FORM FOUR BIOLOGY EXAMINATION - TOPIC: HIV/AIDS (With Marking Scheme)

FORM FOUR BIOLOGY EXAMINATION

TOPIC: HIV/AIDS

Time: 3 Hours

Instructions

• Answer all questions in Sections A and B.
• Answer any two (2) questions from Section C.
• Neat diagrams must be used wherever applicable.

SECTION A (16 Marks)

1. Multiple Choice Questions (10 marks)

Choose the correct answer for each item:

(i) HIV mainly attacks which type of cells in the human body?
a) Red blood cells
b) Platelets
c) White blood cells
d) Skin cells

(ii) Which method is most reliable for determining HIV status?
a) Physical examination
b) Observation of symptoms
c) Blood testing at VCT
d) Asking a sexual partner

(iii) The virus that causes AIDS is classified under:
a) Bacteria
b) Fungi
c) Protozoa
d) Virus

(iv) A common opportunistic infection in AIDS patients is:
a) Cholera
b) Malaria
c) Tuberculosis
d) Typhoid

(v) The window period in HIV infection refers to:
a) Time before birth
b) Time after infection but before symptoms
c) Time when HIV can be cured
d) Time when the virus mutates

(vi) The abbreviation VCT stands for:
a) Virus Control Therapy
b) Voluntary Counseling and Testing
c) Viral Cure Treatment
d) Vaccination Control Test

(vii) HIV can be transmitted through:
a) Sharing utensils
b) Sneezing
c) Unprotected sex
d) Mosquito bites

(viii) Responsible sexual behavior includes:
a) Early marriage
b) Abstinence
c) Peer pressure
d) Frequent testing only

(ix) Which body fluid does NOT transmit HIV?
a) Blood
b) Breast milk
c) Sweat
d) Semen

(x) An individual living positively with HIV means:
a) They spread HIV knowingly
b) They deny their status
c) They maintain health and follow treatment
d) They avoid all people

2. Matching Items (6 Marks)

Match the items in List A with responses from List B:

List A

(i) Breastfeeding by HIV positive mother

(ii) Proper condom use

(iii) VCT services

(iv) Sharing needles

(v) Abstinence

(vi) ARV drugs

List B

a) Prevents new HIV infections

b) Increases risk of HIV transmission

c) Used to control HIV progression

d) A way to know HIV status

e) Sexual self-control

f) Risky traditional practice

Answers:

1. Breastfeeding by HIV positive mother - b) Increases risk of HIV transmission
2. Proper condom use - a) Prevents new HIV infections
3. VCT services - d) A way to know HIV status
4. Sharing needles - f) Risky traditional practice
5. Abstinence - e) Sexual self-control
6. ARV drugs - c) Used to control HIV progression

SECTION B (54 Marks)

3.

Mama Asha, a community health worker, is educating youth about HIV.

a) Explain the importance of VCT in preventing the spread of HIV. (5 marks)

Answer:

1. Identifies HIV-positive individuals who can then take precautions to prevent transmission
2. Provides opportunity for counseling about prevention methods
3. Encourages behavior change through awareness of status
4. Early detection allows for early treatment which reduces viral load and infectiousness
5. Helps prevent mother-to-child transmission through early detection

b) Describe any two methods used in VCT to detect HIV infection. (4 marks)

Answer:

1. Rapid HIV tests: Provide results in 20-30 minutes using blood from finger prick or oral fluid
2. ELISA test: Highly sensitive laboratory test that detects HIV antibodies in blood
3. Western Blot test: Used to confirm positive ELISA results, more specific but expensive
4. PCR test: Detects viral RNA, useful during window period before antibodies develop

4.

Hamisi believes hugging or eating with an infected person can spread HIV.

a) Identify and correct Hamisi's misconceptions. (4 marks)

Answer:

1. Misconception: HIV spreads through casual contact like hugging
   Correction: HIV cannot be transmitted through skin-to-skin contact like hugging
2. Misconception: Eating with infected person spreads HIV
   Correction: HIV is not transmitted through saliva or sharing utensils

b) Outline four main modes of HIV transmission. (5 marks)

Answer:

1. Unprotected sexual intercourse (vaginal, anal, oral)
2. Mother-to-child transmission (during pregnancy, delivery, or breastfeeding)
3. Contact with infected blood (transfusions, needle sharing, occupational exposure)
4. Use of unsterilized sharp objects (tattooing, circumcision, piercing instruments)

5.

