2010 Unit 1 Jun

Question 1

Give three structures found in prokaryotic cells

but not in eukaryotic cells.

Answer 1

• Capsule layer
• Circular DNA
• Plasmid;
• Flagellum

Question 2

Use your knowledge of water potential to explain how the increased secretion of chloride ions causes diarrhoea.

Answer 2

• Lower water potential (in lumen in intestine)

Question 3

What is an HPV antigen?

Answer 3

• Protein

* Causes immune response

Question 4

A vaccine can be used to produce immunity to HPV. Describe how memory cells are
important in this process

Answer 4

• Memory cells produced (from previous infection)
• When individual) comes into contact with virus / antigen
• More antibodies produced
•

Question 5

Some doctors suggested offering the vaccine to young men. Explain the advantage of
vaccinating young men as well as young women.

Answer 5

• HPV destroyed in males

* Prevents males passing on HPV

Question 6

Explain why this enzyme only breaks down gangliosides.

Answer 6

• Active site;
• (Complementary / specific) structure / shape;
• (Only) fits / binds to gangliosides;
• Forms enzyme-substrate complexes

Question 7

Suggest why they cannot give the enzyme as a tablet that is swallowed.

Answer 7

• (Enzymes are) proteins

* Digested / broken down / destroyed (by enzymes / acid);

Question 8

Give two other risk factors associated with coronary heart disease.

Answer 8

• Smoking
• Chloesterol
• Age
• Gender
• Genes

Question 9

Why was it

important that the volunteers were healthy?

Answer 9

• Healthy volunteers have ‘normally’ functioning vessels;

Question 10

Describe how the control group should have been treated

Answer 10

• Same as experimental group

* Chocolate with no flavenoids;

Question 11

Why was it important to have a control group in this investigation?

Answer 11

• (To ensure that results are) not due to some other substance in the chocolate

Question 12

Suggest why an increase in the diameter of the lumen of the main artery in the arm
(lines 11-12) is associated with a reduced risk of coronary heart disease.

Answer 12

• Coronary artery also likely to have a wide lumen
• (Less chance of) high blood pressure;
• (Less chance of) a blood clot

Question 13

Describe how substances can cross a cell surface membrane.

Answer 13

• (Simple / facilitated) diffusion down concentration gradient;
• Small / non-polar / lipid-soluble molecules pass via bilayer
• Large / polar / water-soluble molecules go through proteins;
• Water moves by osmosis from high water potential
to low water potential
• Active transport is movement against concentration gradient
• Active transport / facilitated diffusion involves proteins/ carriers;
• Active transport requires energy / ATP;

Question 14

Describe and explain how the lungs are adapted to allow rapid exchange of oxygen
between air in the alveoli and blood in the capillaries around them.

Answer 14

• Many alveoli / alveoli walls folded provide a large
surface area
• Many capillaries provide a large surface area
• (So) fast diffusion;
• Ventilation / circulation;
• Maintains a diffusion / concentration gradient;
• Maintains a diffusion / concentration gradient;