Topic: Cells

Below is a list of key ideas related to Cells. 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 living things are composed of one or more cells.

Students are expected to know that:

  1. All organisms, including animals, plants, fungi, and microorganisms, are made up of cells.
  2. Cells vary in size, shape, and specialized functions.
  3. Most cells are so small that their details can be seen only with a microscope.
  4. Living things can be made of just one cell to many millions of cells.
  5. Some organisms are made of many types of cells and many of each type.
  6. In single-celled organisms such as bacteria, the single cell carries out all of the functions needed for the organism to stay alive; in organisms made of many cells, individual cells work together with (depend on) other cells to carry out their essential life functions.
  7. In multicellular organisms, the structures that make up those organisms (including brain, muscles, skin, and lungs in animals, and stems and flowers in plants) are made up of cells.

Boundaries:

  1. Students are not expected to know the terms "prokaryote" or "eukaryote" or the differences between these types of cells.
  2. Items will not test students’ knowledge of fungi.
Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

CEM001

All cells are the same size and shape, i.e., there is a generic cell (AAAS Project 2061, n.d.).

43%

37%

CEM005

There are no single-celled organisms (AAAS Project 2061, n.d.).

39%

30%

CEM003

Some living parts of organisms are not made of cells (AAAS Project 2061, n.d.).

36%

29%

CEM004

Plants are not made of cells (AAAS Project 2061, n.d.).

7%

5%

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.

Although there are many different types of cells in terms of size, structure, and function, all cells have certain characteristics in common.

Students are expected to know that:

  1. All cells are composed of complex molecules made by the cells themselves from simpler molecules (such as amino acids, simple sugars, and fatty acids) that enter the cells from outside the cells.
  2. In multicellular organisms, cells provide structural support for the organism they are part of and carry out essential life functions for that organism.
  3. In cells of plants and animals, there are internal structures that perform specialized functions such as extracting energy from food, making new molecules for growth, and eliminating wastes.
  4. In addition to the internal structures that perform specialized functions for cells, the interior of cells is also filled with water and molecules that are dissolved in that water.
  5. A membrane makes up the outer surface of a cell, which controls what enters and leaves the cell. For example, small molecules such as amino acids, fatty acids, and simple sugars can enter and leave through the cell's membrane.
  6. Many of the same basic life processes, such as extracting energy from food, making the materials needed for their own growth, and eliminating wastes, take place within the individual cells of all organisms (including plants, animals, fungi, and microorganisms).
  7. Plant and animal cells need molecules from food, water, oxygen, and a way to eliminate wastes in order to continue to function.
  8. Bacteria need molecules from food, water, and a way to eliminate wastes to continue to function. Some bacteria need oxygen and others do not.

Boundaries:

  1. Students are not expected to know specific internal cell structures (organelles) or differences between bacterial, plant, and animal cells.
  2. Students are not expected to know the process of either active or passive transport through the cell membrane.
  3. Fungi and microorganisms are used as contexts only when students are also told that these are living organisms.
  4. Students are not expected to know which bacteria need oxygen and which do not, and they are not expected to know the terms “anaerobic” and “aerobic.”
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

CE093002

Small molecules enter the cell through the cell membrane.

64%

72%

CE133001

The inside of an animal cell contains liquid water and molecular structures that provide organization and shape.

60%

71%

CE065001

The inside of an animal cell contains both water and solid strutures.

61%

67%

CE075004

Both plant and animal cells perform basic life functions such as making molecules for growth.

58%

71%

CE064001

The inside of an animal cell contains both water and solid structures.

56%

67%

CE056001

Cells make up the basic structure of organisms and perform the basic life functions of organisms.

53%

62%

CE146001

Muscle cells obtain energy from food, and they make molecules for growth.

53%

60%

CE129001

Cells are organized into the body structures and perform the basic life functions of the organism they are part of.

51%

62%

CE132001

The cells of living organisms (e.g. cells of mushrooms) need water and a way to eliminate wastes to function.

50%

60%

CE131001

The cells of living organisms (e.g., mushrooms) need molecules from food and water to function.

51%

56%

CE072004

Both plant and animal cells perform basic life functions such as extracting energy from food.

50%

53%

CE062003

The inside of an animal cell contains water, molecules dissolved in water, and small structures that perform specialized functions for the cell.

46%

55%

CE130001

The cells of living organisms (e.g. cells of mushrooms) need molecules from food and a way to eliminate wastes to function.

49%

49%

CE084002

Bacteria need both molecules from food and water to function.

49%

48%

CE063003

The inside of a plant cell contains water, molecules dissolved in water, and small structures that perform specialized functions for the cell.

42%

52%

CE118002

Bacteria need food and a way to eliminate wastes in order to function.

45%

44%

CE077004

Both plant and bacteria cells perform basic life functions such as making molecules for growth.

40%

52%

CE076004

Both animal and bacteria cells perform basic life functions such as extracting energy from food.

42%

47%

CE074004

Both plant and bacteria cells perform basic life functions such as extracting energy from food.

41%

49%

CE088002

Bacteria need both molecules from food and a way to eliminate wastes to function.

40%

51%

CE092002

Bacteria need both water and a way to eliminate wastes to function.

44%

42%

CE073004

Both animal and bacteria cells perform basic life functions such as extracting energy from food.

39%

50%

CE078004

Both plant and animal cells perform basic life functions such as eliminating wastes.

38%

43%

CE079004

Both animal and bacteria cells perform basic life functions such as eliminating wastes.

34%

43%

CE080004

Both plant and bacteria cells perform basic life functions such as eliminating wastes.

