Macronutrients

Question 1

How are nutrients classed?

Answer 1

macronutrients (carbohydrates, proteins, lipids), micronutrients (vitamins, minerals), water and alcohol

Question 2

Function of macronutrients

Answer 2

provide chemical energy that can be converted into electrical (ionic gradients), mechanical (contraction), thermal and chemical energy (protein synthesis)

Question 3

How is energy measured?

Answer 3

Calorie (1 Cal = 1kcal = 1000 calories) and Joule (J)

Question 4

What nutrients provide energy (calories)?

Answer 4

macronutrients and alcohol

Question 5

Which macronutrient has the greatest energy density?

Answer 5

Fat (9kcal/g) compared to protein (4kcal/g) and CHO (3.75kcal/g)

Question 6

What 3 components make up the Total Energy Expenditure (TEE)?

Answer 6

Basal Metabolic Rate (BMR 60-75% of TEE), physical activity (10-40%), thermogenesis (10-20%)

Question 7

What are the forms of energy storage?

Answer 7

1. fat
2. glycogen
3. protein

Question 8

Factors that affect energy requirements

Answer 8

body size, age, activity, pregnancy/lactation, disease, trauma and treatments

Question 9

How can energy expenditure be measured?

Answer 9

direct calorimetry (metabolic chamber), indirect calorimetry (O2/CO2 measurements), doubly labelled water

Question 10

How is energy intake measured?

Answer 10

data from National Diet Nutrition Survey

Question 11

What are carbohydrates?

Answer 11

compounds made of C, H, O

Question 12

Role of carbohydrates in the body

Answer 12

provide energy (40-80% of total energy intake)

Question 13

How can carbohydrates be classified based on their chemical structure?

Answer 13

monosaccharides, disaccharides, polysaccharides

Question 14

What is the nutritional classification of carbohydrates?

Answer 14

• sugars (mono/disaccharides)
• starches
• non-starch polysaccharide (dietary fibre)

Question 15

Why are complex carbohydrates better for health?

Answer 15

not in a readily available form for absorption (e.g. starch, other polysaccharides, resistant oligosaccharides)

Question 16

What is the difference between available and unavailable carbohydrates?

Answer 16

available CHO are glycaemic and can be digested e.g. starch and sugars. Unavailable carbohydrates are non-glycaemic (fermented by bacteria to produce short-chain FAs and gases) e.g. cellulose and hemicellulose

Question 17

What are polyols?

Answer 17

sugar alcohols

Question 18

Examples of polysaccharides

Answer 18

starch, glycogen, non-starch polysaccharides (NSP)

Question 19

What is the difference between extrinsic and intrinsic sugar?

Answer 19

extrinsic sugars can be milk and milk products (e.g. lactose) or non-milk (e.g. sucrose), and intrinsic sugars are in fruit and vegetables (e.g. fructose and glucose)

Question 20

Which type of sugar is most cariogenic?

Answer 20

extrinsic, non-milk sugars

Question 21

What are added sugars?

Answer 21

sugars and syrups added by manufacturer (does not include sugars in fruit juice or honey)

Question 22

What are free sugars?

Answer 22

added sugars plus sugars naturally present in honey, syrups and unsweetened fruit juice (not including milk and sugars contained in cellular structure)

Question 23

What are total sugars?

Answer 23

total amount of sugars from all sources (free sugars plus those from milk and in structure of foods e.g. fruit and vegetables

Question 24

Which sugars are used in diabetic products?

Answer 24

sugar alcohols (absorbed from gut more slowly)

Question 25

What are oligosaccharides?

Answer 25

short chain CHO (3-6 monosaccharides) found in plant seeds and legumes

Question 26

How are oligosaccharides broken down?

Answer 26

cannot be broken down by digestive enzymes, instead is fermented in large intestine

Question 27

What are dextrins?

Answer 27

short chains of glucose formed by partial hydrolysis of starch

Question 28

What is the carbohydrate store in humans?

Answer 28

glycogen

Question 29

What is the storage carbohydrate in plants?

Answer 29

starch

Question 30

What are the 2 types of starch?

Answer 30

amylose and amylopectin

Question 31

Structure of amylose

Answer 31

unbranched chain of glucose with a1-4 glycosidic bonds

Question 32

Structure of amylopectin

Answer 32

long, highly branched polymer of glucose linked by a1,4 glycosidic bonds and branching every 15-30 glucose units via a1,6 glycosidic bonds

Question 33

In what form is starch digestible?

Answer 33

indigestible when raw, digestible when cooked

Question 34

How is starch broken down?

Answer 34

pancreatic amylase

Question 35

Dietary fibre definition

Answer 35

portion of food derived from cellular walls of plants which is poorly digested in humans

Question 36

3 categories of dietary fibre

Answer 36

non-starch polysaccharide (NSP) e.g. cellulose, and non-cellulose polysaccharides (pectins, glucans), resistant oligosaccharides (FOS, GOS), resistant starch

Question 37

What is resistant starch?

