2010 Unit 1 Jan

Question 1

Use your knowledge of water potential to explain why these adults get diarrhoea when they drink milk.

Answer 1

• Low(er) water potential in lumen / intestine / gut;

* Water enters lumen / leaves (body) cells / by osmosis

Question 2

Describe the path by which oxygen goes from an alveolus to the blood.

Answer 2

• Through alveolar epithelium;

* Through capillary epithelium/endothelium;

Question 3

Explain why people with miner’s lung have a lower concentration of oxygen in their blood.

Answer 3

• (Thicker alveolar wall)

* (So) Longer diffusion pathway / slower diffusion;

Question 4

Describe how ventilation helps to maintain difference in alvelous and lungs oxygen concentration.

Answer 4

(In alveolus)
• Brings in air containing a high(er) oxygen concentration;
• Removes air with a low(er) oxygen concentration;

Question 5

Give one other way that helps to maintain the difference in oxygen concentration.

Answer 5

• Circulation of blood / moving blood;

Question 6

Explain how the drug lowers the rate of reaction controlled by folate reductase.

Answer 6

• drug is a similar shape / structure to
substrate;
• Binds to / fits / is complementary to active site;
• Less enzyme-substrate complexes formed;

Question 7

Explain how mitochondria help the cell to absorb the products of digestion.

Answer 7

• (Site of aerobic) respiration / ATP production / energy
release;
• For active transport

Question 8

The students were advised that they could improve the reliability of their results
by taking additional readings at the same concentrations of sodium chloride.
Explain how.

Answer 8

(Allows)
• Anomalies to be identified / effect of anomalies to be
reduced / effect of variation in data to be minimised;
• A mean to be calculated;

Question 9

The students used a graph of their results to find the sodium chloride solution
with the same water potential as the apple tissue. Describe how they did this.

Answer 9

• Plot (sodium chloride) concentration against ratio / draw line of best
• Find (sodium chloride concentration from the graph)
where the ratio is 1 / there is no change in mass;

Question 10

Describe what the graph shows about the effect of substrate concentration on the
rate of this enzyme-controlled reaction.

Answer 10

Increases then plateaus

Question 11

What limits the rate of this reaction between points A and B?

Answer 11

Substrate concentration

As substrate concentration increases, rate increases

Question 12

What is the advantage of giving results as a ratio

Answer 12

Allows comparison

The idea that discs had different starting masses

Question 13

Graph could be improved by taking additional readings

Answer 13

Line of best fit/curve more precise
Can plot SDvalues/ error bars
To show how spread out the results are

Question 14

Explain why antibodies are referred to as monoclonal

Answer 14

Antibodies produced from same B cell/ plasma cell

Question 15

Protiens are specific why?

Answer 15

Specific primary structure
Specific tertiary structure
complementarty to one antigen

Question 16

A test using
monoclonal antibodies allows vets to identify cattle that are carriers.
The tests using monoclonal antibodies allow vets to identify brucellosis while they are
still on a farm. Explain the advantages of this

Answer 16

Can isolate infected cattle
Reduced spread of disease
Do not need to kill cattle
Infected products not sold

Question 17

The cardiac cycle is controlled by the sinoatrial node (SAN) and the atrioventricular
node (AVN). Describe how.

Answer 17

SAN initiates heartbeat
(SAN) sends wave of electrical activity (across atria) causing atrial contraction
AVN delays (electrical activity
Allowing ventricle to fill with blood before they contract
(AVN) sends wave of electrical activity
down Bundle of His / Purkyne fibres
Causing ventricular systole

Question 18

What is atheroma and how may it cause myocardial infarction?

Answer 18

Cholesterol / plaque cells;
2. In artery wall 
3. Atheroma linked to blood clot 
4. (Blocks) coronary artery 
Reduces oxygen (to heart muscle 
Heart muscle unable to respire