37%

38%

CE145001

Muscle cells get energy from food, and they eliminate wastes.

37%

37%

CE147001

Muscle cells make molecules for growth, and they eliminate their own waste material.

37%

36%

CE135001

Nerve cells both obtain energy from food and eliminate waste material.

35%

35%

CE136001

Nerve cells obtain energy from food and make molecules for growth.

35%

30%

CE138001

Proteins needed for growth and repair of the cell are built by the cell itself.

29%

32%

CE137001

Nerve cells make molecules for growth and eliminate their own waste material.

28%

26%

Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

CEM056

Cells of living organisms do not make molecules for their own growth and repair.

71%

68%

CEM051

Animal cells do not eliminate their own wastes.

44%

43%

CEM055

Bacteria do not extract energy from food.

41%

36%

CEM049

Bacteria do not make molecules for their own growth.

42%

35%

CEM045

Bacteria do not carry out essential life functions for themselves.

41%

35%

CEM052

Bacteria do not eliminate their own wastes.

40%

35%

CEM044

Bacteria do not need a way to eliminate wastes to function.

38%

36%

CEM006

Cells do not need a way to eliminate waste materials to function (AAAS Project 2061, n.d.).

36%

33%

CEM042

Bacteria do not need molecules from food to function.

34%

34%

CEM050

Plant cells do not eliminate their own wastes.

34%

31%

CEM048

Animal cells do not make molecules for their own growth.

33%

32%

CEM043

Bacteria do not need water to function.

32%

32%

CEM039

Cells do not need molecules from food to function (AAAS Project 2061, n.d.).

32%

30%

CEM038

Plant cells do not carry out essential life functions for themselves (AAAS Project 2061, n.d.).

32%

29%

CEM053

Plant cells do not extract energy from food.

31%

31%

CEM054

Animal cells do not extract energy from food.

30%

27%

CEM046

Bacteria do not need food to function.

28%

30%

CEM009

Cells do not carry out essential life functions for the organism they are part of (AAAS Project 2061, n.d.).

29%

24%

CEM047

Plant cells do not make molecules for their own growth.

30%

23%

CEM034

Cells are not organized into the body structures of the organism they are part of.

29%

22%

CEM037

Animal cells do not carry out essential life functions for themselves (AAAS Project 2061, n.d.).

27%

25%

CEM013

Cells do not need water to function (AAAS Project 2061, n.d.).

24%

19%

CEM028

The interior of a cell is completely filled with water (AAAS Project 2061, n.d.).

18%

14%

CEM007

The interior of a cell is solid (AAAS Project 2061, n.d.).

13%

11%

CEM008

The interior of a cell is filled with air (AAAS Project 2061, n.d.).

11%

9%

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.

Cells in multicellular organisms repeatedly divide to make more cells for growth and repair.

Students are expected to know that:

  1. In multicellular organisms, new cells needed for growth and repair come from the division of existing cells.
  2. Cell division results in the formation of two nearly identical cells from a single original cell.
  3. Individual cells grow by creating new complex molecules that make up the cells’ structures, using molecules from food that enter the cells.
  4. In multicellular organisms, both an increase in individual cell mass and an increase in cell number cause the organism of which they are part to increase in size and mass.
  5. The successive duplication of cells explains how multicellular organisms can develop from a single cell.

Boundaries:

  1. Students are not expected to know that following the initial development of an organism’s body structures, only certain types of cells divide.
  2. They are not expected to know that there are differences in rates of division between types of cells, the length of time different cells are alive, or any other details of the life cycle of cells.
  3. Students are not expected to know the terms "mitosis" or "meiosis" or any of the terminology associated with the phases of cell division.
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

CE119002

The difference in size between young children and fully grown adults can be explained by the repetitive process of cell growth and division.

59%

68%

Frequency of selecting a misconception

Misconception
ID Number

Student Misconception

Grades
6–8

Grades
9–12

CEM022

In the early development of an organism, cells that result from cell division do not grow before dividing again (AAAS Project 2061, n.d.).

22%

15%

CEM020

Organisms grow by cell division, but the cells do not themselves increase in size or mass (AAAS Project 2061, n.d.).

22%

15%

CEM023

In the early development of an organism, cells grow in size but the number of cells remains constant (AAAS Project 2061, n.d.).

13%

11%

CEM024

In the early development of an organism, the organism grows in size and mass without cell division or cell growth (AAAS Project 2061, n.d.).

6%

7%

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.

Different body structures are made up of different types of cells.

Students are expected to know that:

  1. The different body structures of plants and animals (including brain, muscles, skin, and lungs in animals, and stems and flowers in plants) are made up of different types of cells.
  2. The different types of cells that make up the body parts of animals develop from one single cell.
  3. The different types of cells that make up the body parts of plants can develop from one single cell.
  4. After a single cell goes through a series of cell divisions, the cells begin to differentiate into a variety of types of cells with specialized structures and functions. The different types of cells continue to reproduce and further differentiate to form the specialized body structures that make up most multicellular organisms.
  5. Groups of cells work together to perform specialized functions in multicellular organisms. These include.red blood cells, which carry oxygen to all cells of the body, muscle cells, which allow movement of the organism, and nerve cells, which transmit electrical signals between the brain and the rest of the body.

Boundaries:

  1. Students are not expected to know the stages of cell differentiation (e.g., blastula, gastrula) or the role of differential gene expression in cell differentiation.
  2. Students are not expected to know the process of cell differentiation.
  3. Students are not expected to know that plants can reproduce asexually (in which case they come from many cells).