Topic 1 1.3

Question 1

Energy budget

Answer 1

Amount of energy taken in by an organism (in food) and the amount of energy used up by an organism

Question 2

Energy imbalance: weight gain

Answer 2

When energy intake is higher than energy output and the body turns excess energy into fat reserves
-> if energy difference is large and sustained over a long time period then the person could become obsese

Question 3

Energy imbalance: weight loss

Answer 3

When energy intake is lower than energy output and the body gets more energy from somewhere else by turning some of its fat reserves into energy
-> if energy difference is large and sustained over a long time period then the person could become underweight

Question 4

Carbohydrates

Answer 4

Large, complex molecules (polymers) made up of long chains of monosaccharides (monomers)
. There’s three types of carbohydrates:
- monosaccharides: small basic molecular units that make up diasaccharides and polysaccharides
- disaccharides: two monosaccharides joined together
- polysaccharides: molecules made up of a large number of monosaccharides joined together

Question 5

Monosaccharides

Answer 5

They are single sugar units (monomers) that are very soluble
. Glucose, galactose and fructose are examples of hexose sugars because they contain 6 carbon atoms
Glucose:
- main source of energy in plants and animals -> its soluble so it can be easily transported and its chemical bonds contain lots of energy
Two types of glucose
- alpha glucose
- beta glucose

Question 6

Disaccharides

Answer 6

Monosaccharides join together by glycosidic bonds in a condensation reactions (where a molecule of water is released) where a hydrogen atom from one monosaccharide bonds to a hydroxyl (OH) group on the other
-> disaccharides are also soluble (not as much as monosaccharides) and their chemical bonds store more energy than monosaccharides

Question 7

Hydrolysis

Answer 7

Breaking down large molecules into smaller ones by the addition of water

Question 8

Different types of Polysaccharides: starch (amylose) -> monomer, structure and function

Answer 8

Monomer: a-glucose
Structure: 1-4 glycosidic bonds
- long, unbranched chain of glucose
- coiled
- compact -> compact as a result of the coiled structure -> allows it to be a good storage molecule as lots fit into a small place (function)
- insoluble -> no osmotic effect on cells

Question 9

Different types of Polysaccharides: starch (amylopectin) -> monomer, structure and function

Answer 9

Monomer: a-glucose
Structure: 1-4 and1-6 glycosidic bonds
- long branched chain of glucose
- lots of side branches -> allow a rapid hydrolysis to release glucose (used in respiration) and provide a large SA for enzymes in hydrolysis to work so glucose is released quickly
- insoluble -> no osmotic effect on cells

Question 10

Different types of Polysaccharides: glycogen -> monomer, storage, functions

Answer 10

Monomer: a-glucose
Structure: 1-4 and 1-6 glycosidic bonds
- more side branches (highly branched) -> allow rapid hydrolysis to release glucose
- compact -> large amount of glucose can be stored in a small place
- insoluble -> no osmotic effect on cells
- large molecules (can’t diffuse across membranes)
Functions: main source of energy in animals (store of excess glucose)

Question 11

Triglycerides

Answer 11

Type of lipid made up of one glycerol with three fatty acids attached through three ester bonds
-> fatty acid molecules:
- they have long tails made up of hydrocarbons which are hydrophobic making lipids insoluble in water
- they consist of the same basic structure but the hydrocarbon tail varies (represented as R)

Question 12

Formation of triglycerides

Answer 12

. Formed by condensation reactions and broken up by hydrolysis reactions
- three fatty acids and one glycerol molecule are joined together by ester bonds -> a hydrogen atom on the glycerol molecule bonds a hydroxyl (OH) group on the fatty acid

Question 13

Saturated lipids

Answer 13

Saturated lipids are mainly found in animal fats
-> diet high in saturated fats increases your risk of developing CVDs as it increases blood cholesterol levels
Properties:
. They don’t have double bonds between carbon atoms in their hydrocarbon tails -> every carbon is attatched to at least two hydrogen atoms (lipid is saturated with hydrogen)
. They have higher melting points because of strong intermolecular bonds between triglycerides

Question 14

Unsaturated lipids

Answer 14

Mainly found in plants
Two types:
- monosaturated: only one double bond between carbons
- poly saturated: 2 or more double bonds between carbons
Properties:
. They have lower melting points because kinks prevent the unsaturated chains packing closely together increasing distance between molecules which weakens the intermolecular forces
. They have double bonds between carbon atoms causing the chains to kink

Question 15

Cholesterol

Answer 15

. Lipid which is insoluble in water -> needs to combine with proteins to form lipoproteins to be transported in the bloodstream

Question 16

Cholesterol: high density lipoproteins (HDL)

Answer 16

. Mainly protein
. They reduce total blood cholesterol when level is too high -> transport cholesterol from body tissues to the lover where its recycled or excreted
. They help to remove fatty plaques of atherosclerosis

Question 17

Cholesterol: low density proteins (LDL)B

Answer 17

. Mainly lipid
. They increase total blood cholesterol when too low -> transport cholesterol from the liver to the blood, circulating until needed by cells
. It may be deposited in the artery wall forming artheromas

Question 18

Reducing risk factors of CVD: diet

Answer 18

Food standards agency encourages food manufacturers to label their products to show the amount of saturated fat in them so people can make an informed choice about what they eat

Question 19

Reducing risk factors of CVD: obesity

Answer 19

Obese people are more likely to develop CVD
. There’s two indicators for obesity
- BMI: body mass (kg) / height 2 (m2) -> all above 30
- waist-to-hip ratio: waist (cm) / hip (cm) -> men: above 1. Women: above 0.85
-> if a person is obese or overweight they can:
. Reduce calorie consumption
. Exercising more regularly
. Change in diet (less saturated fats)

Question 20

Reducing risk factors of CVD: smoking

Answer 20

. TV adverts and warnings in cigarette packets about the risks of smoking
. NHS gives free advice and prescribes nicotine patches

Question 21

Reducing risk factors of CVD: exercise

Answer 21

Campaigns have been set out to encourage people to exercise more frequently

Question 22

Different glycosidic bonds: maltose

Answer 22

Disaccharide: maltose
Monosaccharides: a-glucose + a-glucose
Bonds present: 1-4 glycosidic

Question 23

Different glycosidic bonds: lactose

Answer 23

Disaccharide: lactose
Monosaccharides: B-glucose + galactose
Bonds present: 1-4 glycosidic

Question 24

Different glycosidic bonds: sucrose

Answer 24

Disaccharide: sucrose
Monosaccharides: a-glucose + fructose
Bonds present: 1-2 glycosidic