5.2 Water for Transport - Further Questions

5.2 Water for transport - Further questions

Q1.

Bk Ch5 S5.2 FQ1

Red blood cells contain no nuclei. They survive in the blood for about three months. Using your knowledge of cell structure and function, explain the connection between these two pieces of information.

A1.

Bk Ch5 S5.2 FA1

Red blood cells contain no nuclei but they arise from cells that do have nuclei. The cells are programmed to carry out a particular function, which they are able to do for a time. Because they have no nucleus to maintain cell function in the long term, the cells eventually die.

Q2.

Bk Ch5 S5.2 FQ2

This diagram illustrates the structure of the mammalian heart.

Identify parts (a) to (h). Use arrows to show the path taken by the blood as it travels through the heart.

A2.

Bk Ch5 S5.2 FA2

a, aorta; b, pulmonary vein; c, left atrium; d, left ventricle; e, right ventricle; f, right atrium; g, systemic vein; h, pulmonary artery. Path is g – f – e – h and b – c – d – a.

Q3.

Bk Ch5 S5.2 FQ3

Haemoglobin is the oxygen-carrying pigment present in the blood of mammals.

a Describe the chemical structure of haemoglobin.

b Describe how the shape of red blood cells enhances their oxygen-carrying capacity.

A3.

Bk Ch5 S5.2 FA3

a Haemoglobin is a molecule composed of iron (haem) and protein (globin). There are four polypeptide chains and each is attached to an iron or haem molecule. The iron component is the site of oxygen attachment. The four chains are folded in on themselves to form the haemoglobin molecule.

b Red blood cells are flattened and have a donut appearance. This increases the surface area to volume ratio of the cells which in turn increases the rate of oxygen uptake by the cells.

Q4.

Bk Ch5 S5.2 FQ4

Describe how the chemical composition of blood changes as it is transported around the body. In your answer, name the tissues in which the changes take place.

A4.

Bk Ch5 S5.2 FA4

Blood entering the heart is low in oxygen, having just arrived from the body cells, and high in carbon dioxide. This blood is also rich in nutrients from digestion because blood leaving the small intestine goes to the liver and then the heart to be pumped around the body. From the heart blood first goes to the lungs where exchange of gases occurs—carbon dioxide is removed and oxygen is taken up by the blood. Now the blood is rich in oxygen and low in carbon dioxide. The blood returns to the heart which pumps it to all of the body cells. Blood leaves the heart via the arteries and once it reaches capillaries exchange occurs between the blood and the body cells. Oxygen and the products of digestion leave the blood to be taken up by the cells, and metabolic wastes, such as carbon dioxide and urea produced by cells, are removed from cells and enter the bloodstream. The blood, making its return journey in the veins, is once again low in oxygen and nutrients and high in carbon dioxide and urea. Urea is off-loaded at the kidneys.

Q5.

Bk Ch5 S5.2 FQ5

Foetal haemoglobin is different from the haemoglobin present in the bloodstream after birth.

a Find out how the structure of foetal haemoglobin differs from the structure of adult haemoglobin.

b Haemoglobin is an efficient oxygen-carrying molecule. Why is there a difference between foetal and adult haemoglobin?

A5.

Bk Ch5 S5.2 FA5

a Haemoglobin contains four separate polypeptide chains. In foetal haemoglobin two of the polypeptide chains are different than those in adult haemoglobin. Foetal haemoglobin has a much higher affinity for oxygen than does adult haemoglobin.

b It is important that foetal haemoglobin has a higher affinity for oxygen than adult haemoglobin because the foetus obtains its oxygen from the mother’s blood, which has a lower oxygen concentration than air. This means that the foetus can meet its oxygen requirements. If foetal haemoglobin was the same as adult haemoglobin the foetal oxygen needs could not be met.

Q6.

Bk Ch5 S5.2 FQ6

a Outline the complications sometimes associated with blood transfusions.

b Modified haemoglobin that has been extracted from red blood cells is sometimes used as an alternative to blood transfusions. This kind of treatment is especially useful in treating patients in emergency situations. Outline the advantages of this.

A6.

Bk Ch5 S5.2 FA6

a Potential complications associated with blood transfusions include incompatibility of blood and the transmission of infectious diseases.

b Modified haemoglobin can increase the oxygen intake for a patient in an emergency situation who has lost a great deal of blood because they are being provided with concentrated oxygen-carrying pigment. Modified haemoglobin is transfused in a carrier fluid similar to blood plasma and this also helps to maintain blood pressure.

