MODULE mod7A mod7B mod7C mod7D mod7E mod7F mod7G mod7H mod7I mod7J mod7K mod7L mod8A mod8B mod8C mod8D mod8E mod8F mod8G mod8H mod8I mod8J mod8K mod8L mod9A mod9B mod9C mod9D mod9E mod9F mod9G mod9H mod9I mod9J mod9K mod9L 8aa1
8Aa1 Testing foods 1
Name _____________________________ Class ____________
Using Skills Sheet 62, do the tests for starch and fat on a variety of different foods. Enter your results in the table below and answer the questions.
Recording your results
Fill in this table to show your results.
Name of food
Did it contain starch?
Did it contain fat?
Considering your results/conclusions
How did you know if a food contained starch? _________________________________________
_______________________________________________________________________________
How did you know if a food contained fat? ____________________________________________
Can you tell if some foods contain more starch than others? _______________________________
How can you tell this? ____________________________________________________________
Which of your foods contained the most starch? ________________________________________
Look up the amounts of starch (carbohydrate) in the foods that you tested. Does your answer above match the information that you have found?
[ observing, considering, research ]
8Aa2 Testing foods 2
Sucrose and glucose are both types of sugar. Sugars are types of carbohydrate. Starches are also a type of carbohydrate. However, starch is not a type of sugar. Information like this can be shown on a Venn diagram.
Using Skills Sheets 62, 63 and 64 you are going to so some of the tests for starch, protein, fat, glucose and sucrose. Your teacher may tell you which ones to do. You are going to draw a Venn diagram to show your results.
1 Draw a table to show which of the foods you tested contain which of the food substances that you tested for.
2 Draw a Venn diagram to show which foods contained which food substances. Your diagram might be based on this one.
3 Which food or foods contained the widest variety of different food substances?
Evaluation
4 Try to find nutrition information for two or three of the foods that you tested.
a How well does the nutrition information match your results for each food?
b Why do you think there may be differences between what is actually in the food and what your tests show?
[ knowledge, observing, presenting, considering, evaluating, research ]
8Aa3 True and false foods
1 Write the word 'true' or the word 'false' after each of these sentences.
a Carbohydrates contain a store of energy. _____________________________________
b Proteins are used for growth and repair. _____________________________________
c Meat contains no protein. ________________________________________________
d Fats can be used for energy. _______________________________________________
e Iodine solution can be used to test for sugar. __________________________________
f Two examples of nutrients are fibre and water. ________________________________
g Fats are found in foods like butter, milk and eggs. ______________________________
h It is very important to have an unbalanced diet. _______________________________
i Vitamins and minerals keep our bodies healthy. _______________________________
j Starch is a type of protein. ________________________________________________
2 For the sentences that you think are false in Question 1, write out corrected versions on the lines below.
__________________________________________________________________________
3 Here are two lists of words and phrases. Draw lines from the words in the first list to link them to words in the second list. Some of the words in the second list need to be used more than once. Write a phrase above your lines to show what the link is. One has been done for you.
[ knowledge ]
8Aa4 Food for thought
1 Use the words in the box to complete the sentences.
diet energy fats fibre minerals
nutrients raw repair water
What we eat is known as our ___________________ . Our food provides a source of
___________________ materials to make new substances.
These new substances are used for:
- ___________________ (to help us to move, etc.)
- growth and ___________________
- health.
Carbohydrates, proteins, ___________________ , vitamins and ___________________ are
all ___________________ which means that they provide raw materials.
We also need to eat ___________________ and drink ___________________ .
2 Use the nutrition information label above to answer these questions.
a How much protein is there in 100 g of the food? ___________________
b How much fat would you get if you ate two of these bars? _______________________
______________________________________________________________________
c Name one vitamin shown on the label. _______________________________________
d Name one mineral shown on the label. _______________________________________
e Which of the food substances listed helps the rest of your food to pass through your intestines as it is being digested?
[ knowledge, numeracy, literacy ]
8Aa5 What's in it?
You will need a copy of Skills Sheet 65 to answers the questions on this sheet.
1 Which food contains the most protein per 100 g?
2 a Which food contains the most carbohydrate per 100 g?
b There are different sorts of carbohydrate. Name one of them.
c Describe a test you could do for one type of carbohydrate.
3 Common salt is a mineral (sodium chloride). We need to have it in our diets but some people need to make sure that they do not eat too much. Name three foods which you would advise someone on a 'low sodium' diet to avoid.
4 One substance found in almost all foods is not mentioned in the table. Name it.
5 a Which of the food substances in the table is not a nutrient?
b Why is this substance important in our diets?
6 Teenagers are advised to eat the following amounts of proteins, carbohydrates and fats each day.
Food substance
Amount per day
carbohydrate
300-350 g
fat
60-90 g
protein
50-100 g
a Using the foods on Skills Sheet 65, design a table to show the foods (and the number of grams of each) you would eat to provide these amounts.
b Explain either why you think your list of foods would be healthy to eat every day or why it would be unhealthy to eat every day.
[ knowledge, numeracy ]
8Aa6 RDA
It has been known for a long time that certain foods prevent some diseases. In the 18th century, James Lind discovered that drinking lime juice could prevent scurvy. Scurvy is a disease where your gums bleed, cuts don't heal and your skin bruises easily. However, nobody knew the reason why lime juice prevented scurvy. In 1906 things became a little clearer. In a famous experiment, Frederick Hopkins fed some rats on water and a food containing proteins, fats, carbohydrates and minerals. The rats soon died. He fed another group of rats on the same food but also gave them milk. These rats survived. He came up with a theory that there were 'accessory food factors' in some foods that were needed in the diet. The word vitamin was invented by Casimir Funk in 1912. Since then many vitamins have been identified and we now know how they work. Vitamin C is needed to help wounds heal.
