ch 7

The internal solute concentration of a plant cell is about 0.8M. To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution?

1.0M

Which of the following substances would be most likely to pass through the plasma membrane without the help of a transport protein?

A nonpolar molecule, such as a hydrocarbon

How does cholesterol affect membrane fluidity?

At body temperature, it makes the membrane less fluid.

Why is energy required for active transport?

Because it moves solutes against their concentration gradient

which of the following is correct regarding integral proteins

these proteins exhibit both hydrophlilic and hydrophobic properties

Cells A and B are the same size, shape, and temperature, but cell A is metabolically less active than cell B; cell B is actively converting oxygen to water in cellular respiration. Oxygen will diffuse more rapidly into cell __________ because __________.

B; the diffusion gradient in cell B is steeper

Which of the following statements about diffusion is true?

It is a passive process.

Which of the following plant cells would exhibit the most turgor pressure?

A cell placed in a hypotonic solution

Which of the following would be least likely to diffuse through a plasma membrane without the help of a transport protein?

A large polar molecule

Which of the following is a correct difference between active transport and facilitated diffusion?

Active transport requires energy from ATP, and facilitated diffusion does not.

Which of the following molecules is most likely to passively diffuse across the plasma membrane?

Carbon dioxide

A cell is placed into a solution and the cell shrinks. Which of the following is true regarding the solution?

The solution is hypertonic.

Which of the following is correct regarding peripheral proteins?

These proteins are found only on the surface of the plasma membrane.

Which of the following is correct regarding integral proteins?

These proteins exhibit both hydrophilic and hydrophobic properties.

energy from ATP is used to move sodium ions out of the cell

and potassium ions in

the sodium potassium pump moves ions against their concentration gradient

from where they are less concentrated to where they are more concentrated. this requires energy from the cell known as active transport.

which of the following statements concerning carbohydrates associated with the plasma membrane is correct

membrane carbohydrates function primarily in cell cell recognition

All cells have voltages across their membranes. This voltage is called a(n) __________ and is often maintained by __________.

membrane potential; electrogenic pumps

Which of the following processes and organelle(s) accounts for the replacement of lipids and proteins lost from the plasma membrane?

Exocytosis and smooth and rough ER

Which of the following structural arrangements of the components in biological membranes facilitates the cell membrane's property of selective permeability?

Proteins embedded in two layers of phospholipids

How does the "fluid mosaic model" describe the structure of the plasma membrane?

Proteins in the membrane contribute to the mosaic quality of the membrane while the lateral and rotational movements of phospholipids contribute to its fluidity.

What function do carbohydrates fulfill in the plasma membrane?

Cell-to-cell recognition