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

Key Idea: Genetic information in the form of DNA molecules is transferred from parents to offspring during reproduction.

Sub-Ideas
Items & Student Performance
Misconceptions
NGSS

Students are expected to know that:

In sexually reproducing organisms, only half of the genetic information of each parent is passed to each of its offspring.
During sexual reproduction, parents produce specialized cells called sex cells (e.g., eggs, sperm, pollen) that contain half as many DNA molecules (and, therefore, chromosomes) as are found in the other cells of the organism (body cells).
A sex cell from one parent merges with a sex cell from the other parent in a process called fertilization, and the fertilized egg cell has twice as many DNA molecules as the sex cell and the same number of DNA molecules (and, therefore, chromosomes) as the body cells of each parent.
The offspring that develop from the single cell that was formed from the combination of the two sex cells have traits of both parents because they have DNA from both parents.
In sexually reproducing organisms, traits that are acquired during the lifetime of an organism and affect its body cells (e.g. due to injuries, malnutrition, mutation, weight training) cannot be passed from parent to offspring. Only changes in the DNA of the sex cells of an organism can be inherited by offspring.
In asexually reproducing organisms (uni-cellular or multi-cellular), all of the inherited genetic information comes from one parent cell. The offspring’s DNA molecules (and therefore the offspring’s genes and chromosomes) contain the same information as the DNA molecules of the parent.
Following asexual reproduction, the genetic information contained in the DNA molecules in the resulting cells is the same as the genetic information in the DNA molecules of the original cell.
In both sexually and asexually reproducing organisms, there is no other mechanism by which genetic information is passed to offspring other than by the transfer of DNA.

Boundaries:

Students are not expected to know that sexual reproduction can involve self-fertilization by a single parent having both male and female sex cells.
Students are not expected to know that the amount of genetic material in a sex cell is not exactly half of that found in a body cell due to differences in the sizes of the different sex chromosomes and/or the transmission of the entire mitochondrial DNA molecule.
Students are not expected to know that environmental factors interact with DNA at the molecular level to affect the genetic information that is expressed.

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
RH025002	Eye color of offspring often resembles the eye color of parents because molecules that contain information for specifying eye color are passed from parents to offspring during reproduction.	62%	78%
RH059001	If a cat gets its ears torn off in a fight and then has kittens later, it will have no effect on the ears of any of the kittens.	60%	74%
RH038001	If a mouse loses its tail in a mousetrap and has babies later, there will be no effect on the tails of the baby mice.	58%	67%
RH034002	A sex cell of an organism contains half as many DNA molecules as a fertilized egg cell of that organism.	56%	64%
RH053001	An unfertilized egg cell contains half as many DNA molecules as a fertilized egg cell.	54%	62%
RH033002	If the skin cells of a mouse each contain 40 chromosomes, the sperm cells of a mouse contain 20 chromosomes.	50%	61%
RH052001	There are half as many DNA molecules in an unfertilized egg cell as in a fertilized egg cell.	54%	57%
RH006003	If the sex cells in mice contain 20 chromosomes, then the fertilized egg cell of a mouse contains 40 chromosomes.	53%	53%
RH058001	Children inherit half of the DNA in each of their cells from one parent, and half from the other parent.	45%	55%
RH005005	In sexually reproducing organisms, such as humans, half of the chromosomes contain genetic information from one parent and half from the other parent.	44%	57%
RH055001	In sexually reproducing organisms such as humans, half of a child's DNA comes from each of the parents.	44%	58%
RH049001	Sea anemones can reproduce asexually, and when they do, all of the offspring's DNA is the same as the DNA in its one parent.	46%	50%
RH005004	In sexually reproducing organisms such as humans, half of the genetic information comes from each of the parents.	44%	51%
RH054001	If the sex cells of a mouse contain 20 chromosomes, then the fertilized egg of a mouse must contain 40 chromosomes.	45%	49%
RH051001	In asexually reproducing organisms, all of an offspring's DNA is identical to its parent's DNA.	35%	53%
RH010002	In organisms that reproduce without the combining of two cells, all of the information in the parent's DNA molecules is passed to its offspring.	35%	47%
RH031002	In organisms that reproduce without the combining of two cells, the information in the DNA molecules of parents and offspring is identical.	33%	48%
RH050001	In plants that reproduce asexually, all of the parent's DNA is passed to its offspring.	33%	51%
RH047001	In sexually reproducing organisms such as humans, 50% of the DNA in each of the daughter's body cells is from her father.	30%	47%
RH032002	In sexually reproducing organisms, such as humans, the sex cells contain half the number of DNA molecules as other cells in the human's body.	32%	41%
RH009002	A skin cell of an organism contains the same genetic information as the fertilized egg cell of that organism.	30%	38%
RH008004	In sexually reproducing organisms such as humans, all of the daughter's body cells contain some genetic information from her mother.	22%	29%
RH008003	In sexually reproducing organisms such as humans, all of the son's body cells contain some genetic information from his mother.	19%	25%
RH048001	100% of a son's body cells contain some DNA from his mother.	12%	22%
RH007002	If a mutation occurs to a DNA molecule in an organism's skin cell before the organism reproduces, none of the organism's offspring will have the mutation.	12%	16%

