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 8ba1
8Ba1 Can dead yeast cells respire?
Name _____________________________ Class ____________
You are going to find out if dead cells respire.
Carbon dioxide, water and heat are produced when cells respire. Carbon dioxide can be detected by limewater, which changes from clear to milky if carbon dioxide is bubbled through it. A thermometer can be used to measure an increase in temperature if heat is released.
Prediction
Write down whether you think dead yeast cells will be able to respire or not.
_______________________________________________________________________________
Why do you think this? ___________________________________________________________
Apparatus
- Bottle containing live yeast culture
- Sugar cubes
- Bottle containing boiled yeast culture
- Two boiling tubes
- Two test tubes
- Bottle of limewater
- Two 25 cm3 measuring cylinders
- Test tube rack
- Two bungs fitted with a thermometer
- Marker pen and a delivery tube
- Eye protection
Wear eye protection when handling limewater.
Method
1 Using a clean measuring cylinder put 20 cm3 of live yeast culture into one boiling tube and 20 cm3 of boiled yeast culture into the other boiling tube. Label each tube.
2 Crumble a sugar cube into each tube and swirl them gently to mix and dissolve the sugar.
3 Place a bung with the delivery tube and thermometer attached in the top of each boiling tube.
4 Record the starting temperature of each culture in the results table.
5 Pour equal amounts of limewater into the two test tubes and place the end of a delivery tube into each.
6 Support both sets of apparatus in the test tube rack and leave for about 30 minutes.
7 Measure the final temperature of each culture and observe the appearance of the limewater.
Recording your results
Record your results in this table.
Starting temperature (°C)
Finishing temperature (°C)
Temperature change (°C)
Appearance of limewater
live yeast culture
boiled yeast culture
Considering your results/conclusions
Why did you add sugar to each boiling tube? __________________________________________
Which yeast culture released the most heat_____________________________________________
Where did this heat come from? _____________________________________________________
What does the appearance of the limewater connected to the live yeast culture
tell you?
What does the appearance of the limewater connected to the boiled yeast culture
Was your prediction right? _________________________________________________________
If not, explain what you think now. __________________________________________________
[ observing, considering ]
8Ba2 Yeast cells and respiration
Planning
1 You are going to use live yeast and dead (boiled) yeast for this investigation. Write down a method for your investigation. You may need some of the apparatus listed in the box.
- Sugar
- Boiling tubes
- Test tubes
- 25 cm3 measuring cylinders
- Bungs fitted with a thermometer
- Balance
2 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?
- What will you measure and observe?
- How long will you leave your experiment set up for?
- How will you make sure that you carry out your investigation safely?
3 Show your method to your teacher before you begin.
4 Write down a prediction. Say what you think will happen and why.
5 Make a table to record your results.
6 Using your results write a conclusion. Say what you have found out and why you think it happened. Do your results match your prediction?
Evaluation
7 Were any of your results surprising? If so, try to explain why.
8 Did you do a fair test, or were there some factors that you forgot to keep the same?
9 Do you think you have enough results to support a firm conclusion?
10 How might you improve your experiment?
[ planning, observing, considering, evaluating ]
8Ba3 Signs of life
Body temperature
Temperature (°C)
me
my partner
How is your body heat produced? ___________________________________________________
Peas
live peas
dead peas
What does this experiment show? ___________________________________________________
Hydrogencarbonate indicator
Tube
Colour of indicator at end of experiment
A
B
C
D
Why was tube D set up? __________________________________________________________
Why did tube C have metal foil around it? _____________________________________________
What do the results show? _________________________________________________________
8Ba4 Respiration snap instructions
1 Cut out the cards on Worksheet 8Ba/5 and divide them between you and a partner.
2 Each person turns over one card from their pile at the same time.
3 Call out 'snap!' if one card shows a substance and the other card correctly describes it as a product or a reactant. Remember, energy is not a product.
The word equation for respiration may help you:
glucose + oxygen → carbon dioxide + water
reactants products
For instance, this is a 'snap'.
glucose
reactant
This is not a 'snap'.
oxygen
product
4 The person who calls 'snap!' first wins the two cards. These should placed to one side.
5 When all the cards have been used, turn over your pile and start again.
6 When no more 'snaps' can be made, each player should lay out their cards to make the word equation for respiration. Draw in the '+' signs and the arrow. The winner is the person with the most complete word equation.
[ knowledge ]
8Ba5 Respiration snap cards
water
carbon dioxide
energy
8Ba6 Some useful tests
1 Select the correct words from the brackets to complete the following sentences:
If I blow into limewater it will change from
_________________ (clear/cloudy) to _________________ (clear/cloudy). This shows that
I breathe out the gas __________________________ (oxygen/carbon dioxide).
These tubes all contain hydrogencarbonate indicator.
Hydrogencarbonate indicator can detect the amount of carbon dioxide in the air.
In normal air it looks _________________ (pink/yellow/purple).
In exhaled air it looks _________________ (pink/yellow/purple) because there
_________________ (more/less) carbon dioxide gas in exhaled air than in normal air.
It looks purple in air containing _______________ (more/less) carbon dioxide than normal air.
Body temperature can be measured using a _______________________ (measuring cylinder/thermometer).
Normal body temperature in humans is _________________ (25 °C/37 °C/45 °C)
2 Pond snails respire like us. They take the oxygen they need from water. The following experiment was set up.
After 2 days the snails were removed and hydrogencarbonate indicator was added to each tube.
a What colour do you think the indicator would go if it was added to the tubes at the start of the experiment?
