Science Assessment

Students are expected to know that:

1. Unlike animals, plants do not take in food from their environment.
2. Plants make their own food in the form of sugar molecules by means of a chemical reaction between carbon dioxide molecules and water molecules. Oxygen molecules are also a product of this reaction.
3. The process of making sugar molecules involves linking together carbon atoms that come from molecules of carbon dioxide.
4. The chemical reactions by which sugars are made takes place inside the plants. In most familiar land plants, the carbon dioxide molecules that are used come from the air that enters the plant primarily through its leaves, and that the water molecules that are used in the reaction enter the plant through its roots.

Boundaries:

1. Although there may be limited exceptions to the generalization that unlike animals, plants do not take in food from their environment, students are not expected to be aware of those exceptions.
2. The items do not assess knowledge of any of the chemical structures or formulas of any of the reactants or products either of the overall chemical reaction or of any of the intermediate steps, such as light-dependent and light-independent reactions.
3. The items do not assess exceptions to the expected knowledge: that some plants, such as cacti and some other desert plants do not take in carbon dioxide through their leaves but through their stems, that some plants, such as parasitic plants, do not make their own food and obtain some or all of their food by attaching to the stems or roots of other organisms, or that in addition to plants there are other types of organisms, such as many micro-organisms, that are able to make their own food.
4. The items do not assess the idea that light is involved in the synthesis of sugars from carbon dioxide and water.
5. The items do not use the terms producer, consumer, photosynthesis, organic, or inorganic.

Students are expected to know that:

1. Growth, repair, and replacement of body structures (such as stems, leaves, roots, flowers, fruits, seeds, and the cells of which they are made) involves using sugar molecules to make a variety of larger carbon-containing molecules that become part of the plant’s body structures.
2. Growth of plants and animals requires the addition of molecules made up of linked carbon atoms to their body structures, and this is the only way that body structures can grow. An increase in size associated with taking up water is not considered to be growth.
3. The sugar molecules used to make these larger carbon-containing molecules are already inside the plant.
4. The processes by which sugar molecules are used to make carbohydrates, proteins, and fats involve chemical reactions in which atoms of the sugar molecules are rearranged to form molecules of carbohydrates, fats, and proteins.
5. Other kinds of atoms from dissolved minerals in the soil (such as nitrogen, and sulfur) are also used and incorporated into the molecules that become part of the plant’s body structures, but in much smaller amounts than the carbon atoms from the sugars. Students should know that the incorporation of minerals into body structures does not produce observable growth.

Boundaries:

1. Items do not assess students’ knowledge of the chemical or structural formulas of carbohydrates, proteins, or fats or the processes by which they are made.
2. The idea that simple sugars are the “building blocks” of complex carbohydrates, that amino acids are the building blocks of proteins, and that fatty acids are the building blocks of fats is covered in Benchmark 6C/M2, not this key idea.
3. The idea that water is a major component of cells is part of Benchmark 5C/M4, not this key idea.
4. The idea that carbon, because of its small size and four available bonding electrons can join to several other carbon atoms in chains and rings to form large and complex molecules is part of Benchmark 5C/H8, not this key idea.