Use of fully labelled genetic diagrams to interpret or predict the results of monohybrid and dihybrid crosses involving dominant, recessive and codominant alleles
A genetic diagram maps out which alleles parents pass to offspring. It lets you predict the likely genotypes and phenotypes of the next generation.
Formula
Expected ratio (dihybrid) = 9 : 3 : 3 : 1
Real World
Gregor Mendel's 1866 experiments crossing round-yellow and wrinkled-green pea plants at Brno monastery produced offspring in approximately a 9:3:3:1 ratio, providing the first evidence that traits are inherited independently.
Exam Focus
Show parental phenotypes, genotypes, gametes, Punnett square, and offspring ratios — each stage earns separate marks.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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