In drosophila, the genes crossveinless-c and stubble are linked, about 7 map units apart on chromosome 3. cv-c is a recessive mutant allele of crossveinless-c (cv-c+ is wild type), while sb is a dominant mutant allele of stubble (sb+ is wild type). a dihybrid female drosophila with genotype cv-c sb+/cv-c+sb is testcrossed. the proportion of phenotypically wild-type individuals in the progeny of the testcross will be:
a. 0.035.
b. 0.070.
c. 0.350.
d. 0.465
e. 0.930

A. 0.035.

Explanation:

Female : cv-cSb+/cv-c+Sb

Male : cv-cSb/cv-cSb ( since test cross involves mating with a recessive parent )

Their progeny:

cv-cSb+/cv-cSb : parental

cv-c+Sb/cv-cSb : parental

cv-c+Sb+/cv-cSbc : recombinant

cv-cSb/cv-cSb : recombinant

Wild type phenotype (cv-c+Sb+/cv-cSbc) is a recombinant. Distance between the two genes is 7mu. Since map distance is equal to recombination percentage, there will be 7% recombinants in the progeny. Out of total 7% recombinants, 3.5% will be cv-c+Sb+/cv-cSbc( wild type) and rest 3.5% will be cv-cSb/cv-cSb (mutant type).

Hence, proportion of phenotypically wild-type individuals in the progeny of the test cross will be 3.5% or 0.035.

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.