DB 6 - Discussion board answers PDF

Preview

Summary

Discussion board answers...

Description

As per prior knowledge, we were taught that humans are initially produced through the process of meiosis. The gametes of the male and female combine in order to produce a zygote. When the cells combine, they also share the information that is contained within the DNA of each cell. Then, certain chromosomes are selected within the cell to be dominant, while the others are recessive. Whether certain traits will be dominant or recessive will be dependent on how dominant or recessive a gene or trait is for the parents. The couple presented in the problem has three children who all have brown eyes and blond hair; however, the father has a dominant gene for red hair. In order to predict the probability of their next child to be a brown-eyed red head, I utilized my knowledge of punnett squares as shown below. First I predicted the probability of the child having brown eyes. Key B – Brown eyes b – recessive eye color

B

B

B

BB

BB

b

Bb

Bb

This shows that the probability of their next child having brown eyes is 4 out of 4. Therefore, their next child has a 100% chance of obtaining brown eyes. After that, I predicted the probability of the child being a redhead. Key R – Red hair r – blonde hair r

r

R

Rr

Rr

r

rr

rr

This shows that the probability of the next child having red hair is 2 out of 4, therefore, the next child has a 50% chance of being a red head. As per this data, we can see that the child will be brown-eyed nevertheless, so we can factor that out of out calculations. The red hair, however, only has a 50% chance, therefore, the probability of their child being a brown-eyed red head is 50%, which would be Answer choice D, ½. To further support my answer, I went on to make another punnett square, however, with this one I used the results of both the previous punnett squares so I can combine my data in one place to reflect my answer. Key B – Brown hair b – recessive eye color R – Red hair r - blonde hair

BB

BB

Bb

Bb

Rr

BBRr

BBRr

BbRr

BbRr

Rr

BBRr

BBRr

BbRr

BbRr

rr

BBrr

BBrr

Bbrr

Bbrr

rr

BBrr

BBrr

Bbrr

Bbrr

As per this data, it shows that the chances of the next child having brown eyes and red hair is 8/16, which simplifies to ½. Answer A would be incorrect because although the data set is out of 16, the probability of the desired traits is not 1/16, but is 8/16. Answer B would also be incorrect because the data set would not be out of 8, it is out of 16. Rather, it is simplified to ½, as explained in answer A. Answer C would also be incorrect, because, again, the data set is out of 16 and the probability is 8/16, which simplifies to ½.

Answer D is correct because as per the punnett square, it shows that the couple’s next child has a probability of 8/16 for brown eyes and red hair, which simplifies to 1/2. Therefore, the child has a 50% chance of obtaining brown eyes with red hair and a 50% chance of obtaining brown eyes with blonde hair. Answer E would also be incorrect, because only the probability of brown eyes would be 1, or 4/4, but the probability of red hair would only be 2/4, so when they are combined, the probability of the desired traits is only 50%....