______________________________________________________________________
b What colour do you think the indicator turned in each tube at the end of the experiment?
1 _________________________________________________________________
2 _________________________________________________________________
3 _________________________________________________________________
c Maria has suggested doing a similar experiment by placing pond snails in limewater. Write down what you think about this idea.
[ knowledge, literacy ]
8Ba7 Pea problem
The apparatus shown in the diagram was set up using peas soaked in water and peas which had been boiled. Both sets of peas had previously been sterilised to kill microbes on their surfaces.
The temperature inside each flask was measured every 12 hours over 3 days. The results are shown in the table.
Time (hours)
Flask A
Flask B
0
15
12
20
24
25
36
29
48
31
60
33
72
1 Plot both sets of results as line graphs on the same axes.
2 Why did the temperature rise in flask A?
3 Why did the temperature remain at 15 °C in flask B?
4 What was the temperature in flask A after 20 hours?
[ knowledge, presenting, considering ]
8Ba8 Getting warmer
The temperature inside each flask was measured every 6 hours over 3 days. The results are shown in the table.
16.0
6
19.0
21.0
18
24.0
26.0
30
28.0
27.0
42
31.0
32.0
54
32.5
33.0
66
1 What factor(s) would have been kept the same to make the experiment a fair test?
2 Plot both sets of results as line graphs on the same axes.
3 Were there any unusual results?
4 Why did the temperature rise in flask A?
5 Why did the temperature remain at 16 °C in flask B?
6 What was the temperature in flask A after 20 hours?
7 Predict what the temperature would be in flask A in another 6 hours.
Explain your reasoning.
8Bb1 Back to resting
You are going to find out how long it takes for your pulse rate to get back to normal after exercise.
l Stopclock or stopwatch
1 Hold two fingers firmly on your wrist in the position shown in the diagram. You should be able to feel your pulse. If you cannot feel it, ask your teacher for some help.
2 Once you have found your pulse, start timing and count how many pulses you feel in one minute. Write down your answer in the space below. This is called your resting pulse rate.
I felt ____________________ pulses in 1 minute.
3 Now do some exercise for 2 minutes. Your teacher might give you some ideas, like running or doing star jumps. As soon as you have finished your exercise, measure your pulse rate again.
4 Now wait for 1 minute and then measure your pulse rate again (for 1 minute).
5 Repeat step 4 until your pulse rate is the same as it was before you did the exercise.
Time after finishing exercise (mins)
Pulse rate (pulses/minute)
2
4
8
10
Use your results to plot a line graph on these axes.
How many minutes did it take for your pulse to get back to your resting pulse rate, after you stopped doing the exercise?
What causes the pulse?
Imagine that, for one day, you do no exercise. Work out how many pulses you would expect to measure during this day. Show your working.
Pulses in 1 day = _________________________________________________________________
8Bb2 The circulatory system
1 Colour all the veins in dark red and all the arteries in bright red and colour in the key.
2 Fill in the missing words in the sentences below.
8Bb3 Circulation crossword
1 Fill in the crossword grid using the clues.
1
3
5
7
9
11
13D
i
g
e
s
t
o
n
Across
2 (and 1 down) A gas made by your body.
6 A gas from the air needed by your body.
8 When you exercise your pulse rate goes ____________ .
10 A clear, colourless liquid used to test for a gas which your body gets rid of.
11 A process that releases energy for your body.
Down
1 (and 2 across) A gas produced by your body.
2 The system that carries blood around your body is called the ____________ system.
3 The liquid in which things are carried around your body.
4 Organs inside your body which allow you to take in air and blow it out again.
5 Tubes that carry blood are called blood ____________ .
7 A substance produced by digestion which is an energy resource for your cells.
9 An organ inside your body which pumps.
12 Something that you can feel as blood is pumped around your body.
2 There is no clue for 13 across. Write a clue for this word.
__________________________________________________________________________
8Bb4 William Harvey
William Harvey was an English doctor who lived from 1578 to 1657. He made the real breakthrough in our understanding of the circulation. Harvey made careful observations of the heart and blood vessels and also carried out experiments. He would only say something was a fact if he could prove it in his experiments and he was not put off by superstitions, as previous scientists had been. He discovered that blood was pumped from the heart around the body, then returned to the heart to be re-circulated. He also carried out experiments to prove that there are valves in veins that allow blood to flow in one direction only.
At the time the microscope had not been invented so Harvey never discovered how the arteries and veins were connected - the capillaries were too small to be seen.
1 Underline in red the sentence which explains why Harvey's theories were more likely to be correct than those of previous scientists.
2 Underline in blue two of Harvey's discoveries about the circulation.
3 Complete these sentences.
Harvey found valves inside __________________ . He proved that they allowed
__________________ to flow in __________________ direction only.
4 Why didn't Harvey discover how arteries and veins are connected?
5 What are the tiny blood vessels that connect arteries and veins called?
8Bb5 Blood and circulation
1 The diagram of the heart has a letter next to each major blood vessel and in each chamber.
a Arrange the letters to show the direction that the blood travels through the heart, starting from when blood first enters the heart.
b The artery that takes blood to the lungs is called the pulmonary artery. Which letter represents the pulmonary artery?
c Which letters show parts that carry blood with a lot of oxygen?
d Which letters show parts that carry blood without very much oxygen?
