Question 1

Question

Consider the Punnett square seen here.

It shows the possibility of having either a male child, XY, or a female child, XX. The Gordon family has four boys. Mr. and Mrs. Gordon are hoping for a girl. What is the probability that the next child will be a girl?
Responses
A 1:4 or 25%1:4 or 25%
B 2:4 or 50%2:4 or 50%
C 3:4 or 75%3:4 or 75%
D 4:4 or 100%4:4 or 100%
Question 2
Pea plants were used by Gregor Mendel in the first genetic crosses that enabled him to formulate the laws of inheritance and genetic probability. Consider the Punnett square for pea seed shape and color.

What is the probability that round peas will be produced, regardless of color?
Responses
A 0.50 or 50%0.50 or 50%
B 0.67 or 67%0.67 or 67%
C 0.75 or 75%0.75 or 75%
D 1.00 or 100%

Answer 1

Question 1: The probability of having a girl (XX) or a boy (XY) is always 1:1, or 50%, regardless of the genders of previous children. Therefore, the correct answer is: B 2:4 or 50%

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Question 2: Without the exact details of the Punnett square for pea seed shape and color, I can offer a general principle based on Mendelian genetics. If round peas (R) are dominant over wrinkled peas (r), and assuming the genotypes involved are either heterozygous or homozygous for round peas, you might have a probability of producing round peas among the offspring.

Typically, in a cross of Rr x Rr, you would produce:

• RR (round)
• Rr (round)
• Rr (round)
• rr (wrinkled)

In this cross, 75% of the offspring would be round (RR or Rr) and 25% would be wrinkled (rr). Therefore, the probability that round peas will be produced, regardless of color, would be: C 0.75 or 75%