intro to energy and nutrients

Question 1

FAT - FUNCTIONS

Answer 1

Energy source

Energy store - as largest energy store in body

Cell membranes (phospholipids - these are fats)

Supply essential nutrients

Precursors for hormones - eg sex hormones are steroid hormones that need a fat source to be synthesised adequately

Improve palatability

Question 2

FAT - SOURCES

Answer 2

Main type of fat is triglycerides.

Triglycerides contain 3 fatty acids.

Fatty acids can be saturated or unsaturated.

Triglycerides consist of a mixture of fatty acids.

Question 3

Carbohydrate - functions

Answer 3

Energy source – for immediate use and stores.

Glucose main energy source.

Part of RNA (ribose) and DNA (deoxyribose).

Integral feature of many proteins and lipids (e.g. glycoproteins), especially in cell membranes.

Question 4

Carbohydrate - sources

Answer 4

Large part of energy in human diets.

Mainly obtained from plant material.

Cereal products, vegetables, fruit, nuts.

Milk and milk products.

Sugars in manufactured foods, e.g. sweets, cakes, drinks, many breakfast cereals.

Question 5

role of nutrients

Answer 5

protein, fat, carbs, and alcohol provide energy

Question 6

explain 1 calorie

Answer 6

amount of heat required to raise temperature of 1g of water by 1C.

Question 7

explain 1 kilocalorie (1 kcal or 1 Calorie)

Answer 7

= amount of heat required to raise temperature of 1kg of water by 1C.

Question 8

convert KJ to J

Answer 8

1 kilojoule (kJ) = 1000 J = 103 J

Question 9

convert 1 MJ to J

Answer 9

1 megajoule (MJ) = 1,000,000 J = 106 J

Question 10

convert 1Kcal to KJ

Answer 10

1 kcal = 4.184 kJ

Question 11

convert 1KJ to Kcal

Answer 11

1 kJ = 0.239 kcal

Question 12

explain the principles of energy balance

Answer 12

the energy from our energy intake circulates in the blood stream and some of it is stored, excreted, or released as energy expenditure. 60% of energy expenditure goes towards BMR (basal metabolic rate = how much energy our tissues etc use up. it varies daily, but less than the following 2, 10% towards dietary and cold induces thermogenesis (heat production), and 15-30% towards physical activity

Question 13

what is energy is foods present as

Answer 13

a mixture of energy yielding nutrients.

Question 14

explain food energy densities

Answer 14

Different foods have different energy densities.

low energy density foods have high water content, and high energy densities have low water content

Question 15

how much Metabolisable energy per gram does fat produce

Answer 15

37JK or 9 Kcal

Question 16

how much Metabolisable energy per gram does protein produce

Answer 16

17 KJ or 4 Kcal

Question 17

how much Metabolisable energy per gram does carbs produce

Answer 17

16KJ or 3.75 Kcal

Question 18

how much Metabolisable energy per gram does alcohol produce

Answer 18

29KJ or 7 Kcal

Question 19

how many KJ are in 1Kcal

Answer 19

4.184

Question 20

how many Kcal are in 1 KJ

Answer 20

0.239

Question 21

how do you work out % of energy from fat, protein, carb and alcohol calculation

Answer 21

you times the NO. grams of fat for example by fats Metabolisable energy per gram, to work out the fat energy in KJ. and then divide that by the persons whole KJ of energy from their diet and times that by 100, to get the % of energy.

In a diet providing 8000 kJ of energy and 94 g of fat…
Fat provides 94 x 37 = 3478 kJ energy.
Fat intake = (34788000) x 100 = 43% energy.

Question 22

what sources does food energy come from

Answer 22

fat, protein and carbs

Question 23

what sources does total energy come from

Answer 23

fat, protein, carbs and alcohol

Question 24

what are vitamins

Answer 24

Organic substances or groups of related substances found in foods which have specific biochemical functions in the body and are required in very small amounts.

vitamins are obligatory

Question 25

what are minerals and trace elements

Answer 25

Inorganic elements with a physiological function in the body.

Must be supplied in the diet.

Minerals required in milligrams per day (mg/d).

Trace elements required in micrograms per day (µg/d).

Iron requirement is 5-15 mg/d but sometimes called trace element.

Question 26

examples of minerals

Answer 26

Calcium
Chloride
Fluoride
Iron
Magnesium
Phosphorus
Potassium
Sodium
Sulphur

Question 27

examples of trace elements

Answer 27

Boron Selenium
Chromium Tin
Cobalt Vanadium
Copper Zinc
Germanium
Iodine
Manganese
Molybdenum
Nickel