciltated diffusion
Which transport process is used to move nonpolar gases straight through the plasma membrane?
Simple diffusion
Which transport process is used to move hydrophobic molecules straight through the plasma membrane? Simple diffusion
Which transport process is used to move ions (a.k.a. charged particles) across the plasma membrane?
(not primary active transport)
The image shows a beaker with two NaCl solutions (5% NaCl and 10% NaCl) separated by a semipermeable membrane. In which direction would water move?
Water would move out of the 5% solution and into the 10% solution.
Which transport process uses the energy of one molecule moving DOWN its concentration gradient to power the movement of another molecule UP its concentration gradient?
Secondary active transport
Click on part of the plasma membrane that is considered hydrophobic.
Click on part of the plasma membrane that is considered hydrophilic.
Which part of a phospholipid (in the plasma membrane) is directly touching the water outside of a cell?
The head of the phospholipid
When _____ transport occurs, energy is required.
active
How would estrogen, a hydrophobic hormone, cross the plasma membrane of a cell?
It would use simple diffusion.
How would lysine, a positively-charged amino acid, cross the plasma membrane of a cell?
It would use facilitated diffusion.
How would serine, a hydrophilic amino acid, cross the plasma membrane of a cell?
It would use facilitated diffusion.
How would nicotine, a polar molecule (found in tobacco), cross the plasma membrane of a cell?
It would use facilitated diffusion.
How would gabapentin, a nonpolar pain medication, cross the plasma membrane of a cell?
It would use simple diffusion.
Which part of the plasma membrane is used to move charged ions (like Na+ or Cl-) across the plasma membrane?
Its transport proteins
When _____ transport occurs, energy is NOT required
passive
Which part of the plasma membrane is most responsible for creating a hydrophobic barrier around a cell?
The tails of its phospholipids
Which part of the plasma membrane is used to move polar molecules (like glucose) across the plasma membrane? Its transport proteins
When a molecule moves DOWN (a.k.a. with) its concentration gradient, _____ transport is occuring
passive
When a molecule moves UP (a.k.a. against) its concentration gradient, _____ transport is occurring
active
The image shows a beaker with two NaCl solutions (20% NaCl and 5% NaCl) separated by a semipermeable membrane. In which direction would NaCl move?
NaCl would move out of the solution on the left and into the solution on the right.
Two kinds of energy can be used in active transport
- ATP
- A concentration gradient
ATP
Stores energy in its chemical bonds
Concentration Gradient
As one molecule moves down, that movements pushes a different molecule up its own gradient.
Sodium-potassium pump
Sodium is pumped out of the cell, even though a lot is already outside Potassium is pumped into the cell, even though a lot is already inside
Secondary Active Transport
movement down one concentration gradient is used to power movement up a different concentration gradient