2012 Unit 1 Jan

Question 1

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

Answer 1

• Crush/grind;
• With ethanol
• Then add water
• Goes white

Question 2

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

Answer 2

• Phosphate
• Instead of one of the fatty acids /
and two fatty acids

Question 3

Explain what is meant by an unsaturated fatty acid.

Answer 3

• Double bonds (present)
• Not saturated with hydrogen;
• (Double bonds)
between carbon atoms

Question 4

The diaphragm helps to bring about the changes shown by the curve A. Before using inhaler. Lower than curve B
Explain how.

Answer 4

• (Diaphragm/diaphragm muscle) relaxes/relaxed;
• Domed shape / (diaphragm) moves up;
• Increases pressure;
• Decreases volume;

Question 5

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

Answer 5

• Extend/extrapolate curve/graph

* (Read off where) it flattens/ reaches maximum / peaks;

Question 6

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. Without inhaler

Answer 6

• (Without inhaler) narrower bronchioles / bronchioles not dilated;
• Muscle (surrounding bronchioles) contracted;
• Less air able to pass through

Question 7

The active transport of substances from the cell into the blood

Answer 7

• Mitochondria respire;
• Release energy/ produce ATP;
• Transport against gradient;
• Infolding of membrane;
• Increases area;
• More proteins for active transport

Question 8

The synthesis of enzymes

Answer 8

• Ribosomes make proteins/ enzymes;
• Enzymes are proteins
• Mitochrondria respire;
• Release energy/produce ATP
• (Energy/ATP) for protein / enzyme synthesis

Question 9

Rapid diffusion of substances from the lumen of the gut into the cytoplasm

Answer 9

• Microvilli increase area / have large area;

Question 10

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

Answer 10

• Something that increases chance/probability

Question 11

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

Answer 11

• Left ventricle;

Question 12

Explain how the structure of the left ventricle causes this high pressure.

Answer 12

• Thick muscle/thick walls;

Question 13

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

Answer 13

• Antibody/variable region has specific sequence/primary structure
• The tertiary structure of the binding site;
• Complementary to with these antigens;
• Forms complex between antigen and antibody;

Question 14

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

Answer 14

• Occupies/blocks/binds to active site;

* Substrate no longer complementary to / enzyme-substrate complex not formed;

Question 15

Aspirin may reduce the risk of myocardial infarction

Answer 15

• Prevents/reduces formation of thromboxane;
• Blood clots do not form / less likely to form;
• Do not block) coronary arteries
• Heart muscle/wall gets oxygen

Question 16

Vaccines protect people against disease. Explain how

Answer 16

• Vaccines contain antigens / antigens are injected;
• Dead pathogens / weakened pathogens;
• Memory cells made;
• On second exposure memory cells produce antibodies
• Rapidly produce antibodies / produces more antibodies;
• Antibodies destroy pathogens
• Herd effect / fewer people to pass on disease;