<span>My pea plant has an unknown genotype for flowers, whether it has two dominant traits for white flowers (WW) or one dominant and one recessive (Ww) leading to white flowers; therefore I am doing a testcross in order to determine the genotype of my pea plant. The best plant to do this with is one that has a phenotype of purple flowers (ww) - that is, it is homozygous for the recessive trait.
If I use a homozygous recessive plant, I know exactly what its genotype is. I don't have to worry about whether it's got one or two dominant alleles; I know that at least half of my alleles are going to be the recessive w.
This makes identifying the offspring's genotype very simple. If I find that the offspring have at least some purple flowers among them, I know that my original plant had to be Ww; that is it had to have one dominant and one recessive allele for the flower color gene. If, however, all of the offspring are white flowers, I know that my original pea plant had both dominant alleles (WW).</span>
A hypotonic state of the
bladder, or conduct and duration of labor and peripartum bladder management, and
the use of epidural anesthesia may all contribute to overflow incontinence.
Overflow incontinence is characterized
by uncontrolled, spontaneous passing of urine because of an overfull bladder.
Answer:
C)Parental: 41% Dr, 41% dR; recombinant: 9% DR, 9% dr.
Explanation:
The notation Dr/dR for genotypes means that one homologous chromosome has the alleles Dr and the other homologous chromosome has the alleles dR.
The heterozygous plant Dr/dR will produce 4 types of gametes: two identical to the chromosmes the individual has in its somatic cells (called parental), and two gametes which will be a mix of the alleles in the homologous chromosomes (called recombinant).
- Dr: parental
- dR: parental
- DR: recombinant
- dr: recombinant
To calculate the frequency of each type of gamete, we must use the formula:
Distance (map units) / 100 = frequency of recombination.
18 mu / 100 = 0.18.
The total frequency of recombination between the genes D and R is 0.18, but every time crossing over happens, two recombinant gametes are generated. Therefore, each recombinant gamete will have a frequency of 0.18/2=0.09 = 9%.
The frequency of parental gametes will be:
1 - frequency of recombinant gametes
1 - 0.18 = 0.82
But there are 2 parental gametes, so each of them will have a frequency of 0.82/2=0.41 = 41%.
