Genetics Meiosis and Mendel's Experiments

What process is responsible for the independent assortment of alleles?

How do cells acquire homologous chromosome pairs that carry the alleles that are independently assorted?

Which of the following statements most accurately describes the process of independent assortment?

The principle of independent assortment is best illustrated by events that take place during metaphase II, during which sister chromatids segregate independently of each other.

How many genetically unique types of gametes could be produced by an individual with the genotype RrYY?

Which of the following parental genotypes would yield a 1:1:1:1 phenotypic ratio in the offspring?

In his breeding experiments, Mendel first crossed true-breeding plants to produce a second generation, which were then allowed to self-pollinate to generate the offspring. How do we name these three generations?

Which of the following is true about a plant with the genotype AABbcc?

What is an allele?

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?

The individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the following is the major reason?

Why did Mendel continue some of his experiments to the F2 or F3 generation?

Which of the following differentiates between independent assortment and segregation?

A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?

Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that

Which of the boxes marked 1-4 correspond to plants with dark leaves?

Which of the boxes correspond to plants with a heterozygous genotype?

Which of the plants will be true-breeding?

Mendel worked

You cross a true-breeding red-flowered snapdragon with a true-breeding white-flowered one. All of the F1 are pink. What does this say about the parental traits?

Height in humans generally shows a normal (bell-shaped) distribution. What type of inheritance most likely determines height?

In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?

Cystic fibrosis affects the lungs, the pancreas, the digestive system, and other organs, resulting in symptoms ranging from breathing difficulties to recurrent infections. Which of the following terms best describes this?

Which of the following is an example of polygenic inheritance?

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant trait. The flower color trait in radishes is an example of which of the following?

Skin color in a certain species of fish is inherited via a single gene with four different alleles. How many different types of gametes would be possible in this system?

Tallness (T) in snapdragons is dominant to dwarfness (t), while red (R) flower color is incompletely dominant to white (r). The heterozygous condition results in pink (Rr) flower color. If snapdragons are heterozygous for height as well as for flower color, a mating between them will result in what ratio?

Which of the following provides an example of epistasis?

Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. A cross between a true-breeding sharp-spined cactus and a spineless cactus would produce

A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r, respectively. A third gene for the MN blood group has codominant alleles M and N. Which of the following is a possible partial genotype for the son?

A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r, respectively. A third gene for the MN blood group has codominant alleles M and N. Which of the following is a possible genotype for the mother?

A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r, respectively. A third gene for the MN blood group has codominant alleles M and N. Which of the following is a possible phenotype for the father?

Folk singer Woody Guthrie died of Huntington's disease, an autosomal dominant disorder. Which statement below must be true?

Various procedures can be used to detect genetic disorders before birth. Among the tests discussed in this chapter, which is the least invasive (list first), and which two allow the chromosomes of the fetus to be examined?

Which of the following do you expect if an individual is heterozygous for the sickle-cell trait?

An obstetrician knows that one of her patients is a pregnant woman whose fetus is at risk for a serious disorder that is detectable biochemically in fetal cells. The obstetrician would most reasonably offer which of the following procedures to her patient?

The frequency of heterozygosity for the sickle-cell anemia allele is unusually high, presumably because this reduces the frequency of malaria. Such a relationship is related to which of the following?

Phenylketonuria (PKU) is a recessive human disorder in which an individual cannot appropriately metabolize the amino acid phenylalanine. This amino acid is not naturally produced by humans. Therefore, the most efficient and effective treatment is which of the following?

One of two major forms of a human condition called neurofibromatosis (NF 1) is inherited as a dominant gene, although it may range from mildly to very severely expressed. If a young child is the first in her family to be diagnosed, which of the following is the best explanation?

In each generation of this family after generation I, the age at diagnosis is significantly lower than would be found in nonfamilial (sporadic) cases of this cancer (~ 63 years). What is the most likely reason?

Quantitative characters vary in a population along a continuum. How do such characters differ from the characters investigated by Mendel in his experiments on peas?

Look at the Punnett square, which shows the predicted offspring of the F2 generation from a cross between a plant with yellow-round seeds (YYRR) and a plant with green-wrinkled seeds (yyrr). Select the correct statement about wrinkled yellow seeds in the F2 generation.

Each chromosome in this homologous pair possesses a different allele for flower color. Which statement about this homologous pair of chromosomes is correct?

The pattern of inheritance (monohybrid, dihybrid, sex-linked, and genes linked on the same chromosomes) can be predicted from data if one is given the parent or offspring genotypes or phenotypes. Two organisms, with genotypes BbDD and BBDd, are mated. Assuming independent assortment of the B/b and D/d genes, determine the genotypic ratios in offspring that would occur.

Independent Assortment

Mendel's Principle of Independent Assortment

True-Breeding Plants (P Generation)

First Generation (F1 Generation)

Second Generation (F2 Generation)

Homozygous at Two Loci

Gamete Variation

Phenotypic Ratio

Recessive Trait Reappearing in F2

Incomplete Dominance

Polygenic Inheritance

Pleiotropy

Alleles

Polygenic Nature of Skin Pigmentation

Incomplete Dominance in Radish Flowers

Phenotypic Ratio in Heterozygous Snapdragons

Roan Cattle Cross

Epistasis

Multiple Alleles in Blood Types

Blood Type Inheritance in Offspring

Autosomal Dominant Inheritance

Phenylketonuria (PKU)

Sickle Cell Trait and Malaria Resistance

Prenatal Genetic Testing Techniques

Quantitative Traits

Predicting Offspring Using Punnett Squares

Homologous Chromosomes and Allele Variation

Importance of Homologous Chromosomes