One bag, three lives
370 words over 33 numbered lines, then 8 parts worth 15 marks (Linear Paper 2 (4BI1/2B) style, 14–18 marks). Read the article, answer each part, then open its mark scheme and set your mark.
Illustrative article written for Scholar Lab, not a Pearson text. The biology is real; the studies, people and figures are invented or rounded for practice.
One bag, three lives
Every few seconds, somewhere in the world, someone needs a blood
transfusion. It might be a patient having heart surgery, a mother who
has lost blood during childbirth, or a child with leukaemia. Blood
cannot yet be made in a factory, so hospitals depend on volunteers who
give their blood. In many countries the donors are not paid. The whole
visit takes about an hour, but the donation itself takes only about
ten minutes.
Blood is a tissue. A donor gives about 470 cm³ of blood, out of the
five litres or so in an adult’s body. Before donating, a drop of blood
from the donor’s finger is tested to check that it contains enough
haemoglobin. If the concentration is too low, the donor is asked to
come back another time.
At the blood centre, each bag is spun in a centrifuge to separate it
into three parts: red blood cells, plasma and platelets. One donation
can therefore help up to three different patients. Plasma is the
yellow liquid part of blood; it carries dissolved substances such as
glucose, urea, hormones and most of the carbon dioxide made by the
body’s cells.
Each part is stored differently. Red blood cells are kept at about 4
°C and can be used for up to 35 days. They are not frozen, because ice
crystals would damage the cells. Plasma can be frozen and kept for up
to three years. Platelets, which help blood to clot, must be kept at
room temperature and gently shaken, and they last only seven days.
After donating, the donor’s body replaces the lost plasma within a day
or two, but making new red blood cells takes several weeks. Donors are
advised to eat foods rich in iron, such as red meat, beans and green
vegetables. In some countries, men can donate every 12 weeks and women
every 16 weeks.
Blood services say that they need new donors all the time, especially
young people. Fewer than one in twenty people who could give blood
actually do so. Some patients, such as those with sickle cell disease,
need regular transfusions throughout their lives, and the best match
for them is often blood from donors of the same ethnic background.
Read the article. Use the information in the article and your own knowledge to answer the questions. The lines in brackets show where to look; select them to highlight the text.
Use the information in the article and your own knowledge to answer the questions. The lines in brackets show you where to look; select them to highlight the text.
State what is meant by the term tissue.
(1)Which part of the blood transports most of the carbon dioxide?
(1)Explain why a donor with a low concentration of haemoglobin is asked not to give blood.
(2)Calculate the percentage of the blood in an adult’s body that is given in one donation. Use 5 litres as the volume of blood.
(2)Explain why red blood cells are stored at 4 °C but not frozen.
(3)Describe how platelets help blood to clot.
(2)Explain why donors are advised to eat foods rich in iron.
(2)Suggest why blood services need new donors all the time.
(2)Total for this question: 15 marks
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