Vitamin
RDA
A
800 mg
B1
1.4 mg
B2
1.6 mg
B6
2 mg
B12
1 mg
C
60 mg
D
5 mg
E
10 mg
The amount of a vitamin that you need is very, very small. The amounts are measured in milligrams (1 mg = 0.001 g) or even micrograms (1 µg = 0.000001 g). Vitamins have a Recommended Daily Allowance (or RDA). This is the amount that it is recommended for adults to take each day. The amounts are smaller for children. It is dangerous to take too much of some vitamins. Vitamin A is poisonous if you take 10 times too much each day and your hair may start to fall out. Foods do not contain enough vitamin A to harm you, unless you eat polar bear livers!
1 Name a disease that is caused by a lack of a vitamin. The lack of which vitamin causes this?
2 Name the different food substances fed to the rats in Fredrick Hopkins' first experiment and say why each is necessary in the diet.
3 Who invented the word 'vitamin'?
4 Name one vitamin and an organ that you think it might be stored in.
5 Why do you think it might be dangerous to give adult vitamin tablets to young children?
6 Which vitamin do you think you need the most of?
7 What is an RDA?
8 What are the RDAs for these vitamins, in grams: a B6; b B12; c A?
9 How much vitamin A would you have to take to cause damage to yourself?
10 Find out the following information about another vitamin called 'niacin'.
a The RDA.
b A food that it is found in.
c Another name for it.
d A disease that is caused by a lack of it.
[ knowledge, literacy, numeracy, research ]
8Ab1 Newspaper article 1
Marketing and advertising: food industry's healthy debate
by Alison Maitland
N
ews of a £20 million marketing and advertising campaign by the food industry to persuade customers that British food is safe and healthy has run into criticism from industry observers and consumer groups.
Verner Wheelock, visiting professor of food science at Nottingham University and an industry consultant, says the campaign is 'a complete waste of time'. Food scares like the beef crisis will continue to plague Britain until the industry adopts a positive approach to health issues, he argues.
He cites manufacturers' reluctance to cut salt in processed food or to add folic acid to products for pregnant women to help birth defects as examples of the industry missing the chance to improve its image.
The National Consumer Council agrees that 'the food industry is reluctant to take the bull by the horns and lead on health issues'. Carmen Taboas, food policy officer, says the campaign appears to miss the broader questions raised by recent food scares about whether health problems are caused partly by production methods such as intensive farming. 'It's intensive food production which concerns consumer groups, and whether the new technologies are safe,' she says.
John Young of the independent Leatherhead Food Research Association believes the advertising campaign 'won't make a jot of difference' because so many food scares are rapidly over. He suggests the campaign could even create unnecessary doubt in people's minds about safety. 'I'm not so sure the consumer has a perception of poor quality of food anyway.'
Wheelock says a proactive approach by the industry might not boost sales, but nor would it involve a huge advertising budget. 'There are lots of little companies that are trying to take an ethical approach,' he says, citing Baby Organix, the Dorset-based producer of organic baby foods which was set up in 1992 and now supplies leading supermarket groups.
Wheelock's work reflects his interest in health issues. One of his consultancies is with Klinge, a Scottish company that produces LoSalt, a salt substitute, and he is working for J. Sainsbury on developing 'healthy' products.
He says the government declined to accept a recommendation from its own medical advisers 18 months ago that average sodium intake should be cut by 30 per cent. There were 'strong suspicions that this was under pressure from the food industry'.
'With something like salt, it wouldn't be all that difficult for [the industry] to make some reduction across the board,' he says. 'They would have had a very positive story to put across about how they're seriously concerned about the health of the nation and are taking action to make a genuine contribution.' Wheelock says Heinz has gradually reduced salt in some of its products, testing this on consumer panels to find out when people taste the difference. 'But rather than being positive, most of the industry has been very negative, trying to pick holes in scientific evidence.'
Fortifying flour with folic acid - important in preventing spina bifida in babies - is seen by some specialists as a helpful way of ensuring that all women have enough in their diets. Wheelock says this is an 'ideal opportunity' for the bread industry. But the Federation of Bakers told a meeting last year that bakers would not welcome having to add folic acid to bread for the sake of a small proportion of women.
Supermarkets, which have to deal with customers face-to-face, are very responsive to food scares, Young points out. But trailblazing on health issues can backfire for manufacturers. He cites the case of MD Foods of Denmark, which ran into trouble with the claim that its Gaio yoghurt could cut cholesterol levels. The ASA said this week that the strength of health claims made for some 'functional' foods had begun 'to raise complaints as well as eyebrows'.
Source: Financial Times, 13 June 1996. © 1996, The Financial Times Limited. Reproduced with permission.
8Ab2 Newspaper article 2
Study shakes belief that salt is a risk
by Jeremy Laurance
S
alt is bad for you - or it may be good for you depending on the latest scientific paper you read. The link between salt and health is thrown into confusion today with the publication of a study suggesting that those who eat least die soonest.
Previous research has suggested that high consumption of salt increases the risk of early death and current British government advice is to cut consumption by 30 per cent.
For [the] latest study, researchers at the Albert Einstein College of Medicine in New York examined details of the diets of more than 11 000 people in the United States collected between 1971 and 1975. The participants had been asked to record all they ate in a 24-hour period. The researchers then examined death records for 1992 to see who had died in the intervening 20 years.
They found that those with the highest salt intake - in the top quarter of the study group - had an 18 per cent lower death rate than those in the lowest group.
