Transcript Food and Digestion ppt File - Watford Grammar School for Boys

8A Food and digestion
8A Food and digestion
Food
Balancing your diet
Digestion
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8A Food and digestion
Food
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8A Food – who needs it?
What do we need food for?
Energy to do things
Raw materials to grow larger
Raw materials to repair damaged body parts
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8A So what’s in food?
Food is a complicated mixture of different chemicals.
We can sort these chemicals into different types.
What are the main types?
Proteins
Vitamins
Fats
Minerals
Water
Roughage
Carbohydrates (starch and sugars)
Can you make up a sentence with words starting with
the same letters – a mnemonic?
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8A Which food contains which chemical?
Which foods belong to which food groups?
Proteins
Water
Proteins
Fats
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Fats
Carbohydrates
Carbohydrates
Water
8A What’s in food?
We can test foods to find out what chemicals they
contain.
Orangey-brown iodine turns blue-black when it
reacts with starch.
drop iodine solution onto
the food
black = starch
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8A What’s in food?
Blue Benedict’s solution turns orangey-red when it
is boiled with glucose.
chopped
up food
hot water
heat
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blue turns orange/red
= glucose
8A What’s in food?
In the Biuret test the solution turns purple.
potassium
hydroxide
shake
copper
sulphate
purple = protein
chopped up
food
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8A What’s in food?
Fats go cloudy white when they are mixed with
ethanol and water.
filter
add
water
grind food
with ethanol
cloudy = fat
Now see if you can use these tests to identify the
food chemicals on the next slides.
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8A What’s in food?
For each food, decide on the chemicals found in them.
Food sample
Protein
Test
Result
Iodine solution
orangey-brown
Benedict’s test
blue
Biuret test
purple
Ethanol test
cloudy white
Fats
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Starch
Glucose
8A What’s in food?
For each food, decide on the chemicals found in them.
Food sample
Protein
Test
Result
Iodine solution
blue-black
Benedict’s test
blue
Biuret test
blue
Ethanol test
clear
Fats
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Starch
Glucose
8A What’s in food?
For each food, decide on the chemicals found in them.
Food sample
Protein
Test
Result
Iodine solution
orangey-brown
Benedict’s test
orangey-red
Biuret test
blue
Ethanol test
clear
Fats
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Starch
Glucose
8A What’s in food?
For each food, decide on the chemicals found in them.
Food sample
Protein
Test
Result
Iodine solution
orangey-brown
Benedict’s test
orangey-red
Biuret test
blue
Ethanol test
clear
Fats
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Starch
Glucose
8A Vitamins
Vitamin Found in
Gives you
A
Liver, butter, green
vegetables
B2
Healthy skin
Cheese, milk, liver,
eggs, green vegetables
Citrus fruits, green
Healthy teeth and
vegetables, potatoes
gums, without it you
get scurvy
C
D
Fish liver oil, eggs,
sunlight on the skin
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Healthy skin and
teeth
Healthy bones –
without it you get
rickets (soft bones)
8A Food and digestion
Balancing your diet
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8A A food test for YOU!
1. A balanced diet…
a) contains the same amounts of the main food groups
b) contains healthy amounts of the main food groups
c) doesn’t fall off the table.
2. A balanced diet for most people has more…
a) fat than water
b) carbohydrate than protein
c) crisps than fruit.
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8A A food test for YOU!
3. To test for protein in food you…
a) add iodine solution
b) do the Biuret test
c) poke it with a big stick.
4. Sugar and starch are both…
a) proteins
b) fats
c) carbohydrates.
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8A A food test for YOU!
5. Iodine solutions turns blue-black with…
a) starch
b) protein
c) age.
6. A food went orangey-red when it was boiled with
Benedicts solution. It could be…
a) a carrot
b) a boiled sweet
c) a sausage.
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8A A food test for YOU!
7. Not enough vitamin C gives you…
a) headaches
b) scurvy
c) weak bones.
8. Riboflavin is…
a) a B vitamin
b) a fruit drink
c) an elf from The Lord of the Rings.
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8A Food and digestion
Digestion
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8A Why digestion?
Food is a mixture of molecules.
Some of these molecules are too
large to pass into the body.
Digestion breaks down food in the
gut into smaller molecules.
The body uses these smaller molecules
for energy or to build body parts.
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8A Where it all happens
What happens where? Follow the food down through
the body.
Mouth breaks large lumps of food into smaller lumps.
Stomach produces enzymes to break down proteins.
Intestines produce enzymes to break down proteins,
carbohydrates and fats. Start to absorb food into body.
Colon absorbs water and stores waste until time to
pass out of the body.
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8A Watching the digestives
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8A Absorbing stuff
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8A Digestion - True or False?
True or False?
1. Enzymes are made of protein.
TRUE
2. Enzymes only work in acid solutions.
FALSE
3. Enzymes can only break down molecules.
FALSE
4. A protease is an enzyme that breaks
down protein into smaller molecules.
TRUE
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8A Digestion - True or False?
True or False?
1. An enzyme works best at a particular
temperature.
TRUE
2. Most enzymes in the human body work
best at about 57°C.
FALSE
3. Enzymes work best in boiling water.
FALSE
4. Snakes produce one enzyme that can
digest everything in its victim from the skin
to the bones.
FALSE
5. Amylase is an enzyme that breaks down
starch.
TRUE
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