TAM Exam Questions

Question 1

Some substances can cross the cell surface membrane of a cell by simple diffusion through the phospholipid bilayer.
Describe other ways in which substances cross this membrane. (5)

Answer 1

• osmosis. From an area of high water potential to an area of low water potential across a selectively permeable membrane. Through aquaporins / water channels.
• facilitated diffusion. Using channel/ carrier proteins, down the concentration gradient.
• active transport. Carrier protein / protein pumps, using ATP from respiration. Down the concentration gradient.
• phagocytosis. Engulfing by cell surface membrane to form a vesicle.

Question 2

Some cells lining the bronchi of the lungs secrete large amounts of mucus. Mucus contains protein.

Name one organelle that you would expect to find in large numbers in a mucus-secreting cell and describe its role in the production of mucus.

Answer 2

• Golgi apparatus; packages and processes proteins
• RER; makes polypeptides
• mitochondria; creates ATP
• vesicle; secretes / transports proteins