Science Assessment ~ Ideas ~ 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.

Key Idea: To build body structures, multicellular organisms use monomers (e.g., amino acids, glucose) to make polymers (e.g., proteins, carbohydrate polymers) that make up their body structures. An input of energy is required for these chemical reactions to occur.

Sub-Ideas
Items & Student Performance
Misconceptions
NGSS

Students are expected to know that:

To build body structures for growth and repair, plants use glucose monomers to make carbohydrate polymers and water molecules. Carbohydrate polymers can also be stored in seeds for their offspring.
Plants and some other organisms can use glucose molecules and a source of nitrogen atoms to make amino acids monomers.
Plants can use the amino acids monomers to build protein polymers that can be used immediately or stored (in seeds) for their offspring.
Organisms that eat plants can use carbohydrate and protein polymers as a source of glucose and amino acid monomers needed to build their body structures.
The large carbon-based molecules (polymers) that make up animal body structures are made up of the same types of small carbon-based molecules (monomers) as the food an animal eats but differ in the specific monomer composition and arrangement. Hence, they are different molecules.
These molecules, mainly protein, carbohydrate, and fat polymers, are broken down in the digestive system into smaller carbon-based molecules (monomers) such as amino acids, glucose, and fatty acids, during chemical reactions with water molecules.
Within body cells, the monomers can react with one another to form polymer molecules that become part of the animal’s body. Water molecules are also produced during polymer formation.
When organisms grow or repair, they increase in mass. Atoms are conserved when organisms grow: The increase in measured mass comes from the incorporation of atoms from molecules that were originally outside of the organism’s body.
Energy is required to form proteins and water from amino acids.
Energy is required to form carbohydrate polymers and water from glucose molecules.

Boundaries:

Students are not expected to know that protein digestion does not release sufficient energy for ATP synthesis and that the energy released during digestion is all transferred to the surroundings as heat.
Students are not expected to know that protein synthesis requires much more energy than is released during protein digestion or that the reason is because cells need to correctly sequence the amino acids, which requires synthesis and maintenance of ribosomes.

Percent of students answering correctly (click on the item ID number to view the item and additional data)
Item ID Number	Knowledge Being Assessed	Pre-Test	Post-Test
EB060002	A friend who wants to keep her fingernails from breaking can eat proteins with all the necessary building blocks (amino acids) because her body can carry out chemical reactions to change proteins in her food to keratin.	49%	47%
EB058001	The egg yolk gets smaller as a 5-day old chick grows inside an egg into a 10-day chick because some of the molecules from the yolk are broken down and assembled into new molecules that become part of the chick’s body.	46%	54%
EB056001	When a mouse grows, its increased mass comes from atoms of molecules from its food that were incorporated into its body structures.	37%	49%
EB057001	Some of the molecules from milk a nursing infant drinks are changed into new molecules that become part of its body structures.	27%	36%

Frequency of selecting a misconception
Misconception ID Number	Student Misconception	Pre-Test	Post-Test
MEM059	Food is turned into energy and is used up in the process (Smith & Anderson, 1986).	39%	33%
CEM020	Organisms grow by cell division, but the cells do not themselves increase in size or mass (AAAS Project 2061, n.d.).	28%	18%
M007	Energy can be changed into matter or atoms.	17%	20%
BFM013	The carbohydrates, fats, and proteins from the food people eat are used by the body unchanged; they are not broken down into smaller molecules (AAAS Project 2061, n.d.).	15%	12%
MEM076	Food is simply converted into waste materials and eliminated from the body (Smith & Anderson, 1986).	11%	11%

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.

NGSS Statements
Code	Statement
LS1.C MS	Within individual organisms, food moves through a series of chemical reactions in which it is broken down and rearranged to form new molecules, to support growth, or to release energy.
LS1.C HS	The sugar molecules thus formed contain carbon, hydrogen, and oxygen: their hydrocarbon backbones are used to make amino acids and other carbon-based molecules that can be assembled into larger molecules (such as proteins or DNA), used for example to form new cells.