If a woman is a carrier for the color-blind recessive allele and her husband is normal, what are their chances that a son will be color-blind?
a. none since the father is normal.
b. 50% since the mother is the only carrier.
c. 100% because the mother has the gene.
d. 25% because the mother is a hybrid.
e. none since he will also be just a carrier.

b. 50% since the mother is the only carrier.

Explanation:

Color blindness is a X linked recessive trait characterized by difficulty in differentiating between some colors. Let us assume

C = dominant allele

c  = recessive allele

Given,

mother is a carrier = XCXc

father is normal = XCY

Hence their children:   XC          Xc

                        XC       XCXC     XCXc

                          Y        XCY        XcY

The sons can either be XCY (normal) or XcY (color blind). Hence they have half or 50% chance to be colorblind since half of the sons will get one recessive allele from the carrier mother.

false because ozone (o3) depletion does not cause global warming, but both of these environmental problems have a common cause: human activities that release pollutants into the atmosphere altering it.

global warming is caused primarily by putting too much carbon dioxide into the atmosphere when coal, oil, and natural gas are burned to generate electricity or to run our cars.

explanation: