cells

Question 1

Human breast milk is produced and secreted by gland cells. These gland cells have adaptations that include many mitochondria and many Golgi vesicles. The milk contains a high concentration of protein.

Explain the role of these cell adaptations in the production and secretion of breast milk.

Answer 1

Many mitochondria) release energy / ATP for movement of vesicles / synthesis of protein / active transport;

Must include function of organelle and use in context of milk production.

Ignore reference to lipid / triglyceride

Reject reference to mitochondria undergoing anaerobic respiration

Reject “produce energy”.

Reject “energy for respiration”

2. (Many Golgi) vesicles transport protein / glycoprotein / milk to cell membrane / out of cell;

Question 1

Coeliac disease is a disease of the human digestive system. In coeliac disease, the structures labelled Z are damaged.

Although people with coeliac disease can digest proteins they have low concentrations of amino acids in their blood.

Explain why they have low concentrations of amino acids in their blood.

z is micro villi

Answer 1

Reduced surface area; (So) less absorption;

Neutral: structure Z incorrectly named

(Membrane-bound) enzymes less effective;
(So) proteins / polypeptides not digested;

Reduced surface area for absorption gains 2 marks

Cell membranes damaged;
(So) Fewer / less effective carrier / channel proteins;

Accept: references to diffusion and active transport for ‘absorption’

Carrier / channel proteins damaged;
(So) less absorption;

Question 2

The structure of a plasma membrane is described as a fluid mosaic.
Explain why.

Answer 2

Fluid = molecules move around;
Mosaic = proteins floating among phospholipids/not just phospholipids/
other molecules in it/made of different sorts of molecules;

Question 3

The epithelial cells of the small intestine have large numbers of organelle A.
Explain how this is an adaptation for the function of these cells.

A is mitochondria

Answer 3

provide / produce energy or ATP (reject create energy);
(disqualify first mark if ‘for respiration’)
high respiration (rate) (accept lots) for active uptake / transport
(accept description);
absorption of digested food / substances / products / correctly named product

(only accept monosaccharides, amino acids, dipeptides);