Review Questions

Mendel performed hybridizations by transferring pollen to the female ova from what part of the male plant?

Which is one of the seven characteristics that Mendel observed in pea plants?

Imagine you are performing a cross involving garden pea plants. What $F_1$ offspring would you expect if you cross true-breeding parents with green seeds and yellow seeds? Yellow seed color is dominant over green.

Consider a cross to investigate the pea pod texture trait, involving constricted or inflated pods. Mendel found that the traits behave according to a dominant/recessive pattern in which inflated pods were dominant. If you performed this cross and obtained 650 inflated-pod plants in the $F_2$ generation bred from true-breeding stock, approximately how many constricted-pod plants would you expect to have?

The observable traits expressed by an organism are described as its ________.

A recessive trait will be observed in individuals that are what for that trait?

If black and white true-breeding mice are mated and the result is all gray offspring, what inheritance pattern would this be indicative of?

The ABO blood groups in humans are controlled by the IA, IB, and I alleles. The IA allele encodes the A blood group antigen, IB encodes B, and I encodes O. Both A and B are dominant to O. If a heterozygous blood type A parent (iAi) and a heterozygous blood type B parent (iBi) mate, one quarter of their offspring will have AB blood type (IAIB) in which both antigens are expressed equally. Therefore, the ABO blood groups are an example of _______.

In a mating between two individuals that are heterozygous for a recessive lethal allele that is expressed in utero, what genotypic ratio (homozygous dominant : heterozygous : homozygous recessive) would you expect to observe in the offspring?

The forked line and probability methods make use of what probability rule?

In pea plants, smooth seeds (S) are dominant to wrinkled seeds (s). In a genetic cross of two plants that are heterozygous for the seed shape trait, the Punnett square is shown. What is the missing genotype?

If the inheritance of two traits fully obeys Mendelian laws of inheritance, where may you assume that the genes are located?

How many different offspring genotypes are expected in a trihybrid cross between parents heterozygous for all three traits? How many phenotypes are expected if the traits behave in a dominant and recessive pattern?

Four-o’ clock flowers may be red, pink or white. In the crossing of a true-breeding red and true-breeding white plants, all the offspring are pink. Use a Punnett square to determine the correct genotype of the offspring if the red parent has genotype RR and the white parent has genotype rr.

Which cellular process underlies Mendel’s law of independent assortment?

While studying meiosis, you observe that gametes receive one copy of each pair of homologous chromosomes and one copy of the sex chromosomes. This observation is the physical explanation of Mendel’s law of ______.

In some primroses, the petal color blue is dominant. A cross between a true-breed blue primrose and a white primrose yields progeny with white petals. A second gene at another locus prevented the expression of the dominant coat color. This is an example of ______.

Purple flowers (P) are dominant over white flowers (p), and long pollen grains are dominant over round pollen grains. When purple flowers and long pollen grain plants were crossed with plants with white flowers and round pollen grains, all the $F_1$ plants showed purple flowers and long pollen grains. The $F_1$ plants were crossed and the results are in the table.

What conclusions about the physical relationship between the traits can be drawn from the experiment?

When the expression of one gene pair masks or modifies the expression of another, the genes show _______.