In jimsonweed, purple flowers are dominant to white. Self-fertilization of a particular purple-flowered jimsonweed produces 28 purple-flowered and 10 whiteflowered progeny. What proportion of the purpleflowered progeny will breed true?

1/3

Explanation:

Let's assume that the allele "P" imparts purple phenotype to flowers while the allele "p" gives white phenotype. The self-fertilization of purple-flowered parent plants gave purple and white progeny in almost 3:1 (28:10) ratio. This means that the parent plants were heterozygous and the genotype of each was "Pp".

A cross between Pp and Pp produces progeny in the following genotype ratio=

1/4 PP: 1/2 Pp: 1/2 pp

So, out of total 3/4 purple progeny, 1/3 is homozygous for the purple allele (PP) while the rest 2/3 is heterozygous dominant.

straight probes are used primarily for measuring flow as it is approaching the test area. its geometry allows the probe to be mounted so that it is in the direct line of airflow.