Transport in Animals (OCR A Level Biology)

Figure 2.1 shows the oxygen dissociaton curve for the haemoglobin of adults (HbA), as well as for a special type of haemoglobin produced by the cells of foetuses prior to birth; this second type of haemoglobin is known as foetal haemoglobin (HbF).

Figure 2.1

Describe and explain the shape of the curve for HbA shown in Figure 2.1.

Use Figure 2.1 to determine the percentage saturation of the following with oxygen at a partial pressure of oxygen of 4kPa:

• • HbA
  • HbF

Sickle cell disease is a genetic condition in which a mutation in the gene coding for part of the haemoglobin molecule causes red blood cells to take on a sickled, or crescent, shape. This influences the ability of the red blood cells to pass easily through the capillaries.

An experimental treatment for sickle cell disease involves gene therapy to increase the expression of the gene that codes for HbF, a gene that is normally switched off in adults.

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Another form of oxygen-binding protein that exists in the tissues of humans is myoglobin. Myoglobin is present in the muscles where it functions as an oxygen store. It has a higher affinity for oxygen than both HbA and HbF.

Sketch a suggested dissociation curve for myoglobin on Figure 2.1

Figure 3.1 below shows changes in pressure in parts of a human heart during one second.   

Figure 3.1

What does curve Y in Figure 3.1 represent? Explain your answer.

Between 0.5 and 0.8 seconds in Figure 3.1 there is a period of low blood pressure in the left ventricle. Use your knowledge of the cardiac cycle and the human heart to suggest a reason for this.

Describe two functions of valves in the mammalian circulatory system. Include a named example.

Oedema is a condition characterised by an abdomen and limbs that are swollen with  fluid. It is prevalent in poorly developed areas in the African continent due to the low  protein diet of the people living there. Explain how a low protein diet could result in oedema.

Figure 4.1 shows a representation of parts of the circulatory system.

Figure 4.1

Identify the following blood vessels:

J

K

L

M

The heart chambers connecting to blood vessels J and M are similar in structure but not identical.

Describe and explain one structural difference between the two heart chambers.

Figure 4.2 shows the changes in pressure in the heart and some of the blood vessels.

Figure 4.2

Describe and explain the differences in pressure between the heart chamber and blood vessel M.

Explain why blood pressure in Figure 4.2 continues to drop in blood vessel O and in the capillaries.

Figure 5.1 shows the external view of the mammalian heart.

Figure 5.1

Identify the structure marked X.

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Suggest and explain one possible symptom that might result from a blockage inside structure X

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Figure 5.2 shows the pressure changes in various parts of the heart during the cardiac cycle.

Figure 5.2

Calculate the heart rate of the individual in Figure 5.2

Figure 5.2 shows separate lines for the left and right ventricles.

State the reason for this difference

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Explain the benefits of this difference to the function of the circulatory system

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Identify the times on Figure 5.2 at which the following events take place:

The first ventricular systole begins.

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The semilunar valves close.

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Diastole begins.

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The mammalian circulatory system is described as a closed double circulation.

Explain why it is called a closed and double circulation.

Explain how the contractions of the chambers of the heart are coordinated during one cardiac cycle.

The oxygen dissociation curves for adult haemoglobin and fetal haemoglobin are shown in Fig. 6.1.

Fig. 6.1

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   • When oxygen first becomes available, myoglobin saturation increases at a constant
           rate of 8% per mmHg of oxygen.
   • When there is a slightly higher partial pressure of oxygen, the rate of oxygen binding
           slows gradually until the myoglobin is 100% saturated.
   • The partial pressure at which myoglobin reaches 100% saturation is the partial
           pressure at which adult haemoglobin is 80% saturated.

Answer on Fig. 6.1 .................................................... [2]

Haemocyanin is an oxygen‐binding pigment that is found in many invertebrate animals, including lobsters.

Fig. 6.2 shows the oxygen dissociation curves for haemoglobin and haemocyanin.

Fig. 6.2

What can you conclude about the habitat of a lobster?

