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Grade 10 · unit review

Review: Inheritance probabilities and their limits

Use an explicit simple inheritance model to infer possibilities and assess probabilistic outcomes.

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Bring the unit skills together

Use these 4 new cases to check your reasoning. Choices are temporary and are not saved to an account, sent to staff or recorded as school grades. Download your current review choices before leaving or reloading.

Unit review questions
1. Under the exact fictional dominance model, PP × Pp parents contribute alleles independently. What is white pp probability?
2. A purple unknown parent crossed with pp has a correctly recorded pp offspring. With no mutation and the exact model, what is the purple parent?
3. A fictional cross gives white probability 1/4 for each of two independent offspring. What is the chance both are white?
4. A model gives white probability 1/2. In 10 independent outcomes the record has 7 whites. Which is accurate?

The download contains your current choices and any checked feedback. Keep the separate transfer-task work in your own document; downloading its instructions does not mark it complete.

Use the skills in a new task

Write an explanation for a fictional plant breeder’s paper model, using P as dominant purple and p as recessive white. An unknown purple parent crossed with pp has one correctly recorded white offspring; assume no mutation and an exact single-gene model. Infer the parent, state per-offspring probabilities, find the chance both of two independent offspring are white, and assess a separate 8-offspring sample with 6 whites.

Work on paper or in your own document. Explain the choices you made.

  • Infer Pp using the white offspring and the model assumptions.
  • Give 1/2 white and 1/2 purple per offspring.
  • Calculate both-white probability 1/4 under independence.
  • Compare expected four whites in eight with observed six without treating expectation as a guarantee.
  • State that this simplified model is not a prediction tool for human traits.
Compare with a model response

The pp offspring needs p from each parent, so the unknown purple parent is Pp under the exact no-mutation model. Pp × pp gives 1/2 white and 1/2 purple per offspring. Two independent whites have probability 1/2 × 1/2 = 1/4. For eight outcomes, expected whites are four; six observed whites can occur and do not alone refute the model. This deliberately simplified plant model should not be used to predict a person’s traits.

A different response can also meet the criteria. Compare the evidence and reasoning, rather than copying the wording.