2 Look at these pictures of blood vessels.
a Which one shows a capillary?
b What is the name of the liquid that leaks out of capillaries and surrounds the cells?
c Blood consists of cells and a liquid. What is the name of this liquid?
d Name one substance that the liquid in part c carries.
e Name one substance that a red blood cell carries.
Optional Extra
3 Try to find out the correct names for all the blood vessels and chambers of the heart which are labelled with letters in Question 1. Make a copy of the heart diagram and label it with the names you have found.
[ knowledge, research ]
8Bb6 Blood
Blood consists of plasma, white blood cells, red blood cells and platelets.
Red blood cells carry oxygen. When they are carrying oxygen they are said to be oxygenated and when they are not they are said to be deoxygenated. They are a bright red colour when they are oxygenated and a dark red colour when they are deoxygenated. Red blood cells contain a special chemical called haemoglobin (hee-mow-glow-bin) which carries oxygen. Haemoglobin contains iron atoms which help it carry the oxygen. The chemical turns into oxyhaemoglobin when it is carrying oxygen.
There are a number of ways in which red blood cells are adapted to their functions.
Red blood cells drawn at a scale of ×2000.
Red blood cells are discs that have a concave hollow on each side. They are described as biconcave discs. This shape gives them a greater surface area than a flat disc and it also allows all the haemoglobin molecules to be close to the surface of the cell.
Unlike most cells, red blood cells do not have a nucleus. This means they have more room for haemoglobin molecules. They only last for about 120 days before they are destroyed by the liver. Red blood cells are extremely small and there are about 5 000 000 of them in each cubic millimetre of blood. The cells are also flexible and can bend to fit through even the smallest capillary.
1 Why do you think iron is an important mineral in the diet?
2 Make a table of the adaptations of a red blood cell and say why these adaptations are useful.
3 a Work out how big a red blood cell is in real life. Give your answer in micrometres (mm) - there are 1000 mm in 1 mm.
b Why do you think red blood cells have to be so small?
c How many red blood cells are there in 1 cm3 of blood?
4 What is oxyhaemoglobin?
5 Where are old red blood cells destroyed?
6 a The liquid that surrounds blood cells is called plasma. What job does it do?
b Try to find out what the other parts of the blood are for.
[ knowledge, literacy, numeracy, research ]
8Bb7 William Withering
In the 18th century many people died of a disease called dropsy, which was caused by poor heart function. The heart was not strong enough to pump blood around the body and fluid would leak out of the blood vessels causing the tissues to swell. Sometimes the liquid caused the arms and legs to swell so much that they couldn't be moved. The sufferer literally drowned as their lungs slowly filled with their own body fluid.
Drawing fluid from a patient with dropsy.
A foxglove.
William Withering was an English doctor who lived from 1741 to 1799. He was also an expert botanist, and had an extensive knowledge of plants. Withering heard that it was possible to cure dropsy using a herb mixture. He obtained the recipe and tested each herb individually on his dropsy patients to discover which was the one that worked. He identified that foxglove leaves could be used to cure the illness.
He extracted a drug from foxglove leaves and called it digitalis, from the Latin name for the plant, Digitalis purpurea. The drug digitalis caused the heart to beat more forcefully. He spent 10 years experimenting with different doses and documented its dangerous side effects. If too much was given it caused severe headaches and violent sickness and diarrhoea. It could even cause death.
The plant extract was used to treat a weak heart until the 1970s. By then the active ingredient in the plant extract had been identified and was produced in a pure form. It is called digitoxin and is still used today.
1 What is a botanist?
2 a Name the drug that William Withering produced.
b Name the plant from which this drug is extracted.
3 What causes the disease called dropsy?
4 Give some of the symptoms of this disease.
5 How did William Withering identify that foxglove leaves could be used to treat dropsy?
6 What effect does digitalis have on the heart?
7 Digitalis is a very toxic drug if given in too high a dose. List its harmful side effects.
8 How do you think William Withering worked out what was a safe dose to give to his patients?
9 What is the name of the drug, derived from digitalis, that is used today?
10 Why do you think this is a better drug than digitalis?
8Bb8 Understanding the human circulation
Galen.
Andreas Vesalius.
William Harvey.
William Withering.
Ibn-al-Nafis.
Michael Servetus.
Realdo Columbo.
Leonardo da Vinci.
Girolamo Fabrici (Fabricius).
1 Above are the names of some scientists who have developed ideas about the human circulation. Using reference books, CD-ROMs or the internet try to find out about their ideas.
Show the information as a time line, giving the names of the scientists in chronological (date) order with a list of their main ideas.
Make sure you set it out clearly - you could use a large piece of paper.
2 a The theory about the circulation of blood has been modified over the years because predictions made from earlier beliefs could not be supported by evidence.
Scientists used to think that blood could flow in either direction in veins. Find out what evidence William Harvey used to show that blood moved only in one direction through veins.
b Find out how one other part of the theory of circulation was changed and what evidence was used to support this change. Write down where you got your information from.
[ knowledge, literacy, research ]
8Bc1 Exercise and breathing rate
You are going to find out if exercise affects your breathing rate.
Do you think your breathing rate will get faster, slower or stay the same when you exercise?
- Stopclock
1 Sit still and count how many times you breathe in in one minute.
This is your resting breathing rate. Write it in the results table below.
2 Do light exercise, like walking, for 1 minute.
Sit down and count your breathing rate again
3 Do hard exercise, like running on the spot, for 1 minute.
Sit down and count your breathing rate.
