Topic 10: Infectious Diseases

Question 1

Definitions I:
(a) Pathogen
(b) Transmission
(c) Antibiotic

Answer 1

(a) Pathogen: Microbe causing infectious disease. (1 mark)
(b) Transmission: Spread of pathogens between hosts. (1 mark)
(c) Antibiotic: Drug killing bacteria, not viruses. (1 mark)

Question 2

State the pathogen type and name for cholera and malaria. [2 Marks]

Answer 2

Cholera: Bacterium, Vibrio cholerae (1 mark); Malaria: Protoctist, Plasmodium spp. (1 mark). (2 marks)

Question 3

Name the pathogens causing TB and HIV/AIDS and their types. [2 Marks]

Answer 3

TB: Bacteria, Mycobacterium tuberculosis/bovis (1 mark); HIV: Virus, human immunodeficiency virus (1 mark). (2 marks)

Question 4

In a village, explain how cholera is transmitted through water. [2 Marks]

Answer 4

Vibrio in contaminated water (1 mark); Ingested, spreads via faeces (1 mark). (2 marks)

Question 5

Describe malaria transmission by mosquitoes in a tropical area. [2 Marks]

Answer 5

Plasmodium in mosquito saliva (1 mark); Injected via bite, infects blood (1 mark). (2 marks)

Question 6

In a crowded city, explain TB transmission via air. [3 Marks]

Answer 6

Mycobacterium in coughed droplets (1 mark); Inhaled into lungs (1 mark); Spreads in crowds (1 mark). (3 marks)

Question 7

Outline HIV transmission during unprotected contact. [3 Marks]

Answer 7

HIV in blood/semen (1 mark); Enters via cuts, sex (1 mark); Infects immune cells (1 mark). (3 marks)

Question 8

Discuss biological factors in controlling cholera in a rural community. [3 Marks]

Answer 8

Bacterium thrives in water (1 mark); Sanitation kills Vibrio (1 mark); Vaccination boosts immunity (1 mark). (3 marks)

Question 9

In an urban setting, explain social and economic factors in preventing TB. [3 Marks]

Answer 9

TB spreads in dense populations (1 mark); Poverty delays treatment (1 mark); Education improves hygiene (1 mark). (3 marks)

Question 10

Analyse factors for controlling malaria and HIV in a developing country. [4 Marks]

Answer 10

Malaria: Vector control, nets (1 mark); HIV: Condoms, testing (1 mark); Poverty limits drugs (1 mark); Awareness reduces spread (1 mark). (4 marks)

Question 11

Explain how penicillin acts on bacteria and not viruses in an infection. [2 Marks]

Answer 11

Penicillin disrupts bacterial cell walls (1 mark); Viruses lack walls, unaffected (1 mark). (2 marks)

Question 12

Discuss antibiotic resistance consequences and prevention in a hospital. [4 Marks]

Answer 12

Resistance stops treatment (1 mark); Overuse drives resistance (1 mark); Limit prescriptions (1 mark); New drugs needed (1 mark). (4 marks)