Energy, carbohydrates and fats T1

Question 1

State what will happen to the additional energy if an individual takes in more energy than is required.
(1)

Answer 1

-Stored as glycogen/fat/lipids in body cells.

Question 2

Explain the meaning of causal relationship.

1

Answer 2

-Change in one variable is the direct result of a change in another variable.

Question 3

Describe how amino acids join together to form the 3-D structure of an amino acid.
(4)

Answer 3

• Peptide bonds joining between amino acids.
• Between amino group and carboxyl group.
• Folding of primary structure held together by bonds.
• Disulphide bridges, hydrogen bonds, ionic bonds.
• Between R groups.

Question 4

What are the factors that increase risk of CVD?

Answer 4

• High alcohol consumption
• Lack of activity
• High salt diet
• High saturated fat intake
• Stress
• High LDL cholesterol intake

Question 5

Describe how glucose moves into the cells by facilitated diffusion.
(2)

Answer 5

• Carrier protein in cell surface membranes.
• Glucose moves from high to low concentration gradient.
• Glucose binds to carrier protein, carrier protein changes shape to move across membrane.

Question 6

Explain how the structure of glycogen allows it to be an energy store.
(3)

Answer 6

• Polymer of glucose.
• To provide glucose for respiration.
• Branches/contains 1,6 bonds for rapid hydrolysis.
• Compact to allow a large amount of glucose/energy to be stored in a small space.
• Insoluble therefore no osmotic effect on cells.

Question 7

Compare HDL’s and LDL’s.

Answer 7

• LDL cholesterol is deposited in the artery walls causing atheroma’s.
• HDL cholesterol lowers blood cholesterol levels and helps remove fatty plaques of atherosclerosis.
• Therefore it is preferable to have a higher HDL:LDL ratio.
• Saturated fat in the diet is shown to increase HDL and LDL levels.
• Unsaturated fat decreases both LDL and HDL levels.

Question 8

Compare saturated and unsaturated fats.

Answer 8

-Saturated fats, fatty acid chains contain maximum no. of hydrogen atoms.
-Their fatty acid hydrocarbon chain is long and straight.
/
-Monounsaturated fats have a double bond between the carbon atoms in each fatty acid chain.
-Polyunsaturated fats have a larger no. of double bonds.
-This double bond causes a kink in the hydrocarbon chain.

Question 9

What is the structure of a triglyceride.

Answer 9

• Three fatty acids
• One glycerol molecule
• Ester bond holds glycerol and fatty acids together, by a condensation reaction, removing water.

Question 10

Describe the reaction that joins two molecules forming a disaccharide.
(2)

Answer 10

• Condensation reaction

- Water is formed/involving OH groups on both molecules

Question 11

What is the structure of starch?

Answer 11

• Compact of amylose and amylopectin.
• Amylose is a straight chain of 1,4 glycosidic bonds, spiral shape. Compact of glucose molecules.
• Amylopectin is also compact of glucose molecules. But has 1,6 glycosidic bonds side branches onto main chain.