3.2b Graded Survey: Sex-linked Traits

Quiz Instructions

This activity will vary in how long it takes you to complete based on how comfortable you are with the genetics material so far. Hopefully, it won’t take longer than 15 minutes. I am adding an optional Discussion Forum for Questions and Answers on this particular question. It will appear in the Module right below this graded survey. The purpose of this graded survey is to give you a chance to try to work through the logic of sex-linked traits on your own. It’s less important that you “get it right” so much as you understand the concepts behind the “right answers”, which is why everybody gets full points for completing this.

Question 1 (1 pt)

For this set of questions, we’re going to simplify things a little bit. Humans have three genes that control colorblindness, but we’re going to pretend that there’s only one.

Imagine that there is a Homozygous woman with color vision and sex-chromosomes: X X

Imagine that there is a male with colorblindness, whose sex chromosomes are: XC Y

If these two people were to have children, there are two potential sex chromosome combinations. I’ve filled in a couple of the answers for you.

• _________% chance an offspring will be XC X (female carriers of the color-blindness gene)
• _________ % chance an offspring will be 

50% chance an offspring will be X X (female with normal color vision)

50% chance an offspring will be XC Y (male with colorblindness).

Question 2 (1 pt)

For this example, imagine that there is a Homozygous woman who carries the gene that produces color blindness, but is not herself color-blind. We can depict this scenario as: XC X

Imagine that there is a male with colorblindness, whose sex chromosomes are: XC Y

If these two people were to have children, there are four potential sex chromosome combinations. Please fill them in below

•  __________% chance an offspring will be XC XC (female with colorblindness)
•  __________% chance an offspring will be XC X (female carrier that can see colors)
•  __________% chance an offspring will be XC Y (male with color-blindness)
•  __________% chance an offspring will be  (male that can see colors)

25% chance an offspring will be XC XC (female with color blindness)

25% chance an offspring will be XC X (female carrier that can see colors)

25% chance an offspring will be XC Y (male with color blindness)

25% chance an offspring will be X Y (male that can see colors)

Question 3 (1 pt)

Thinking about the two examples you just worked through, can males (those with XY combinations) inherit a gene that produces color-blindness from their father?

______Yes

______No

Yes, males (those with XY combinations) can inherit a gene that produces color-blindness from their father. In the second example, the male offspring has a chance to inherit the XC gene from the mother, which would result in him having the XC Y combination and being colorblind. In the first example the male offspring has no chance to inherit the gene from the mother since she doesn’t have the gene.