Question

which are correct examples of physical (p), chemical (c), and biological (b) barriers?
○ p: complement system; c: saliva; b: coughing
○ p: coughing; c: saliva; b: complement system
○ p: coughing; c: sneezing; b: complement system
○ p: complement system; c: saliva; b: sneezing

Explanation:

1. Recall the definitions:

• Physical barriers (P) are mechanical actions or structures that remove pathogens (e.g., coughing, sneezing, skin, mucus).
• Chemical barriers (C) are substances that inhibit or kill pathogens (e.g., saliva with enzymes like lysozyme, stomach acid).
• Biological barriers (B) involve immune system components (e.g., complement system, immune cells).

1. Analyze each option:

• Option 1: Complement system is biological (not physical), saliva is chemical, coughing is physical. Incorrect.
• Option 2: Coughing (physical), saliva (chemical), complement system (biological). Matches definitions.
• Option 3: Sneezing is physical (not chemical), complement system is biological. Incorrect.
• Option 4: Complement system is biological (not physical), sneezing is physical (not biological). Incorrect.

Answer:

B. P: coughing; C: saliva; B: complement system