[Not in Spec] Topic 2A - Gas Exchange, Cell Membranes and Transport

Question 1

What does cholesterol do to the membrane

Answer 1

Makes it more rigid

Question 2

Name the 6 molecules found in the fluid mosaic model

Answer 2

• channel protein
• protein
• phospholipid
• glycolipid
• glycoprotein
• cholesterol

Question 3

why is the bilayer ‘fluid’

Answer 3

because the phospholipids are constantly moving

Question 4

State the permeability of the membrane

Answer 4

partially permeable

Question 5

what molecules can move through gaps between the phospholipids

Answer 5

small molecules

Question 6

what molecules can only pass through special membrane proteins

Answer 6

large molecules and ions

Question 7

name the special membrane proteins

Answer 7

channel proteins and carrier proteins

Question 8

what is osmosis

Answer 8

osmosis is the diffusion of free water molecules across a partially permeable membrane from an area of higher concentration of water molecules to an area of lower concentration

Question 9

true/false:the cell membrane is mainly composed of glycolipids

Answer 9

false

Question 10

true/false:the molecules that make up the cell membrane are constantly moving

Answer 10

true

Question 11

true/false:molecules can only pass through the cell membrane via channel proteins

Answer 11

false

Question 12

is facilitated diffusion passive?

Answer 12

yes it doesnt use energy

Question 13

what do carrier proteins help transport

Answer 13

large molecules

Question 14

what do channel proteins help transport

Answer 14

charged particles

Question 15

describe how carrier proteins facilitate diffusion of large molecules

Answer 15

• large molecule attaches to a carrier protein in the membrane
• the protein changes shape
• this releases the molecule on the other side of the membrane

Question 16

does facilitated diffusion move particles up or down a concentration gradient

Answer 16

down

Question 17

which membrane protein is used in active transport

Answer 17

carrier protein

Question 18

is active transport up or down a concentration gradient

Answer 18

up

Question 19

whats endocytosis

Answer 19

when cells take in substances

Question 20

whats exocytosis

Answer 20

when cells secrete substances

Question 21

EQ. Describe the role of the CFTR protein in ensuring that the mucus produced in the lungs has the right consistency. (4 marks)

Answer 21

• chloride ions leave the cell through the CFTR protein and go into the mucus
• sodium ions follows the chloride ions out of the cell
• this draws water out of the cell into the mucus by osmosis
• because there is a greater concentration of solute in the mucus

Question 22

What are the 3 properties of water that make it a good transport medium?

Answer 22

• water is polar so polar substances, like ionic and hydrophilic substances can easily dissolve in water.
• the specific heat capacity of water is very high to maintain homeostasis
• water has a high boiling point due to the hydrogen bonds

Question 23

How are glycoproteins made in animal cells released

Answer 23

exocytosis