EXAM 3 Bio 1610

Phenylketonuria is an inherited disease caused by a recessive autosomal allele. If a woman and her husband are both carriers, what is the probability that their first child will be a phenotypically normal girl? 3/16 3/8 1/4 1/16

3/8

Assuming independent assortment, how many genetically distinct gametes can be produced by an individual with the genotype YyRr? 1 2 4 8 16

4

Gamete

Male/Female reproductive cells (sperm/egg)

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

gametophytes produce gametes by mitosis

Homozygous and heterozygous show...

genotypes

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

Corresponding segments of non-sister chromatids are exchanged.

Monohybrid Cross

Cross that considers a single trait

Gene interaction

two or more genes work together to control a single phenotype

Albinism is a recessive trait. A man and woman both show normal pigmentation, but both have one parent who has albinism (without melanin pigmentation). What is the probability that their first child will have albinism? 1 0 1/4 1/2

1/4

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 0 1/4 1/6 1/2

0

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

0

A man has extra digits (six fingers on each hand and six toes on each foot). His wife and their daughter have the normal number of digits (five fingers on each hand and five toes on each foot.) Having extra digits is a dominant trait. The couple's second child has extra digits. What is the probability that their next (third) child will have extra digits? 1/8 1/2 3/4 1/16

1/2

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 crosses BbTt × BBtt will be expected to have black fur and long tails? 1/16 1/2 9/16 3/8

1/2

If an IAIB man marries an IBi woman, what is the chance that their first child will have type B blood? (type B blood results for an IBIB or IBi genotype) 0 1/4 1/2 3/4 1

1/2

What is the probability of producing the genotype AABBCC in a cross of individuals who both possess this genotype: AaBbCc? 1/64 1/8 1/4 1/16

1/64

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? 190 250 65 750 565

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? 3:1 1:1 1:2:1 1:1:1:1

1:1

Assuming independent assortment, how many genetically distinct gametes can be produced by an individual with the genotype AABbcc 1 2 4 8 16

2

If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be 0.25x. 4x. 2x. x. 0.5x.

2x

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? 1/4 1/16 9/16 3/16

3/16

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 producing plants with white axial flowers? 9/16 3/16 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%

A triploid cell contains three sets of homologous chromosomes. If a cell of a diploid species that normally has 42 chromosomes per cell is triploid, this cell would be expected to have which of the following sets of chromosomes? 21 chromosome pairs and 21 unique chromosomes 63 chromosomes in 21 sets of 3 63 chromosomes in 31 1/2 pairs 63 chromosomes, each with 3 sister chromatids

63 chromosomes in 21 sets of 3

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

8

In humans, ABO blood types refer to glycoproteins in the membranes of red blood cells. There are three alleles for this autosomal gene: IA, IB, and i. The IA allele codes for the A glycoprotein, The IB allele codes for the B glycoprotein, and the i allele doesn't code for any membrane glycoprotein. IA and IB are codominant, and i is recessive to both IA and IB. People with type A blood have the genotypes IAIA or IAi, people with type B blood are IBIB or IBi, people with type AB blood are IAIB, and people with type O blood are ii. If a woman with type AB blood marries a man with type O blood, which of the following blood types could their children possibly have? AB and O A, B, AB, and O A, B, and O A and B

A and B

What is a karyotype? The collection of all the mutations present within the genome of an individual The combination of chromosomes found in a gamete 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 A system of classifying cell nuclei

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

A black guinea pig crossed with a guinea pig with albinism produced 12 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? Albinism is a recessive trait; black is a dominant trait. Albinism is a recessive trait; black is codominant. Albinism is a dominant trait; black is incompletely dominant. Albinism and black are codominant.

Albinism is a recessive trait; black is a dominant trait.

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 and black are codominant. Albino is recessive; black is codominant. Albino is dominant; black is incompletely dominant. Albino is recessive; black is dominant.

Albino is recessive; black is dominant.