Resting breathing rate
Breathing rate after light exercise
Breathing rate after hard exercise
(breaths per minute)
Plot your results as a bar chart on the axes below.
What do your results show_________________________________________________________
Was your prediction right? ________________________________________________________
8Bc2 Respiration and circulation summary cards
1 Cut out the statements and sort them into true and false sets.
2 Read the true statements and arrange them into a sensible order to produce two lists of summary statements. One list should be about respiration and the other about circulation.
3 Stick them into your book or write them out.
------------------------------------------------------------------------------------------------------------------------------
Capillaries are very small blood vessels.
Respiration produces glucose.
Respiration produces water.
Capillaries are very small electrical wires.
Blood flows backwards and forwards in the blood vessels.
Respiration uses carbon dioxide.
Substances are carried from the blood in capillaries to tissues in a liquid called tissue fluid.
Respiration takes place all the time.
Blood is pumped around the body by the heart.
Respiration releases energy.
Anaerobic respiration uses oxygen.
Respiration uses glucose.
Veins carry blood back to the heart from the body.
Cells die when someone gets frostbite. Frostbite is caused by too little oxygen reaching the cells.
Arteries carry blood back to the heart from the body.
Respiration uses water.
Carbon dioxide is carried around the body attached to white blood cells.
Respiration uses up energy.
Anaerobic respiration means respiring without oxygen.
Respiration produces carbon dioxide.
Glucose is transported around the body in paper bags.
Respiration uses oxygen.
Oxygen is transported around the body by red blood cells.
Respiration occurs in all living cells.
The left side of the heart pumps blood to the lungs.
Capillaries have very thick walls.
Glucose is transported around the body dissolved in the plasma.
Carbon dioxide is carried around the body dissolved in the blood plasma.
The left side of the heart is bigger than the right because it pumps blood around the body.
Respiration produces oxygen.
Cells die if they don't get enough oxygen.
Respiration occurs only in plant cells.
8Bc3 Breathing and exercise
Michael and Bhavesh wanted to find out if exercise affected their breathing rates.
They measured their breathing rates before a race and every minute afterwards until their rates returned to normal again.
Their results are shown in the table.
Name
Breathing rate (breaths per minute)
Before race
Time after finishing the race (minutes)
Bhavesh
22
Michael
14
38
27
17
1 Plot their results on the grid on the right. Draw both line graphs on the same grid.
2 What affect did running have on breathing rate?
___________________________
3 a Who do you think was the fittest, Bhavesh or Michael?
______________________
b Why do you think this?
[ knowledge, considering ]
8Bc4 Exercise and the body
An experiment was carried out on a Year 8 pupil, Ben, to see how exercise affected his body.
Ben's temperature, heart rate, breathing rate and volume of air he took in each breath were measured before and after running.
The results are shown in the table.
Heart rate (beats/minute)
Breathing rate (breaths/minute)
Volume of air per breath (cm3)
at rest
36.6
62
400
after running
37.2
128
900
When answering the following questions you may need to consider the word equation for aerobic respiration, which is:
glucose + oxygen → carbon dioxide + water (+ energy)
1 a What effect did exercise have on Ben's temperature?
b Why do you think this happened?
2 Why do you think Ben's heart rate increased during exercise?
3 a Calculate the total volume of air breathed in per minute at rest.
b Calculate the total volume of air breathed in per minute after running.
c How much more air is breathed in per minute after running?
d Why do you need to take in more air when you exercise?
4 a About 20% of the air breathed in is oxygen. Using your answer to Question 3a, calculate how much oxygen Ben breathes in each minute at rest.
b The body uses about 4% of the oxygen breathed in. Calculate how much oxygen Ben uses each minute at rest.
8Bc5 Marathon running
The following passage is an extract from an article written by marathon runner, Katie Nutley.
Running can be very good for the body. It places extra demands on the body so all of the vital functions are improved through training. The muscles are strengthened, the capacity of the heart and lungs are increased, and bones become thicker.
Running a marathon is a challenge for many runners because of the fitness which it requires. Even experienced runners start to prepare several months before a race.
The most important part of marathon training is to do a long run every week. These runs bring endurance - they teach the body to keep going for several hours. Runners also need to do shorter, faster runs which build strength in the muscles.
Before running it is important to stretch the muscles by warming up gently. When the muscles are cold and tight it is easy to strain them, and by shooting off on a fast run the muscles can be pulled and damaged. Stretching also increases the blood circulation to the muscles.
It is also important to drink plenty of water before, during and after a run. If the body loses too much water through sweating, the blood will not be able to circulate around the body so well, to carry nutrients and oxygen to the muscles. Many runners use sports drinks which contain carbohydrates.
At the end of the race there is a great feeling of achievement. The fastest male runners can run a marathon (26.2 miles) in about 2 hours and 7 minutes. The fastest women can cover the distance in about 2 hours and 22 minutes.
1 List the benefits of running.
2 When training for a marathon, why should people do:
a long runs each week
b short runs each week?
3 What are the benefits of 'warming up gently'?
4 Name two important substances carried by the blood to muscles?
5 Suggest why blood cannot 'circulate around the body so well' if a runner loses too much water.
6 Runners often get sore nipples where their shirts rub. What force causes this soreness?
7 a Apart from water, what do 'sports drinks' contain?
b Why are these substances useful?
