Table 1 shows measurements from a study of 14-year-old students. Each student wore a movement sensor for one week. A scan was then used to estimate bone min...
Question 1 Report
Table 1 shows measurements from a study of 14-year-old students. Each student wore a movement sensor for one week. A scan was then used to estimate bone mineral density in the hip. Fig. 1 shows the hip joint area included in the scan. All students had a similar daily food intake of calcium.
| Mean daily weight-bearing activity / minutes | Mean hip bone mineral density / arbitrary units |
|---|---|
| 15 | 0.71 |
| 30 | 0.76 |
| 45 | 0.82 |
| 60 | 0.87 |
| 75 | 0.89 |
(a) Describe the relationship shown in Table 1. [2]
(b) Explain how weight-bearing movement can increase bone density. [3]
(c) State why keeping daily calcium intake similar improves this investigation. [1]
(d) Which type of joint is shown in Fig. 1? [1]
(e) Name the bone that forms the long lower part of the hip joint. [1]
(f) Suggest one reason why the results do not prove that activity alone caused the differences. [2]
Answer Details
(a) Bone mineral density increases as daily weight-bearing activity increases. It rises from \(0.71\) to \(0.89\) arbitrary units, with the increase becoming smaller at higher activity levels. [2]
(b) Weight-bearing activity places stress or force on bones. Bone cells respond by depositing minerals such as calcium, making the bones stronger and denser. [3]
(c) Keeping calcium intake similar controls this variable, so the comparison is fair and calcium is less likely to explain density differences. [1]
(d) The hip is a ball-and-socket joint. [1]
(e) The long lower bone is the femur. [1]
(f) The data show correlation, not proof of cause. Genetics, vitamin D exposure, other dietary factors, or body mass may differ between students and could affect bone density. Any two valid points gain credit. [2]
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