Ventilation & the thorax

The diagram shows parts of the human respiratory system with some structures labelled.

Which of these is the structure labelled X?

State why a lung is described as an organ.

Explain how contraction of the diaphragm causes air to move into the lungs.

A scientist compared the rate at which oxygen is used during exercise by a person who is a non-smoker with a person who is a smoker. The rate is measured in cm³ per minute for each kilogram of body mass. The table shows the scientist’s results.

Calculate the volume of oxygen used in 30 minutes by a non‑smoker with a mass of 70 kg.

volume =_........ ³

Explain the effect of cigarette smoking on the rate at which oxygen is used.

Complete the passage about the lungs by writing a suitable word in each blank space.

The organs of gas exchange in humans are the lungs. A single tube called the_........ allows air to move towards the lungs. This tube splits into two tubes called_........ which then divide into many narrow tubes called_........ . At the end of these narrow tubes are air sacs called_........ . These are where gas exchange takes place. The lungs are inflated by the contraction of a muscular sheet

The_........ muscles also contract to move the ribs to expand the chest cavity.

Scientists can investigate the effect of exercise on breathing rate. An athlete wears a face mask that covers their nose and mouth. The mask contains electronic sensors that measure and record the athlete’s breathing rate as they exercise. An investigation using this mask produces these results.

Calculate the percentage change in the breathing rate from the start of exercise to the breathing rate at 10 minutes.

percentage change =_........

Plot a line graph to show how breathing rate changes during exercise. Join your points with straight lines.

Explain the change in breathing rate during the 12 minutes of exercise.

Explain why the breathing rate would remain high for a few minutes after the exercise has finished.

The difficulty with measuring breathing rate during exercise is that wearing a mask may affect breathing rate and performance. A different method of recording breathing rate is to wear a shirt that contains sensors that record chest movements. Suggest one advantage and one disadvantage of using a shirt that measures breathing rate by recording chest movements.

advantage

disadvantage

The diagram shows a piece of apparatus used as a model for breathing. The rubber sheet can be pulled down and pushed up to represent breathing.

Name the structure that the rubber sheet represents in a human.

Which row in the table gives the changes in volume and pressure inside the glass jar when demonstrating inhalation?

Give two reasons why the apparatus does not give an accurate representation of human ventilation.

The diagram shows the structure of an alveolus.

Which of these is the order of the structures that air passes through, from the mouth to the alveolus, during inhalation?

The total surface area of the alveoli in lungs is very large. A typical human lung has 480 000 000 alveoli. Each alveolus has a surface area of 0.0040 mm². Calculate the total surface area, in mm², of the alveoli in one typical human lung. Give your answer in standard form.

total surface area in one human lung =_........ mm²

Explain two ways that a single alveolus is adapted to maximise gas exchange.

Describe a simple laboratory experiment to investigate the effect of exercise on the rate of carbon dioxide release from a human.

3 (a) A student investigates the differences between inhaled and exhaled air using this apparatus.

They use solution X to compare the concentration of carbon dioxide in inhaled and exhaled air. Give the name of solution X.

Explain the changes that will take place in solution X in test tube A and in test tube B.

Other than concentration of carbon dioxide, state one other difference between exhaled air and inhaled air.

Another student investigated the effect of the duration of exercise on their breathing rate. These are their results.

Give the independent variable in this investigation.

Plot a line graph to show the effect of duration of exercise on breathing rate. Join the points with straight lines.

Describe the effect of duration of exercise on breathing rate.

Give one way the student could improve the reliability of their investigation.

Gas exchange occurs in the respiratory system. The human respiratory system is located in the thorax.

The diagram shows some of the structures in the human thorax.

What is the name of the structure labelled X?

Which of these describes what happens when a person breathes in?

The table shows the percentage of some of the gases in inhaled air and exhaled air.

Explain the differences between the percentages of gases in inhaled air and in exhaled air.

Air in the alveoli has a composition of 14% oxygen and 7% carbon dioxide.

Suggest why the composition of air in the alveoli is different from exhaled air.

Vital capacity is the maximum volume of air that a person can force out of their lungs in one breath.

The graph shows the relationship between vital capacity and age for a large number of people.

The vital capacity plotted is the median value for each age.

State what is meant by the term median.

Give a reason why the median is used rather than the mean.

Describe the relationship between vital capacity and age shown by the graph.

Explain why vital capacity changes with age.

Age is not the only variable that can change vital capacity.

Give two other variables that can affect a person’s vital capacity.

Describe a method you could use to demonstrate the effect of exercise on breathing rate in students.

The diagram shows part of a human thorax with structures labelled R and S.

What is the name of structure R?

Explain how changes in structure S enable a person to breathe in.

