Download 3.3

Intermediate 1 Chemistry
Section 3.3 Learning Outcomes
1
A balanced diet provides the body with all the essential elements
and compounds.
2
Elements are present in the diet and in the body as chemical
compounds and not as free elements.
3
Essential compounds include Carbohydrates, Fats and Proteins.
4
The major constituent elements of the human body are Oxygen,
Carbon, Hydrogen and Nitrogen.
5
More than 60% of body weight is made up of water.
6
Minerals supply the body with small quantities of Calcium for bones
and teeth, Iron for the blood, as well as trace elements.
e.g. Zinc, Copper, Selenium and Iodine.
7
Some trace elements if taken in too large quantities are toxic.
e.g. Copper.
8
Carbohydrates are an important class of food made by plants.
9
Carbohydrates are used by the body to produce energy.
10
Carbohydrates are compounds containing Carbon, Hydrogen and
Oxygen. (C, H, O).
11
Carbohydrates can be divided into
a)Sugars
e.g. Sucrose (table sugar), Glucose, Maltose and Fructose.
b) Starches
e.g. Starch
12
Most sugars can be detected by the Benedict's test.
Benedict's goes from clear blue to cloudy orange.
13
Sucrose is the sugar that does not give a positive Benedict's
test. (No carbohydrate beginning with an S gives a positive
Benedict's test).
14
Starch is detected using Iodine solution
Iodine solution goes from brown to black.
15
Starch is not sweet and does not dissolve properly in water.
(this is why starch is tasteless).
16
Sugars dissolve easily in water (soluble) and are all very sweet.
17
Sugars are Carbohydrates with small molecules.
18
Starch is a polymer made of many Glucose monomers linked
together.
19
Glucose monomers are joined together by a process called
polymerisation.
20
Plants convert the glucose into starch for storing energy.
(Starch is too big to pass through cell membranes).
21
During Digestion starch is broken down into glucose, which is
carried by the blood stream to body cells where respiration occurs.
22
Starch can be broken down by Acid and by Enzymes.
(Hydrochloric acid in your stomach, the enzyme amylase in your
mouth).
23
Body enzymes work best at body temperature (37°C) and are
destroyed at higher temperatures (over 40°C).
24
Fats and Oils are an important class of food obtained from both
plants and animals.
25
Fats and Oils are a much more concentrated sources of energy
than carbohydrates,
26
Fats and oils can be detected by a filter paper test.
They leave a greasy spot on the paper that lets light through
easily, making it almost see-through.
27
Saturated fats are believed to increase the level of cholesterol in
your blood and this in turn may lead to heart disease.
(saturated fats lead to heart attacks).
28
Polyunsaturated fats are less harmful to your heart.
(polyunsaturated fats do not give you heart attacks).
29
Medical opinion says eat less fat. It is better to eat
polyunsaturated fat rather than saturated fat.
30
Proteins are an important class of food obtained from both plants
and animals.
31
Proteins provide material for growth and repair of the body.
32
Proteins can be detected by heating with soda lime and testing
with pH paper for an alkali gas coming off.
33
Proteins are chemical compounds containing Carbon, Hydrogen,
Oxygen and Nitrogen. (C, H, O, N).
34
Proteins are polymers made of amino acid monomers linked
together.
35
In the body, animals make particular proteins for specific purposes.
36
The amino acids required to make animal proteins are obtained
from animal and vegetable foods.
37
During digestion proteins are broken down into amino acids.
38
A vegetarian diet must include a wide variety of vegetables to
supply all the necessary amino acids.
(Lots of which are not native to Europe).
39
Fibre keeps the gut working well, preventing constipation.
40
Fibre absorbs water and swells; this provides bulk for the gut
muscles to work on as food is squeezed along.
41
Vitamins are complex carbon compounds, which are required to
keep the body healthy.
42
Lack of vitamins can cause poor health
e.g. Lack of Vitamin C causes Scurvy
(your gums fall apart and your teeth fall out).
43
Food additives can be used to
 supply or enhance (increase) the nutritional value of food
e.g. Vitamins and minerals give food nutritional value
 improve the keeping qualities of food,
e.g. Food Preservatives make food keep better
 alter the appearance of food,
e.g. Food Colourings make food look nicer
 alter the flavour of food,
e.g. Food Flavourings give the food strong flavours
44
Food additives can only be used if they have been tested and
approved (they will have an E number).