Which of the following are all forms of defence that prevent the entry of pathogens into the body? (A) Cilia, sweat, saliva - HSC - SSCE Biology - Question 3 - 2012 - Paper 1

To determine which option includes only those forms of defense that prevent the entry of pathogens, we can analyze each option:

1. Cilia, sweat, saliva (A): These are indeed first-line defenses. Cilia help move pathogens out of the respiratory tract, sweat can wash away potential pathogens, and saliva contains enzymes that can kill harmful bacteria.

2. T cells, B cells, antibodies (B): While certainly crucial components of the immune response, these are not physical barriers or direct defenses as they act post-infection rather than preventing entry.

3. Inflammation, skin, phagocytosis (C): The skin acts as a barrier, but inflammation and phagocytosis are more associated with responses to pathogens that have already entered the body.

4. Stomach acid, mucus, lymph system (D): Stomach acid destroys pathogens that have been ingested, mucus traps pathogens in the respiratory tract, and the lymphatic system plays a role in immune defense, but some components are reactive rather than purely preventative.

After evaluating these options, we find that option (A) is the only one that includes entirely defensive forms that block pathogen entry.