Mississippi Science GEN.4.1

ScienceGrades 9–12Genetics

The Standard

GEN.4: Students will analyze and interpret data collected from probability calculations to explain the inheritance of traits within a population.

Demonstrate Mendel’s law of dominance and segregation using mathematics to predict phenotypic and genotypic ratios.

2026 Mississippi College- and Career-Readiness Standards for Science · Classic Mendelian Genetics

Teacher's field guide

What Students Need to Do: Students track how each parent passes one allele to an offspring. They use probability to predict genotype and trait ratios when one allele masks another.
What Mastery Looks Like: For Pp × Pp, students predict a 1 PP : 2 Pp : 1 pp genotype ratio and a 3 purple : 1 white flower ratio. They explain why a purple offspring can carry p.
Common Misconceptions: Students may think a dominant allele is always the most common allele. They may think recessive alleles vanish in purple offspring, or that a 3:1 ratio guarantees exactly three purple plants in every four.
How to Assess It: Exit ticket: For Pp × Pp, with purple dominant, give the expected genotype and flower-color ratios. Explain how two purple plants can have a white offspring.

Lesson moves

Give pairs two bags, each with P and p tiles; draw once from each, replace the tiles, and tally 40 offspring.
Ask: If two purple-flowered pea plants have a white-flowered offspring, what must each parent's genotype be? Explain your answer.
Play genotype match: call out crosses such as Pp × pp; students write genotype and flower-color ratios on mini whiteboards.
Give students a pea breeder's record showing Pp × Pp; ask how many of 40 plants they expect to have white flowers.

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A ready-to-print activity worksheet aligned to GEN.4.1, with an answer key for the teacher on its own page. No account needed.

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