The results, published in The Lancet medical journal, are valuable, according to the researchers, because they link salt intake with eventual death rather than with blood pressure, as other studies have done. The researchers conclude that the results are not strong enough to justify advice to increase salt intake but they also 'do not support current recommendations for routine reduction of sodium consumption'.
However, British scientists said that the paper contained 'misleading statements and methodological flaws' and said the practice of assessing salt intake on the basis of a 'single dietary recall' was notoriously inaccurate.
Consensus Action on Salt and Hypertension, a group of scientists concerned with salt and its effect on health who are led by Professor Graham MacGregor of St George's Hospital Medical School in London, said that there was 'overwhelming evidence' that a high salt intake was a major cause of high blood pressure. 'Blood pressure in the most important predisposing factor to strokes and heart attacks, the commonest cause of death in the Western world,' the professor said.
The Committee on Medical Aspects of Nutrition Policy, set up to advise the Government, recommended in its report on heart disease that average salt intake in the United Kingdom should be reduced from nine grams to six grams a day.
Most salt is hidden in processed food and the scientists say that more must be done to reduce the salt content and to label it clearly in these foods.
Source: The Independent, 14 March 1998. © 1998, Independent Newspapers (UK) Limited. Reproduced with permission.
8Ab3 Food wheels
1 Cut out the two wheels below, and the parts marked on Wheel 1.
2 Place each wheel over a lump plasticine and push the end of a pair of scissors through the centre of each wheel to make a hole.
3 Your teacher will tell you what to write in the spaces on Wheel 2.
4 You can now join the two wheels together with a butterfly tag pushed through the holes. Wheel 1 goes on top of Wheel 2.
8Ab4 A Big Burger meal
Answer the questions about this meal.
You can use the words listed below to
help you.
energy
growth and repair
health
minerals
sugar
vitamins
water
1 Name one type of food substance that might be found in each part of the Big Burger meal and say why the body needs it.
a Bread roll Food substance: _____________________________________
Why the body needs it: _______________________________
b Beef Food substance: _____________________________________
c Tomato Food substance: _____________________________________
2 a The fries are cooked in oil. What food substance does oil contain? _________________
b What does the body use this for? ___________________________________________
3 a What substance does the cola drink mainly contain? ____________________________
b What other substance does it contain? _______________________________________
c Suggest why this substance might be bad for you if you had too much.
4 a If you only ate this meal, do you think you would get enough vitamins?
b Explain your answer. ____________________________________________________
[ knowledge, literacy ]
8Ab5 What's on the menu?
There are seven things needed for a good diet; carbohydrate, fat, protein, vitamins, minerals, fibre and water. These things are needed for energy, growth and repair, and health. Answer the questions about these three meals.
Meal A
Meal B
Meal C
two sausages and a few chips, cola
two fish fingers, peas, carrots, mashed potato, milk
small amount of pasta with beans, lettuce and tomatoes, water
no pudding
apple pie
a pear
1 a Which meal would be best for an active, growing teenager?
b Explain your answer.
2 a Which meal would be best for someone who wants to lose some body mass?
c People often say that they are going on a diet. What does the word 'diet' really mean?
3 a Choose one of the meals and say what food substances are missing.
b What does the body need these substances for?
4 a Name one food from each meal that contains carbohydrates.
b One type of carbohydrate is sugar. Pick out the one thing from all the meals that you think contains the most sugar.
c What might happen if you have too much sugar?
5 What mineral would you expect to find in milk?
8Ab6 Balanced diets
Look at this 'food pyramid' and answer the questions below.
To get a balanced diet, people should eat food from each of these groups every day. People should
aim to eat more from the groups lower in the triangle.
1 What is meant by a 'balanced diet'?
2 Here are three meals served in a restaurant.
Fish and chips.
The 'Pasta special' is pasta with a creamy sauce containing ham and spinach. It also comes with a side salad.
The 'All Day Breakfast' contains fried eggs, sausages, bacon, bread and butter.
a Explain which one is the best example of a balanced meal and say why.
b Say what a person who has eaten one of the other meals might have for pudding to help make the meal more balanced.
3 Write down what you have eaten today.
a Is what you have eaten a 'balanced diet'?
b If it is not, explain what you might change to make it more balanced.
8Ab7 Salt - good or bad?
Adults who are overweight, smoke, drink too much alcohol, do only a little exercise and have too much salt in their diet are likely to develop high blood pressure. This may lead to heart disease. The following extracts show some different views about salt and how it might be bad for us to eat too much.
1 Look at the extracts. Copy out a sentence which:
a contains a fact b contains an opinion c contains a claim.
2 a Which source of information do you think is the best for trying to back up an argument?
b Explain why you think this.
3 Do you think there is enough information on this page to support the statement: 'salt is bad for you'? Explain your reasoning.
4 a Look at the article from the website. Why do you think the 'nutrition community' (doctors who advise people on what to eat) criticised this investigation?
b Do you think that there is enough information given in this article to be able to say that the results of the investigation 'seem to indicate that it's the low salt intake and not the kind of diet that lowers blood pressure'? Explain your reasoning.
c If you were asked to do this investigation, would you do anything differently? If so, what?
[ literacy, considering, evaluating ]
8Ab8 The work of a food scientist
Food scientists have to work out what substances are in foods and how much of each one is there. They use this information to write nutrition information labels for foods.
Imagine that a food scientist has to write a nutrition label for a new food. The first thing to find out is how much sugar is in the food. The fact that sugar is soluble and most of the other major substances are insoluble, can be used to separate the sugar.
The amounts of food substances found in the food are shown in the table.
