Ch.4 Plasma Membrane

Question 1

What is the term for the movement of molecules across the plasma membrane along their concentration gradient, without requiring energy input?

Answer 1

Passive Transport

Question 2

What is the term for the diffusion of water across a selectively permeable membrane?

Answer 2

Diffusion

Question 3

What is the term for the process of taking in materials into the cell by forming vesicles from the plasma membrane?

Answer 3

Endocytosis

Question 4

What is the term for the direct use of ATP to pump molecules across the membrane against their gradient?

Answer 4

Active Transport

Question 5

What are the two main components of the plasma membrane?

Answer 5

Lipids & proteins

Question 6

Ions like sodium and calcium enter and exit the cell through:

Answer 6

Ion Channels

Question 7

How does the sodium-potassium pump help a cell maintain homeostasis?

Answer 7

It helps to maintain osmotic equilibrium and concentration gradient in cells.

Question 8

How do endocytosis and exocytosis differ in their direction of vesicle movement?

Answer 8

Endocytosis - vesicles move in the cell
Exocytosis - vesicles move out from the cell

Question 9

What are the three types of tonic solutions? What happens to a cell when submerged in each type of solution?

Answer 9

Hypotonic - water enters the cell, the cell swells & expands

Hypertonic- water exits the cell, the cell shrinks

Isotonic - nothing chnages

Question 10

Describe how the diffusion of ions across a cell membrane differs from the diffusion of nonpolar molecules across the cell membrane.

Answer 10

Unlike the hydrophobic nonpolar molecules - who directly enter through the membrane easily by shrinking, ions however, enter through facilitated ion channels, or only with active transport.

Question 11

What invention of humankind is similar to phospholipids and is responsible for doubling the lifespan of human beings? What is the mechanism that makes it work into keeping humans healthy?

Answer 11

• Soap.
• Since soap has polar ends, it attracts the polar molecules of water which eventually washes away the germs present. Being hydrophobic, it helps a lot in increasing our lifespan rid of bacteria.

Question 12

When a cell takes in a food particle by endocytosis, the vesicle that is formed may fuse with the lysosome. How does this fusion help with digestion of the food particle?

Answer 12

Since lysosomes contain digestive enzymes, they are able to break down food particles more efficiently, especially with vesicles.