Site author Richard Steane
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The BioTopics website gives access to interactive resource material, developed to support the
learning and teaching of Biology at a variety of levels.
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NUTRITIONAL CONTRIBUTION (use ++, +, -) |
amount required by adult per day (RDA) (1 g=1,000 mg=1,000,000 µg) |
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CLASS OF FOOD | for growth and repair | for energy | to stay healthy | |
MAJOR COMPONENTS | . | . | . | |
CARBOHYDRATES | + | ++ | + | 300g |
FATS and OILS | + | ++ | - | 50-100g |
PROTEINS | ++ | - | + | 80-100g |
MINOR COMPONENTS | ||||
VITAMINS | + | + | + | A: 300-1200 µg C: 20--60 mg |
MINERALS (IONS) | + | - | + | a few grams |
FIBRE | - | - | + | 30 g |
WATER | + | - | + | . |
> cell (& other internal) membranes
Which part of the human cell consists mainly of water & protein?
Which part of the human cell consists mainly of nucleic acids and proteins?
> nucleus
Which components of diet are said to be "body building"?
> protein (and minerals)
Which part of the PLANT cell consists mainly of "fibre"?
Name two units in which the energy content of food is measured, and give the conversion factor between them.
> Calories = > 4.2 kilojoules (kJ)
What processes can food energy be used for? (clue: there are 7 of them, including getting food, and extracting energy!)
> feeding >respiration >movement > growth
> excretion > sensitivity > reproduction
We all need different amounts of energy, and consequently different amounts of food (or at least, energy-providing foods!).
What factors may affect our energy requirements?
>age > sex > lifestyle/occupation
What are the likely long-term consequences of eating
1) too much food > fatness/obesity 2) not enough food? > loss of weight
NOT Anorexia - a nervous condition: anxiety over slimming etc
A balanced diet is not just one providing enough energy. It must also provide the right amounts of the major and minor dietary components. No single food contains these in entirely correct proportions. For this reason, it is a good idea to eat a variety of different foods.
Examples of food types | |||
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Baked Beans | Example 2. | Example 3. | |
Total amount required to give 11,000 kJ | 10 (450 g) cans! | . | . |
CARBOHYDRATES | 437g + | . | |
FATS and OILS | 20g - | . | . |
PROTEINS | 216g ++ | . | . |
Any other contributions? | fibre 310g ++++! | . | . |
water 3.14 litres | . | . |
Carbohydrates | Proteins | Fats |
> sugar/fruits > starch - rice/potatoes/pasta/bread |
> meat/fish > peas & beans |
> butter, margarine |
> kwashiorkor/marasmus
If not enough of each are available, then "deficiency diseases" can result. Nevertheless, none of these components is likely to be lacking in a sensible modern western diet, but they may have great effects in poor and under-developed countries.
How do vitamins and minerals differ chemically? (Don't get too technical!)
Vitamins are > complex organic compounds (many C-C [carbon to carbon] bonds)
whereas minerals are > simpler inorganic substances, salts, ions
Try to find out how many vitamins are considered essential for the human body, and give their (code) names. > A, B (several, e.g. B1, B6, B12), C, D, E, K
Fill in the table below with information about the main ones.
Vitamin | Source | Importance for health | Lack causes | Notes |
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vitamin C (ascorbic acid) |
fruits, green vegetables | healthy skin & gums | scurvy | added to food to stop fats "going off" |
vitamin D (also called calciferol) |
cod liver oil | helps body absorb calcium for bones etc | rickets (see also calcium) |
also made in skin by action of UV light |
........ | ........ | ........ | ........ | ........ |
>Vitamins A,D,(K) soluble in fat > Vitamins B,C soluble in water
Similarly, list some details about minerals needed by the body:
Mineral Element | Source | Importance for health | Lack causes | Notes( incl RDA?) |
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Calcium | milk, eggs | strong bones & teeth | rickets | ....... |
Iron | liver | part of haemoglobin - in red blood cells | anaemia | ....... |
Fill this in as before.
Good source of fibre | Importance for health | Notes |
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brown rice | gives gut muscles something to act on | processed out of modern food |
brown bread | gives gut muscles something to act on | |
? | ? | ? |
> They contain minerals, e.g. Fe
>They contain fibre
>"Mum says so"!
Give two reasons why sugar may be bad for you. Qualify your statements.
> (in presence of bacteria) cause tooth decay
> (eaten in excess) can cause you to get fat
Is brown sugar any better? Explain why.
> No > Brown colour is not the same as fibre
Are potatoes necessarily bad for you? Explain as fully as you can.
> No > skin has protein, fibre, vitamin C high water content - only 20% starch" Potatoes are good for us becase they give us energy in the satisfying form of starch "
How good a food is milk? Find out what dietary components it does and does not provide.
Fill in the two sides of this chart.
Milk contains | Milk does not contain |
protein | fibre |
carbohydrate - sugar: lactose | some vitamins |
fat (good energy source, especially for babies!), and fat soluble vitamins A & D |
? |
minerals, e.g. calcium (good for bones & teeth) | ? |
Vegetarian diet is HIGH in: | Vegetarian diet is LOW in: |
fibre | some vitamins |
carbohydrates | possibly proteins |
? | ? |