Amount in 100 g of the new food
24 g
starch
34 g
8 g
16 g
fibre
5 g
To work out how much energy the food contains, 1 g of the food is burnt in a piece of equipment called a bomb calorimeter. Inside the bomb calorimeter, the burning food heats up some water. The amount of energy contained in the food can be worked out from the temperature rise of the water. The new food raised the temperature of 100 g of water by 44 °C.
1 To separate out the sugar, the food is mixed with water. What process might be used to separate the sugar solution from the rest of the food?
2 The food scientist finds some food colourings in the food. What process might be used to separate them?
3 a Use the information on the food label to add up the total mass of substances in 100 g of the food.
b Why doesn't this total add up to 100 g?
4 What percentage of the food is made of carbohydrates?
5 Work out the total energy in 100 g of the food using these figures. Show your working.
1 g of carbohydrate can release 17 kJ of energy.
1 g of protein can release 23 kJ of energy.
1 g of fat can release 39 kJ of energy.
6 What piece of apparatus can be used to find out the energy content of a food?
7 The results of burning the food can also be used to work out the energy content. Use the equation below to help you work out the energy content in kJ/100 g of the food. Show your working.
Mass of water used × temperature rise × 4.2 = energy content in J/g
8 a Is the figure you calculated in Question 7 higher or lower than the one calculated in Question 5?
b Try to explain this. (Hint: Think about what else might be in the food which is not a nutrient.)
[ knowledge, considering ]
8Ac1 A model small intestine 1
It is very difficult to do practical work with a real small intestine but we can make a model of how it works. Visking tubing can be used. This has very tiny holes in it that are too small to see.
Apparatus
- Visking tubing - Skills Sheets 62 and 64
- Starch suspension - Benedict's solution
- Water bath - Tripod
- Syringe - Gauze
- Pipette - Bunsen burner
- Elastic band - Beaker
- Boiling tubes - Heatproof mat
- Iodine solution - Eye protection
- Boiling tube rack
Wear eye protection.
Method
1 Take some Visking tubing and tie a knot in one end. Using a syringe, carefully add 5cm3 of starch suspension to the tubing.
2 Holding the top of the tubing, wash the outside of it under a tap (to clean off any starch that may have been spilt).
3 Place the tubing inside a boiling tube of water and leave the boiling tube in a warm water bath for 20 minutes.
4 Make a copy of the apparatus above and label it to show what you have done.
5 Using Skills Sheets 62 and 64, test the water outside the tubing for starch and for glucose.
1 Did you detect any starch in the water outside the tubing after 20 minutes?
2 Why do you think you got the results that you did? Think about how big the particles of starch may be compared to the holes in the Visking tubing.
3 In this experiment you built a model. In the model, which part of the apparatus represents each of these parts?
a the intestine
b the insides of the intestines
c the blood flowing around the intestines
4 What do you think you could do to the starch to allow it to get out of the tubing?
[ observing, considering ]
8Ac2 In the guts 1
1 Label the parts of the digestive system on the diagram below. Use these letters as your labels:
A - the large intestine
B - where small, soluble molecules are taken into the body (absorbed)
C - where faeces are stored
D - this organ contains a strong acid
E - the gullet
F - where feeding happens
G - the anus
2 The answer to each of these questions in one of the letters in question 1.
a Saliva is produced here. _________________________
b This is called the small intestine. _________________________
c Faeces are eliminated (or egested) here. _________________________
d Food travels from the mouth to the stomach here. _________________________
e Water is removed from undigested food here. _________________________
f This is called the stomach. _________________________
g This is called the rectum. _________________________
3 Enzymes are chemicals that chop up large molecules into smaller ones. There are enzymes in the small intestine. Explain why these are needed.
8Ac3 In the guts 2
1 The phrases in the left-hand column can be linked with those in the right-hand column using another phrase. Complete the middle column with linking phrases. One has been done for you.
Feeding (or ingestion) is when you put food in your mouth.
Swallowing ____________________________________ gullet.
Strong acid ____________________________________ stomach.
Small molecules ____________________________________ small intestine.
Water ____________________________________ large intestine.
Faeces ____________________________________ rectum.
Elimination (or egestion) ____________________________________ anus.
2 The drawing shows a model of the small intestine that can be used to help us to imagine what happens in the small intestine. The small intestine is where food molecules are taken into the body (absorbed). The circles represent food molecules.
a Draw a circle around each of the food molecules that will go into the blood.
b Explain why you have selected these molecules. _______________________________
c Suggest which molecules the smallest circles represent. __________________________
d What must happen to the other molecules for them to get into the blood?
Use the word enzyme in your answer. ______________________________________
[ literacy, knowledge ]
8Ac4 Teeth and decay
We use teeth to help us cut through food and grind it up. The incisors and canine teeth help us to bite through food. In large carnivorous animals (like tigers) the canine teeth are much longer and help to kill the prey. The molars and premolars grind up our food to help digestion.
The enamel that covers our teeth is extremely hard and helps to protect the teeth from being worn away. However, many people get holes in the enamel. These holes are called cavities. When you eat, some of the food gets stuck to your teeth. Tiny organisms called bacteria eat this food. Together, the bacteria and the stuck food are called plaque. The bacteria grow very quickly if the plaque contains a lot of sugary food. The bacteria produce an acid which attacks the enamel and forms a hole. The hole can get bigger and bigger. If the hole reaches through the enamel, it quickly goes through the dentine and into the pulp. This can be very painful.
A dentist can fill in small holes as soon as they appear and it is a good idea to go to the dentist every 6 months. You should also brush your teeth twice a day to remove the plaque. The fluoride in toothpastes helps to keep the enamel strong.
1 a How many teeth do you think an adult should have?
b Why might an adult have fewer teeth than this?
