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Key Idea: Multicellular organisms have a hierarchical structural organization, in which any one system is made up of numerous parts and is itself a component of the next level. The systems that make up an organism’s body work together to carry out functions needed for growth and survival.

Students are expected to know that:

  1. Multicellular organisms need a way to obtain oxygen for cellular respiration and eliminate carbon dioxide produced. The respiratory system, including the lungs, take in air rich in oxygen, which passes into blood vessels, and gives off air rich in carbon dioxide that has come from blood vessels.
  2. Multicellular organisms need a way to transport molecules from one body system to another. The circulatory system (including a heart that pumps blood and vessels of various diameters including capillaries) transports the reactants and products of various chemical reactions in response to changes in the body’s needs.
  3. Multicellular organisms need energy to move and grow. At the macroscopic level, muscle contraction moves bones.
  4. Systems of specialized cells within organisms help them perform the essential functions of life, which involve chemical reactions that take place between different types of molecules, such as water, proteins, carbohydrates, lipids, and nucleic acids.
  5. Groups of specialized cells (tissues) use proteins to carry out functions that are essential to the organism.
  6. The large carbon-based molecules that make up an animal’s food must be broken down into smaller molecules that can be transported to cells that use them. The chemical reactions involved occur in the digestive system.


  1. The body systems and parts of those systems that are mentioned above were selected to illustrate the hierarchical organization and to enable students to make sense of phenomena involving biological growth and motion. Students are not expected to know all the parts of all the eleven different body systems.
Frequency of selecting a misconception

ID Number

Student Misconception

Pre-Test Post-Test


Cells are smaller than atoms (Tretter et al., 2006).



Frequency of selecting a misconception was calculated by dividing the total number of times a misconception was chosen by the number of times it could have been chosen, averaged over the number of students answering the questions within this particular idea.