Homozygous

An organism that contains two identical alleles (or forms) for a trait ex. AA

Heterozygous

An organism that has two different alleles (or forms) for a trait ex. Aa

Albinism is a recessive trait. A man and woman who both have normal pigmentation have one child out of three who has albinism (without melanin pigmentation). What are the genotypes of this child's parents? Both parents must be heterozygous. One parent must be homozygous for the recessive allele; the other parent can be homozygous dominant, homozygous recessive, or heterozygous. One parent must be homozygous dominant; the other parent must be heterozygous. One parent must be heterozygous; the other parent can be homozygous dominant, homozygous recessive, or heterozygous.

Both parents must be heterozygous.

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? HT Hh HhTt T

HT

Which of the following is true of a species that has a chromosome number of 2n = 16? A gamete from this species has 4 chromosomes. The species has 16 sets of chromosomes per cell. Each cell has 8 homologous pairs. 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.

A gene for the MN blood group has codominant alleles M and N. If both children are of blood type M, which of the following is possible? Both children are heterozygous for this gene. Each parent is either M or MN. Each parent must be type M. Neither parent can have the N allele.

Each parent is either M or MN.

Principle of Segregation

Genes come in pairs that separate in the formation of gametes (genes separate during meiosis 1 because genes are on chromosomes and chromosomes split)

Genotype

Genetic constitution of an individual

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. What is the most probable genotype of each parent? GG x gg Gg x Gg GG x Gg gg x Gg

Gg x Gg

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 I, II, III, IV, and V I, II, and IV II, III, and IV II, IV, and V

II, III, and IV

If a cell has completed meiosis I and the first cytokinesis, and is just beginning meiosis II, which of the following is an appropriate description of its genetic contents? It has one-fourth the DNA and one-half the chromosomes as the parent cell. It has half the amount of DNA as the cell that began meiosis. It is genetically identical to another cell formed from the same meiosis I event. It has half the chromosomes but twice the DNA of the parent cell.

It has half the amount of DNA as the cell that began meiosis.

Which of the following is true about a plant with the genotype AABbcc? See Concept 14.1 It will not express the recessive c allele. It is homozygous at two loci. It is heterozygous at two loci. It has recessive alleles at three loci. It is triploid.

It is homozygous at two loci.

Folk singer Woody Guthrie died of Huntington's disease, an autosomal dominant disorder. Which statement below must be true? His sons will develop Huntington's disease but not his daughters. His daughters will die of Huntington's disease but not his sons. All of his children will develop Huntington's disease. It is very likely that at least one of Woody Guthrie's parents also have had the allele for Huntington's disease There is not enough information to answer the question.

It is very likely that at least one of Woody Guthrie's parents also have had the allele for Huntington's disease

Locus

Location on the chromosome where the gene is found

A gene's location along a chromosome is known as which of the following? Variant Allele Trait Sequence Locus

Locus

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

Meiosis I only

Which of the following statements describes a major difference between meiosis II and mitosis in a diploid animal? Crossing over of chromosomes takes place in meiosis II. Sister chromatids separate in mitosis, and homologous chromosomes separate in meiosis II. Meiosis II occurs in a haploid cell, while mitosis occurs in diploid cells. Homologous chromosomes align on the metaphase plate in meiosis II.

Meiosis II occurs in a haploid cell, while mitosis occurs in diploid cells.

Are particular combinations of alleles inherited together? Yes No

No

Phenotype

Observable characteristics

Pleiotropy

Occurs when a single gene influences multiple traits

Incomplete Dominance

Occurs when the phenotype of the heterozygote lies somewhere between the phenotype of either homozygote

Codominance

Occurs when the phenotypes associated with each allele are expressed in a heterozygote Neither of the two alleles are dominant or recessive

Complete Dominance

Phenotype of heterozygote is exactly like the phenotype of ONE of the homozygotes

Which of the following describes the ability of a single allele to have multiple phenotypic effects? multiple alleles epistasis incomplete dominance pleiotropy

Pleiotropy

Which of the following inheritance patterns describes the ability of a single allele to have multiple phenotypic effects? incomplete dominance pleiotropy multiple alleles epistasis

Pleiotropy

Filling in the squares of a Punnett square represents the process of Segregation (separation) of gene pairs Independent assortment Crossing over Random Fertilization All of the above

Random fertilization

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? Both red and white are pleiotropic. Pink is dominant, and red and white are recessive. Red is completely dominant. Red shows incomplete dominance over white.

