A variable feature of some chromosomes in corn is the presence or absence of knobs at particular sites.Suppose that one member of each of two pairs of chromosomes in a corn plant has a knob.If this plant is crossed with a knobless plant, what percentage of the offspring is expected to be knobless?
A)100%
B)75%
C)50%
D)25%
E)0%

Question

Quizplus · Accepted Answer

If one member of each of two pairs of chromosomes in a corn plant has a knob, it means that half of the chromosomes in that plant have knobs. When this plant is crossed with a knobless plant, all the gametes of the knobless plant will have no knobs, and only the gametes of the corn plant with knobs will have knobs. During fertilization, the offspring will randomly inherit one chromosome from each parent, so there's a 50% chance of inheriting a knobbed chromosome and a 50% chance of inheriting a knobless chromosome. Therefore, the expected percentage of offspring that is knobless is 50%, or 1/2. This is equivalent to 25% of the offspring having inherited two knobless chromosomes, which is the correct answer choice.

A Variable Feature of Some Chromosomes in Corn Is the Presence