8 a How far is a marathon in miles?
b There are 1.6 kilometres to 1 mile. How far is a marathon in kilometres?
c Work out the average speed of the fastest male marathon runner in km/h.
d Work out the average speed of the fastest female marathon runner in km/h.
[ literacy, knowledge, numeracy, revision ]
8Bd1 Looking at a sheep's lungs
Look carefully at the sheep's lungs.
What colour are they? _____________________________________________________________
How big are they? _______________________________________________________________
What do they feel like? ____________________________________________________________
Can you find the following structures? Tick those that you see.
trachea (windpipe)
bronchi
heart
What is the trachea (windpipe) like?
Why do you think it is like this?
Draw what the lungs look like.
8Bd2 Air sacs
The diagram shows an air sac from a lung.
1 What sort of blood vessels are found surrounding air sacs? _______________________
2 a Draw some red blood cells on the diagram. Do not shade them in.
b Blood cells change colour slightly depending on how much oxygen they are carrying (they are bright red when carrying a lot of oxygen). Find two coloured pencils, one bright red and one dark red. In the correct areas, shade some of the red blood cells dark red and some of them bright red.
3 a On the diagram, draw a labelled arrow showing which direction oxygen particles are going.
b On the diagram, draw a labelled arrow showing which direction carbon dioxide particles are going.
c Your two arrows show a process that occurs in the lungs. What is the name of this process?
d In which part of the blood is carbon dioxide carried? ____________________________
8Bd3 Breathing for respiration 1
1 Label the diagram with the following words.
air sacs
diaphragm
lung
rib
windpipe
This drawing shows the breathing system and some of the bones in the chest.
2 Fill in the missing words in these sentences, using the words in the box.
You may need to use some words more than once.
blood vessels carbon dioxide exhaling
heart inhaling lungs oxygen respiration
Breathing in is called ____________________ . Air goes into the
____________________ . A from the air called ____________________ goes into the
blood. A waste gas dissolved in the blood, called ____________________ , goes into the
lungs. Breathing out is called ____________________ ____________________ . When
we do this, the waste gas goes into the air.____________________ gas, from the air, is
needed by the cells in the body for ____________________ . The gas is carried by the
blood. The ____________________ is an organ that pumps the blood. The blood travels
around the body in tubes called ____________________ ____________________ .
8Bd4 Breathing for respiration 2
1 a Write down the letters A-F. Write the name of the part corresponding to each letter.
b How do the parts labelled C allow oxygen to get into the blood easily?
Drawing P.
Drawing Q.
a Which drawing shows someone with lungs full of air?
b What happens to the parts labelled X when someone inhales?
c What moves these parts?
d What happens to the part labelled Y when someone exhales?
3 Gas exchange happens in the lungs. Explain what 'gas exchange' is.
4 Oxygen and carbon dioxide are carried in the blood, through tubes.
a What is the general name for a tube that carries blood?
b How is oxygen carried in the blood?
c How is carbon dioxide carried in the blood?
d What is the name of the process that requires the oxygen?
e Copy and complete the word equation for this process.
_______________ + glucose → carbon dioxide + _______________ (+ energy)
8Bd5 Lung diseases
The breathing (or respiratory) system has various adaptations to prevent microbes, which might cause an infection, from entering the lungs.
In the nose, hairs filter out dust, and microbes are trapped in a sticky fluid called mucus. We usually swallow the mucus or get rid of it by sneezing. The mucus also contains a chemical that kills microbes.
Once air enters the trachea and bronchi it passes over more mucus that is produced by special cells called goblet cells. This traps even more microbes. To prevent a build up of 'dirty' mucus in the air passages, which might cause an infection, there are tiny hairs called cilia lining the trachea and bronchi. These are constantly moving and they waft the mucus up and out of the lungs to the back of the throat where it is swallowed. If a large object is accidentally inhaled it is usually expelled quickly by coughing.
Despite these mechanisms we all suffer from infections of the respiratory system from time to time. Any part of the system can become infected. For example, laryngitis is when the larynx, or voice box, becomes swollen and inflamed. This is often associated with a loss of voice and sore throat. Tracheitis is inflammation of the trachea. Bronchitis is when the bronchial tubes become inflamed. This can make it difficult to breathe because these tubes are fairly narrow and any swelling will partially block them. All these infections are associated with an increased production of mucus that also blocks the airways. For this reason coughing is usually another symptom of a chest infection.
Surrounding each lung are two delicate membranes called the pleural membranes. One membrane lines the chest cavity and the other covers the lung. Between them is a fluid, which acts as a lubricant so that the lungs can move easily when you breathe in and out.
Pleurisy is an infection of the pleural membranes. They cannot slide over each other easily and this makes breathing very difficult and painful.
Many people today suffer from asthma. This is when the muscles in the walls of the tiny tubes, called bronchioles, contract making them become even narrower. This makes breathing difficult. Asthma sufferers must always carry an inhaler. This contains a drug that makes the muscles relax, so the tubes widen again.
Tuberculosis, or TB, is a very serious lung disease caused by a bacterium that destroys the lung tissue and causes fever and weight loss. TB used to kill many people. Nowadays it is rare because most people are immunised against it.
Lung cancer is a major killer disease today. It is when cells in part of the lung grow and divide uncontrollably. Eventually a large lump forms which blocks some of the airways. If it is left untreated it grows bigger and bigger making breathing more and more difficult. Some of the cancer cells may break off and get carried to other parts of the body where they can cause another cancer to form. This is called a secondary growth. People who smoke are at a much greater risk of developing lung cancer than non-smokers.