2 What is plaque?
3 Why do you think large cavities are painful?
4 Using some simple labelled diagrams, explain how a large painful cavity is formed.
5 Why do you think dentists tell us not to eat too many sugary foods?
6 Explain why:
a most toothpastes contain fluoride
b most toothpastes are weak alkalis.
7 Find out what a 'wisdom tooth' is.
[ knowledge, literacy, research ]
8Ad1 Amylase action
Amylase is an enzyme found in saliva. It breaks down starch, turning it into a sugar. You are going to investigate how temperature affects how well amylase works.
Prediction
What temperature do you think the amylase will work best at? Choose from one of these temperatures by ticking one box.
0-10 °C 35-40 °C 60-100 °C
Explain why you have chosen this temperature. ________________________________________
- Iodine solution - Spotting tile - Six test tubes
- Test tube rack - Two syringes - Pipette
- Amylase solution - Starch suspension - Stop clock
- Beaker of water (to wash out the pipette)
1 Using a syringe, put 5 cm3 of the starch suspension into three of the test tubes. Place these tubes into three water baths at different temperatures.
2 Using another syringe, put 1 cm3 of amylase solution into three more test tubes. Place these into the three water baths.
3 Start the stop clock and time 5 minutes. While you are waiting, use the pipette to add one drop of iodine solution to each well on the spotting tile. Wash out the pipette when you have finished.
4 After 5 minutes, pour the amylase into the starch suspension in each water bath and swirl the tubes to mix the contents.
5 Take one drop from a tube with the starch and amylase in, and add it to a well on the spotting tile. A blue/black colour shows that starch is there. Wash out the pipette before taking each drop and test all three tubes in this way.
6 Reset and start the stop clock. Repeat step 5 every 2 minutes. Fill in your results below
Use this grid to record your results. Place a tick in the grey boxes if a blue/black colour appeared.
Temperature of tube (°C)
Time after adding amylase (mins)
At which temperature do you think the amylase was working best? _________________________
How do you know this? ___________________________________________________________
Does this result agree with your prediction? ___________________________________________
Explain why you think the amylase works best at this temperature. ________________________
How would you improve this experiment to find more precisely which temperature amylase works
best at?
[ observing, considering, evaluating ]
8Ad2 Amylase in action
Amylase is an enzyme found in saliva. It breaks down starch, turning it into a sugar. You are going to investigate how temperature or pH affects how well
amylase works.
1 Write down a prediction. Say what you think will happen and why.
Planning
2 Write down a method for your investigation. You may need some of the following apparatus.
- Iodine solution - Spotting tile - Test tubes
- Test tube rack - Syringes - Pipette
- Amylase solution - Starch suspension - Stopclock
- Acid solution - Alkali solution - Eye protection
3 You will also need to think about these questions:
- Which factors will you vary and which will you keep the same?
- How will you make sure you do a fair test?
- How will you find out if the amylase is working?
- What will you measure?
- How often will you make measurements?
- What ranges will you use for the factors you are varying?
- What will you do to make sure you stay safe?
4 Show your method to your teacher before you begin.
5 Make a table to record your results.
6 Plot a bar chart to show your results.
7 Using your bar chart, write a 'conclusion'. Say what happened and why you think it happened. Do your results match your prediction?
8 Were any of the results surprising? If so, why?
9 Did you do a fair test, or were there some factors that you forgot to keep the same?
10 Do you think you have enough results to support your conclusion?
11 How might you improve your experiment?
[ planning, observing, considering, evaluating ]
8Ad3 A model small intestine 2
- Visking tubing - Elastic band
- Starch solution - Digestive juice solution
- Water bath - Boiling tube
- Two syringes - Iodine solution
- Benedict's solution - Bunsen burner
- Gauze - Tripod
- Heatproof mat - Beaker
- Pipette - Two test tubes
- Eye protection - Skills Sheets 62 and 64
1 Take some Visking tubing and tie a knot in one end. Using a syringe, carefully add 5 cm3 of starch solution to the tubing.
2 Using the other syringe, add 1 cm3 of the digestive juice solution.
3 Holding the top of the tubing, wash the outside of it under a tap (to clean off any starch that may have been spilt).
4 Place the tubing inside a boiling tube of water and leave the boiling tube in a warm water bath for 20 minutes.
5 Make a copy of the apparatus below and label it to show what you have done.
6 Using Skills Sheets 62 and 64, test the water outside the tubing for starch and for glucose.
1 What did you find when you tested the water outside the tubing for starch and glucose?
2 What do the following things represent in your model small intestine?
a the Visking tubing
b the liquid inside the tubing solution
c the water outside the tubing
3 Name one way in which this model is not like a real small intestine.
4 Why do you think the boiling tube was put into a warm water bath?
5 Try to explain your results.
8Ad4 The digestive system
On the diagram below, write in the name of the organ that each line is pointing to. Use these words:
rectum small intestine stomach mouth gullet large intestine
Now cut out the boxes at the bottom of the page showing the functions of these organs. Stick the correct box underneath the correct organ name.
-----------------------------------------------------------------------------------------------------------
Water is absorbed here.
Faeces are stored here.
Takes food to the stomach.
More enzymes are added here, to complete digestion. The soluble food is absorbed.
Food is ground up here and mixed with saliva which contains an enzyme to digest starch.
The food is churned up with strong acid here and enzymes digest proteins.
8Ad5 Flicker-book digestion
1 Cut out the pieces along the dotted lines. 2 Put them in order in a pile and staple the top. 3 Flick the pages! 4 Write down what you are observing.