Q7.

Bk Ch5 S5.2 FQ7

Research and write a magazine-style article about blood donation in New South Wales which answers the following questions:

· What products are extracted from donated blood?

· How are these products used?

· Name the diseases for which donated blood is checked.

· Who can be a blood donor?

· What is the role of the Australian Red Cross Blood Bank?

A7.

Bk Ch5 S5.2 FA7

Article should include the following information:

The Australian Red Cross is responsible for collecting and processing blood and blood products before making them available for donation to patients who require it. When blood donations are made the blood must be processed before it can be used in transfusions. The blood is centrifuged, a process that separates the different components. At the end of centrifuging blood is divided into red blood cells, plasma and platelets. The blood is also routinely tested for a number of diseases including syphilis, hepatitis B, hepatitis C, HIV1, HIV2 and HTLV (a rare virus that is linked to a form of leukaemia and neurological disease).

When the blood has been fully processed and tested and deemed to be safe it can be administered. Whole blood can be used to replace blood in patients undergoing surgery or who have lost blood in accidents. Blood components are used in patients according to their needs. Blood donations are accepted from healthy individuals between the ages of 17 and 60 years who meet the guidelines established to protect the donor and potential recipients of blood.

Q8.

Bk Ch5 S5.2 FQ8

Investigate a disease of the circulatory system. Choose from the list below, or consult with your teacher before deciding on a different disease.

high blood pressure atherosclerosis angina coronary heart disease cardiomyopathy

For the disease you have chosen:

· describe how the condition affects the heart and the rest of the body

· outline the symptoms suffered by a patient

· summarise the possible causes

· describe the treatment, including dietary recommendations.

The National Heart Foundation’s website (heartfoundation.com.au) may be a useful place to begin your research.

A8.

Bk Ch5 S5.2 FA8

Example: Coronary heart disease.

• The coronary arteries are the arteries that supply the heart muscle with blood and therefore all of the nutrients it needs to continue functioning. Coronary heart disease occurs when the inside of these arteries becomes lined with a substance called plaque that reduces the elasticity of the artery walls and reduces the volume of blood that is able to flow through them. This condition means that the heart muscle does not receive all of the nutrients it needs to do its job efficiently. As a result heart function becomes impaired and its ability to pump blood to all of the body cells is also affected. High blood pressure also results from coronary heart disease.

• Coronary heart disease patients may suffer from chest pain called angina that occurs when the heart muscle suffers a lack of oxygen. Because the heart is unable to pump blood efficiently, body cells do not receive the oxygen and other nutrients they need to function at optimum levels, and patients will find that they tire easily and are unable to engage in strenuous activity. Shortness of breath results from a lack of efficient blood flow and therefore gas exchange at the lungs.

• Coronary heart disease is usually related to a number of factors including poor diet that is high in saturated fats and salt; cigarette smoking is also a significant contributing factor, as is stress. Some people have a genetic predisposition to the disease.

• Patients suffering from coronary heart disease may be treated in several ways including diet (reducing fatty foods, especially saturated fats from animal products, reducing salt intake), exercise, stopping smoking, using medication and in extreme cases surgery to bypass the affected arteries.

Q9.

Bk Ch5 S5.2 FQ9

a What is ringbarking?

b Explain why ringbarking kills trees.

c Suggest a way of treating a tree that has been ringbarked so that it has a chance of surviving.

A9. Bk Ch5 S5.2 FA9

a A tree is ringbarked when a layer of bark is removed in a ring all the way around the trunk.

b Ringbarking kills trees because the bark contains the phloem of the vascular tissue. The phloem is responsible for transporting the products of photosynthesis to all of the cells of the plant. When the phloem vessels are interrupted materials can no longer be transported from the leaves to the roots and the roots will die. When the roots of a tree die the entire plant will die, since the roots are the site of water and mineral uptake.

c When a tree has been completely ringbarked there is little that can be done to help it to survive because the vascular tissue has been completely interrupted, halting the passage of organic compounds produced in photosynthesis from the leaves to the roots. The roots no longer receive energy they need to survive. When the roots die the rest of the tree will die too. If even a small amount of the bark is left intact the tree may survive, because the passage of nutrients can still flow from the leaves to the stems and vice versa. The tree will be affected and growth can be expected to be slow until the bark has regenerated.

5.2 Water for transport FQA page 1 of 4