week 4-5 (membranes/membrane transport/osmosis)

Question 1

define diffusion

Answer 1

it is how molecules move around/through and between cells.
it occurs passively (does not require energy).
can occur across membranes, however does not need a membrane to occur.

Question 2

list the main features of a membrane

Answer 2

phospholipids
sterols
- cholesterol in animal cells
- phytosterol in plant cells
glycoproteins and glycolipids
- glycoproteins attach to membrane proteins
- glycolipids attatch to membrane lipids

Question 3

define and compare antigens and antibodies

Answer 3

antigens are molecules with a particular shape, that the body recognises as ‘not self’, therefore triggers the immune system to attack. There are the A antigens and B antigens, depending on your blood type determines what kind of antigens a person has.

antibodies are proteins which bind to antigens, and work with the immune system to get rid of the antigen it has binded to.

Question 4

what is simple diffusion good for transporting?

Answer 4

dissolved gases (O2 and CO2)
small uncharged molecules (H2O and ethanol)
hydrophobic molecules

Question 5

what is facilitated diffusion good for transporting?

Answer 5

anything charged (ions, amino acids)
larger hydrophobic molecules (sugars)

Question 6

difference between simple diffusion and facilitated diffusion

Answer 6

simple diffusion does not require transport/channel proteins, where facilitated diffusion does

Question 7

explain the difference between primary active transport and secondary active transport

Answer 7

primary active transport uses ATP to pump one solute out of the cell, and one solute into the cell simultaneously.
secondary active transport uses ATP to form one concentration gradient.

Question 8

what are gap junctions

Answer 8

gap junctions are what connect animal cells to one another.
they provide a passage for small molecules and ions to flow between cells.

Question 9

what are plasmodesmatas

Answer 9

plasmodesmatas are small tubes running through the cell walls of plant cells.
allows for the diffusion of molecules between cells.

Question 10

list the types of bulk transport

Answer 10

exocytosis
- cell getting rid of molecules
endocytosis
- phagocytosis is the cell taking in bulk solids
- pinocytosis is the cell taking in bulk liquids

Question 11

define osmolarity

Answer 11

the process of water moving towards an area with a high concentration gradient.

Question 12

what happens to a cell when water enters it (answer for both animal and plant cells)

Answer 12

animal cells = lyse (burst)
plant cells = turn turgid

Question 13

what happens to a cell when water exits it (answer for both animal and plant cells)

Answer 13

animal cells = crenate (shrivelled)
plant cells = turn flacid

Question 14

what happens to cells when sat in an isotonic solution?

Answer 14

nothing

Question 15

what happens to cells when sat in a hypotonic solution?

Answer 15

animal cell = lyse/burst
plant cell = plasmolyse/turn turgid

Question 16

what happens to cells when sat in a hypertonic solution?

Answer 16

animal cell = crenate/shrivel
plant cell = plasmolyse/turn flacid