CAIE IGCSE Biology 16.6 Sexually Transmitted Infections

Practise defining STIs, tracing HIV transmission and effects, and selecting evidence-based methods that limit infection spread.

Exam points

distinguish sexual-fluid or blood transmission from coughing, saliva and other non-routes
link HIV infection to lymphocyte destruction and possible progression to AIDS
select condoms, testing, contact tracing, education and sterile needles as STI controls

Covered syllabus points

16.6.1—Sexually transmitted infection (STI)16.6.2—Human immunodeficiency virus (HIV) is 16.6.3—HIV infection may lead to AIDS 16.6.4—Methods of transmission of HIV 16.6.5—Spread of STIs is controlled

[Maximum number: 4]

Fig. 4.1 is a diagram of the human female reproductive system.

Fig. 4.1

(a)

Chlamydia is caused by a bacterium.

[ 4 ]

(i)

State the name of one other STI.

[ 1 ]

(ii)

Complete the sentences about the spread of STIs.

STIs are transmitted through the transfer of during sexual contact. One way individuals can avoid the spread of STIs is to use a type of contraception. One example of this type of contraception is

[ 3 ]

[Maximum number: 1]

Which disease is caused by a virus?

AIDS

kwashiorkor

cholera

MRSA infection

[Maximum number: 4]

Fig. 4.1 is a diagram of a virus.

Fig. 4.1

The human immunodeficiency virus (HIV) infects and destroys lymphocytes.

The number of lymphocytes in the blood of a person infected with HIV was measured over a period of 84 months.

The results are shown in Fig. 4.2.
number of lymphocytes per $\mathrm{mm}^{3}$ of blood

Fig. 4.2

Outline the consequences of the changes in the number of lymphocytes for the health of the person infected with HIV.

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Covered syllabus points

16.6 Sexually transmitted infections question 1

Question (a)

Question (i)

Question (ii)

16.6 Sexually transmitted infections question 2

16.6 Sexually transmitted infections question 3