Chapter 7 - Cont. (7.3 - 7.4)

Question 1

What is one of the most important functions of the cell membrane?

Answer 1

Maintaining homeostasis is one of the most important functions of the cell membrane. Another important function is the regulation of what comes in and out.

Question 2

What is passive transport?

Answer 2

Passive transport is the movement of materials across the cell membrane without using cellular energy.

Question 3

What is diffusion?

Answer 3

Diffusion, a passive transport, is the process by which particles move from an area of high concentration to an area of low concentration.

Question 4

Why does diffusion require no additional energy?

Answer 4

Diffusion requires no additional energy because it happens randomly.

Question 5

What is facilitated diffusion?

Answer 5

Facilitated diffusion, passive transport, is when molecules use special protein channels to pass through the cell membrane.

Question 6

Why does water have a difficult time passing through the cell membrane?

Answer 6

Water has a difficult time passing through the cell membrane because parts of the cell membrane are hydrophobic, “water-hating”

Question 7

What are aquaporins?

Answer 7

Aquaporins are water channel proteins that allow water to pass through the cell membrane. This method is a form of facilitated diffusion.

Question 8

What is osmosis?

Answer 8

Osmosis is the diffusion of water through a selectively permeable membrane from an area of high concentration to an area of low concentration.

Question 9

When are two solutions isotonic?

Answer 9

Two solutions are isotonic when the concentration is the same on both sides of the membrane.

Question 10

What is a hypertonic solution?

Answer 10

The more concentrated sugar solution is “above strength” or hypertonic.

Question 11

What is a hypotonic solution?

Answer 11

The dilute sugar solution is hypertonic.

Question 12

What is osmotic pressure?

Answer 12

The net movement of water out of or into a cell exerts a force known as osmotic pressure.

Question 13

What happens to water in a hypertonic solution? Why does this happen?

Answer 13

In a hypertonic solution, water rushes out of the cell, causing animal cells to shrink and plant cell vacuoles to collapse. It does this because the solution has a higher solute concentration on the outside rather than the inside of the cell, causing a net movement of water molecules out of the cell because there are no internal solutes to block them from leaving, thus they rush out of the cell.

Question 14

What happens to the cell in a hypertonic solution?

Answer 14

In a hypertonic solution, the cell shrinks because there are less solutes inside the cell. This means that the water is unobstructed and can leave the cell while the increased solute outside blocks water from getting in. Thus, the cell shrinks.

Question 15

What happens to water in an isotonic solution?

Answer 15

In an isotonic solution, water is neither lost nor gained.

Question 16

What is active transport?

Answer 16

Active transport requires cellular energy. It is the movement of materials against a concentration difference.

Question 17

What happens to the cell in a hypotonic solution? Why does this happen?

Answer 17

In a hypotonic solution, the cell swells because the solution has a lower solute concentration than the cell. The solution has a lower osmotic pressure than another solution. There is a net movement of water into the cell because there are less solutes on the outside of the cell that would have otherwise blocked their entrance.

Question 18

Where are particles moved in active transport?

Answer 18

In active transport, particles move from an area of low concentration to an area of high concentration.

Question 19

What is bulk transport?

Answer 19

Bulk transport is the transportation of larger molecules by movements of the cell membrane.

Question 20

How are larger molecules and clumps of material actively transported across the cell membrane?

Answer 20

Larger molecules and clumps of material are actively transported across the cell membrane by processes known as endocytosis and exocytosis.

Question 21

What is endocytosis?

Answer 21

Endocytosis, active transport, is the process of taking material into the cell by means of infoldings, or pockets, of the cell membrane.

Question 22

What are the two subtypes of endocytosis?

Answer 22

The two subtypes of endocytosis are phagocytosis, where the cell takes in food, and pinocytosis, where the cell takes in liquid.

Question 23

What is exocytosis?

Answer 23

Exocytosis, active transport, is when cells release large amounts of material from the cell.

Question 24

How do unicellular organisms maintain homeostasis?

Answer 24

Unicellular organisms maintain homeostasis by growing, responding to their environment, transforming energy, and reproducing. To maintain homeostasis, they need sources of energy/food.

Question 25

How do the cells of multicellular organisms maintain homeostasis?

Answer 25

To maintain homeostasis, the cells of multicellular organisms become specialized for particular tasks and communicate with one another.

Question 26

What happens to the specialized cells of multicellular organisms?

Answer 26

The specialized cells of multicellular organisms are organized into tissues, then into organs, and finally into organ systems.

Question 27

What is tissue?

Answer 27

Tissues are groups of similar cells that perform a particular function.

Question 28

What happens when equilibrium is reached?

Answer 28

When the equilibrium is reached, there is an equal net movement in and out of the cell so nothing is gained nor lost.

Question 29

How do cells communicate?

Answer 29

Cells communicate by sending chemical messages which can only be responded to if a cell has a receptor.