[ literacy, knowledge, observing ]
8Ad6 Digestion 1
1 Complete the sentences using the words in the box.
absorbed anus enzymes intestine
juices mouth insoluble soluble
Digestion makes ____________________ substances into ____________________ ones. This process starts in the ____________________ . During digestion, digestive ____________________ are added to the food. These contain ___________________ . When the food that can be digested has been broken down, it is ____________________ by the small ____________________ . Food that cannot be broken down is passed out of the body through ____________________.
2 For each of the things below, say what it does to help with digestion:
The stomach: _____________________________________________________________
_________________________________________________________________________
Teeth: ___________________________________________________________________
3 Some food cannot be digested. This is called fibre. Write the names of the organs listed in the box in the order that a piece of fibre would go through them.
i __________________ ii __________________ iii __________________
iv __________________ v __________________ vi __________________
vii __________________
anus gullet large intestine mouth rectum
small intestine stomach
8Ad7 Digestion 2
The Fab Food Company make a sandwich called a 'Healthy Delight'. It contains bread, butter, celery and ham.
1 Write down the main food substance contained in:
a bread b butter c ham.
2 Do you think the 'Healthy Delight' is healthy? Explain your reasoning.
3 'Stringy' vegetables, like celery, contain a lot of fibre. Fibre is not digested by the body. Write down, in order, the names of the organs that the fibre passes through when it is eaten.
4 The table shows the names of some enzymes, what they do and where they are found. Amylase from the salivary gland is destroyed in the stomach and so another amylase is added in the small intestine.
Enzyme
Where it's found
What breaks down
amylase
salivary gland
lipase
small intestine
pancreatic amylase
pepsin
stomach
trypsin
a Where do you think the 'salivary gland' is?
b Where do you think most digestion happens? Explain your reasoning.
c Copy the table below. Place ticks in the boxes to show which part of the 'Healthy Delight' sandwich will be digested in the various parts of the digestive system. There can be more than one tick for each food.
Bread
Butter
Celery
Ham
mouth
gullet
8Ad8 Saliva and starch
Vijay wanted to see how saliva affected starch. He took five test tubes, each containing 5 cm3 of starch suspension. To each one he added 1 cm3 of saliva. He then put the tubes into water baths at different temperatures. Every 10 minutes he took one drop from each tube and mixed it with a drop of iodine solution on a spotting tile and looked for a black colour. His results looked like this:
1 What substance was Vijay testing for with iodine solution?
2 a After 40 minutes, the sample taken from the tube at 25 °C did not produce a black colour with iodine. Why do you think this was?
b What kind of substance in saliva caused this to happen?
3 Draw a graph of Vijay's results. Put temperature on the horizontal axis.
4 a At what temperature did the saliva appear to have no effect?
b Why do you think this might be?
5 a At what temperature did the saliva work fastest?
[ knowledge, considering, presenting ]
8Ad9 When enzymes attack
A television company is making a programme called 'When enzymes attack'. In part of the programme the producer wants to explain the process by using people to illustrate what happens. Some people will represent food molecules and others will represent enzymes.
The voice-over for this part of the programme has already been written.
Programme ID
EN28-ML1
Delivery date
TBC
Programme name
When enzymes attack
Client
Body TV
Producer
James Johnson
Part
Visuals & Sound FX
Time code
Voice-over script
1
00.00
Enzymes are complicated substances. They are made out of proteins and their job is to break apart large food molecules.
2
Only small food molecules can pass through the wall of the small intestine.
3
Enzymes break apart the large food molecules into small ones. They basically act like chemical scissors.
4
This process is called digestion.
5
Now the new molecules formed by the enzymes can pass through the wall of the small intestine.
1 You have been asked to write the 'visuals' for the programme - what people will see happening. For each part of the voice-over script write down how you would use people to show these things.
2 TV programmes need to be carefully timed. When the voice-over artist reads out the script, he or she will watch the film and start to read each part when a certain time is reached. This time is called the 'time code'. It is written out in minutes and seconds. Think how long each of your scenes (1-5) is going to last and then write down the time codes that you want the voice to start at.
3 To make it more interesting you could add some sound effects. Write down any sound effects that you want to use and where you want to use them.
Optional extras
4 You may think that the voice-over script is a bit dull. You could try to re-write some of it to make it sound a little more interesting.
5 If you have a video camera you could try to film this part of the programme. You may need:
- a cast
- a camera operator
- a director
- a person to help organise the people in the cast (properly called a third assistant director)
- a voice-over artist
- a sound effects person (properly called a Foley artist).
[ literacy, knowledge, numeracy ]
8Ae1 Food for life
1 Fill in the missing words in these sentences, using the words in the box.
blood carbohydrate carbon dioxide lungs oxygen
protein respiration substances
Some digested food is used in a process called _________________ to provide us with energy.
This process also needs _________________ . This process releases waste products, like
_________________ _________________. waste is put back into the _________________
and removed from the body by the _________________. An example of a food substance
used for energy _________________.
Some food is used by the body to make new _________________ for growth and repair.
An example of a food substance used for this is _________________.
2 Look at these nutrition information labels.
Serious Cereal
Nutrition information
Fishy Fillets Nutrition information
Pete's Peas Nutrition information
Amount per 100 g
Energy
465 kj
750 kj
127.5 kj
Carbohydrate
62 g
14 g
3 g
Protein
13 g
Fat
21 g
0.5 g
Fibre
6 g
1 g
a Which food has the most energy in it? _______________________________________
b Which food has the least energy in it? _______________________________________
c Walking uses 15 kJ per minute. How long would you have to walk for to use up all the energy in 100 g of each food? (Hint: Energy per 100 g ÷ the amount of energy used per minute.)
i Serious Cereal ? ____________________________________________________
ii Fishy Fillets ______________________________________________________
iii Pete's Peas _______________________________________________________
[ knowledge, literacy, numeracy ]
8Ae2 Digestion concept map 1
This sheet shows some of the key words and ideas about food and digestion. Each box contains an important word. Many boxes are linked by a linking word or a phrase.
