4 Biology

The diagram models the time-lapse movement of particles across a cell membrane. The particles have characteristics that allow them to pass freely across the membrane.

-the particles crossing the membrane could be water (H20) or oxygen (O2) -the movement across the membrane does not require added energy -the particles crossing the membrane do not have a charge

What does facilitated diffusion across a cell membrane require?

C

The diagram shows a model of a biological membrane. What do labels I, II and III illustrate?

C 111Hydrophilic phosphate head 11Intergal protein 1Glycoprotein

Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?

CO2

Which component is the peripheral protein?

D

Which component is cholesterol?

E

Which statements are characteristics of diffusion through membranes? I. Polysaccharides can be transported. II. It can be facilitated by special channels. III. It is affected by concentration gradients.

II and III only

Which of the following statements is correct about diffusion?

It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

What do diffusion and osmosis have in common?

They are passive transport mechanisms

According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?

They can move laterally along the plane of the membrane.

Which means of particle transport requires input of energy from the cell?

active transport

Diffusion is the movement of molecules from

an area of high concentration to an area of low concentration.

A protein that spans the phospholipid bilayer is

an integral protein.

I am doing an experiment on osmosis. I take some dialysis tubing (a semi-permeable membrane) and fill it with a 50% sugar solution. Sugar molecules are very big and cannot pass through the membrane. If I want to make the cell gain weight, which beaker should I place it into?

beaker of water

The presence of cholesterol in the plasma membranes of some animals

enables the membrane to stay fluid more easily when cell temperature drops.

Which cell process is represented by the diagram below?

endocytosis

Active transport 'is a way for molecules to move across the plasma membrane. When active transport is used to move molecules, what is required?

energy that the cell provides

Diffusion occurs because

molecules constantly move and collide with each other.

When the concentration of molecules on both sides of a membrane is the same, the molecules will

move across the membrane in both directions.

The diffusion of water across a selectively permeable membrane is called

osmosis.

An organism with a cell wall would most likely be unable to take in materials through

phagocytosis

Which of the following types of molecules are the major structural components of the cell membrane?

phospholipids and proteins

The cell membrane contains channels and pumps that help move materials from one side to the other. What are these channels and pumps made of?

proteins

Which of the following is a function of the cell membrane?

regulates which materials enter and leave the cell

What kinds of molecules pass through a cell membrane most easily?

small and hydrophobic

Which structural feature of the cell membrane allows molecules such as oxygen and carbon dioxide to diffuse into and out of the cell?

the cell membrane is made up of two layers of phospholipids

A red blood cell is placed into an aqueous solution. The red blood cell has a lower concentration of protein and sugar than the aqueous solution, as shown in the diagram. In the diagram, the volume of the cell is equal to the volume outside the cell.

water from the red blood cell will diffuse into the solution.

A student performs an experiment to study the transport of water in and out of cells. He uses clear, semi-permeable plastic bags to represent the cell membrane. The student places three plastic bags of the same size, each containing a 1% concentration sucrose solution, into three different beakers. One beaker contains distilled water, another beaker contains a 3% concentration sucrose solution, and the third beaker contains a 1% concentration sucrose solution. The diagram shows the student's experimental setup, the plastic bag before it is placed in the beakers, and the appearance of the bags after an hour in each solution.

water movement into the cell is dependent on the percent concentration of solutes both inside and outside the cell.

An animal cell that is surrounded by fresh water will burst because the osmotic pressure causes

water to move into the cell.