At a youth seminar, students were taught about responsible sexual behavior.

a) State three examples of responsible sexual behavior. (3 marks)

Answer:

1. Abstinence (delaying sexual debut)
2. Mutual faithfulness to one uninfected partner
3. Consistent and correct condom use

b) Explain the importance of each example in preventing HIV. (6 marks)

Answer:

1. Abstinence: Completely eliminates risk of sexual HIV transmission, especially important for youth
2. Mutual faithfulness: Reduces exposure to multiple partners and potential HIV infection
3. Condom use: Creates physical barrier preventing exchange of infected body fluids

6.

A nurse is training people on the role of ARVs.

a) What are ARVs and how do they work? (4 marks)

Answer:

ARVs (Antiretroviral drugs) are medications used to treat HIV infection. They work by:

1. Inhibiting viral replication at different stages of the HIV life cycle
2. Reducing viral load in the body
3. Preserving immune function by protecting CD4 cells
4. Preventing progression to AIDS

b) Why is it important to adhere to ARV medication schedules? (5 marks)

Answer:

1. Maintains consistent drug levels in blood to suppress viral replication
2. Prevents development of drug-resistant HIV strains
3. Ensures maximum effectiveness of treatment
4. Maintains low viral load which preserves immune function
5. Reduces risk of transmitting HIV to others

7.

A young couple plans to marry and visits a health clinic.

a) Explain the purpose of pre-marital HIV testing. (4 marks)

Answer:

1. Allows couples to make informed decisions about their relationship
2. Enables early treatment if either partner is HIV-positive
3. Helps prevent transmission between partners
4. Provides opportunity to discuss prevention of mother-to-child transmission
5. Reduces stigma by normalizing HIV testing

b) List five benefits of knowing your HIV status. (5 marks)

Answer:

1. Early access to treatment if positive
2. Ability to take precautions to prevent transmission
3. Peace of mind if negative
4. Better family planning decisions
5. Reduced anxiety through knowledge of status
6. Opportunity to adopt healthier lifestyle choices

8.

A family is caring for an HIV positive child.

a) Describe three ways the family can support the child's health. (6 marks)

Answer:

1. Medical care: Ensure regular clinic visits and adherence to ARV medication
2. Nutrition: Provide balanced diet to boost immune system
3. Hygiene: Maintain clean environment to prevent infections
4. Education: Help child understand and manage their condition appropriately
5. Social support: Encourage normal childhood activities and schooling

b) Why is emotional support important in HIV management? (3 marks)

Answer:

1. Reduces stress which can weaken immune system
2. Improves medication adherence
3. Helps prevent depression and mental health issues
4. Promotes better quality of life

SECTION C (30 Marks)

Answer any two (2) questions from this section.

9.

Discuss the social and economic impacts of HIV/AIDS at the family and national level. (15 marks)

Answer:

Family Level Impacts:

1. Economic:
   • Loss of income due to illness/death of breadwinners
   • Increased medical expenses
   • Reduced productivity of family members
2. Social:
   • Orphaned children and strained family structures
   • Stigma and discrimination against affected families
   • Disruption of children's education to care for sick relatives

National Level Impacts:

1. Economic:
   • Reduced workforce productivity
   • Increased healthcare costs
   • Reduced GDP growth
   • Increased dependency ratio
2. Social:
   • Overburdened healthcare systems
   • Increased number of orphans and vulnerable children
   • Reduced life expectancy
   • Strain on social services

10.

Describe the life cycle of the HIV virus and explain how this contributes to the difficulty in curing HIV. (15 marks)

Answer:

HIV Life Cycle:

1. Attachment: HIV binds to CD4 receptors on host cells
2. Fusion: Viral envelope fuses with cell membrane
3. Reverse transcription: Viral RNA converted to DNA by reverse transcriptase
4. Integration: Viral DNA incorporated into host genome
5. Replication: Host cell produces viral components
6. Assembly: New virus particles assembled
7. Budding: New viruses released from host cell

Challenges for Cure:

1. Integration into host DNA: Makes complete viral eradication difficult
2. High mutation rate: Leads to drug resistance
3. Latent reservoirs: Virus hides in dormant cells
4. Immune system evasion: Virus attacks immune cells
5. Genetic diversity: Multiple HIV subtypes exist

11.