A scientist uses this method to investigate the effect of exercise on the ventilation rate of a person.

Step 1: rest for 10 minutes

Step 2: measure the volume of air in each breath

Step 3: measure the breathing rate

Step 4: ride a bicycle at 15 kilometres per hour for 10 minutes

Step 5: measure the volume of air in each breath

Step 6: measure the breathing rate

The scientist repeats Step 4, Step 5 and Step 6 at increasing cycling speeds.

The table shows some of the results.

State the independent variable in the investigation.

At a cycling speed of 35 km per hour the person has a breathing rate of 25 breaths per minute.

They also have a ventilation rate of 65 dm³ per minute.

Calculate the volume of air, in cm³, in each breath.

[1 dm³ = 1000 cm³]

volume =_........ ³

Comment on the effect of increasing cycling speed on ventilation rate.

Refer to the data in the table in your answer.

State how the scientist could make the investigation more reliable.

1 (a) The diagram shows apparatus a student uses to compare inhaled and exhaled air.

The student breathes into and out of the mouthpiece for one minute.

Explain which flask exhaled air passes through.

Explain the changes that will happen in the limewater in flask A and in flask B.

The student uses limewater to compare the composition of exhaled and inhaled air. Suggest an alternative substance that they could use.

Describe the role of the diaphragm and the intercostal muscles in inhalation.

The diagram shows the human thorax.

Which of these are structures Q and R?

Explain how structure S helps a person to exhale.

The graph shows how the volume of air exhaled varies with time during one breath.

This is shown for a person with a lung disease and a person with healthy lungs.

Explain why the person with lung disease is often breathless and unable to exercise.

The table lists values that can be obtained in practical investigations.

Complete the table by naming pieces of laboratory apparatus that can be used to help obtain these values.

The first one has been done for you.

The diagram shows a red blood cell viewed through a microscope.

The actual width of this red blood cell is 8 µm.

The magnification of this red blood cell can be calculated using this formula.

Calculate the magnification of this red blood cell.

The diagram shows the location of the lungs in a horse.

The part labelled X is the

Which blood vessel transports blood to the horse’s lungs?

Which row of the table describes what happens when the horse breathes in?

The table shows the percentage of total blood flow in different body parts of a horse at rest and when running.

Comment on the changes in the percentage of total blood flow in these body parts.

The horse breathes faster and deeper when running. Explain why the horse continues to breathe faster and deeper for a period of time after it has stopped running.

Alveoli are involved in gas exchange.

The diagram shows a section through one alveolus and its associated blood capillary.

Name the organ that contains alveoli.

There are 5 000 000 red blood cells per mm³ of blood in the capillary.

Give the number of red blood cells per mm³ in standard form.

Explain why gas exchange is possible at the alveolus.

The graph shows the relationship between the total surface area of alveoli and the respiration rate in different sized animals.

Give two conclusions that can be made from this graph.

The respiration rate shown on the graph is measured in cm³ of oxygen used per minute.

When the respiration rate is measured in cm³ per minute, a human has a higher respiration rate than a mouse.

When the respiration rate is measured in cm³ per minute per gram of body mass, a human has a lower respiration rate than a mouse.

Explain why a human has a lower respiration rate than a mouse when the rate is measured in cm³ per minute per gram of body mass.

This apparatus can be used to measure the respiration rate of a small animal.

Explain how the apparatus should be used to obtain reliable data.

A scientist investigates the effect of exercise on breathing rate. She measures the breathing rate in breaths per minute of two people, P and Q, every 5 minutes for 30 minutes. This is her method.

• measure their breathing rate every 5 minutes while they exercise for 20 minutes

• measure their breathing rate every 5 minutes for a further 10 minutes while they recover from the exercise

The table shows her results.

Plot a line graph of the results for person P and person Q. Use a ruler to join your points with straight lines.

Explain the change in breathing rate during exercise.

Explain why the breathing rates of persons P and Q remain high for five minutes after they have finished exercising.

The time taken to recover from exercise is often a good measure of fitness. The scientist concluded that person P is much fitter than person Q. Comment on the validity of this conclusion.

A teacher uses this bell jar model of the thorax to show the process of ventilation.

State how the teacher could demonstrate breathing in using this model.

Explain why the balloons inflate during this demonstration.

Evaluate whether the bell jar model can completely demonstrate the process of ventilation.

Some people have problems with their breathing system. They struggle to breathe and can become breathless. These people may use inhalers to reduce their symptoms. The inhalers deliver drugs called bronchodilators into their lungs. The photograph shows a person using an inhaler.

(Source: © Ljupco Smokovski/Shutterstock)

Suggest how bronchodilators help these people to breathe.

Explain why these people can become more breathless during exercise.