2021HSCShort answer

Q23

3 marks

Question

Ovulation in women is associated with a rapid increase in luteinising hormone (LH). Test strips can be used to detect high levels of LH in urine. Once a test strip is used, a control line should appear and the presence of a test line indicates high levels of LH in urine. The image below represents four different results that were obtained.
Which of the results indicates a valid test which shows that ovulation is NOT occurring?
Justify your answer.

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Solution

Result 2. It is valid because the control line is present, showing the test worked. The test line is absent, indicating no high LH level was detected; therefore there is no LH surge and ovulation is not occurring.

3 Marks:

Correctly identifies the valid result
Provides a suitable justification
Includes reference to test line and control line

Sample answer: Strip 2 is the only valid negative result. The control line is present therefore indicating that the test itself has worked. No LH surge line has been detected in strip 2 therefore it is a negative result (unlike test 3 and 4 which have no control line, making those results invalid). Ovulation is not occurring according to test 2.

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Syllabus alignment

Module 5 · HeredityWorking Scientifically

ReproductionAnalyse fertilisation, implantation and hormonal control of mammalian pregnancy and birth.

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