Chapter 4: Practice Test Questions

What does it mean for a molecule to diffuse down a concentration gradient?

It means the molecule will move from an area of high concentration to an area of low concentration. This is passive transport.

Large amoeboid-type cells, called macrophages, remove viruses and worn-out red blood cells by a process called _____.

Phagocytosis

Name one thing that does not influence the rate of diffusion?

pH level

The diffusion of water across a differentially permeable membrane is called _____

Osmosis

The diffusion of water across a differentially permeable membrane is called ______.

Osmosis

How would the following substances get inside the cell—oxygen, carbon dioxide, glucose, water, amino acids, neurotransmitters, sodium ion, calcium ion, chlorine ion.

-Carrier protein: Glucose, amino acids -Receptor Protein: Neurotransmitters -Channel Protein: sodium, calcium, chlorine, water -Bi-layer: Carbon: Oxygen, carbon dioxide, water

What is the difference between a carrier and channel protein?

-Carrier: Changes shape and helps molecules move out of cell. It directly acts with the substances. -Channel: Has no direct interactions with the molecules; it just acts as a passageway through the membrane

What is the function of cholesterol? Peripheral proteins?

-Cholesterol: Stiffens and strengthens membrane and regulates fluidity -Peripheral Proteins: Provide structure for cell membrane

Name all the structures found in a cell membrane

1. Enzymatic Protein 2. Channel Protein 3. Receptor Protein 4. Carrier Protein 5. Glycoprotein 6. Glycolipid 7. Cholesterol 8. Phospholipids 9. Peripheral Proteins 10. Integral Proteins 11. Hydrophobic Heads of Phospholipids 12. Hydrophilic Tails of Phospholipids

List the conditions of Facilitated Transport

1. requires specific carrier proteins 2. transports molecules down the concentration gradient 3. transports molecules from one side of the membrane to the other side 4. transports molecules through the membrane much faster than simple diffusion

Upon observation of an electron micrograph, a scientist noted a large number of mitochondria near a plasma membrane within a particular cell. The scientist would probably hypothesize that the cell used energy for ______ purposes.

Active Transport

Which process will transport sodium ions to the outside of the cell and potassium ions to the inside of the cell?

Active Transport

How is active transport different than simple diffusion and facilitated diffusion?

Active Transport requires ATP energy anytime it is moving something against the concentration gradient.

Predict: If the transport proteins that carry amino acids into a cell stopped working, how might the process affect the cell?

Amino acids would not be able to build proteins, and proteins are needed to help regulate cell's activity, so without amino acids, the cell could shut down and die.

The cells of a multicellular organism "talk" to one another by using signaling molecules sometimes called ______.

Chemical Messengers

______ is the net movement of molecules from a region of higher concentration to a region of lower concentration.

Diffusion

Why is the cell membrane called Fluid-Mosaic?

It is fluid because the membrane is constantly moving, and it is mosaic because it is made of many different proteins.

The process that requires a vesicle to fuse with the membrane, thereupon discharging its contents, is called ______.

Endocytosis

The prefix exo- means "out of" and the prefix endo- means "taking in". How do these meanings relate to the meaning of exocytosis and endocytosis?

Exocytosis is the moving of large substances out of the cell. Endocytosis is the moving of large substances into the cell.

How does facilitated diffusion differ from simple diffusion?

Facilitated diffusion uses carrier proteins to move molecules into the cell. Simple diffusion only moves molecules across the lipid bilayer.

Which term best describes the condition of red blood cells when placed in a hypotonic solution?

Hemolysis

What is the function of a receptor protein?

It has a specific shape to allow certain molecules to bind to it. Once they are bound, a signal is sent out that triggers a response from.

Suppose a thistle tube containing a 10% sugar solution is covered at one end by a differentially permeable membrane and is placed in a beaker containing a 5% sugar solution. What will happen to the water?

More water will enter the thistle tube than leave the thistle tube.

Do receptor proteins allow molecules into the cell?

No

The exchange of substances between the maternal blood and fetal blood is an example of ______.

Receptor-Mediated Endocytosis

Tonicity refers to the ______.

Strength of a solution in relationship to osmosis

Infer: What might you conclude about the membrane structure of the final vesicle formed during exocytosis and the cell membrane?

The cell membrane and the vesicle are both made of the same materials. This is because then the vesicle and the membrane can easily fuse together to move substances in and out of the cell.

What will happen to a houseplant if you water it with salt water (a hypertonic solution)?

The plant will shrivel up because the hypertonic solution will cause the water to move from an area of high concentration to an area of low concentration. So the water would move out of the cell.

Do you think that endocytosis and exocytosis can occur within the same cell? Explain your reasoning.

Yes because wastes need to exit the cell and nutrients need to be able to get into the cell, so for both of those things to happen, you'd need both endocytosis and exocytosis to work inside the cell.