Mosquito's Role in Disease Transmission

Steps:

• Identify the mosquito's action: It carries and passes a disease-causing organism between hosts.
• Recall key biology terms: Parasite harms hosts directly; pathogen causes disease; vector transmits without causing harm; receptor binds molecules.
• Match description: Mosquito transmits pathogen, not causing disease itself.
• Select term: Vector fits transmission role.

Why D is correct:

• A vector is defined as a living organism, like a mosquito, that transmits a pathogen from one host to another without being the disease cause.

Why the others are wrong:

• A. Parasite: Feeds on host and causes harm, unlike the mosquito's transmission role.
• B. Pathogen: The actual disease-causing agent, not the carrier.
• C. Receptor: A molecule that receives signals, unrelated to transmission.

Final answer: D