iGCSE Biology (0610)-16.6 Sexually transmitted infections

Question

(a) HIV infection can lead to AIDS.

(i) State the words that the letters HIV represent.
(ii) Describe ways of reducing the risk of a person becoming infected with HIV.

(b) Chlamydia, gonorrhoea and syphilis are sexually transmitted infections (STIs).
Table 7.1 shows the numbers of people infected with these STIs in one country from 2014 to 2018.

(i) The list shows some conclusions.
Place ticks (✓) in the boxes to identify two correct conclusions for the data shown in Table 7.1.

(ii) Syphilis can be treated with antibiotics.
Suggest the type of organism that causes syphilis.

▶️ Answer/Explanation

Solution

(a)(i) human immunodeficiency virus ;

Explanation: HIV stands for human immunodeficiency virus, which attacks the immune system and can lead to AIDS if untreated.

(a)(ii) any three from:
• (sexual) abstinence ;
• barrier methods of contraception / condom / femidom ;
• clean / do not share, needles ;
• blood screening (for transfusion) / AW ;
• HIV screening (of sexual partners) / AW ;
• bottle feeding infants / AW ;
• avoid contact with (infected) blood / AW ;
• sterilise medical equipment ;
• AVP ; e.g. PrEP / ref to pregnancy such as caesarean section or anti-viral drugs

Explanation: HIV transmission can be reduced by avoiding exposure to infected bodily fluids, using protection during sex, and ensuring medical safety protocols.

(b)(i)

Explanation: The data shows that chlamydia was the most common STI (highest numbers) and gonorrhoea infections increased each year (consistent rise from 2014-2018).

(b)(ii) bacteria ;

Explanation: Syphilis is caused by the bacterium Treponema pallidum, which is why it can be treated with antibiotics.

Question

(a) A sexually transmitted infection (STI) is an infection transmitted through sexual contact.

Table 6.1 shows some STIs and the type of pathogen that causes the infection.

State the names of the STIs shown in Table 6.1 that can be treated using antibiotics.

(b) (i) Antibiotics are one type of drug.
Describe what is meant by the term drug.
(ii) State why the effectiveness of some antibiotics has reduced over time.

(c) HIV can be transmitted through sexual contact.
The box on the left contains the term HIV.
The boxes on the right contain some methods of disease transmission.
Draw two lines to show two other ways that HIV can be transmitted from one person to another.

(d) Table 6.2 shows the number of people infected with different STIs in one country.

(i) State the STI in Table 6.2 that has half the number of people infected that AIDS has.
(ii) State the STI in Table 6.2 that has the highest number of people infected.

(e) Describe how the spread of STIs can be controlled.

▶️ Answer/Explanation

Solution

(a) Chlamydia, gonorrhoea, syphilis

These STIs are caused by bacteria (Chlamydia trachomatis, Neisseria gonorrhoeae, Treponema pallidum), which can be treated with antibiotics. Viral STIs (e.g., HIV, genital herpes) do not respond to antibiotics.

(b)(i) A drug is any substance that alters chemical processes in the body, affecting physical or mental functions.

(ii) Antibiotic effectiveness decreases due to bacterial resistance, where pathogens evolve to survive treatment.

(c) HIV can also spread via:
1. Breastfeeding (mother to child).
2. Sharing needles (bloodborne transmission).

(d)(i) Gonorrhoea (50,000 cases) is half of AIDS (100,000).
(ii) Chlamydia (200,000 cases) has the highest infection rate.

6(e) STI spread can be controlled by:
1. Condom use (barrier protection).
2. Regular testing and early treatment.
3. Education on safe practices.

iGCSE Biology (0610)-16.6 Sexually transmitted infections – iGCSE Style Questions Paper 3

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