energy intake

Question 1

what is the first law of thermodynamics

Answer 1

Energy cannot be created or destroyed but only changed between different forms.

Question 2

what energy do plants use and what do they use it for

Answer 2

Plants use solar energy to synthesise proteins, fats & CHOs.

Question 3

what energy do animals use and what for

Answer 3

Animals depend on the chemical energy in these plant molecules, taken as food, as their energy source.

Question 4

what is chemical energy used to perform

Answer 4

mechanical work, electrical work & chemical work.

Question 5

what is 1 calorie

Answer 5

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

Question 6

what is 1 kilocalorie (1 kcal or 1 Calorie)

Answer 6

amount of heat required to raise temperature of 1kg of water by 1degreeC

Question 7

convert 1 KJ to J

Answer 7

1 kilojoule (kJ) = 1000 J = 103 J

Question 8

convert 1 MJ to J

Answer 8

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

Question 9

convert 1kcal to KJ

Answer 9

1 kcal = 4.184 kJ

Question 10

convert 1 JK to kcal

Answer 10

1 kJ = 0.239 kcal

Question 11

what does capital or non capital C on calorie mean

Answer 11

When word calorie has a capital C were talking about kilocalories, when it has small c were talking about calories

Question 12

what is the gross energy of food

Answer 12

Total chemical energy in food

Question 13

chemical energy stored in the bonds of what

Answer 13

Protein + Carbohydrate + Lipids + Alcohol

Question 14

gross energy can be measured using what

Answer 14

a bomb calorimeter (this changes energy into heat):

Organic material + O2 -> CO2 + H2O + oxides of N + S + heat (GE)

Question 15

name the 2 types of bomb calorimetry and explain them

Answer 15

Ballistic
Temperature rise of metal jacket is measured directly.

Adiabatic
Water-cooled jacket, kept at constant temperature as sample burns.
More accurate than ballistic.

Question 16

what is energy lost in

Answer 16

Faeces (microbes, undigested fibre)

Urine (incomplete oxidation of N to urea)

Combustible gases from microbial action: H2, CH4

Question 17

how do u work out the metabolisable energy

Answer 17

ME = Gross energy minus urinary & faecal energy losses.

This is the E available to the body.

Question 18

what is metabolizable energy

Answer 18

the energy we can used form the foods

Question 19

what is the metabolizable energy per gram of fat

Answer 19

37KJ or 9kcal

Question 20

what is the metabolizable energy per gram of protein

Answer 20

17KJ or 4kcal

Question 21

what is the metabolizable energy per gram of carbs

Answer 21

16KJ or 3.75kcal

Question 22

what is the metabolizable energy per gram of alcohol

Answer 22

29KJ or 7kcal

Question 23

what is the metabolizable energy per gram useful for estimating

Answer 23

estimating E which can be obtained from food by healthy individuals on a normal diet

Question 24

name factors affecting metabolizable energy

Answer 24

Gastro-intestinal disease (celiac disease)e.g. malabsorption by gut - Finger like projections (microvilli) become chopped and lost, due to attack from bodys immune system. so less absorption

Unusual diet composition e.g. sports supplements (such as protein supplements)

Renal disease e.g. increased protein loss in urine
(Protein in urine usually is very low but in renal disease more and larger proteins are lost in urine

Diabetes mellitus i.e. increased glucose loss in urine

Parenteral nutrition i.e. fed intravenously so no gut losses

High fibre diets i.e. low carbohydrate absorption

Question 25

for accurate measure of metabolizable energy in an individual what needs measured

Answer 25

the energy content of the food, urine, and faeces by bomb calorimetry + volume of combustible gases (if possible).

Question 26

what is energy balance

Answer 26

the relationship between energy intake and energy output.

Energy = Energy – Energy
Balance Intake Expended

Question 27

what is positive energy balance

Answer 27

Energy intake > energy expenditure

Question 28

what is negative energy balance

Answer 28

Energy intake < energy expenditure

Question 29

Achievement of energy balance is driven by what

Answer 29

1st law of thermodynamics.

Question 30

what happens to body stored if energy intake = energy expenditure

Answer 30

body stores remain constant

Question 31

what can energy be stored as

Answer 31

fat, glycogen, or protein