Frequency of selecting a misconception
Misconception ID Number	Student Misconception	Grades 6–8	Grades 9–12
RHM126	In sexually reproducing organisms, half of the organism's body cells contain DNA from the mother and half contain DNA from the father.	45%	50%
RHM040	Some characteristics of an offspring are determined by the parents' environmentally acquired characteristics (Lawson, 1988).	41%	30%
RHM033	Each parent contributes genetic information for certain characteristics and not others (e.g. a child has his father's nose and his mother's eyes) (Clough & Wood-Robinson, 1985).	34%	25%
RHM125	The genetic information in a fertilized egg is divided up among different cells as they divide during development (see Banet & Ayuso, 1999).	29%	28%
RHM123	In asexually reproducing organisms, half of the parent's DNA is passed to its offspring.	30%	22%
RHM081	In asexual reproduction, half of the offspring's DNA is the same as the DNA in its one parent (AAAS Project 2061, n.d.).	29%	22%
RHM117	The specialized cells used for sexual reproduction contain the same number of DNA molecules as the other cells of the body (see Lewis et al., 2000).	23%	22%
RHM120	A fertilized sex cell has the same number of chromosomes as an unfertilized sex cell (AAAS Project 2061, n.d.).	21%	24%
RHM082	In asexual reproduction, the amount of DNA in an offspring that is identical to the DNA in its parent varies from offspring to offspring (AAAS Project 2061, n.d.).	25%	18%
RHM015	The timing of the occurrence of an environmentally induced characteristic will affect whether the characteristic is transmitted to offspring (Kargbo et al., 1980).	29%	24%
RHM124	Genetic information is inherited from the same-sex parent (i.e. daughters get their DNA from their mother, and sons get their DNA from their father) (see Clough & Wood-Robinson, 1985; Kargbo et al., 1980).	23%	15%
RHM119	The specialized cells used for sexual reproduction contain the same number of chromosomes as the other cells of the body (see Lewis et al., 2000).	20%	19%
RHM118	A fertilized egg cell contains the same number of DNA molecules as an unfertilized egg cell.	18%	16%
RHM023	How old an organism is when it acquires an environmentally induced characteristic will affect whether the characteristic is passed on to its offspring (e.g. If a father lost a finger as a child he will pass the missing-finger trait to his children, but if he lost his finger as an adult he will not pass the missing-finger trait to his children) (Kargbo et al., 1980).	11%	11%
RHM002	Offspring resemble parents because trait-bearing "particles" are transferred from parents to offspring during reproduction, e.g. particles of blue for blue eyes (Lewis & Kattman, 2004).	13%	7%
RHM012	In sexually reproducing organisms, genetic information or traits are inherited from only one parent (Clough & Wood-Robinson, 1985; Kargbo et al., 1980).	10%	10%
RHM121	Genetic information is inherited from the same-sex parent (i.e. daughters get their chromosomes from their mother, and sons get their chromosomes from their father) (see Clough & Wood-Robinson, 1985; Kargbo et al., 1980).	12%	7%
RHM013	Genetic information or traits are inherited from the same-sex parent (i.e. daughters get their mother's DNA and sons get their father's DNA) (Clough & Wood-Robinson, 1985; Kargbo et al., 1980).	11%	7%
RHM122	In sexually reproducing organisms, DNA is inherited from only one parent (see Clough & Wood-Robinson, 1985; Kargbo et al., 1980).	8%	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.

NGSS Statements
Code	Statement
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.
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.
LS3.A MS	Variations of inherited traits between parent and offspring arise from genetic differences that result from the subset of chromosomes (and therefore genes) inherited.
LS3.B MS	In sexually reproducing organisms, each parent contributes half of the genes acquired (at random) by the offspring. Individuals have two of each chromosome and hence two alleles of each gene, one acquired from each parent. These versions may be identical or may differ from each other.