1 Write down the numbers 1-20 and for each one write down a linking word or linking phrase.
2 From your knowledge, add one more link or an important word with a link to your concept map.
[ revision ]
8Ae3 Digestion crossword
Use the clues to fill in the correct words on the grid.
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
ACROSS
3 Food substance used for energy.
5 The substance that is used in all cells to release energy from.
13 Breathing out carbon dioxide is an example of this life process.
14 Process that cells use to release energy.
19 Calcium is one of these.
20 Food substance that helps clean your intestines.
22 Food substance that is needed for good health.
23 Food is absorbed here.
24 Unit of energy found on food packets.
DOWN
1 Name of a digestive juice.
2 Process used to break apart food.
4 Faeces are stored here.
6 Organ containing a strong acid.
7 Food substance used for growth and repair.
8 Tube carrying food from the mouth to the stomach.
9 Food substance that makes things taste sweet.
10 A product of respiration.
11 Very small tube that carries blood.
12 Food substance stored in the body to provide energy in the future.
13 Substance used to break down food.
15 Getting rid of waste food that cannot be digested.
16 Tube that carries blood away from the heart.
17 Putting food into your mouth.
18 We need to eat a wide variety of foods to get a diet that is ______________.
21 The small intestine is lined with these.
[ knowledge, literacy, revision ]
8Ae4 Food absorption
1 The diagram shows how food gets into the body. Label the parts using the words in the box.
artery small intestine starch sugar vein villus
2 Explain how the small intestine is adapted to get food into the blood very quickly.
3 a In what liquid is food transported around the body? ____________________________
b Name the process that food is needed for, in every cell in the body.
c What do cells get from this process? ________________________________________
8Ae5 Digestion concept map 2
Design a concept map to summarise food and digestion. Each important word or important point should be linked to another by a 'linking word' or 'linking phrase'. For example, you might start off your concept map like this:
You may find these words and phrases helpful but also add some of your own.
Some examples of important words and phrases
anus blood calcium carbohydrate egestion energy enzymes faeces fat fibre growth and repair gullet heat insulation iodine solution kilojoules large intestine making new substances minerals mouth moving nutrients producing heat protein rectum respiration saliva small intestine solvent starch stomach store of energy sugars vitamin C vitamins water
Some examples of linking phrases
measured in released by small molecules absorbed by travel in
travels through these organs used for
[ literacy, knowledge, revision ]
8Ae6 Eat to live
Proteins contain the elements carbon, hydrogen, oxygen and nitrogen. The proteins that we eat are digested into amino acids. Cells inside our bodies use these amino acids to produce new proteins that we need. Muscle cells contain a lot of protein.
Fats contain the elements carbon, hydrogen and oxygen. The fats that we eat are digested into fatty acids and another substance called glycerol The body uses these to make different types of fat. Cell membranes contain a lot of fat.
Carbohydrates also contain carbon, hydrogen and oxygen but in different proportions to fats. Carbohydrates are digested into small sugars. Glucose is the main sugar that is produced and this is used in respiration. If more carbohydrates are eaten than can be respired, the extra is turned into fat and stored.
The word equation for respiration is:
glucose + oxygen + water + carbon dioxide (+ energy)
It can be shown that food is used in respiration by using radioactive markers. One type of carbon is slightly radioactive. Rats fed on glucose containing this sort of carbon are found to breathe out radioactive carbon dioxide!
1 a What are proteins digested into?
b Name one place in the body where new proteins are made.
2 a What are fats digested into?
b Name one place where fats are important.
3 a What are the reactants in respiration?
b How do each of these reactants reach the cells?
4 a What are the products of respiration?
b Explain how carbon dioxide is excreted from the body.
5 Proteins are not usually used for respiration. Explain how a scientist would show that proteins are not used in respiration.
8Ae7 Surface area
The small intestine can be represented as a tube. In adults this is 6.5 m long and has a diameter of 2.5 cm. The surface area is given by this formula:
Surface area of a tube = 2prh
p = 3.142 r = radius
h = height or length
1 What is the radius of the small intestine in metres (m)?
2 Work out the surface area of the small intestine in square metres (m2). Show your working.
3 The villi increase the surface area by 20 times. Work out the surface area of the small intestine with villi.
4 Each villus is made of a single layer of cells all of which have microvilli on them.
The microvilli increase the surface area by another 300 times. Work out the surface area of the small intestine, taking both villi and microvilli into account. Show your working.
A villus
5 Difficult! Work out how long the small intestine would have to be if there were no villi or microvilli. Show all your working.
6 A disease in humans, called Coeliac disease, causes the villi in the small intestine to get smaller. People with the disease start to become weak and ill. Explain why this might be.
8A Summary Sheets
Food and digestion
We need to eat a wide variety of foods to provide our bodies with all the substances that are needed. When we do this, we are said to have a balanced diet.
Substance needed
Examples
Why it's needed
Good sources
starch, sugars
for respiration to release energy
pasta, bread
for growth and repair
meat, beans
vitamin C
for health
fruits and vegetables - oranges contain a lot vitamin C
calcium
fruits, vegetables and dairy products - milk contains a lot of calcium
for health; helps to keep our intestines clean stop them getting blocked up (constipation)
wholemeal bread
for health; water is important solvent in the body
We can do tests to find out which substances are in foods. For example, starch makes iodine solution go a blue-black colour.
Nutrition information labels on foods tell us what the food contains. The labels also tell us how much chemical energy is stored in the food. The amount of energy is measured in kilojoules (kJ).
