Biological molecules

Question 1

Describe the structure of a plasma cell surface membrane
3 marks

Answer 1

phospholipid bilayer containing proteins
hydrophyllic head facing outwards and hydrophobic tail facing inwards
intrinsic and extrinsic glycoproteins sticking out of the bilayer

Question 2

Describe the effect of high temperature on the structure of the yeast cell membranes.
4 marks

Answer 2

phospholipids vibrate more
increase number of gaps in membrane
bilayer becomes more fluid
glycoproteins are denatured

Question 3

State two functions of membranes within cells.
2 marks

Answer 3

separates organelles from cytoplasm
site of metabolic reactions

Question 4

Describe the arrangement and functions of two named components of a cell surface
membrane.
4 marks

Answer 4

phospholipid bilayer
provides a barrier to large molecules
channel proteins
facilliatated diffusion

Question 5

Which component of a cell membrane becomes more fluid as temperature increases?
1 mark

Answer 5

phospholipid bilayer

Question 6

Which component of a cell membrane denatures as temperature increases?
1 mark

Answer 6

glycoproteins

Question 7

State the term used to describe a membrane through which some substances can pass freely
but others cannot.
1 mark

Answer 7

partially permeable

Question 8

State what is meant by cell signalling.
1 mark

Answer 8

communication between cells

Question 9

Explain how cell surface membranes contribute to the process of cell signalling.
4 marks

Answer 9

glycoproteins have receptors
that receptor is specific
receptor and signal are complimentary
the attachment of a signal molecule cause change
membrane allows the entry of some signal molecules

Question 10

State three roles of membranes inside cells.

Answer 10

produce organelles
isolate substances
site for attachment of enzymes
provide selective permeability

Question 11

Outline how the vesicles are moved from one organelle to another.
2 marks

Answer 11

microtubles provide pathways
vesicles move along these
using ATP