Iron is a mineral that the body needs in only small amounts each day in order to stay healthy. Fig 3.1 is a bar chart that compares the mass of iron actuall...
Question 1 Report
Iron is a mineral that the body needs in only small amounts each day in order to stay healthy. Fig 3.1 is a bar chart that compares the mass of iron actually taken in by one person in their daily diet with the recommended daily amount, known as the RDA, for that person. The height of each bar shows the mass of iron in milligrams. The chart makes it possible to see whether the person is taking in enough iron or whether their intake falls short of what is recommended. Use the values shown on the bar chart to answer the questions that follow.
(a) Using the chart, calculate the person's iron intake as a percentage of the RDA. Show your working. [2]
(b) Calculate the extra mass of iron, in mg, the person needs each day to reach the RDA. [1]
(c) Name the substance made in red blood cells for which iron is needed. [1]
(d) Explain why a person who is short of iron may feel tired and become short of breath. [4]
(e) State one group of people whose iron requirement is higher than average. [1]
Answer Details
This question uses the iron bar chart, reading the diet bar at \(9\ \text{mg}\) and the RDA bar at \(14\ \text{mg}\), then linking iron to healthy blood.
(a) [2] Intake as a percentage of the RDA: \[ \frac{9}{14} \times 100 \quad[1] = 64.3\% \ (\text{accept } 64\%) \quad[1] \]
(b) [1] Extra iron needed to reach the RDA: \[ 14 - 9 = 5\ \text{mg} \quad[1] \]
(c) [1] The substance made in red blood cells that needs iron is haemoglobin [1].
(d) [4] If iron is short, less haemoglobin is made [1]; therefore less oxygen is carried by the red blood cells (the blood) [1]; so less oxygen reaches the body cells for respiration [1]; and with less respiration less energy is released, leaving the person tired, and they breathe faster (feel short of breath) to try to take in more oxygen [1].
(e) [1] One group with a higher-than-average iron requirement: pregnant people (accept menstruating people or rapidly growing children) [1].
Exam tip: for a percentage of a target, put the measured value over the target value, then multiply by \(100\).
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