Which of the following best describes the term "pathogen"?

• A type of white blood cell

• A substance that triggers an immune response

• A microorganism that causes disease

• A protein produced by the immune system

Describe the process of phagocytosis and explain its role in the immune response.

• The production of antibodies to neutralize pathogens

• The engulfing and digestion of pathogens by certain white blood cells

• The release of histamines to increase blood flow

• The recognition of antigens by T-cells

Why do most animals and many plants have some form of immune system with varying degrees of complexity?

• To help them move faster

• To protect them from invading pathogens

• To enable them to photosynthesize

• To assist in reproduction

Which of the following best describes the first line of defence against infection in the human body?

• Natural barriers to infection

• White blood cells

• Vaccinations

• Antibiotics

Barriers to infection can be classified as which of the following types?

• Only physical

• Only chemical

• Physical or chemical

• Only biological

How does the secretion of sweat and oils on the skin surface help protect the body from bacteria?

• By making the skin surface basic, which supports bacterial growth.

• By making the skin surface acidic, which inhibits bacterial growth.

• By providing nutrients for bacteria to thrive.

• By increasing the temperature of the skin.

Given the various types of mucosa shown in the diagram, which of the following is NOT a type of mucosa listed?

• Cardiac mucosa

• Nasal mucosa

• Gastric mucosa

• Intestinal mucosa

Which of the following best describes the function of chemical barriers in innate immunity?

• They prevent infection through chemical means.

• They physically block pathogens from entering the body.

• They produce antibodies to fight infections.

• They only function after an infection has occurred.

Which of the following is NOT typically included as a chemical barrier in innate immunity?

• Small peptides

• Enzymes

• Antibodies

• Bodily secretions

Explain how chemical barriers contribute to the prevention of infection as part of innate immunity. Use evidence from your understanding of their components.

• By physically trapping pathogens in mucus

• By using small peptides, enzymes, and other proteins to neutralize or destroy pathogens before they cause infection

• By producing memory cells for future infections

• By increasing the body temperature to kill pathogens