1 List the ways in which the body is adapted to prevent microbes from entering the lungs.
2 a What is the proper name for the voice box?
b What is an infection of the voice box called?
c What are the symptoms of this disease?
3 Why do you often cough when you have a chest infection?
4 Describe what pleurisy is.
5 a Why do asthma sufferers find it hard to breathe?
b How do inhalers help them to breathe?
6 a Why is it rare for someone to catch tuberculosis today?
b Find out what tuberculosis used to be called.
7 Describe what happens when lung cancer develops.
8Be1 Investigating inhaled and exhaled air
You are going to find out about some of the differences between inhaled and exhaled air.
Experiment 1: Investigating the amount of carbon dioxide
- Limewater
- 2 delivery tubes
- 2 double-holed bungs
- Y-shaped tube
Wear eye protection.
1 Set up the apparatus as shown in the diagram.
2 Gently breathe in and out through the mouthpiece for two minutes.
3 Notice what happens as you do this.
On the diagram, draw arrows to show the direction of airflow through the apparatus.
Mark on the diagram any changes you saw in the limewater.
Which had the most carbon dioxide - inhaled or exhaled air? ______________________________
Where did this extra carbon dioxide come from? ________________________________________
______________________________________________________________________________
Experiment 2: Is water vapour present in exhaled air?
- Mirror
- Forceps
- Beaker of water
- Pipette
- Dry cobalt chloride paper
Do not handle cobalt chloride paper with fingers. If you touch the paper accidentally, wash your hands immediately.
1 Cobalt chloride paper is blue when it is dry. Put a drop of water onto a piece of dry cobalt chloride paper and notice what happens.
2 Breathe out heavily onto a mirror several times.
3 Put a second piece of dry cobalt chloride paper onto the mirror.
What happened when you put water onto the blue cobalt chloride paper? ____________________
What did you see on the mirror when you breathed onto it? _______________________________
What happened when you put blue cobalt chloride paper onto the mirror? ___________________
What does the colour change of cobalt chloride paper on the mirror tell you about exhaled air?
Why has your breath got water vapour in it? ___________________________________________
Experiment 3: Investigating the temperature of inhaled and exhaled air
- Thermometer
1 Measure the temperature of the air with the thermometer.
2 Breathe heavily onto the bulb of the thermometer several times and record the temperature of your breath.
Record the temperatures in this table.
Air temperature (°C)
Breath temperature (°C)
How is breath temperature different from the air temperature in this room? ___________________
Explain this difference in temperature. ________________________________________________
8Be2 Burning candles
You are going to find out how long a candle can burn in normal air and in exhaled air.
Write down in which sample of air you think the candle will burn for the longest time.
- Trough of water - 2 gas jars with lids
- Clean tubing - Stopclock
- 2 deflagrating spoons with tea lights
1 First you need to collect a gas jar of exhaled air. Fill one of the gas jars with water and turn it upside down in the trough without letting any water come out of it.
2 Put one end of the clean tubing into the gas jar and breathe into it through the other end.
3 Keep exhaling into the gas jar until it is full of exhaled air.
4 Seal the top of the gas jar with a lid whilst it is still underwater.
The other gas jar will already be filled with normal air.
5 Light one of the candles and quickly put it into the normal air on the spoon.
6 Start the stopclock and time how long the candle burns for.
7 Do the same thing with the exhaled air. You'll have to remove the lid and put the candle in quickly.
8 If you have time you could repeat your experiment a few times to make your results more accurate.
Record your results in the table below.
Time candle burned for (s)
Mean times (s)
normal air
exhaled air
If you repeated the experiment record all your readings and calculate a mean for each air sample.
To calculate a mean:
- add up all the times for each air sample
- divide your answer by the number of readings you took for that sample.
What do your results show? ________________________________________________________
Was your prediction right ? ________________________________________________________
If not, explain what you think now. _________________________________________________
Were any of your results surprising? _________________________________________________
If so, suggest a reason for this.
How was your experiment a fair test?
[ observing, considering, evaluating ]
8Be3 A burning experience
1 Write down a prediction. Say what you think will happen and why.
2 Write down a method for your investigation. You may need some of the apparatus listed in the box.
- Trough of water - Gas jars with lids
- Clean tubing - Deflagrating spoons
- Tea lights - Stopclock
3 You will also need to think about the following questions.
- What factors will you vary and what will you keep the same?
- How will you make it a fair test?
- How will you collect exhaled air?
- What will you measure?
- How many measurements will you take?
- How will you make sure you stay safe?
4 Show your method to your teacher before you begin.
6 Write a conclusion. Say what your results show and why this happened. Do your results match your prediction?
7 Were any of your results surprising? If so, why?
8 Did you do a fair test, or were there some factors that you did not keep the same?
9 Do you think that you have enough results to support your conclusion?
[ planning, observing, presenting, considering, evaluating ]
8Be4 Respiring organisms
You are going to find out what affects the amount of carbon dioxide produced by respiring organisms.
Hydrogencarbonate indicator solution changes colour depending on how much carbon dioxide is dissolved in it. If normal air is bubbled through the indicator, it turns pink. With air containing less carbon dioxide it turns purple. With air containing more carbon dioxide it turns yellow.
1 Write down a method for your investigation and draw a diagram to show how you will set up the apparatus.
2 You will need to think about these questions:
- What factors will you vary (e.g. mass of living material used, temperature, activity of organisms) and what will you keep the same?
