Mississippi Science BIO.3B

BIO.3B is a cluster heading. These are the individual standards under it.

• BIO.3B.1

  Demonstrate Mendel’s law of dominance and segregation using mathematics to predict phenotypic and genotypic ratios by constructing Punnett squares with both hom...

• BIO.3B.2

  Apply Mendel’s law of independent assortment to interpret dihybrid crosses.

• BIO.3B.3

  Investigate traits that follow non-Mendelian inheritance patterns (e.g., incomplete dominance, codominance, multiple alleles in human blood types, and sex-linka...

• BIO.3B.4

  Analyze and interpret data (e.g., pedigrees, family, and population studies) regarding Mendelian and complex genetic traits (e.g., sickle-cell anemia, cystic fi...

01

What Students Need to Do

Students use Punnett squares and probability to predict offspring genotypes and traits for one-gene and two-gene crosses. They compare predictions with offspring counts and use pedigrees to estimate disease risk. They also work with blood types, sex-linked traits, and traits that do not follow simple dominance.

02

What Mastery Looks Like

They show that AA × Aa gives half AA and half Aa offspring, all with the dominant trait. For AaBb × AaBb, they find the 9:3:3:1 trait ratio when the genes assort independently. They use a pedigree to estimate disease risk and explain why actual counts can differ from predicted ratios.

03

Common Misconceptions

Students often think dominant means common, or that a 25% risk guarantees exactly one affected child in four births. They may assume two genes always pass together. They may call a blended trait codominance or overlook sex chromosomes when reading a pedigree.

04

How to Assess It

Exit ticket: For Aa × Aa, where A is dominant, give genotype and trait probabilities. Explain why 12 offspring might not match the predicted trait ratio.

1. 01

   Label both coins A on heads and a on tails; flip 40 pairs for an Aa × Aa cross and compare genotypes with predictions.

2. 02

   Show a pedigree with two unaffected parents and a child with cystic fibrosis; ask, "What inheritance pattern fits, and why?"

3. 03

   Give pairs AB, Ab, aB, and ab cards for each parent; race to complete an AaBb × AaBb Punnett square and tally traits.

4. 04

   Use a fictional maternity record listing one AB parent and one O parent; ask which blood types their child could have.

• L.8.4B.1

  Analyze and interpret data (e.g., pictures, graphs) to explain how natural selection may lead to increases and decreases in specific traits in populations over ...

• PHY.1

  Students will investigate and understand how to analyze and interpret data.

• GEN.4

  Students will analyze and interpret data collected from probability calculations to explain the inheritance of traits within a population.

• GEN.5

  Students will apply population genetic concepts to explain the variability of organisms within a population.