2.1.5 Biological Membranes

Question 1

The role of membranes within cells and at the
surface of cells

Answer 1

• partially permeable barriers between the cell and its environment, between organelles and the cytoplasm and within organelles
• sites of chemical reactions
• sites of cell communication (cell signalling).

Question 3

The fluid mosaic model of membrane structure and the roles of its components

Answer 3

phospholipids
cholesterol
glycolipids
proteins
glycoproteins

the role of membrane-bound receptors as sites where hormones and drugs can bind.

Question 4

factors affecting membrane structure and
permeability

Temperature and solvents

Question 5

the movement of molecules across
membranes

Passive methods

Answer 5

diffusion and facilitated diffusion

Question 6

active transport
endocytosis and exocytosis as
processes requiring adenosine triphosphate (ATP) as
an immediate source of energy.

Question 7

the movement of water across membranes
by osmosis and the effects that solutions of
different water potential can have on plant
and animal cells

Answer 7

Osmosis to be explained in terms of a water
potential gradient across a partially-permeable
membrane.