Ch. 7: Membrane Structure & Function Dynamic

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

What plant cells would exhibit the most turgor pressure?

A cell placed in a hypotonic solution

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

A large polar molecule

What substance would be most likely to pass through the plasma membrane without the help of a transport protein?

A nonpolar molecule, such as a hydrocarbon

What is a correct difference between active transport and facilitated diffusion?

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

How does cholesterol affect membrane fluidity?

At body temperature, it makes the membrane less fluid

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

Why is energy required for active transport?

Because it moves solutes against their concentration gradient

If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells?

Both cells would lose water; the red blood cell would shrivel and the plant plasma membrane would pull away from the cell wall.

What molecule is most likely to passively diffuse across the plasma membrane?

Carbon dioxide

What function do carbohydrates fulfill in the plasma membrane?

Cell-to-cell recognition

In facilitated diffusion, _____ proteins provide openings in the plasma membrane for substances to flow through without changing structure, and _____ proteins allow passage of substances through the plasma membrane after undergoing a subtle change in shape

Channel; carrier

A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via which process?

Endocytosis

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

Exocytosis and smooth and rough ER

What describes some aspect of facilitated diffusion?

Facilitated diffusion of solutes may occur through channel or transport proteins in the membrane.

What about diffusion is true?

It is a passive process

What 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

What about passive transport is correct?

Passive transport permits the solute to move in either direction, but the net movement of the population of solute molecules occurs down the concentration gradient of the molecule.

What molecules are most abundant in the plasma membrane?

Phospholipids

What about the role of phospholipids in the structure and function of biological membrane is correct?

Phospholipids form a selectively permeable structure

What cell structure exhibits selective permeability between a cell and its external environment?

Plasma membrane

What 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.

Red blood cells contain approximately a 2% concentration of solutes. A red blood cell is placed into a solution that contains a 4% concentration of solutes to which the cell is not permeable. What will happen to the red blood cell?

The cell will decrease in size as water flows out of it.

The plasma membrane exhibits selective permeability. This means that

The plasma membrane allows some substances to flow through it more easily than others

A cell is placed into a solution and the cell shrinks. What is true regarding the solution?

The solution is hypertonic

What is correct about peripheral proteins?

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

What is correct about integral proteins?

These proteins exhibit both hydrophilic and hydrophobic properties.

The sodium-potassium pump

Transports sodium ions out of the cell and transports potassium ions into the cell