In fruit flies, the allele for red eyes, r, is dominant. which genotype represents a white-eyed male fruit fly?

a. xrxr
b. xry
c. xry
d. xrxr

The correct answer would be B. XrY.

In fruit flies, XY codes for males and XX codes for females.

Gene encoding color of eyes is present in X chromosome only and carrier two alleles R and r.

In females, R is a dominant allele that codes for red eyes in homozygous as well as heterozygous condition whereas r is a recessive allele that codes for white eyes when present in homozygous condition only.

In males, only one X chromosome is present. So, if it carries R allele then the fruit fly would exhibit red eyes whereas if it carries r then the fruit fly would exhibit white eyes.

Only two out of four options are male fruit flies: XrY and XRY.

XrY would exhibit white eyes and XRY would exhibit red eyes.

Hence, we can conclude that XrY would be the white-eyed male fruit fly.

answer: "circumcision is a common procedure in which the skin covering the tip of the penis is surgically removed."

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.