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Genetics Punnett Square

Biology challenge: Punnett squares predict offspring genotype and phenotype ratios. Master mono- and dihybrid crosses.

Scenario

In pea plants, yellow seed colour (Y) is dominant over green (y). Round shape (R) is dominant over wrinkled (r). You cross a dihybrid parent YyRr × YyRr.

Scored questions

Question 1

In a YyRr × YyRr cross, what fraction of offspring will be Yellow AND Round?

Question 2

How many of the 16 offspring boxes will show the genotype YYRR (homozygous dominant for both)?

Question 3

What is the expected ratio of Green Wrinkled (yyRr or yyrr) offspring?

Question 4

Two heterozygous Tt parents cross (tall T dominant). What percentage of offspring are expected to be SHORT (tt)?

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