Biology: difussion

Question 1

what is osmosis?

Answer 1

Osmosis is the diffusion of water. The passive net movement of water molecules through a partially permeable membrane, from a region of low solute concentration to a region of high solute region concentration.

Question 2

what is osmolarity?

Answer 2

• Is the total concentration of solutes in a solution
• A cell in a solution with a high osmolarity is said to be in a hypertonic solution
• A cell in a solution with a low osmolarity is said to be in a hypotonic solution.
• The tonicity of a solution is only influenced by solutes that cannot diffuse across the semi permeable membrane

Question 3

isotonic…

Answer 3

of a solution, having the same osmotic pressure as the cytoplasm

Question 4

Hypertonic…

Answer 4

of a solution, having a higher osmolarity than the cytoplasm

Question 5

Hypotonic…

Answer 5

of a solution, having a lower osmolarity than the cytoplasm.

Question 6

what is diffusion?

Answer 6

The passive net movement of a substance from a region of high concentration to a region of low concentration. (when the molecules are evenly spread out, we say they have reached equilibrium, which is a low energy state.)

Question 7

what is simple diffusion?

Answer 7

Is the process of smaller molecules moving across a plasma membrane with no proteins or channels or energy required. (Molecules can enter a cell through the phospholipid bilayer if they are small and neither charged nor polar)

Question 8

what is facilitated diffusion?

Answer 8

Is the process of larger molecules moving across a plasma membrane with the help of a protein channel/or/via specific transmembrane integral proteins.

Question 9

what is active transport?

Answer 9

Is the active movement of molecules against their concentration gradient, across a membrane via specific transmembrane integral proteins. (Molecules can also be moved against their concentration gradient by a carrier protein, but this is in an active process, it requires ATP energy)

Question 10

where is ATP (active transport) produced?

Answer 10

produced in the mitochondria by cellular respiration. ATP diffuses to places in the cell where active processes are taking place.

Question 11

what is Exocytosis?

Answer 11

Bulk transport of molecules out of a cell

Question 12

what is Endocytosis?

Answer 12

Bulk transport into a cell from the extracellular fluid (reverse of exocytosis)

Question 13

what is Phagocytosis?

Answer 13

endocytosis of solid material, such as bacteria

Question 14

what is Pinocytosis?

Answer 14

endocytosis of fluid material, such as lipids

Question 15

what is the phospholipid tail?

Answer 15

it is a Non-polar Hydrophobic tail, and it hates water

Question 16

what is the phospholipid head?

Answer 16

it is Polar Hydrophilic head, and it loves water.

Question 17

what do cells need?

Answer 17

oxygen, glucose, water and salts

Question 18

what is model cell theory?

Answer 18

1)The cell is the smallest living unit in all organisms
2)All living things are made of cells
3)All cells come from other pre-existing cells

Question 19

prokaryotic cells…

Answer 19

are small, have only ONE chromosome, dna is stored circular, and they do not have membrane bound organelles.

Question 20

eukaryotic cells…

Answer 20

are big, contain multiple chromosomes, dna is stored linear, and they have membrane bound organelles.

Question 21

SA:V ratio

Answer 21

Cell size is limited by the ratio of surface area to volume and the efficiency of the exchange of nutrients in the cell.