- What will your control be to show that the indicator did not alter on its own?
- What ranges will you use for the factors you will vary?
- How long will you leave the experiment set up for?
- What will you measure/observe?
- What will you do to make sure you stay safe?
3 Write down a prediction. Say what you think will happen and why.
5 Record your results in a table.
6 a Say what happened and why you think it happened.
b Are there any trends or patterns in your results?
c Write a conclusion, in one sentence, to summarise what your results show.
7 Look at the results of others in the class. Are there any other conclusions you can make?
Evaluating
8 Were any of your results surprising? If so, why?
9 Was your experiment fair, or did you forget to keep some things the same?
10 Do you think you have enough results to support your conclusion?
11 How could you improve your method?
12 Are there any further investigations you could do to support your conclusion?
8Be5 Respiration Review
1 Label the following parts on the diagram.
lungs heart small intestine muscle cell blood vessel
2 Cut out the cards below. Rearrange them into a logical order to produce a flow chart showing how the carbon dioxide in exhaled air comes from glucose.
---------------------------------------------------------------------------------------------------------
Glucose is absorbed into the blood from the gut and carried to respiring cells.
Carbon dioxide is exhaled.
Oxygen is absorbed into the blood and carried to the respiring cells.
Digestion breaks down carbohydrates into glucose.
Respiration releases energy from glucose using oxygen.
Carbon dioxide is carried to the lungs in the blood.
Carbon dioxide and water are waste products of respiration.
8Be6 Breathing and respiration
1 Use the words in the box to complete the sentences below. You may need to use some words more than once.
blue carbon dioxide cleaner cloudy cobalt chloride
energy glucose heat limewater lungs oxygen pink
respire warmer water
All organisms __________________ all the time.
Respiration releases __________________ from food. In humans a lot of this energy is
released as __________________ .
The food substance used in respiration is called __________________ .
The other reactant in respiration is the gas __________________ .
The chemical products of respiration are __________________ __________________
and __________________ .
Ventilation is the movement of air in and out of the __________________ .
You can show that you produce carbon dioxide by breathing out into __________________ .
It turns from clear to __________________ .
You can show that you breathe out water vapour using __________________
__________________ paper that turns from __________________ to _________________ .
The air we breathe out contains more __________________ __________________ and less
than the air we breathe in. It is also __________________ and __________________ .
8Be7 Do other organisms respire?
The diagram shows an experiment that was set up to find out whether an animal carries out respiration.
1 What does soda lime do?
2 What do you think is the purpose of bottle A?
3 What changes, if any, would you expect to see in bottle A and bottle B?
4 What would it show if the limewater in bottle B went cloudy?
5 a If a dead animal had been used instead of a living animal how would the results have been different?
8Be8 Air and breathing
The following experiment was set up:
The gas syringe was filled with 100 cm3 of air. Pyrogallol absorbs oxygen. The apparatus was left for 20 minutes.
1 By how much would you expect the volume of air in the gas syringe to decrease? (Hint: look at the pie chart.)
2 Another conical flask containing potassium hydroxide solution was attached to the gas syringe in place of the one containing pyrogallol. Potassium hydroxide absorbs carbon dioxide. After 20 minutes, the volume of air in the gas syringe appeared to be the same. Explain this observation.
3 This experiment was repeated using exhaled air. Copy and complete the table of results.
Normal air
Exhaled air
Original volume (cm3)
Volume remaining after using pyrogallol (cm3)
84
Volume remaining after using potassium hydroxide (cm3)
80
Volume of oxygen present in the original sample (cm3)
Volume of carbon dioxide present in the original sample (cm3)
4 What percentage of exhaled air is oxygen?
5 What percentage of exhaled air is carbon dioxide?
6 What percentage of nitrogen do you think exhaled air contains?
7 Draw a pie chart to show the percentages of the gases in exhaled air.
8 Why is more carbon dioxide exhaled than is inhaled?
9 Smoking covers some of the surfaces in the lungs with a thick tar. What effect might this have on the volume of oxygen breathed out? Explain your answer.
10 There is another gas in normal air which exhaled air contains far more of. What is this gas?
[ knowledge, numeracy ]
8B Summmary Sheets
Respiration
All living cells need to respire to release energy. Energy is needed by organisms to help them move, grow and make new substances to help them stay alive.
Respiration normally requires oxygen and so it is called aerobic (with air) respiration. It is a series of chemical reactions which can be summarised in a word equation:
Glucose and oxygen are the reactants. Carbon dioxide and water are the products. Energy is released but it is not a chemical substance so we can either miss it out of the equation or put it in brackets.
Glucose is supplied by the digestion of carbohydrates. It is carried around the body dissolved in the plasma of the blood. The blood travels through blood vessels and is pumped by the heart. The heart and the blood vessels form the circulatory system.
The oxygen is absorbed from the air by the lungs. The lungs are part of the breathing system.
The alveoli give the lungs a large surface area so that oxygen can quickly diffuse from the air inside the lungs into the blood contained in capillaries. The walls of the alveoli and the walls of the capillaries are only one cell thick which also makes it easy for oxygen to diffuse into the blood. The oxygen is carried by the red blood cells.
Tissue fluid comes out of other capillaries around the body and bathes the tissues in the body. Tissue fluid contains oxygen and glucose. The cells take the oxygen and glucose that they need from the tissue fluid and put the carbon dioxide that is produced back into the tissue fluid. The tissue fluid soaks back into other capillaries and the carbon dioxide dissolves in the blood plasma.
