Wednesday 9th January 2013

Question 1

Explain how downward movement of the diaphragm leads to air entering the lungs. 2 marks

Answer 1

• Increase volume
• Lowers pressure
• Air pushed in by outside pressure

Question 2

Pulmonary ventilation equation? 1 mark

Answer 2

Tidal volume * ventilation rate

Question 3

Function of the mitochondria? 1 mark

Answer 3

• Aerobic respiration

Question 4

This photograph was taken using a transmission electron microscope. The structure of the organelles visible in the photograph could not have been seen using an optical (light) microscope. Explain why. 2 mark

Answer 4

• Low resolution

- Wavelength is too long

Question 5

Monosaccharides that make up sucrose? 1 mark

Answer 5

• Glucose

- Fructose

Question 6

Monosaccharides that makeup lactose? 1 mark

Answer 6

• Galactose

- Glucose

Question 7

Where is amylase produced and what are the products? 1 mark

Answer 7

• Pancreas

- Maltose

Question 8

Where is maltase produced and what are the products? 1 mark

Answer 8

• Maltase

- Produces glucose

Question 9

Cholera bacteria produce toxins which increase secretion of chloride ions into the lumen of the intestine.
Explain why this results in severe diarrhoea (watery faeces). 3 marks

Answer 9

1. Water lost into gut/water moves into gut/ water leaves cells;
2. Low(er) water potential of intestine/gut (lumen);
3. Osmosis/movement down a WP gradient;
4. Less/not enough water (re)absorbed;

Question 10

The water potential of solution B with starch was higher (less negative) than the water potential of solution A with glucose.
Explain why.

Answer 10

• Starch is not very soluble

- Does not dissolve well

Question 11

Addition of a phosphate group to the non-functional form of TK leads to the production of the functional form of TK.
Explain how. 2 marks

Answer 11

• Phosphate changes the active site/ shape of the enzyme

- It is now complementary to the substrate and can form E-S complexs

Question 12

The binding of the functional form of TK to its substrate leads to cell division. Chronic myeloid leukaemia is a cancer caused by a faulty form of TK. Cancer involves uncontrolled cell division.
Suggest how faulty TK leads to chronic myeloid leukaemia. 2 marks

Answer 12

• Faulty TK has a functional active site without phosphate.

- TK not controlled by phosphate.

Question 13

Using all of the information, describe how imatinib stops the development of chronic myeloid leukaemia. 2 marks

Answer 13

• Non-competitive inhibitor
• Causes TK to be in non-functional form = active site not formed.
• So, uncontrolled cell division stopped

Question 14

Name the blood vessel to which the artificial heart is connected. 1 mark

Answer 14

• Aorta

Question 15

In these patients, the right ventricle still produces sufficient blood flow to keep the patient alive.
Suggest why the left ventricle requires the help of the artificial heart but the right ventricle does not. 2 marks

Answer 15

• Left ventricle pumps to the whole body.

- Left ventricle does most work.

Question 16

The groups of men selected for this investigation were matched.
Other than being men, suggest one factor for which they should have been matched. 1 mark

Answer 16

• Age

- No heart condition

Question 17

Explain why the pulse recordings in the doctor’s surgery were taken when the men were lying down. 1 mark

Answer 17

• Patients were at risk

- Not moving

Question 18

The pulse felt in the artery in the wrist can be recorded and used to measure heart rate.
Suggest why the pulse felt can be used to measure heart rate. 2 marks

Answer 18

• Caused by pressure

- From one contraction

Question 19

The portable heart rate monitor recorded the men’s heart rates continuously.
This gave more reliable mean heart rates than those obtained by recording the pulse in the wrist for 1 minute.
Suggest why it is more reliable. 2 marks

Answer 19

• More data collected from the monitor.
• Human errors can cause errors.
• Monitor records HR over a range of activities during the day/pulse rate only records for a single set of conditions

Question 20

People with AIDS die because they are unable to produce an immune response to pathogens (lines 2– 4).
Explain why this leads to death. 3 marks

Answer 20

• Susceptible to other infections
• Pathogens cause disease
• Damage cells
• Release toxins

Question 21

Explain why each of the following means that a vaccine might not be effective against HIV.
HIV rapidly enters host cells (lines 6 –7). 2 marks

Answer 21

• HIV enters cells before antibodies can destroy it

- Antibodies cannot enter cells to destroy HIV.

Question 22

HIV shows a lot of antigenic variability (lines 7– 8). 2 marks

Answer 22

• Antigen on HIV changes

- Specific antibody so the receptor no longer binds to new antigen.

Question 23

So far, these types of vaccine have not been considered safe to use in a mass vaccination programme (lines 14 – 15).
Suggest why they have not been considered safe. 3 marks

Answer 23

• The inactive virus may become active
• The non-pathogenic virus may mutate and harm cells
• Genetic information from HIV may harm cells
• People may become HIV positive after the vaccine

Question 24

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

Answer 24

OSMOSIS

• From a high to low water potential
• Through water channels

ACTIVE TRANSPORT

• Protein pumps
• Against concentration gradient
• Using ATP from respiration

Question 25

Atheroma formation increases a person’s risk of dying. Explain how. 5 marks

Answer 25

• Atheroma is fatty material
• In wall of artery
• Higher risk of blood clot
• Blocks cornary artery
• Less oxygen to the heart
• Reduces respiration
• Causes a heart attack
• Blocks artery to the brain
• Causes stroke