Answer 37

a form of dietary fibre composed of starch and starch degradation products not fully digested in small intestine

Question 38

What are oligosaccharides commonly known as?

Answer 38

prebiotics

Question 39

What happens to food not digested in the small intestine?

Answer 39

fermented by colonic microflora to short chain fatty acids and gases

Question 40

3 basic types of short chain fatty acids (SCFAs)

Answer 40

acetic acid, propionic acid, butyric acid

Question 41

Function of short chain fatty acids

Answer 41

health benefits (e.g. propionic acid lowers cholesterol) and act as an energy source

Question 42

What is the maximum percentage of daily energy intake that free sugars should account for?

Answer 42

5%

Question 43

Recommended fibre daily intake

Answer 43

30 g/day

Question 44

What are fats?

Answer 44

compounds made of carbon, hydrogen and oxygen

Question 45

Role of dietary fats

Answer 45

energy, essential fatty acids, fat-soluble vitamins

Question 46

What fats are found in food?

Answer 46

mainly triacylglycerols. Also cholesterol, plant sterols, phospholipids, fat soluble vitamins

Question 47

Structure of triacylglycerol

Answer 47

1 glycerol + 3 FAs

Question 48

Structure of a phospholipid

Answer 48

1 glycerol + 1 phosphate + 2 FAs

Question 49

Structure of a sterol

Answer 49

1 FA

Question 50

What is the basic structure of a fatty acid

Answer 50

CH3(CH2)nCOOH

Question 51

Which structural factors affect properties of fatty acids?

Answer 51

number of C atoms (chain length), presence of double bonds (saturated or unsaturated)

Question 52

Term given to fatty acid with one double bond

Answer 52

monounsaturated

Question 53

Term given to fatty acid with more than one double bond

Answer 53

polyunsaturated

Question 54

What is the configuration of double bonds in unsaturated fats e.g. vegetable oils?

Answer 54

cis (kink created)

Question 55

Which type of isomer of fatty acids is industrially produced?

Answer 55

trans (hydrogenated vegetable oils)

Question 56

Examples of essential fatty acids (EFA)

Answer 56

linoleic acid (LA), alpha-linolenic acid (ALA), LC PUFA AA, EPA, DHA

Question 57

Roles of essential fatty acids (EFA)

Answer 57

cell membranes, biologically active compounds e.g. eicosanoids, growth and development

Question 58

Examples of eicosanoids

Answer 58

prostacyclins (vasodilation, inhibit platelet aggregation), thromboxane (vasoconstriction, stimulate platelet aggregation), leukotrienes (promotes inflammation)

Question 59

Which aspects of growth and development require essential fatty acids?

Answer 59

brain, nervous tissue membrane, photoreceptors in retina

Question 60

Functions of proteins

Answer 60

structural and functional components of cells, provide 10-15% of dietary energy supply

Question 61

How can amino acids be classified by essentiality?

Answer 61

essential, non-essential, conditionally essential amino acids

Question 62

What are essential amino acids?

Answer 62

aa that cannot be synthesised in body

Question 63

What are non-essential amino acids?

Answer 63

can be synthesised from precursors in sufficient amounts

Question 64

What are conditionally essential amino acids?

Answer 64

precursor for aa may be insufficient in certain situations (e.g. during growth/childhood)

Question 65

Examples of essential/indispensable amino acids

Answer 65

isoleucine, leucine, threonine, lysine, valine

Question 66

Examples of non-essential/dispensable amino acids

Answer 66

alanine, arginine, aspartic acid, asparagine, cysteine

Question 67

Examples of conditionally essential amino acids

Answer 67

cysteine, tyrosine, arginine

Question 68

What determines protein structure?

Answer 68

sequence of the amino acid chain and arrangement of amino acid chains

Question 69

Example of a fibrous protein that is elastic (single alpha-helix)

Answer 69

keratin

Question 70

Example of a fibrous protein that is inelastic (more than one alpha-helix)

Answer 70

collagen

Question 71

Example of a globular protein made up of a single folded chain

Answer 71

myoglobin

Question 72

Example of a globular protein made up of more than one folded chain

Answer 72

haemoglobin

Question 73

What bond joins adjacent amino acids?

Answer 73

peptide bond (NH-CO)

Question 74

What is a dipeptide?

Answer 74

2 amino acids joined by peptide linkages

Question 75

What is a polypeptide?

Answer 75

more than 2 amino acids joined by peptide linkages

Question 76

What does protein quality refer to?

Answer 76

which amino acids are present (no just quantity of protein consumed)

Question 77

What is the RNI of protein?

Answer 77

0.75g/kg body weight/day