Mass Transport in Animals (AQA A Level Biology)

With reference to the different partial pressures of oxygen (ppO₂) throughout the body explain how haemoglobin supplies oxygen to different areas of the human body.

The oxyhaemoglobin dissociation curves for adult haemoglobin (HbA) and foetal haemoglobin (HbF) are shown in the Figure 1 below. 

Figure 1

Haemoglobin can change shape. Explain how a change in shape results in the S-shaped curve seen for HbA.

Say Figure 1 represents the haemoglobin of a pregnant mother and her unborn foetus. If the partial pressure of oxygen in the placenta is 3.4kPa, using the graph in part (b) work out the percentage of the oxygen in the adult haemoglobin that will be dissociated and what percentage of the foetal haemoglobin will become saturated in the placenta.

When a baby is born, only 2% of their haemoglobin is adult haemoglobin. When they reach 6 months of age nearly 100% of their haemoglobin is adult, with all the foetal haemoglobin having disappeared.

Using  Figure 1, explain why this change is advantageous for a baby.

Oxyhaemoglobin is the name of the complex that forms when oxygen combines with haemoglobin. This is a reversible reaction meaning oxygen can be offloaded. Explain why a higher amount of oxygen is offloaded in an active muscle?

There is a new performance enhancing drug (drug X) that has been found on the black market. Upon investigation scientists found that the drug, taken at a particular dose on a regular basis, increases the number of red blood cells in an individual. Suggest why this would be beneficial for endurance athletes.

Drug X can increase blood pressure. Suggest why.

Some athletes prefer to rely on different methods to enhance their performance. Caffeine is a legal substance that can be found in supermarkets across the globe. 

The pressure in the left ventricle for a young male athlete is shown in the graph below.Immediately after he consumes caffeine his cardiac cycle shortens by 12.5%. Use this information and the data in the Figure 1 to calculate the heart rate in bpm for the athlete just after they have consumed caffeine.

Figure 1

Describe and explain two ways in which red blood cells are adapted to oxygen transport.

A scientist is looking at a red blood cell under an electron microscope and takes an electron micrograph. The actual diameter of the red blood cell is 7 µm, but in the micrograph image it measures 5 cm. Using Figure 1, calculate the magnification used and state the assumption that has been made in order to calculate it. Give your answer to the nearest 100.

Figure 1

When red blood cells are placed in pure water, they undergo haemolysis. This is when water enters the cells by osmosis and they burst. When the red blood cells burst, they release their red pigment.

Scientists collected red blood cell samples from four different mammals: cats, rats, hares and goats. The samples were placed in different concentrations of sodium chloride solution for the given amount of time.

The solution turned red if the red blood cells burst by haemolysis. The intensity of the red colour was measured using a colorimeter. A more intense red colour suggested a greater amount of haemolysis. The scientists used this method to calculate the percentage of red blood cells that were haemolysed in each sodium chloride solution.

Figure 2 below shows their results.

Figure 2

Describe two differences between the results for the goat and rat.

Calculate the difference in the percentage of haemolysed cells between the cat and hare at a sodium chloride concentration of 0.3%.

Sludge worms are small and thin segmented worms that live in sediments of lakes and rivers. They do not have a specialised circulatory system or gas exchange system Figure 1 below is an accurate depiction of the sludge worms body.

Figure 1

Use Figure 1 and the information provided above to explain how two features of a sludge worm’s body allows for efficient gas exchange.

Larger multicellular organisms have specialised cells and tissues that form mass transport systems. Why do they need a mass transport system? 

The circulatory system in mammals is an example of a specialised mass transport system.Table 1 below shows the volume of blood in a man’s left ventricle at different times during one second.

Table 1

Use Table 1 to determine the cardiac output if cardiac output = stroke volume x heart rate.

An individual's maximum cardiac output can act as an indicator of fitness . Suggest how you would measure this.

Describe the structure of haemoglobin in detail.

Oxyhaemoglobin is crucial for the transport of oxygen throughout the human body. Explain why oxyhaemoglobin retains its oxygen until it reaches the capillaries in the tissues.

Figure 1 below shows the oxygen haemoglobin dissociation curves for three species of bird.

Figure 1

Species X lives at high altitudes at the top of a mountain range. Species Z lives nearer sea level at the base of the mountain range. The oxygen haemoglobin dissociation curve for species X is to the left of the curve for species Z. Explain the advantage to species X of having haemoglobin with a curve in this position.

Species X and Y live at the same altitude at the top of the mountain range but species Y is more active. Suggest the advantage to species Y of having an oxygen haemoglobin dissociation curve to the right of that for species X.

A substance (X) that is naturally produced in the body helps to increase the production of red blood cells. Synthetic substance X can be made artificially. It has been used to treat patients with a particular form of anaemia that results in a lower RBC count. Scientists investigated the effect of the synthetic form of the substance on volunteers. The scientists injected synthetic substance X in a salt solution into patients in the experimental groups. There were also control groups.

