Mastering Biology chapter 13 and 14

In a plant's sexual life cycle _____. -gametophytes produce gametes by meiosis -sporophytes produce gametes by meiosis -sporophytes produce gametes by mitosis -gametophytes produce gametes by mitosis

gametophytes produce gametes by mitosis

When homologous chromosomes cross over, what occurs? -Maternal alleles are "corrected" to be like paternal alleles and vice versa. -Two sister chromatids exchange identical pieces of DNA. -Corresponding segments of non-sister chromatids are exchanged. -Two chromatids get tangled, resulting in one re-sequencing its DNA.

Corresponding segments of non-sister chromatids are exchanged.

Gray seed color in peas is dominant to white. Assume that Mendel conducted a series of experiments where plants with gray seeds were crossed among themselves, and the following progeny were produced: 302 gray and 98 white. (a) What is the most probable genotype of each parent? (b) Based on your answer in (a) above, what genotypic and phenotypic ratios are expected in these progeny? (Assume the following symbols: G = gray and g = white.) (a) gg × Gg; (b) genotypic = 1:2, phenotypic = 3:1 (a) GG × gg; (b) genotypic = 3:1, phenotypic = 1:2:1 (a) GG × Gg; (b) genotypic = 1:2:1, phenotypic = 2:1 (a) Gg × Gg; (b) genotypic = 1:2:1, phenotypic = 3:1

(a) Gg × Gg; (b) genotypic = 1:2:1, phenotypic = 3:1

In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short? 1/4 1/2 1 0

0

In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short? 0 1 1/6 1/4 1/2

0

Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of the cross BbTt × BBtt will have black fur and long tails? 2/8 1/16 3/16 1/2 9/16

1/2

Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower color and location assort independently. If 1,000 F2 offspring resulted from the cross, approximately how many of them would you expect to have red, terminal flowers? 750 565 65 250 190

190

When Mendel crossed yellow-seeded and green-seeded pea plants, all the offspring were yellow seeded. When he took these F1 yellow-seeded plants and crossed them to green-seeded plants, what genotypic ratio was expected? 1:1:1:1 1:2:1 1:1 3:1

1:1

Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower color and location assort independently. Among the F2 offspring, what is the probability of plants with white axial flowers? 3/16 9/16 1/4 1/16

3/16

When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype? -0% -25% -50% -75% -100%

50%

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE? 4 8 32 64 16

8

What is a karyotype? -- The set of unique physical characteristics that define an individual -- A display of every pair of homologous chromosomes within a cell, organized according to size and shape -- The combination of chromosomes found in a gamete --A system of classifying cell nuclei -- The collection of all the mutations present within the genome of an individual

A display of every pair of homologous chromosomes within a cell, organized according to size and shape

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

AaBb, aabb

A black guinea pig crossed with an albino guinea pig produced twelve black offspring. When the albino was crossed with a second black animal, six blacks and six albinos were obtained. What is the best explanation for this genetic situation? -Albino is recessive; black is dominant. -Albino is dominant; black is incompletely dominant. -Albino and black are codominant. -Albino is recessive; black is codominant.

Albino is recessive; black is dominant.

Which of the following statements most accurately describes the process of independent assortment? -Alleles of different genes segregate from one another in a random manner. -Alleles found on separate chromosomes segregate based upon their origin. -Genes located on the same chromosome assort as an independent unit. -Dominant alleles segregate with recessive alleles.

Alleles of different genes segregate from one another in a random manner. The random distribution of alleles is required for independent assortment.

Which of the following is true of a species that has a chromosome number of 2n = 16? -Each cell has 8 homologous pairs. -The species has 16 sets of chromosomes per cell. -A gamete from this species has 4 chromosomes. -The species is diploid with 32 chromosomes per cell. -During the S phase of the cell cycle there will be 32 separate chromosomes.

Each cell has 8 homologous pairs.

True or false? 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. True False

False The principle of independent assortment is best illustrated by events that take place during metaphase I, during which nonhomologous chromosomes segregate independently of each other.