Eating too much of some foods can cause problems. Too much fat may cause heart disease.
To make use of the food, our bodies need to break it up into smaller sized molecules. This is called digestion. Digestion turns large insoluble substances into small soluble ones. The organs of the digestive system help us digest food. Many of them produce enzymes (chemicals that break up food).
To help absorb the digested food, the small intestine is covered with villi. These increase the surface area.
The digested food substances are carried around the body in the blood. The blood travels through blood vessels. Arteries carry blood away from the heart and veins carry blood towards the heart. The smallest blood vessels are capillaries. Substances enter and leave the blood through capillaries. Cells get the substances they need from the blood in capillaries.
Cells need food substances to:
- release energy
- make new substances.
Cells use a chemical reaction called respiration to release energy from a sugar called glucose.
8ATarget sheet
Topic
Targets
Before the unit
I have learned this
I have revised this
8Aa
Know what nutrients and other substances are found in food.
Know how to test for some food substances.
Know why water is important.
Know why fibre is important.
8Ab
Know what a balanced diet is.
Know why some people need more food than others.
Know which foods contain what substances.
Know what the food substances are needed for.
8Ac
Know the where the organs in the digestive system are.
Know the functions of the organs in the digestive system.
Know why food needs to be digested.
Know what breaks down food.
8Ad
Know where digested food is taken into the body.
Know how to use a model to illustrate digestion.
Know that enzymes are affected by temperature.
Know that enzymes are affected by pH.
8Ae
Know how digested food is taken into the body.
Know how digested food is carried around the body.
Know how digested food is used.
Know the names and jobs of the blood vessels in the circulatory system.
8A Word sheets
Word sheets that include new words from the 'Focus on:' pages are available on the Exploring Science website.
8Aa - On a diet
Word
Pronunciation
Meaning
constipation
con-stip-ay-shun
When the intestines get blocked up.
diet
The food that you eat.
feye-ber
Substance found in food which cannot be used by the body. It helps to keep our intestines clean.
nutrition information
new-trish-un
Information label found on a food packet to tell you what is in the food.
nutrients
new-tree-ents
Substances needed in the diet to provide raw materials.
raw materials
Substances used to make other substances out of.
solvent
A liquid that can dissolve other substances.
Type of insoluble carbohydrate found in plants.
A compound made of hydrogen and oxygen which the body uses as a solvent.
8Ab - Keeping it balanced/Different diets
balanced diet
Eating a wide variety of foods to give us all the things that we need.
car-bO-high-drate
Substance found in food that is used for energy.
chemical energy
Energy stored in chemicals like food.
Substance found in food that is stored to be used for energy in the future. It also helps to keep heat in our bodies.
heart disease
Disease caused by narrowing of the arteries carrying the blood to the muscles of the heart, so the heart muscles do not receive enough oxygen.
kilojoule (kJ)
kill-O-jool
Unit of energy used on food packets. There are 1000 J in 1 kJ.
mineral
Properly called a 'mineral salt' and found in food. Needed in small quantities for health (e.g. calcium).
Substance found in food that is used for growth and repair.
Type of soluble carbohydrate. Glucose is an example of a sugar.
vitamin
Substance found in food that is needed in small quantities for health (e.g. vitamin C).
8Ac - You've got guts
absorbed
When soluble substances go through the wall of the small intestine into the blood.
anus
The opening at the end of the gut.
appendix
Small tube branching off the large intestine. It has no function in humans.
contract
Something gets smaller.
digestion
dye-jes-jun
Process that breaks food into soluble substances in our bodies.
digestive juices
A liquid containing enzymes that break down food.
digestive system
A group of organs that carry out digestion.
egestion
ee-jes-jun
When faeces are pushed out of the anus.
enzyme
A chemical that can break up large molecules.
faeces
fee-sees
Waste food material produced by the intestines.
feeding
Putting food into your mouth. Also called ingestion.
Tube that goes from the mouth to the stomach. Sometimes called the 'food pipe' but properly called the oesophagus.
gut
All the organs of the digestive system apart from the mouth.
ingestion
in-jes-jun
Putting food into your mouth.
insoluble
Something that does not dissolve is said to be insoluble.
large intestine
Organ that takes water out of waste food.
molar
Grinding tooth at the back of the mouth.
rectum
Organ that stores faeces before they are egested.
saliva
sall-eye-va
A digestive juice. It contains an enzyme that breaks down starch into sugar.
sall-eye-vor-ee
Found in the mouth. It makes saliva.
Organ where most digestion happens. The soluble substances produced by digestion are absorbed into the body here. It is about 6.5 m long in adults.
stum-uck
Organ containing strong acid which mixes food up and digests proteins.
8Ad - Break down
am-e-laze
An enzyme found in saliva that breaks starch down into sugar.
digestive juice
8Ae - In the blood
artery
Blood vessel that carries blood away from the heart.
blood
Liquid that flows around the body carrying various substances which are either made by the body or needed by the body.
blood vessel
Tubes in which blood flows. There are capillaries, veins and arteries.
capillaries
cap-pill-arr-ees
Tiny tubes that carry blood.
circulatory system
System containing the heart and blood vessels.
heart
Organ that pumps blood around the body.
respiration
ress-per-ay-shun
Process that uses up oxygen to release energy from food. Carbon dioxide is produced as a waste gas.
tissue
A group of cells of the same type all doing the same job.
tissue fluid
A liquid that leaks out of capillaries carrying dissolved food and oxygen to cells.
vein
vane
Blood vessel that carries blood towards the heart.
villi
vill-ee
Small finger-like parts of the small intestine. They increase the surface area so that digested food is absorbed more quickly. Singular = villus.