2014 Unit 1

Question 1

Describe how phospholipids are arranged in a plasma membrane

Answer 1

• Bilayer
• Hydrophobic/ fatty acid/ lipid tails to inside
• Polar/ phosphate group/ hydrophilic head to outside

Question 2

Cells that secrete enzymes contain a lot of rough endoplasmic reticulum (RER) and a
large Golgi apparatus.

Describe how the RER is involved in the production of enzymes.

Answer 2

• Rough Endoplasmic Reticulum has ribosomes

* To make a protein (which is an enzyme)

Question 3

Describe how the Golgi apparatus is involved in the secretion of enzymes

Answer 3

• Golgi Apparatus modifies proteins
• Golgi Apparatus packages/ puts into Golgi vesicles
• Transport to cell surface/ vacuole

Question 4

Give two risk factors associated with coronary heart disease.

Answer 4

• Smoking
• High (blood) cholesterol
• High blood pressure
• Obesity
• Gender
• Age
• Genes

Question 5

During a myocardial infarction, areas of heart muscle begin to die.
Explain why.

Answer 5

• Reduced blood flow in coronary artery/ coronary artery blocked
• Less/no oxygen
• Respiration drops/stops (so cells begin to die)

Question 6

Describe how bacteria are destroyed by phagocytes.

Answer 6

• Phagocyte engulfs to form phagosome
• Lysosome empties contents into phagosome
• Releasing enzymes that digest/hydrolyse bacteria

Question 7

Give two structures a bacterial cell may have that a white blood cell does not have

Answer 7

• Cell wall
• Capsule layer
• Circular DNA
• DNA without histones
• Flagellum
• Plasmid

Question 8

Give two structures in the epithelial cells in the small intestine that are adaptations that make it possible for the rapid absorption of glucose

Answer 8

• Microvilli
• Mitochondria
• Vesicles

Question 9

Microvilli/Mitochondria/ Vesicles, explain how it is an adaptation to make possible the rapid absorption of glucose in small intestine.

Answer 9

• Microvilli increase surface area for transport proteins/ for diffusion)
• Mitochondria to supply ATP/ energy for active transport/ co-transport
• Vesicles to bring carrier proteins to membrane

Question 10

The absorption of glucose into the cell leads to the movement of water into the cell.
Explain how

Answer 10

• Lowers water potential of the cell

* Water moves in by osmosis

Question 11

Explain how the pressure in the dog’s ventricle is

related to blood flow into the aorta.

Answer 11

• Ventricle pressure rises then blood starts to flow into aorta
• Because pressure above that in aorta causes semi-lunar valve to open/ pressure below that in aorta causes semi-lunar valve to be shut
• Ventricle pressure starts to fall so blood flow falls

Question 12

Explain how the pressure in the dog’s ventricle is

related to the thickness of the ventricle wall

Answer 12

• Thickness of wall increases because ventricle wall contracts
• Contraction causes an increase in pressure

Question 13

Use your knowledge of digestion to suggest how the addition of the inhibitor could lead
to a lower blood glucose concentration.

Answer 13

• Fewer enzyme-substrate complexes formed
• (With inhibitor) less/no starch digest to maltose
• So less glucose from maltose
• So less absorption of glucose

Question 14

People given whole-cell vaccines were more likely to develop harmful side effects than
the people given the vaccines containing parts of the bacterial cells. Explain why

Answer 14

Whole Cell Vaccines
• Some might still be alive/active
• If so bacteria could reproduce
• Bacteria or toxins attacking/ killing person’s cells

Question 15

People given whole-cell vaccines produced a greater range of antibodies against the
bacterium than the people given the vaccines containing parts of the bacterial cells

Answer 15

Whole Cell Vaccines
• Contains many different/ greater range of antigens
• Each antigen causes its own immune response

Question 16

In humans, the enzyme maltase breaks down maltose to glucose.This takes place at normal body temperature.
Explain why maltase:
• only breaks down maltose
• allows this reaction to take place at normal body temperature.

Answer 16

• Tertiary structure means active site complementary to substrate
• Induced fit- When a substrate molecule collides with an enzyme, if its composition is specifically correct, the shape of the enzyme’s active site will change so that the substrate fits into it
• Enzyme is a catalyst
• Lowers activation energy
• By forming enzyme-complex

Question 17

Scientists have investigated the effects of competitive and non-competitive inhibitors of
the enzyme maltase.
Describe competitive and non-competitive inhibition of an enzyme

Answer 17

• Inhibitors prevent formation of enzyme-substrate complexes
Competitive Inhibition
• Inhibitor similar shape to substrate
• Binds to active site of enzymes
• Inhibition can be overcome by more substrate
Non-competitive Inhibition
• Inhibitors binds to site on enzyme other than active site
• Changes shape of active site
• Cannot be overcome by adding more substrate