How do cells acquire homologous chromosome pairs that carry the alleles that are independently assorted? -Meiosis -DNA replication -Fusion of gametes -Mitosis

Fusion of gametes During fertilization, gametes bring together homologous chromosomes to generate a diploid individual.

Which of the life cycles is typical for animals? I and III II only III only I only

I only

Which of the life cycles is typical for most fungi and some protists? I only II only III only I and III

II only

Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common? I. Alternation of generations II. Meiosis III. Fertilization IV. Gametes V. Spores -II, III, and IV -I, II, III, IV, and V -II, IV and V -I, II, and IV

II, III, and IV

Which of the life cycles is typical for plants and some algae? I only II only III only I and III

III only

A gene's location along a chromosome is known as which of the following? -trait -sequence -variant -allele -locus

Locus

What process is responsible for the independent assortment of alleles? -Cytokinesis. -Meiosis. -Mitosis -DNA replication.

Meiosis The role of meiosis is to separate homologous chromosomes and their respective alleles, which are assorted in an independent manner.

In a life cycle such as that shown in part III of the figure above, if the zygote's chromosome number is 10, which of the following will be true? -The sporophyte and gametophyte each have 10 chromosomes per cell. -The sporophyte's chromosome number per cell is 5 and the gametophyte's is 10. -The sporophyte's chromosome number per cell is 10 and the gametophyte's is 5. -The sporophyte and gametophyte each have 5 chromosomes per cell.

The sporophyte's chromosome number per cell is 10 and the gametophyte's is 5.

How many genetically unique types of gametes could be produced by an individual with the genotype RrYY? -One -Eight -Two -Three

Two: either Ry or rY

Consider pea plants with the genotypes GgTt and ggtt . These plants can each produce how many type(s) of gametes? two... one four ... two four ... one one ... two one ... one

four.... one

Mendel's second law of independent assortment has its basis in which of the following events of meiosis I? -crossing over -synapsis of homologous chromosomes -separation of cells at telophase -arrangement of chromosome pairs at the equator

arrangement of chromosome pairs at the equator

The bulldog ant has a diploid number of two chromosomes. Therefore, following meiosis, each daughter cell will have a single chromosome. Diversity in this species may be generated by mutations and _____. -crossing over -independent assortment -crossing over and independent assortment -nothing else

crossing over and independent assortment

The individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the following is the major reason? -recurrent mutations forming new alleles -crossing over during prophase I -the tendency for dominant alleles to segregate together -different possible assortment of chromosomes into gametes

different possible assortment of chromosomes into gametes

Independent assortment of chromosomes occurs during _____. -meiosis I only -mitosis and meiosis I -mitosis and meiosis II -meiosis II only

meiosis I only

The F1 offspring of Mendel's classic pea cross always looked like one of the two parental varieties because -the traits blended together during fertilization. -each allele affected phenotypic expression. -one phenotype was completely dominant over another. -no genes interacted to produce the parental phenotype. -different genes interacted to produce the parental phenotype.

one phenotype was completely dominant over another.

Independent assortment of chromosomes is a result of _____. -the random distribution of the sister chromatids to the two daughter cells during anaphase II -the random way each pair of homologous chromosomes lines up at the metaphase plate during meiosis I -the diverse combination of alleles that may be found within any given chromosome -the random combinations of eggs and sperm during fertilization

the random way each pair of homologous chromosomes lines up at the metaphase plate during meiosis I

Imagine that there are twenty-five different species of protists living in a tide pool. Some of these species reproduce both sexually and asexually, and some of them can reproduce only asexually. The pool gradually becomes infested with disease-causing viruses and bacteria. Which species are more likely to thrive in the changing environment? -Sexually and asexually reproducing species are equally likely to thrive. -the sexually reproducing species -the asexually reproducing species

the sexually reproducing species

Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that -new mutations were frequently generated in the F2 progeny, "reinventing" traits that had been lost in the F1. -members of the F1 generation had only one allele for each character, but members of the F2 had two alleles for each character. -the traits were lost in the F1 due to blending of the parental traits. -the mechanism controlling the appearance of traits was different between the F1 and the F2 plants. -traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1.

traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1.