Nutrition in Humans

Question 1

Balanced diet consists of
2 SOURCES PER

Answer 1

Carbohydrates - bread, rice
Proteins - meat, fish
Lipids - butter, oil
Dietary Fibre - vegetables, whole grains
Vitamins - fruits and vegetables
Minerals - vegetables, meats
Water - are u srs rn

Question 2

Sources + Function of:
Calcium
Iron
Vitamin D
Vitamin C
Vitamin A

Answer 2

Dairy, Strong teeth and bones
Red meat, making haemoglobin
Sunlight, helps body absorb calcium
Citrus, forms part of collagen
Meat, needed to make pigment in retina

Question 3

How do energy requirements vary

Answer 3

Age, activity levels, pregnancy

Question 4

Mouth/Salivary Glands

Answer 4

Mechanical Digestion - teeth break food into smaller pieces (>SA:V ratio)
Amylase saliva digest starch into maltose
Food is shaped into a bolus by the tongue and lubricated in saliva

Question 5

Oesophagus

Answer 5

Tube that connects mouth to stomach
Wave-like contractions push the bolus down without relying on gravity

Question 6

Stomach

Answer 6

Food mechanically digested by churning actions
Protease enzymes chemically digest proteins
HCL kills bacteria in food, provides optimum pH of 2 for enzymes

Question 7

Duodenum

Answer 7

Enzymes produced here and in the pancreas finish digesting the food out of the stomach
pH of small intestine is slightly alkaline to neutralise the fluid out of the stomach

Question 8

Ileum

Answer 8

Absorption of digested food molecules
Long and has a highly folded surface lined with villi to increase SA over which absorption can take place

Question 9

Large intestine

Answer 9

Water is absorbed from remaining material to produce faeces, stored in the rectum and egested through the anus

Question 10

Pancreas

Answer 10

Produces Amylase, Protease and Lipase

Question 11

Liver

Answer 11

Produces bile to emulsify fats

Question 12

Gall Bladder

Answer 12

Stores Bile

Question 13

Peristalsis

Answer 13

Circular muscles behind bolus contract Longitudinal muscles ahead contract
Circular muscle layer contract to push bolus forward
Mucus constantly lubricates food mass
Fibre provides roughage for muscles to push against

Question 14

Amylase
Maltase
Protease
Lipase
Pepsin

Answer 14

Starch -> Maltose
Salivary glands, pancrease, small intest.
Maltose -> Glucose
Proteins -> Amino acids
Pancreas, small intestine
Lipids -> glycerol + fatty acids
Pancreas
Proteins-> Smaller polypeptide chains
Stomach

Question 15

Role of Bile:

Answer 15

Neutralising HCL from stomach - bile is slightly alkaline
Emulsifing Fats - increases SA:V ratio

Question 16

Adaptation of Villi

Answer 16

Microvilli on villus further increase SA
Short diffusion distance: one cell thick
Steep concentration gradient:
-Network of blood capillaries transporting glucose and amino acids away from the small intestine
-A lacteal through the centre of the villus transports fatty acids and glycerol away from the small intestine

Question 17

Practical: Energy Content - Food sample

Answer 17

Measure out 25cm^3 of water and pour into boiling tube
Record initial temp of water
Weigh initial mass of food sample
Light the food sample and hold it 2cm from tube until it is completely burned
Record final temp of water
Weigh the mass of remaining food
Repeat with different food samples
Energy transferred = mass of water x 4.2 x increase in temp / mass of food

Question 18

Test for starch

Answer 18

Iodine
Orange brown -> blue black

Question 19

Test for protein

Answer 19

Biuret solution
Blue -> violet/purple

Question 20

Test for lipids

Answer 20

4cm^3 ethanol and shake
Colourless -> cloudy

Question 21

Test for glucose

Answer 21

Benedict
Light blue -> brick red
(depends on concentration)