Wednesday 11th January 2012

Question 1

Some seeds contain lipids. Describe how you could use the emulsion test to show that a seed contains lipids. 3 marks

Answer 1

• Crush
• Add ethanol
• Add water
• Forms emulsion - cloudy

Question 2

A triglyceride molecule is formed by condensation. From how many molecules is this triglyceride formed? 1 mark

Answer 2

4

Question 3

The structure of a phospholipid molecule is different from that of a triglyceride. Describe how a phospholipid is different. 2 marks

Answer 3

• 2 fatty acid tails

- Phosphate group

Question 4

Use the diagram to explain what is meant by an unsaturated fatty acid. 1 mark

Answer 4

• Double bonds

- Between carbon atoms

Question 5

The diaphragm helps to bring about the changes shown by the curve A. Explain how. 3 marks

Answer 5

• Diaphragm relaxes
• Domed shape
• Increased pressure
• Decrease volume

Question 6

You could use curve A to find the total volume of air that this person could breathe out in one complete breath. Describe how. 2 marks

Answer 6

• Extend graph

- Read of the graph where it flattens

Question 7

The inhaler which the person used contained a substance that dilates bronchioles. Use this information to explain why curve A is different from curve B. 2 marks

Answer 7

• Without inhaler the bronchioles are narrower
• Muscles surrounding the bronchioles contract
• Less air able to pass through

Question 8

This cell is adapted for the three functions listed below. Use the diagram to explain how this cell is adapted for each of these functions.
Use a different feature in the diagram for each of your answers.
The active transport of substances from the cell into the blood. 2 marks

Answer 8

• Mitochondria respire
• Release ATP
• Transport against gradient

Question 9

This cell is adapted for the three functions listed below. Use the diagram to explain how this cell is adapted for each of these functions.
Use a different feature in the diagram for each of your answers.
The synthesis of enzymes. 2 marks

Answer 9

• Ribosomes make proteins/enzymes

- Enzymes are proteins

Question 10

This cell is adapted for the three functions listed below. Use the diagram to explain how this cell is adapted for each of these functions.
Use a different feature in the diagram for each of your answers.
Rapid diffusion of substances from the lumen of the gut into the cytoplasm. 1 mark

Answer 10

• Microvilli - increase surface area.

Question 11

Scientists who investigate disease may look at risk factors. What is a risk factor? 1 mark

Answer 11

• Something that increases chance

Question 12

The scientists concluded that substances in the air from vehicle exhausts did not cause the increase in asthma between 1976 and 1980. Explain why. 3 marks

Answer 12

• Correlation does not mean causation
• Other factors
• Negative correlation

Question 13

The human heart has four chambers.

In which one of the four chambers of the human heart does pressure reach the highest value? 1 mark

Answer 13

• Left ventricle

Question 14

Explain how the structure of this chamber causes this high pressure. 1 mark

Answer 14

Thick walls

Question 15

What is the evidence from the diagram that this antibody has a quaternary structure? 1 mark

Answer 15

4 polypeptide chains

Question 16

Scientists use this antibody to detect an antigen on the bacterium that causes stomach ulcers. Explain why the antibody will only detect this antigen. 3 marks

Answer 16

• Antibody region has a specific amino acid sequence
• Shape of the binding site
• Complementary with antigens
• Forms complex between antigen and antibody.

Question 17

Name the monomers that make up the active site of the enzyme. 1 mark

Answer 17

• Amino acid

Question 18

Aspirin only affects one of the enzymes in this pathway. Use information in lines 5 – 7 to explain why aspirin does not affect the other enzymes. 2 marks

Answer 18

• Affects one amino acid

- Not found in all active sites

Question 19

Aspirin is an enzyme inhibitor. Explain how aspirin prevents substrate molecules being converted to product molecules. 2 marks

Answer 19

• Occupies active site

- E-S no longer form

Question 20

Aspirin may reduce the risk of myocardial infarction (lines 8 – 12). Explain how. 3 marks

Answer 20

• Prevents formation of thromboxane
• Blood clots less likely to form
• Don’t block coronary arteries
• Heart muscle gets oxygen

Question 21

Vaccines protect people against disease. Explain how. 5 marks

Answer 21

• Vaccines contain antigens
• Dead pathogens
• Memory cells made
• On second exposure memory cells produce antibodies
• Rapidly produce antibodies / produces more antibodies
• Antibodies destroy pathogens;
• Fewer people to pass on disease;

Question 22

Oral rehydration solutions (ORS) are used to treat diarrhoeal disease. What does an ORS consist of and how does it work? 5 marks

Answer 22

• Contains glucose
• Sodium
• Co-Transport
• Sodium and glucose taken up from the lumen.
• Increases water potential gradient
• Water taken up by osmosis