While doing fieldwork in Madagascar, you discover a new dragonfly species that has either red (R) or clear (r) wings. Initial crosses indicate that R is dominant to r. You perform three crosses using three different sets of red-winged parents with unknown genotype and observe the following data: Cross Phenotypes 1 72 red-winged, 24 clear-winged 2 12 red-winged 3 96 red-winged Which cross is likely to have at least one parent with the genotype RR?

crosses 2 and 3.

Explanation:

Crosses 2 and 3 are likely to have at least one parent with genotype RR.

Since R has been established to be dominant over r, in order for the outcome of a cross to yield 100% red-winged offspring as obtained in crosses 2 and 3, at least one of the parents must have RR as genotype. The other parent can have rr, RR or Rr genotype.

RR   x    rr

Progeny: all Rr genotype with red-winged phenotype

RR   x   RR

Progeny: all RR, red-winged

RR   x   Rr

progeny: RR, Rr, RR, Rr. All red-winged in appearance.

In order to produce clear wings (rr) as in cross 1, at least one r allele must be present in the genotype of the two parents, there cannot be RR genotype.

Hence, only crosses 2 and 3 requires at least one parent with RR genotype.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products