Topic: Matter and Energy in Living Systems

Below is a list of key ideas related to Matter and Energy in Living Systems. For each key idea, you will find a list of sub-ideas, a list of items, results from our field testing, and a list of student misconceptions. After clicking on a tab, click on it again to close the tab.

All organisms need food as a source of molecules that provide chemical energy and building materials.

Students are expected to know that:

  1. Food consists of carbon-containing molecules in which carbon atoms are linked to other carbon atoms.
  2. Carbon-containing molecules serve as the building materials that all organisms (including plants and animals) use for growth, repair, and replacement of body parts (such as leaves, stems, roots, bones, skin, muscles, and the cells that make up these structures) and provide the chemical energy needed to carry out life functions.
  3. If substances do not provide both chemical energy and building material, then they are not food for an organism.
  4. Chemical energy from carbon-containing molecules is the only form of energy that organisms can use for carrying out life functions.
  5. Carbohydrates (including simple sugars and starch), fats, and proteins are molecules that are food.
  6. Light is not food because it is not made of atoms and therefore cannot provide building material, and even though substances such as water, carbon dioxide, oxygen, and various minerals provide atoms for building materials for some types of organisms, they are not food because they do not contain carbon atoms that are linked to other carbon atoms and cannot be used as a source of chemical energy.

Boundaries:

  1. The idea that there are other atoms besides carbon (mainly hydrogen and oxygen atoms) in carbon-containing molecules that are used as food is not part of this key idea.
  2. Students are not expected to know what chemical energy is other than it resides in the molecules of substances.
  3. Although students are expected to know that any molecule with carbon atoms linked to other carbon atoms could be food for organisms, they are not expected to know which of these other carbon-containing molecules are or are not food for any particular type of organism.
Percent of students answering correctly (click on the item ID number to view the item and additional data)
Item ID
Number

Knowledge Being Assessed

Grades
6–8

Grades
9–12

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ME160001

Food is anything that is a source of both energy and building materials for plants and animals.

63%

71%

ME100002

Children need food as a source of energy and as a source of material for building or repairing body structures such as muscles.

66%

71%

ME098002

Animals and plants need food as a source of energy and as a source of material for building body parts, such as muscles in animals and leaves in plants.

60%

63%

ME161001

A solution of sugar water is a source of food because the sugar in the solution is a source of energy and building materials.

49%

60%

ME104002

Fats, proteins, and carbohydrates are sources of food for animals, but minerals are not.

52%

53%

ME149001

Milk is food for people because food is something that provides energy and building materials, and milk provides energy and building materials.

44%

58%

ME106003

Molecules made of several carbon atoms linked to each other and to hydrogen and oxygen atoms could be food for plants (item uses molecular models).

45%

55%

ME150001

Fat is a source of food for animals.

40%

51%

ME147003

Molecules made of several carbon atoms linked to each other and to hydrogen and oxygen atoms could be food for plants.

37%

39%

ME147001

Molecules made of several carbon atoms linked to each other and to hydrogen and oxygen atoms could be food for plants.

37%

N/A

ME159001

Water is not a souce of food for plants and animals because food must contain molecules that have carbon atoms linked to other carbon atoms, and water molecules do not have carbon atoms linked to other carbon atoms.

16%

33%

Plants make their own food in the form of sugar molecules from carbon dioxide molecules and water molecules. In the process of making sugar molecules, oxygen molecules are produced as well.

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.
Percent of students answering correctly (click on the item ID number to view the item and additional data)
Item ID
Number

Knowledge Being Assessed

Grades
6–8

Grades
9–12

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ME095004

The sugar molecules in plants are made by the plants.

38%

42%

ME095005

The sugar molecules in plants are the result of a chemical reaction.

31%

41%

ME029006

A plant makes its food from carbon dioxide and water.

33%

40%

ME109003

Plants use sugars that they make as food.

22%

27%

ME095006

The sugar molecules in plants are made of carbon atoms linked to other carbon atoms.

25%

22%

All organisms, including plants and animals, have mechanisms for storing molecules from food for later use.