In the lungs the dissolved carbon dioxide diffuses out of the blood and into the air in the lungs. That is why we breathe out (exhale) more carbon dioxide than we breathe in (inhale). The carbon dioxide is excreted by the lungs. Carbon dioxide can be tested for by using limewater which turns from clear to cloudy. Oxygen diffusing into the blood and carbon dioxide diffusing out of the blood is called gas exchange.
Inhaled air
nitrogen gas
78%
oxygen gas
21%
16%
carbon dioxide gas
0.03%
4%
water vapour
variable
more
Composition of inhaled and exhaled air.
When you exercise, your breathing rate (number of breaths in one minute) and your pulse rate (number of times your heart beats in one minute) increase. This is because your cells need more oxygen and glucose for respiration.
In some diseases or when there is little air (e.g. at the top of a mountain) the body cannot get enough oxygen. People in these situations often feel short of breath and tired. If too little oxygen gets to cells, the cells cannot release energy from food and so they die.
8B Target Sheet
Topic
Targets
Before the unit
I have learned this
I have revised this
8Ba
Know what digested food is needed for.
Know how energy is released in the body.
Know what substance is used as the main energy resource in the body.
Know the similarities and differences between burning and respiration.
8Bb
Know how oxygen gets into the blood and how it is transported around the body.
Know what system the heart and blood vessels belong to.
Know why the heart has two halves.
Know what the different blood vessels in the body are.
8Bc
Know how exercise affects the pulse rate and breathing rate.
Know how the body gets rid of carbon dioxide.
Know what happens in aerobic respiration.
Know how oxygen and digested food get from the blood to the cells that need them.
8Bd
Know what happens when you breathe.
Know how the lungs are adapted to their job.
Know how gases get into and out of the blood.
Know how the lungs are kept clean.
8Be
Know the differences between inhaled and exhaled air.
Know how to detect water vapour.
Know what limewater is used to test for.
Know how to detect the differences between inhaled and exhaled air.
8B Word Sheets
Word sheets that include new words from the 'Focus on:' pages are available on the Exploring Science website.
8Ba - Energy for life
Word
Pronunciation
Meaning
aerobic respiration
Process that releases energy from digested food. Needs oxygen from the air. Carbon dioxide is produced as a waste gas.
A type of sugar.
New chemical formed in a chemical reaction.
Chemical that is used up in a chemical reaction.
respiration
ress-per-ay-shun
Process that uses up oxygen to release energy from food. Carbon dioxide is produced as a waste gas.
word equation
A way of writing out what happens in a chemical reaction.
8Bb - Round and round
absorb
To take in, e.g. when soluble substances pass through the wall of the small intestine and into the blood.
artery
Blood vessel that carries blood away from the heart.
capillaries
cap-ill-arr-ees
The smallest blood vessels. Substances enter and leave the blood through the thin walls of capillaries.
chamber
The heart contains four compartments called chambers.
circulatory system
System containing the heart and blood vessels.
Organ that pumps blood around the body.
plasma
Part of the blood. A liquid that surrounds the blood cells.
pulse
The feel of your blood being pumped.
pulse rate
The number of times you can feel your blood being pumped in one minute.
red blood cells
Cells in the blood that carry oxygen.
tissue fluid
The liquid formed when plasma leaks out of capillaries, carrying oxygen and food to cells.
vein
vane
Blood vessel that carries blood to the heart.
8Bc - Aerobics/Transporting chemicals (continued)
The liquid formed when plasma leaks out of capillaries, carrying oxygen and digested food to cells.
8Bd - Air supply
Groups of alveoli in the lungs where oxygen comes out of the air and goes into the blood. Carbon dioxide is also transferred from the blood to the air in these.
alveolus
al-vee-O-lus
Small, round pocket that is grouped with other alveoli to form air sacs in the lungs. Plural = alveoli.
blood
Contains cells and a liquid called plasma. It flows around the body carrying various substances which are either made by the body or needed by the body.
breathing
Moving muscles in order to make air flow into and out of the lungs.
breathing system
Set of organs (lungs, windpipe, diaphragm) that allow air to be taken into and out of the body.
bronchus
Tube in the lungs that connects the windpipe to the air sacs. Plural = bronchi.
cilia
sil-lee-a
Small hairs on the surface of some cells.
cilated epithelial cell
sil-lee-ay-ted
eppy-theel-ee-al
Cells with cilia that are found in the lungs.
diffusion
diff-you-shun
The natural movement of particles from a place where there are a lot of them to a place where there are fewer of them.
digestive system
The group of organs that carry out digestion.
exhale
To breathe out.
gas exchange
Taking oxygen into the blood and getting rid of carbon dioxide into the lungs. Happens in the air sacs in the lungs.
inhale
To breathe in.
mucus
Slimy substance which traps dirt and microbes and is moved out of the lungs by cilia.
respiratory system
System containing the lungs, bronchi and trachea.
trachea
Windpipe.
ventilation
Air moving into and out of the lungs.
8Be - Detecting respiration
Air that is breathed out.
gill
A series of flaps of tissue with a good blood supply just behind the head of an organism which is used to take oxygen out of water. Fish have gills.
hydrogencarbonate
An indicator that can be used to show how much carbon dioxide there is in
indicator
something.
inhaled air
Air that is breathed in.