Osmosis and Diffusion

Question 1

What is the cell membrane made of?

Answer 1

A phospholipid bilayer that is fluid.

Question 2

Fluid mosaic model

Answer 2

The phospholipids and all the other proteins in, around, on top of, and underneath the membrane.

Question 3

Why is the word “mosaic” significant?

Answer 3

It refers to the membrane being a mixture of proteins in the bilayer functioning in transport, cell recognition, and binding.

Question 4

Semi-permeable membrane

Answer 4

Molecules like O2 and CO2 can move through, others require transport proteins, and others cannot move through at all.

Question 5

Define diffusion.

Answer 5

The movement of molecules from an area of high concentration to an area of low concentration until equilibrium is reached.

Question 6

What does the rate of diffusion depend on?

Answer 6

The medium (solid, liquid, or gas), temperature, and concentration.

Question 7

If temperature increases, the rate of diffusion…

Answer 7

Increases.

Question 8

Equililbrium

Answer 8

An equal amount is dispersed throughout.

Question 9

Concentration gradient

Answer 9

The direction of the flow (high to low).

Question 10

Facilitated diffusion

Answer 10

Diffusion with help. Help=proteins moving molecules into the cell.

Question 11

Osmosis

Answer 11

Diffusion of water from high to low concentration until equilibrium is reached.

Question 12

Osmotic pressure

Answer 12

The force of osmosis.

Question 13

Isotonic medium

Answer 13

There is an equal number of solutes inside and outside the cell. Water moves in and out.

Question 14

“Iso” means

Answer 14

Balanced.

Question 15

Hypertonic medium

Answer 15

There are more solutes outside the cell than inside the cell. Water moves out of cell (high to low concentration). Cell volume shrinks.

Question 16

Hypotonic medium

Answer 16

There are more solutes inside the cell than outside the cell. Water moves into the cell. Cell can balloon up and possibly burst.

Question 17

Isotonic medium 2

Answer 17

Concentration is equal on both sides of the membrane, no net movement. Water moves in and out of animal cells; not plant cells because of cell wall.

Question 18

In which medium do cells function best?

Answer 18

Isotonic.

Question 19

Hypotonic medium 2

Answer 19

High concentration of water OUTSIDE the cell, cell gains water.

Question 20

How does a cell wall help a plant cell in a hypotonic medium?

Answer 20

A cell wall keeps the plant cell from bursting due to the growing vacuole and (?) membrane.

Question 21

Hypertonic medium 2

Answer 21

More water inside the cell, more solute outside. Cells lose water.

Question 22

Turgor/osmotic pressure

Answer 22

The pressure building in the cell as it continually takes in water. Can lead to eventual bursting in animal cells.

Question 23

What can a hypertonic medium do to an animal cell?

Answer 23

It can dehydrate it.

Question 24

What can a hypertonic medium do to a plant cell?

Answer 24

Plagmolysis: Membrane and organelles in plants shrink because of water loss. Cell wall stays the same.

Question 25

Active transport

Answer 25

Movement of molecules from low to high concentration, requiring energy (ATP) and membrane proteins.

Question 26

Examples of active transport?

Answer 26

Liver and intestines absorbing nutrients/sugar in digestion, root cell absorbing minerals, kidney absorbing ucrea from blood, plant spending energy taking minerals into cells from dirt.

Question 27

Endocytosis

Answer 27

Engulfing molecules too big for diffusion. Producing a vesicle to bring the particles into the cell.

Question 28

What is one kind of endocytosis?

Answer 28

Phagocytosis, in which large, solid molecules are transported into the cell.

Question 29

An example of phagocytosis?

Answer 29

An amoeba eats a protist that is about its size by oozing its cell membrane around the protist and digesting it.

Question 30

Exocytosis

Answer 30

Releasing the food waste particle after digestion.

Question 31

How might a substance such as a digestive enzyme be produced, stored, and then secreted from the cell?

Answer 31

The DNA in the nucleus has directions for ribosomes to make proteins. The ribosomes are made in the nucleolus. (Digestive enzymes are a type of protein.) The proteins are transported through the rough ER and then collected and stored in the Golgi body. They are then transported from the Golgi body when the ends of the Golgi body pinch off to form a vesicle around the protein. Mitochondria are needed to produce energy for the exocytosis of the protein, which means that the protein leaves the cell in the vesicle which becomes a part of the cell membrane once it pushes the protein out after traveling through the cytoplasm.