Students are expected to know that:

  1. Some of the carbon-containing molecules that become part of an animal’s or plant’s body structures can be used later (as a source of chemical energy or building materials).
  2. Molecules typically used for storage include fats (in both plants and animals) and some carbohydrates, such as starch (in plants).
  3. Molecules used for storage are often stored in specialized structures. Specialized structures for food include fat tissue in animals and seeds in plants, both of which store fat molecules; and seeds, bulbs, and some roots in plants, all of which store starch molecules.

Boundaries:

  1. Items do not assess knowledge of other storage molecules such as triglycerides or glycogen or the chemical or structural formulas of any storage molecules.
Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

MEM126

Molecules from food are not stored in the bulbs of plants.

53%

60%

MEM125

Molecules from food are not stored in the seeds of plants.

25%

28%

MEM128

Animals cannot store molecules from food in their bodies (AAAS Project 2061, n.d.).

29%

20%

MEM127

Molecules from food are not stored in the fat tissue of animals.

33%

20%

MEM129

Plants cannot store molecules from food in their body structures (AAAS Project 2061, n.d.).

27%

26%

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.

All organisms need food as a source of molecules that provide chemical energy and building materials.
-and-
Plants make their own food in the form of sugar molecules from carbon dioxide molecules and water molecules. In the process of making sugar molecules, oxygen molecules are produced as well.

These items have been aligned to more than one key idea. To view the sub-ideas click on a key idea below.

  • All organisms need food as a source of molecules that provide chemical energy and building materials.

    Students are expected to know that:

    1. Food consists of carbon-containing molecules in which carbon atoms are linked to other carbon atoms.
    2. Carbon-containing molecules serve as the building materials that all organisms (including plants and animals) use for growth, repair, and replacement of body parts (such as leaves, stems, roots, bones, skin, muscles, and the cells that make up these structures) and provide the chemical energy needed to carry out life functions.
    3. If substances do not provide both chemical energy and building material, then they are not food for an organism.
    4. Chemical energy from carbon-containing molecules is the only form of energy that organisms can use for carrying out life functions.
    5. Carbohydrates (including simple sugars and starch), fats, and proteins are molecules that are food.
    6. Light is not food because it is not made of atoms and therefore cannot provide building material, and even though substances such as water, carbon dioxide, oxygen, and various minerals provide atoms for building materials for some types of organisms, they are not food because they do not contain carbon atoms that are linked to other carbon atoms and cannot be used as a source of chemical energy.

    Boundaries:

    1. The idea that there are other atoms besides carbon (mainly hydrogen and oxygen atoms) in carbon-containing molecules that are used as food is not part of this key idea.
    2. Students are not expected to know what chemical energy is other than it resides in the molecules of substances.
    3. Although students are expected to know that any molecule with carbon atoms linked to other carbon atoms could be food for organisms, they are not expected to know which of these other carbon-containing molecules are or are not food for any particular type of organism.
  • Plants make their own food in the form of sugar molecules from carbon dioxide molecules and water molecules. In the process of making sugar molecules, oxygen molecules are produced as well.

    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.
Percent of students answering correctly (click on the item ID number to view the item and additional data)
Item ID
Number

Knowledge Being Assessed

Grades
6–8

Grades
9–12

Select This Item for My Item Bank

ME112005

The carbon dioxide used by plants comes from the air.

41%

44%

ME004012

A plant's food are the sugars that it makes--not minerals, water, or carbon dioxide.

40%

39%

Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

MEM121

Minerals are food for plants (Horizon, n.d.; Vaz et al., 1997).

25%

30%

MEM017

Plants use oxygen during photosynthesis (Horizon Research; Wandersee, 1983).

21%

22%

MEM119

Water is food for plants (Horizon, n.d.; Lee & Diong, 1999; Vaz et al., 1997, Wandersee, 1983).

22%

16%

MEM015

Carbon dioxide is absorbed through the roots of plants (Simpson & Arnold, 1982).

19%

15%

MEM130

Carbon dioxide is food for plants (AAAS Project 2061, n.d.).

12%

15%

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.