O-LevelBiologyTransport in Humans5090/22 · Oct/Nov 2019 · Q313 Marks

Syphilis is an infectious disease transmitted by sexual contact. It is possible to test the blood of a person for the presence of antibodies produced after infection with the pathogen that causes syphilis.

(a)(i)State each of the following: the type of pathogen that causes syphilis[1]
(a)(ii)State each of the following: the component of an infected person's blood that produces antibodies[1]
(a)(iii)State each of the following: the component of an infected person's blood that transports these antibodies.[1]
(b)(i)The diagram shows part of a kit for testing a sample of blood for the presence of antibodies for syphilis. [Figure of test kit] If antibodies for syphilis are in the drop of blood added at S, a coloured line will form at the test region, T. The presence of a coloured line at the control region, C, indicates that sufficient blood has been added and that the result at the test region, T, is valid. If a person believes that they may have been infected with syphilis, a doctor may suggest that they have a blood test. Suggest why it is advisable for a person to wait until some time after their last sexual contact has taken place before the test is carried out.[1]
(b)(ii)Three possible outcomes of the test are shown below. [Figure of three test outcomes X, Y, Z] Complete the table below by entering either the word yes or the word no in each box to summarise the significance of each outcome.[2]
(b)(iii)State one first symptom shown by a person with primary stage syphilis. State the type of drug that should be given to a person with primary stage syphilis to prevent the disease from progressing to the secondary stage.[2]
(c)(i)The graph shows the number of reported cases of syphilis in men in a country between 1995 and 2012. [Graph of number of reported cases of syphilis per 100000 population vs. year] Calculate the percentage increase in the number of reported cases of syphilis in men between 2004 and 2012. Show your working.[2]
(c)(ii)Suggest why the actual increase in the number of cases of syphilis in men may have been higher than shown in the graph.[1]
(c)(iii)Suggest two recommendations that may be made to men in order to reduce the number of new cases of infection with syphilis.[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2019). The mark or mark type is shown in brackets.

[1] bacterium / bacteria / spirochete / treponema;
[1] white (blood) cells / lymphocytes ; Ig WBC
[1] plasma;
[1] production AW + of antibodies OR time for immune response;
[2] test valid (X) yes + (Y) yes + (Z) no; test for infection conclusive (X) yes + (Y) no + (Z) no;
[2] first symptom sore / ulcer / chancre + genitals / named genital / mouth / anus ; type of drug antibiotic / named antibiotic; R antibodies
[2] 83 / 83.3 / 83.33 ; Ig working shown if answer correct
[1] not all tested / not all have symptoms / other reason for not being tested / not all reported / some unaware they are infected / tested too soon AW;
[2] condom; no sexual intercourse ; reduce / only one + sexual partner(s);