revision - nutrition + enzymes feb 2023

Question 1

chemical elements in carbohydrates

Answer 1

carbon, hydrogen + oxygen

Question 2

chemical elements in protein

Answer 2

all have hydrogen, nitrogen, carbon + oxygen
most have sulfur

Question 3

chemical elements in lipids

Answer 3

all contain carbon, hydrogen + oxygen
some have nitrogen, sulfur and phosphorus

Question 4

describe the structure of carbs, proteins and lipids

Answer 4

larger molecules made from smaller, basic units

Question 5

building blocks of carbs

Answer 5

made from starch and glycogen (polysaccharides), which are made from simple sugars (monosaccharides like glucose and fructose)

Question 6

building blocks of protein

Answer 6

amino acids

Question 7

building blocks of lipids

Answer 7

fatty acids and glycerol

Question 8

test used for detecting glucose

Answer 8

benedict’s solution - orange/brick red if there is, blue, greeny-yellow if there isn’t much (requires heating to 80c)

Question 9

test used for detecting protein

Answer 9

biurets solution - blue = none, lilac = has protein

Question 10

test used for detecting lipids

Answer 10

emulsion test - add ethanol and water to solution and shake. milky white in presence of lipids

Question 11

test used for detecting starch

Answer 11

iodine test - add iodine (blue/black if there’s starch, stays brown/orange if there isn’t)

Question 12

functions of enzymes

Answer 12

biological catalysts in metabolic reactions, speeding up the reactions without really being affected itself

Question 13

how temperature effects enzymes

Answer 13

Enzymes have an optimum temperature which is the temperature where the enzyme works the most effectively. enzymes aren’t living so they can’t die. but when enzymes exceed their optimum temperature, the shape of their active site changes, meaning the lock and key mechanism no longer works. we say that the enzyme is denatured

Question 14

experiment with enzymes and temperature

Answer 14

iodine test for starch, heating enzymes and solution to different temperatures (use amalyse and starch)

Question 15

what food groups would a balanced diet contain

Answer 15

carbs, proteins, lipids, vitamins, minerals, water, dietary fibre

Question 16

sources and purposes of carbs

Answer 16

Carbohydrates (e.g.potatoes and bread)
Carbohydrates provide energy to our bodies and are one of the most important parts of our diets. They give us a steady source which keeps us going for a while. Too little carbs and we feel tired and lack energy, but too much may lead to obesity (over time), but in short term we have too much energy.

Question 17

sources and purposes of proteins

Answer 17

Protein
(e.g meats like sausage or fish, but also things like nuts) Proteins are required to build up new cells, growth or muscle. They also form antibodies as part of our immune system. This is an incredibly important part of our diet.Too little can result in stunted growth, disease or bad immunity. However, too much can mean obesity, and sometimes, organ damage

Question 18

sources and purposes of lipids

Answer 18

Lipids
(e.g. avocado is a fruit which is very high in lipids, but other examples of lipids are things like butter) Lipids, put simply as fat and oils, is a long term energy storage. They also form protective layers around important organs and keep us warm. They make up a smaller proportion of our diet but are still important. Too little causes fatigue or starvation (extreme case), but too much can mean obesity, heart disease or increased risk of cancer.

Question 19

purposes of vitamins in general

Answer 19

Vitamins
Vitamins help to keep specific tissues in the body strong, keeping us healthy. A lack of vitamins can cause certain disease It is hard to have an excess of natural vitamins, but overdoses of vitamin supplements can cause long term damage.

Question 20

effect of pH on enzymes

Answer 20

also denatures if pH is not right. Most enzymes optimum pH is around 7 but some exceptions, e.g. Pepsin with optimum pH of 2 cause it works in stomach (acidic place)

Question 21

uses and sources of vitamin A

Answer 21

Vitamin A - used for vision, growth, reproduction, immunity + cell division (found in vegetables, fish oils, etc)

Question 22

uses and sources of vitamin C

Answer 22

Vitamin C - reduces risk of heart disease and dementia, lowers blood pressure, protects body against free radicals (citrus fruits, broccoli etc)

Question 23

uses and sources of vitamin D

Answer 23

Vitamin D - help body absorb and retain calcium and phosphorus (the sun, fish, egg)