Question

levels of biological organization
the kidney of a dolphin is considered an organ because it is composed of different
multiple choice
cells.
organs.
organelles.
tissues.
molecules.

Explanation:

To determine why a dolphin's kidney is an organ, we recall the biological organization levels. An organ is a structure made of different tissues (groups of similar cells with a common function) working together. Cells make up tissues, tissues make organs, organs make organ systems. So the kidney (an organ) is composed of different tissues.

• "cells": Cells are the basic unit, but organs are made of tissues (groups of cells), not just cells.
• "organs": Organs are made of tissues, not other organs (that would be an organ system).
• "organelles": Organelles are inside cells, not a component of organs at the tissue - organ level.
• "molecules": Molecules are part of cells, not a direct component of organs in the tissue - organ hierarchy.

Answer:

D. tissues.