Biology 2.2 Movement Across Membranes

Question 1

The cell membrane

Answer 1

• The concentration of chemicals is different between the inside of the cell (intracellular environment) and the outside of the cell (extracellular environment).
• The cell needs to maintain precise chemical concentrations (including water and waste levels) so that proteins function properly.
• The cell membrane’s structure allows for the movement of a range of molecules.

Question 2

For materials to be exchanged the cell membrane must be:

Answer 2

thin, moist, semi-permeable, and high SA:V ratio

Question 3

Molecules may pass through the cell membrane through what techniques?

Answer 3

Passively (without energy) or actively (wuith energy)

Question 4

The two types of passive transports

Answer 4

Diffusion or Osmosis

Question 5

does diffusion move in high to low or low to high

Answer 5

The movement of a substance from an area of high concentration to an area of low concentration.

Question 6

What does facilitated diffusion do?

Answer 6

A special type of diffusion where molecules move across a membrane with the help of a channel or carrier protein.

Question 7

Does osmosis move through water from low to high or high to low concentration?

Answer 7

The movement of water through a semi -permeable membrane from an area of low concentration to an area of high concentration of the dissolved substance.

Question 8

What are the three types of active transport?

Answer 8

Membrane pumps, endocytosis and exocytosis

Question 9

In active transport does subtance move from high to low or low to high concentration?

Answer 9

Active transport requires energy and uses this eneryg to move a substance against a concentration gradient. Substances move from an area of low concentration to high concentration.

Question 10

What is membrane pumps and how does it work?

Answer 10

Proteins called membrane pumps can be used to actively move materials against the concentration gradient.

Question 11

How does endocytosis work?

Answer 11

Endocytosis is the movement of larger molecules into a cell via a vesicle. Phagocytosis (cell-eating) which means the intake of particles. Pinocytosis (cell-drinkig) which means the intake of liquids.

Question 12

How does exocytosis work?

Answer 12

Exocytosis is the movement of larger molecules out of a cell via a vesicle. Vesicles inside the cell fuse with the mebrane and the contents are released outside the cell.