SC15.7.12 | ALEX

Science (2015) Grade(s): 7

Developing and Using Models

Cause and Effect

Students know:

Chromosomes are the source of genetic information.
Organisms reproduce, either sexually or asexually, and transfer their genetic information to offspring.
Variations of inherited traits from parent to offspring arise from the genetic differences of chromosomes inherited.
In sexual reproduction, each parent contributes half of the genes acquired (at random) by the offspring.
Individuals have two of each chromosome, one acquired from each parent; therefore individuals have two alleles (versions) for each gene. The alleles (versions) may be identical or may differ from each other.

Students are able to:

Construct a model for a given phenomenon involving the differences in genetic variation that arise from genetic differences in genes and chromosomes and that additional variations may arise from alteration of genetic information.
Identify and describe the relevant components of the model.
Describe the relationships between components of the model.
Use the model to describe a causal account for why genetic variations occur between parents and offspring.
Use the model to describe a causal account for why genetic variations may occur from alteration of genetic information.

Students understand that:

During reproduction (both sexual and asexual) parents transfer genetic information in the form of genes to their offspring.
Under normal conditions, offspring have the same number of chromosomes (and genes) as their parents.
In asexual reproduction: Offspring have a single source of genetic information and their chromosomes are complete copies of each single parent pair of chromosomes. Offspring chromosomes are identical to parent chromosomes.
In sexual reproduction: Offspring have two sources of genetic information that contribute to each final pair of chromosomes in the offspring because both parents are likely to contribute different genetic information, offspring chromosomes reflect a combination of genetic material from two sources and therefore contain new combinations of genes that make offspring chromosomes distinct from those of either parent.