Unit 05 · Heredity
The big ideas here are how traits pass between generations: meiosis producing genetic variation, Mendel's rules of segregation and independent assortment, the probability behind crosses, and the patterns — codominance, incomplete dominance, sex linkage — that go beyond simple Mendelian ratios. Mastery means solving genetics problems and tracing inheritance back to chromosomes.
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Meiosis & variation | Confuses meiosis with mitosis. | Knows meiosis halves chromosomes; vague on variation. | Links crossing over and assortment to genetic variation. |
| Punnett / probability problems | Cannot set up a cross. | Solves monohybrid crosses but stumbles on dihybrid. | Solves mono- and dihybrid crosses and states probabilities. |
| Non-Mendelian patterns | Treats all traits as simple dominance. | Recognizes one non-Mendelian pattern. | Identifies and solves codominance, incomplete, and sex linkage. |
| Pedigree analysis | Cannot read a pedigree. | Reads symbols but infers genotypes inconsistently. | Deduces inheritance mode and genotypes from a pedigree. |
| Connecting to molecular basis | Sees genetics as separate from DNA. | Links genes to traits loosely. | Connects alleles to genes, chromosomes, and phenotypes. |
| Integration (cross-domain) | Treats the science as isolated facts; makes no cross-domain connection. | Names a link to history, reading, or writing but cannot defend why it matters. | Connects the unit to its anchor across History · Reading · Writing (plus chosen electives) and defends why the connection matters. |
“Two heterozygous parents give a 3-to-1 ratio because the recessive trait only shows when both alleles are recessive. I set up the Punnett square, and it’s just probability — a quarter come out homozygous recessive.”
“The big letter beats the little letter. The square gives you the offspring. I’m not sure why it works out to three to one.”
You demonstrate this unit by solving cross and pedigree problems live and explaining your reasoning aloud — not by recall alone. A criterion is mastered when you can work a fresh problem and justify every step.
A 5-page clipboard packet — unit overview, key terms, the mastery rubric, anchor examples, and a score sheet you can print and grade against.