Chapter 3 Mastering Genetics

When a F1 plant (heterozygote--Gg) undergoes meiosis, what gamete types will it produce, and in what proportions?

Answer explanation

1/2 G and 1/2 g

What are Punnett squares used for?

Answer explanation

Representing the types and frequencies of gametes and progeny in experimental crosses. The probability of two independent events occurring simultaneously is the product of their individual probabilities

Mendel's Law of Segregation

Answer explanation

Allele pairs segregate equally into gametes during meiosis. A gamete will have only one allele of any given gene and that the probability of a gamete having one allele or the other is equal.

True-Breed

Answer explanation

The alleles are homozygous.

Which of the following would be true of a plant heterozygous for a single gene controlling flower color? (assume complete dominance).

Answer explanation

If crossed with another heterozygous plant, the majority of progeny will have the dominant flower color.

The 3:1 phenotypic ratio observed among progeny of an F1 X F1 cross requires random union of gametes.

Answer explanation

True

The 1:2:1 genotypic ratio

Answer explanation

Represents relative probabilities of gamete combinations based on the assumption that gamete union is random

Of the methods listed below, which would be the best way to determine which of the two alleles of a gene is dominant to the other?

Answer explanation

Observe the relevant phenotype in the progeny that result from a cross between individuals from two different pure-breeding lines.

A couple has two boys and is expecting a third child. The probability that the third child will be a boy is 1/2.

Answer explanation

True; the probability of having a girl is also 1/2. The sex of the previous children does not influence the sex of the third child.

What is the probability of a family with six children having three boys and three girls?

Answer explanation

20/64