Science Assessment ~ Ideas ~ "Theme 1" Genetic information is encoded in DNA molecules.

Key Idea: Every body cell of an individual organism (with a few exceptions) contains an identical set of DNA molecules and, therefore, contains identical genetic information.

Sub-Ideas
Items & Student Performance
Misconceptions
NGSS

Students are expected to know that:

DNA molecules are smaller than cells and, therefore, can fit inside cells.
DNA, and the chromosomes and genes that are made of DNA, are located inside almost all types of cells in the body.
Every body cell (not a sex cell) that contains DNA in a multi-cellular organism contains identical DNA molecules to every other body cell because every body cell is descended from a single fertilized egg cell, and the DNA in each cell is duplicated every time a cell divides.
In all organisms, whenever a single body cell forms two body cells, the resulting body cells each contain the same number of DNA molecules (and, therefore, the same number of chromosomes) as the original body cell.
Each DNA molecule in a body cell is a member of a pair of DNA molecules. With the exception of the sex-determining DNA molecules, the two DNA molecules that make up a pair contain instructions affecting the same traits. The two DNA molecules making up a pair contain similar sequences of subunits and are similar in length.
One member of each pair of DNA molecules contains genetic information from the mother and the other member of the pair contains genetic information from the father.

Boundaries:

Students are not expected to know that some cells in the body may not have an identical set of DNA molecules, because some cells may have DNA that has mutated.
Students are not expected to know that some cells in the body (e.g. red blood cells) do not have DNA..
Students are not expected to know specifically where in a cell the DNA is located (e.g., nucleus, mitochondria).
Students are not expected to know anything about DNA in viruses, bacteria, plasmids, or polyploidy.

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
RH003001	DNA molecules are found inside all types of cells in an animal's body.	55%	67%
RH004002	The correct order from smallest to largest is: atom, chromosome, cell.	43%	56%
RH003002	Chromosomes are located inside all types of cells in an animal's body.	44%	50%
RH004001	The correct order from smallest to largest is: atom, DNA molecule, cell.	42%	51%
RH011001	Brain cells and skin cells both contain DNA molecules, which contain the same genetic information.	40%	54%
RH035004	A new skin cell of a cow contains the same number of chromosomes as the existing skin cells.	33%	56%
RH035003	A new skin cell of a cow contains the same number of DNA molecules as the existing skin cells.	31%	58%
RH018003	DNA molecules in skin cells contain information about both skin color and eye color.	37%	39%
RH036004	The cells of a leaf and the cells of a flower contain the same genetic information.	31%	41%
RH036003	The DNA molecules in the cells of a plant’s leaves and its in flowers is the same.	29%	40%
RH018004	DNA molecules in muscle cells also contain information about both skin color and eye color.	32%	32%
RH011002	Brain cells and skin cells contain the same genetic information.	27%	38%
RH039002	When a muscle cell of a chimpanzee divides, the new muscle cells contain the same number of chromosomes as the original muscle cell.	25%	35%
RH012001	The genetic information that affects eye color is found in all the different kinds of body cells.	22%	31%
RH013002	The sequence of subunits in the DNA of a stomach cell in a mouse is the same as the sequence of subunits in the DNA of other cells in the mouse’s body.	21%	31%

Frequency of selecting a misconception
Misconception ID Number	Student Misconception	Grades 6–8	Grades 9–12
RHM116	The different cell types (skin, muscle, cartilage, etc.) found in a given individual’s body contain different DNA (see Hackling & Treagust, 1984).	61%	55%
RHM020	Each cell contains only the specific genetic information required for its function (Banet & Ayuso, 1999; Lewis & Kattman, 2004; Lewis et al., 2000a).	42%	44%
RHM019	Chromosomes and/or genes do not occur in all types of cells (Banet & Ayuso, 1999).	43%	42%
RHM109	The different cell types (skin, muscle, cartilage, etc.) found in a given individual’s body contain different genetic information (See Hackling & Treagust, 1984).	44%	37%
RHM111	The cells found in different parts of an individual plant (flower, leaf, stem, root, etc.) contain different genetic information (see Hackling & Treagust, 1984 for a similar statement about animals).	43%	38%
RHM114	The cells found in different parts of an individual plant (flower, leaf, stem, root, etc.) contain different DNA molecules (see Hackling & Treagust, 1984 for a similar statement about animals).	38%	34%
RHM115	Genetic information exists in the body part it controls but not in other places in the body (see Venville et al., 2005).	36%	33%
RHM021	Chromosomes are divided up at each cell division, such that when a single body cell forms two body cells, the resulting cells each contain fewer chromosomes than the original cell (Lewis & Wood-Robinson, 2000).	36%	33%
RHM057	A cell is smaller than DNA (AAAS Project 2061, n.d.).	30%	28%
RHM050	Chromosomes are located inside sex cells but not inside any other types of cells in an animal's body (Banet & Ayuso, 2000).	26%	32%
RHM058	Cells are smaller than chromosomes (AAAS Project 2061, n.d.).	31%	25%
RHM110	Not all types of cells contain genetic information (see Banet & Ayuso, 1999).	28%	23%
RHM113	Not all types of cells contain DNA molecules (see Banet & Ayuso, 1999).	19%	14%
RHM052	DNA is located inside sex cells but not inside any other types of cells in the body (Banet & Ayuso, 2000).	16%	12%
RHM053	DNA is located inside blood cells but not inside any other types of cells in an animal's body (AAAS Project 2061, n.d.; Venville et al., 2005).	17%	11%
RHM051	Chromosomes are located inside blood cells but not inside any other types of cells in an animal's body (AAAS Project 2061, n.d.).	16%	10%
RHM048	Only animals have DNA; plants and mushrooms do not have DNA (Banet & Ayuso, 2000).	13%	11%
RHM112	Only the cells of animals contain genetic information; the cells of plants and mushrooms do not contain genetic information (see Banet & Ayuso, 2000).	10%	8%
RHM107	Human brain cells do not contain DNA molecules (AAAS Project 2061, n.d.).	9%	5%
RHM108	Human skin cells do not contain DNA molecules (AAAS Project 2061, n.d.).	6%	4%

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
PS1.A MS	Substances are made from different types of atoms, which combine with one another in various ways. Atoms form molecules that range in size from two to thousands of atoms.
LS1.A HS	All cells contain genetic information in the form of DNA molecules. Genes are regions in the DNA that contain the instructions that code for the formation of proteins, which carry out most of the work of cells.
LS3.A HS	Each chromosome consists of a single very long DNA molecule, and each gene on the chromosome is a particular segment of that DNA. The instructions for forming species' characteristics are carried in DNA. All cells in an organism have the same genetic content, but the genes used (expressed) by the cell may be regulated in different ways. Not all DNA codes for a protein; some segments of DNA are involved in regulatory or structural functions, and some have no as-yet known function.
LS1.B HS	In multicellular organisms individual cells grow and then divide via a process called mitosis, thereby allowing the organism to grow. The organism begins as a single cell (fertilized egg) that divides successively to produce many cells, with each parent cell passing identical genetic material (two variants of each chromosome pair) to both daughter cells. Cellular division and differentiation produce and maintain a complex organism, composed of systems of tissues and organs that work together to meet the needs of the whole organism.