Different experimental groups were given different doses of synthetic substance X and different lengths of treatment.

The scientists measured each patient’s haemoglobin concentration at the beginning and end of each treatment. From these, the mean increase in haemoglobin concentration was calculated.

The results can be seen in Table 1 below.

Table 1

The dose of synthetic substance X was measured per kilogram per week.

Explain why the scientists measured the dose per unit mass and per unit time.

Explain how the results from this experiment could be used by doctors treating patients with anaemia.

Artificial substance X has been found on the black market, with large quantities being bought by professional athletes. Suggest why taking artificial substance X would be beneficial for endurance athletes.

International sports authorities want to try and eliminate the use of artificial substance X by professional athletes. Athletes are being tested to determine if the concentration of substance X in their blood is above normal. Suggest how scientists would determine the normal concentration of substance X in blood.

Larger multicellular organisms have specialised cells and tissues that form mass transport systems. Why do they need a mass transport system?

The circulatory system in mammals is an example of a specialised mass transport system.

Table 1 below shows the volume of blood in a man’s left ventricle at different times over the course of one second.

Table 1

 Use the information in Table 1 to state the number of times the ventricle would contract per minute.

Use the information given in Table 1 and your answer to part b) to calculate the man’s cardiac output.

Scientists set up an experiment to investigate the differences in cardiac outputs between highly trained athletes and regular students. All participants were asked to cycle on a stationary bike as fast as they could for 5 minutes and their maximum stroke volume and heart rates were measured. The results are shown in Table 2 below.

Table 2

Explain which factor is responsible for the large difference in mean cardiac outputs between groups. Suggest how training would affect this factor.

Calculate the number of heart beats a woman has had by the time of her 80th birthday, assuming that throughout her life she has had an average heart rate of 65 bpm? Write your answer in standard form.

When red blood cells are placed in pure water they undergo haemolysis. This is when water enters the cells by osmosis and they burst. When the red blood cells burst they release their red pigment.

Researchers collected red blood cell samples from four different mammals: cats, rats, hares and goats. The samples were placed in different concentrations of sodium chloride solution for a given amount of time.

The solution turned red if the red blood cells burst by haemolysis. The intensity of the red colour was measured using an instrument called a colorimeter. A deeper red colour suggested a greater amount of haemolysis. The scientists used this method to calculate the percentage of red blood cells that were haemolysed in each sodium chloride solution. Figure 1 below shows their results.

Figure 1

Describe two differences between the results for the goat and rat.

Explain the relationship shown in Figure 1 between the intensity of the red colour in the solution and the amount of haemolysis that has taken place. 

During treatment a vet may be required to give an infusion of sodium chloride solution directly into a vein for any of the mammals in the figure above. The concentration of  the sodium chloride solution used by vets is 0.9%, no matter the species of mammal. 

Explain why the vet would use this concentration. 

Figure 1 below shows an oxyhaemoglobin dissociation curve. 

Figure 1

Using Figure 1 and your own knowledge describe the structure of haemoglobin and explain how it transports oxygen around the body.

Figure 2 below shows the oxygen haemoglobin dissociation curves for three species of bird.

Figure 2

Species X lives at high altitudes at the top of a mountain range. Species Z lives near sea level at the base of the mountain range. Use Figure 2 to identity which species’ haemoglobin has the highest affinity for oxygen.

Species X and Y live at the same altitude at the top of the mountain range but species Y is more active. Suggest the advantage to species Y of having an oxygen haemoglobin dissociation curve to the right of that for species X.

Suggest another habitat in which haemoglobin with a high affinity for oxygen would be advantageous for an organism.

The oxyhaemoglobin dissociation curves for adult haemoglobin (HbA) and foetal haemoglobin (HbF) are shown in Figure 1 below. 

Figure 1

Haemoglobin can change shape. Explain how a change in shape results in the s-shaped curve seen in Figure 1 for HbA.

Figure 1 shows the different oxygen dissociation curves for adult vs foetal haemoglobin. Predict and explain what would happen to the foetus if the curves were identical.

Sickle cell disease (SCD) is a genetic disease that occurs due to abnormal adult haemoglobin. The faulty haemoglobin has a reduced ability to transport oxygen around  the body. Scientists investigated the use of a novel drug (substance Y) to treat babies suffering from SCD. Substance Y alters the concentration of foetal haemoglobin (HbF) in the blood.

Explain how an increase in the concentration of HbF in the babies’ blood would help treat SCD. 

The scientists investigated the effectiveness of the drug with 105 babies who had SCD. Each baby was given the drug for 36 months. The scientists calculated the mean change in the concentration of HbF (foetal haemoglobin) in the babies’ blood.

Their results are shown in Table 1 below. 

Table 1

Using the information in Table 1, evaluate whether treatment with substance Y will significantly increase the concentration of oxygen in the blood of babies with SCD