Lesson 6.3.1

6.3.1 Routes into the body and barriers to infection Quiz: Pearson Edexcel Biology, Unit 6

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 6.3.1, Routes into the body and barriers to infection: 20 multiple choice questions for the Pearson Edexcel Biology (9BI0), Unit 6: Immunity, Infection and Forensics, written with Revision Ninja.

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The 20 questions

  1. How do respiratory pathogens such as influenza primarily enter the human body?

    • Inhaled droplets
    • Insect vectors
    • Direct skin contact
    • Ingested food

  2. Which primary entry route allows pathogens like Salmonella to infect the digestive tract?

    • Ingestion
    • Inoculation
    • Absorption
    • Inhalation

  3. Which transmission route allows pathogens to bypass the skin barrier completely?

    • Food ingestion
    • Droplet inhalation
    • Sexual contact
    • Direct inoculation

  4. What type of barrier against infection is provided by intact skin?

    • Chemical barrier
    • Immune response
    • Cellular barrier
    • Physical barrier

  5. Which property of stomach acid enables it to destroy ingested pathogens?

    • Low viscosity
    • High pH
    • High salinity
    • Low pH

  6. How do normal gut flora protect against pathogenic bacteria?

    • Phagocytosing bacteria
    • Competing for resources
    • Secreting stomach acid
    • Producing antibodies

  7. Which substance in the respiratory tract traps inhaled pathogens?

    • Sebum
    • Mucus
    • Keratin
    • Lysozyme

  8. Which enzyme present in tears and saliva breaks down bacterial cell walls?

    • Amylase
    • Lipase
    • Pepsin
    • Lysozyme

  9. Which outer layer of skin is broken during a cut, allowing pathogens to enter?

    • Epidermis
    • Endothelium
    • Hypodermis
    • Dermis

  10. What process prevents pathogens colonising skin due to resident microbiota?

    • Opsonisation
    • Phagocytosis
    • Competitive exclusion
    • Agglutination

  11. Sexually transmitted pathogens usually enter the body across which structure?

    • Mucous membranes
    • Basement membranes
    • Keratinised skin
    • Serous membranes

  12. Which two primary barriers protect the digestive system from ingested pathogens?

    • Saliva and tears
    • Bile and enzymes
    • Acid and flora
    • Mucus and skin

  13. How are physical barriers like intact skin most commonly bypassed by pathogens?

    • Osmotic pressure
    • Wounds and cuts
    • Active transport
    • Enzyme secretion

  14. Which structure allows vertical transmission of pathogens from mother to fetus?

    • Ureter
    • Cervix
    • Oviduct
    • Placenta

  15. Which insect acts as a vector to transmit Plasmodium to humans?

    • Aphid
    • Housefly
    • Mosquito
    • Flea

  16. What structural feature makes mucous membranes easier for pathogens to penetrate than skin?

    • Thick lipid coating
    • Dry surface cells
    • Rigid cell walls
    • Unkeratinised layer

  17. What property of the skin surface primarily restricts pathogen colonisation?

    • High moisture content
    • Constant warmth
    • Alkaline pH
    • Dryness and acidity

  18. Which physical barrier protects the respiratory tract against pathogens in inhaled droplets?

    • Keratinised skin
    • Blood clotting
    • Stomach acid
    • Mucociliary escalator

  19. Which type of microorganism is most susceptible to destruction by lysozyme?

    • Gram-negative bacteria
    • Fungal spores
    • Gram-positive bacteria
    • Enveloped viruses

  20. Which structures beat rhythmically to move pathogen-laden mucus away from the lungs?

    • Goblet cells
    • Microvilli
    • Cilia
    • Flagella

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