A pea plant that has round seeds has the genotype Rr. It is crossed with a pea plant that has wrinkled seeds and the genotype rr. What is the probability that the offspring will have wrinkled seeds?

2 Answers
Mar 5, 2018



Well just study the analysis shown below,if you don't understand any point of the diagram below, let me know,but it will be better if you try to understand the way to find the nature of offsprings of your own.

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so,we can see out of the #4# offsprings, #2# are having round seed and #2# are having wrinkled seed.

So,probability of offsprings with wrinkled seed is #2/4=1/2#

Mar 5, 2018

#2/4 or 50%#


Before we start, we need to understand this:

  • The capital #color(red)R# represents a dominant trait - smooth peas
  • The lowercase #color(red)r# represents the reccessive trait - wrinkled peas.

The easiest way to solve this problem is to make a Punnett square like this:

Put the two genotypes of the two pea plants above and on the left side.
As you can see, all you have to do is bring the two letters in to where they belong. In the top left box, for example, they brought in the capital #color(red)R# from the left vertical column, and the lowercase #color(red)r# from the top horizontal column. Same goes for the lower left box.

Now that we've finished with the diagram, we need to go back to the question. It asked what the probability of these pea plants producing wrinkled peas. You need to understand:

  • Wrinkled peas need to have genotype rr, since the wrinkled trait (r) is recessive.

How many genotypes of rr are there in our diagram? 2! Out of how many? 4!
So the probability is #2/4# or #50%#