Review Questions

Review Questions

Mendel performed hybridizations by transferring pollen to the female ova from what part of the male plant?
  1. anther
  2. pistil
  3. stigma
  4. seed
Which is one of the seven characteristics that Mendel observed in pea plants?
  1. flower size
  2. leaf shape
  3. seed texture
  4. stem color

Imagine you are performing a cross involving garden pea plants. What F1 offspring would you expect if you cross true-breeding parents with green seeds and yellow seeds? Yellow seed color is dominant over green.

  1. 100 percent yellow-green seeds
  2. 100 percent yellow seeds
  3. 50 percent yellow, 50 percent green seeds
  4. 25 percent green, 75 percent yellow seeds

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 ross and obtained 650 inflated-pod plants in the F2 generation bred from true-breeding stock, approximately how many constricted-pod plants would you expect to have?

  1. 600
  2. 165
  3. 217
  4. 468

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

  1. alleles
  2. genotype
  3. phenotype
  4. zygote
A recessive trait will be observed in individuals that are what for that trait?
  1. diploid
  2. heterozygous
  3. homozygous or heterozygous
  4. homozygous

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

  1. codominance
  2. dominance
  3. incomplete dominance
  4. multiple alleles

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 ________.

  1. codominance and incomplete dominance
  2. incomplete dominance only
  3. multiple alleles and incomplete dominance
  4. multiple alleles and codominance

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?

  1. 1:2:1
  2. 3:1:1
  3. 1:2:0
  4. 0:2:1
The forked line and probability methods make use of what probability rule?
  1. monohybrid rule
  2. product rule
  3. sum rule
  4. test cross

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 drawn below.

The figure shows a table with two columns and two rows. From left to right, the columns are labeled uppercase s, lowercase s. From top to bottom, the rows are labeled uppercase S, lowercase S.  Three of the cells contain two letters each. The top left cell contains uppercase S and uppercase S. The top right cell contains uppercase S and lowercase s. The bottom left cell contains uppercase S and lowercase S. The bottom right row contains a question mark.
Figure 12.23

What is the missing genotype?

  1. SS
  2. Ss
  3. sS
  4. ss
If the inheritance of two traits fully obeys Mendelian laws of inheritance, where may you assume that the genes are located?
  1. on any autosomal chromosome or chromosomes
  2. on Y chromosomes
  3. on the same chromosome
  4. on separate chromosomes
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?
  1. 64 genotypes; 16 phenotypes
  2. 16 genotypes; 64 phenotypes
  3. 8 genotypes; 27 phenotypes
  4. 27 genotypes; 8 phenotypes
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.
  1. RR and Rr
  2. Rr and rr
  3. Rr only
  4. RR only
Which cellular process underlies Mendel’s law of independent assortment?
  1. Chromosomes align randomly during meiosis.
  2. Chromosomes can exchange genetic material during crossover.
  3. Gametes contain half the number of chromosomes of somatic cells.
  4. Daughter cells are genetically identical to parent cells after mitosis.

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 ________.

  1. dominance
  2. independent assortment
  3. random distribution of traits
  4. segregation

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 ________.

  1. codominance
  2. hemizygosity
  3. incomplete dominance
  4. epistasis

Purple flowers (P) are dominant over red 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 F1 plants showed purple flowers and long pollen grains. The F1 plants were crossed and the results are in the table.

A cross is made between plants with swollen pods and plants with shriveled pods. In the F 1 generation, 314 plants have swollen pods and 298 have shriveled pods. Next, a cross is made between plants with swollen pods from the F 1 generation. In the F 2 generation from this cross, 594 plants have swollen pods and 97 have shriveled pods.
Figure 12.24

What conclusions about the physical relationship between the traits can be drawn from the experiment?
  1. The traits are probably linked.
  2. The traits follow the law of independent assortment.
  3. The traits are located on different chromosomes.
  4. There was epistasis.

When the expression of one gene pair masks or modifies the expression of another, the genes show ________?

  1. codominance
  2. epistasis
  3. incomplete dominance
  4. partial linkage