Explain five major strategies that can be used in Tanzania to reduce the spread of HIV/AIDS. Support your answer with relevant examples. (15 marks)

Answer:

1. Comprehensive sex education:
   • School-based programs teaching abstinence and safe sex
   • Example: Peer education programs in secondary schools
2. Promotion of VCT services:
   • Mobile testing units to reach rural areas
   • Example: National HIV testing campaigns
3. Prevention of mother-to-child transmission (PMTCT):
   • ARVs for pregnant women and safe delivery practices
   • Example: PMTCT programs in antenatal clinics
4. Harm reduction for high-risk groups:
   • Needle exchange programs for drug users
   • Example: Programs in Dar es Salaam for intravenous drug users
5. Stigma reduction campaigns:
   • Public awareness to encourage testing and treatment
   • Example: Media campaigns featuring HIV+ individuals
6. Condom promotion and distribution:
   • Free condoms in health facilities and public places
   • Example: Government condom distribution program

FORM FOUR BIOLOGY EXAMINATION ANSWERS

TOPIC: HIV/AIDS

SECTION A ANSWERS (16 Marks)

1. Multiple Choice Answers

1. c) White blood cells
2. c) Blood testing at VCT
3. d) Virus
4. c) Tuberculosis
5. b) Time after infection but before symptoms
6. b) Voluntary Counseling and Testing
7. c) Unprotected sex
8. b) Abstinence
9. c) Sweat
10. c) They maintain health and follow treatment

2. Matching Items Answers

List A	List B
Breastfeeding by HIV positive mother	b) Increases risk of HIV transmission
Proper condom use	a) Prevents new HIV infections
VCT services	d) A way to know HIV status
Sharing needles	f) Risky traditional practice
Abstinence	e) Sexual self-control
ARV drugs	c) Used to control HIV progression

SECTION B ANSWERS (54 Marks)

3a. Importance of VCT in preventing HIV spread

1. Identifies HIV-positive individuals who can take precautions
2. Provides opportunity for counseling about prevention
3. Encourages behavior change through awareness
4. Early detection allows for early treatment
5. Helps prevent mother-to-child transmission

3b. Two VCT detection methods

1. Rapid HIV tests (20-30 minute results)
2. ELISA test (laboratory antibody detection)

4a. Correcting misconceptions

1. HIV doesn't spread through hugging - no skin transmission
2. Eating together doesn't transmit HIV - not through saliva

4b. Modes of HIV transmission

1. Unprotected sexual intercourse
2. Mother-to-child transmission
3. Contact with infected blood
4. Use of unsterilized sharp objects

5a. Responsible sexual behavior examples

1. Abstinence
2. Mutual faithfulness
3. Consistent condom use

5b. Importance in HIV prevention

1. Abstinence eliminates sexual transmission risk
2. Faithfulness reduces exposure to multiple partners
3. Condoms create barrier against infected fluids

6a. ARVs and how they work

ARVs (Antiretroviral drugs) treat HIV by:

1. Inhibiting viral replication
2. Reducing viral load
3. Protecting CD4 cells
4. Preventing AIDS progression

6b. Importance of ARV adherence

1. Maintains consistent drug levels
2. Prevents drug-resistant strains
3. Ensures treatment effectiveness
4. Preserves immune function
5. Reduces transmission risk

7a. Purpose of pre-marital HIV testing

1. Informed relationship decisions
2. Early treatment if positive
3. Prevent partner transmission
4. Discuss mother-to-child prevention

7b. Benefits of knowing HIV status

1. Early treatment access
2. Take prevention precautions
3. Peace of mind if negative
4. Better family planning
5. Reduced anxiety

8a. Supporting HIV+ child's health

1. Ensure medical care and ARV adherence
2. Provide balanced nutrition
3. Maintain clean environment
4. Help child understand condition

8b. Importance of emotional support

1. Reduces stress that weakens immunity
2. Improves medication adherence
3. Prevents depression

SECTION C ANSWERS (30 Marks)

9. Social and economic impacts of HIV/AIDS

Family Level:

• Economic: Loss of income, medical expenses
• Social: Orphans, stigma, education disruption

National Level:

• Economic: Reduced productivity, healthcare costs
• Social: Overburdened systems, reduced life expectancy

10. HIV life cycle and cure challenges

Life Cycle:

1. Attachment to CD4 cells
2. Fusion with cell membrane
3. Reverse transcription
4. Integration into host DNA
5. Replication and assembly
6. Budding of new viruses

Cure Challenges:

• Integration into host DNA
• High mutation rate
• Latent reservoirs
• Immune system evasion

11. Tanzania HIV reduction strategies

1. Sex education: School programs teaching safe sex
2. VCT promotion: Mobile testing units
3. PMTCT: ARVs for pregnant women
4. Harm reduction: Needle exchange programs
5. Stigma reduction: Media campaigns