Question

1. the respiratory system includes a layer of cells in the air passages that clean the air before it gets to the lungs. this layer of cells is best classified as a) an organ b) an organelle c) an organ system d) a tissue

Explanation:

• Organelle: A part within a cell (e.g., mitochondria), not a layer of cells.
• Organ: Made of different tissues (e.g., heart has muscle and connective tissue). A single - layer of cells is not an organ.
• Organ system: Multiple organs working together (e.g., respiratory system with lungs, trachea etc.). A single layer of cells is not a system.
• Tissue: A group of similar cells performing a specific function. The layer of cells cleaning air is a tissue.

Answer:

D. a tissue