8.4 Circulatory System

The function of red blood cells is to transport oxygen around the body in the blood. 

Explain how the shape of a red blood cell is related to its function. 

As well as its shape, the red blood cell also has internal adaptations to allow it to carry out its function. 

One of these is that it doesn't have a nucleus. 

Explain why this is beneficial for the functioning of the cell. 

Figure 1 shows the number of blood cells per dm³ of blood of two people.

Figure 1

Calculate the difference in the number of white blood cells per dm³ of blood between person A and person B. 

Of the two people in Figure 1, one of them is infected with a pathogen.

Identify the infected person and give a reason for your answer. 

Figure 1 shows a diagram of the heart. 

Figure 1

Compare the thickness of the walls of chamber A and chamber B.

The heart contains valves that can sometimes experience faults.

Describe what would happen to the blood flow in the heart if one of the valves did not function effectively.

Blood from the body enters the heart through the vena cava.

Describe how this blood flows through the heart and lungs to leave the heart through the aorta.

Include references to the chambers of the heart and the relevant valves in your answer.

Name the part of the blood that carries out clotting and state one advantage to this process. 

A student wanted to work out how long it takes blood to clot at different temperatures. 

They repeated their experiment three times and calculated an mean. 

Figure 1 shows the results of their investigation. 

Figure 1

Calculate the mean time taken for blood to clot when the temperature was 35°C. 

Using your answer to part (b), draw a graph to show the data in Figure 1. 

Using your answer to part (c), describe the relationship between temperature and the time time taken for the blood to clot.

Give two safety precautions that the student should use when handling blood samples. 

Figure 1 shows the stroke volume at different heart rates of a person with a high level of fitness and of a person with a low level of fitness.

Figure 1

Using Figure 1, compare the effect of heart rate on stroke volume of the fit person with the unfit person. 

Calculate the cardiac output for the fit person when the heart rate is 140 beats per minute.

Give the units in your answer.

Explain why it is beneficial for the fit person to have a high stroke volume whilst exercising. 

Suggest a reason for the difference in stroke volume between the fit person and the unfit person.

Figure 1 shows a diagram of a red blood cell from a turtle and a diagram of a red blood cell from a human.

(1)

(2)

...............................μm

.................................mm

Red blood cells are carried in veins and arteries.

Figure 2 shows the equipment used to measure the elasticity of an artery.

(3)

Figure 3 shows the circulatory system of a frog.

Explain why the circulatory system of a frog is less efficient at carrying oxygen to the tissues than the circulatory system of a human.

Figure 1 shows the estimated blood flow through some parts of the body when a person is at rest and during exercise.

Figure 1

Compare the rate of blood flow through the body when this person is at rest and during exercise.

Explain why there is a change in the rate of blood flow through the digestive system during exercise.

The stroke volume is the amount of blood leaving one chamber of the heart per beat.

From which chamber of the heart does this volume of oxygenated blood flow?

A person has a cardiac output of 4.9 litres per minute. The stroke volume of each heart beat is 70 ml.

Calculate the heart rate.

Figure 1 shows the stroke volume at different heart rates of a person who has trained for a marathon and of a person who has not trained for a marathon.

Figure 1

(3)

Blood from the body enters the heart through the vena cava.

Describe how this blood flows through the heart and lungs to leave the heart through the aorta.

Include references to the chambers of the heart and the relevant valves in your answer.

Figure 1 shows a cross section of an artery and a vein.

Figure 1

Line A is 8 mm and line B is 4 mm.

State the ratio of the thickness of the artery wall to the thickness of the vein wall.

(1)

A scientist investigated the relationship between exercise and the ability to run at 3 metres per second for 20 minutes.

The scientist collected data from six groups of people.
Each group exercised for a different number of hours per week for six months.

There were 100 people in each group.

Figure 2 shows their results.

Figure 2

(2)

(3)

Carbon dioxide is carried in blood plasma.

Human blood also contains red blood cells and white blood cells.

Explain how the structure of red blood cells and white blood cells is related to their function.

Figure 1 shows the structure and actual size of red blood cells (erythrocytes).

Figure 1

(2)

.................................. mm

(3)

(1)

Some blood transfusions contain red blood cells.

Red blood cells are stored in a solution containing 5.0% glucose and 0.9% salt.

Explain why red blood cells cannot be stored in pure water.

Exercise causes changes in the circulation of the blood.

In an investigation, the change in blood flow to different parts of the body during exercise was measured.

All the volunteers used in the study were healthy females of the same age.

Figure 1 shows the results of this investigation.

Figure 1

(3)

.....................................%