When old red blood cells are broken down, each haem group is converted to a molecule called bilirubin. Bilirubin passes through the digestive system. Bilirubin gives faeces their characteristic colour.

Explain why bilirubin production and processing is an example of excretion.

Fig. 16 shows pressure changes during the cardiac cycle.

Fig. 16

The heart supplies oxygenated blood to the tissues.

VO₂^max is a measurement of the maximum volume of oxygen that an individual can use during intense exercise in a given time.

Smart watches can estimate the VO₂^max of an individual by measuring heart rate while exercising.

Having a higher VO₂^max is associated with improved aerobic fitness.

Two male students exercised for 30 min and used smart watches to record their VO₂^max.

Table 16 shows their masses and the VO₂^max values they recorded.

                                       Table 16

Student 1 drew the following conclusion from this result:

Student 2 said that this conclusion is invalid because several variables have not been controlled.

State three variables necessary for a valid comparison that have not been controlled in the above experiment.

Brown fat is a type of tissue.

Brown fat has a higher need for oxygen because fat cells in this tissue carry out aerobic respiration at a higher rate than fat cells in other tissues.

Suggest which organelle is present in higher numbers in brown fat cells than in other fat cells.

Mammals and fish both need circulatory systems to transport oxygen to respiring tissues. They have different circulatory systems because they have different oxygen requirements.

Compare and contrast the circulatory systems of mammals and fish.

Acetylcholine (ACh) is a neurotransmitter in mammals. Studies have suggested that it also functions as a hormone in some invertebrate species, such as squid.

When ACh comes into contact with specialised cells in squid skin, it causes them to change colour. These colour changes allow the squid to communicate and to camouflage itself.

ACh is made by cells in the centre of the squid’s body.

Explain how it is possible for ACh to have an effect on cells in the skin of the squid.

Squid blood contains a blue oxygen-carrying protein called haemocyanin.

High partial pressures of carbon dioxide reduce the affinity for oxygen of haemocyanin.

Suggest a mechanism by which carbon dioxide could reduce the affinity for oxygen of haemocyanin.

Resistance training with weights can increase muscle mass in the body. It can also lead to vascularisation, where blood vessels become more visible through the skin. Fig. 19.1 shows vascularisation.

Fig. 19.1

Vascularisation occurs in bodybuilders because blood vessels are pushed to the surface by increased muscle mass. They can also become more visible due to reduced body fat and dehydration.

Explain why the visible blood vessels are likely to be veins.

Some bodybuilders use anabolic steroids to increase their muscle mass.

Suggest why anabolic steroids are effective when applied to the surface of the skin.

The illegal use of steroids is widespread in professional sport.

The International Olympic Committee (IOC) tests the urine of athletes to help prevent steroid abuse. 

Fig. 19.2 is a graph showing tests carried out by the IOC between 1986 and 1994.

 
• The bars represent the number of urine samples tested.
• The line shows the percentage of samples testing positive for the steroid testosterone.

Fig. 19.2

number of samples = .......................................................... [3]

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The electrical activity of the heart can be monitored using an electrocardiogram (ECG) trace.

Fig. 16.1 shows the ECG pattern for a single normal heartbeat.

Fig. 16.1

Fig. 16.2 shows an ECG trace for a person with normal heart rhythm and Fig. 16.3 shows the trace for a person with tachycardia.

Fig. 16.3

Fig. 16.4 is an ECG trace of a person with an abnormal heart rhythm.

Fig. 16.4

Using the information from Fig. 16.4, what conclusions can you draw about the way in which this person’s heart is functioning abnormally?

Fig. 21.1 shows a transverse section of a human adrenal gland.

Fig. 21.1

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Phaeochromocytoma is a rare tumour of adrenal gland tissue. It causes increased hormone release from the adrenal glands.

Fig 21.2 shows three ECG traces showing the heart rhythms of three different patients.

•     Patient X has a normal heart rhythm.
•     Patient Y has phaeochromocytoma.
•     Patient Z has bradycardia.

Sketch a trace for a patient who has entered atrial fibrillation.

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