Question

an organism that lives in or on another organism, often with harmful side effects—but without benefits is a ______. options (with blue boxes and dots): bacterium, virus, parasite, pest

Explanation:

To solve this, we analyze each option:

• Bacterium: Some bacteria are beneficial (e.g., gut bacteria), so not all live on others without benefits.
• Virus: Viruses infect host cells but the relationship isn't always just harmful without benefits in all cases, and the definition here matches parasite better.
• Parasite: By definition, a parasite lives in or on another organism (host), often harming it and deriving benefit without providing benefit in return.
• Pest: Pests are organisms that are destructive to crops, livestock, etc., but the term "pest" is broader and not defined by the "lives in/on another organism without benefit" as precisely as parasite.

Answer:

Parasite (the option labeled "Parasite" among the choices)