Question

in pea plants, tall plant height is dominant over short plant height. if there are 200 short plants in the f2 generation from a cross that followed mendels methods, about how many plants will be tall in that generation?
200
300
600
1,000

Explanation:

Step1: Recall Mendelian ratio

In a monohybrid cross following Mendel's methods, the F2 - generation phenotypic ratio of dominant to recessive is 3:1. Let the number of tall plants be $x$ and the number of short plants be $y = 200$.

Step2: Set up proportion based on ratio

The ratio of tall to short plants is $\frac{x}{y}=\frac{3}{1}$.

Step3: Solve for $x$

Substitute $y = 200$ into the proportion $\frac{x}{200}=\frac{3}{1}$. Cross - multiply gives $x=3\times200 = 600$.

Answer:

C. 600