Red shows incomplete dominance over white.

In peas, round seeds (R.) are dominant to wrinkled seeds (r.) and yellow seeds (Y) are dominant to green seeds (y). A testcross of plant growth from a round and yellow seed produced the following offspring 115 round yellow 121 wrinkled yellow Therefore, the genotype of the plant grows for the round, yellow seed is RrYy RrYY RRYy RRYY

RrYY

Genetic variation leads to genetic diversity in populations and is the raw material for evolution. Biological systems have multiple processes, such as reproduction, that affect genetic variation. They are evolutionarily conserved and shared by various organisms. Which of the following statements best represents the connection between reproduction and evolution? In order to increase genetic diversity for evolution in sexually reproducing organisms, mutations must occur in the zygote after fertilization. Sexual reproduction increases genetic variation because random mutations can be shuffled between organisms. Plants that use sexual reproduction are rare since this type of reproduction in plants does not contribute to genetic diversity. Since prokaryotic organisms reproduce asexually, there is no mechanism for them to add genetic diversity for evolution.

Sexual reproduction increases genetic variation because random mutations can be shuffled between organisms.

Meiosis II is similar to mitosis in that the daughter cells are diploid. sister chromatids separate during anaphase. the chromosome number is reduced. homologous chromosomes synapse. DNA replicates before the division.

Sister chromatids separate during anaphase.

Allele

Specific form a gene

In a monohybrid cross, the dominant phenotype is first learned by the phenotype of The parents The F1 The F2

The F1

How do cells at the completion of meiosis compare with cells that are in prophase of meiosis I? The cells have half the number of chromosomes and one-fourth the amount of DNA. The cells have half the amount of cytoplasm and twice the amount of DNA. The cells have half the number of chromosomes and half the amount of DNA. The cells have the same number of chromosomes and half the amount of DNA.

The cells have half the number of chromosomes and one-fourth the amount of DNA.

Mendel crossed yellow-seeded and green-seeded pea plants and then allowed the offspring to self-pollinate to produce an F2 generation. The results were as follows: 6,022 yellow and 2,001 green (8,023 total). Which of the following statements correctly describes the relationship of the allele for green seeds to the allele for yellow seeds? The green allele is recessive to the yellow allele. The two alleles exhibit incomplete dominance. The two alleles are codominant. The green allele is dominant to the yellow allele.

The green allele is recessive to the yellow allele.

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? the sexually reproducing species the asexually reproducing species Sexually and asexually reproducing species are equally likely to thrive.

The sexually reproducing species

In plants, meiosis does NOT directly result in the formation of sex cells True False

True

Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents? XCXC and XcY XCXc and XCY XcXc and XcY XcXc and XCY XCXC and XCY

XCXc and XCY

Height in humans generally shows a normal (bell-shaped) distribution. What type of inheritance most likely determines height? a combination of multiple alleles and codominance a combination of complete dominance and environmental factors a combination of epistasis and environmental factors incomplete dominance a combination of polygenic inheritance and environmental factors

a combination of polygenic inheritance and environmental factors

Gene

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

Mendel's law of independent assortment has its basis in which of the following events of meiosis I? crossing over of homologous pairs of chromosomes the division of cells at telophase synapsis of homologous chromosomes alignment of pairs of homologous chromosomes along the middle of the cell

alignment of pairs of homologous chromosomes along the middle of the cell

Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division? anaphase I of meiosis anaphase II of meiosis metaphase II of meiosis prophase I of meiosis

anaphase I of meiosis

Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by which of the following? the knowledge that multiple alleles are involved environmental factors such as soil pH affect the phenotype the allele for blue hydrangea is completely dominant over the allele for pink hydrangea the alleles are codominant

environmental factors such as soil pH affect the phenotype

In lentils, a gene known as spotted has two alleles. The A1 allele leads to large spots on lentil seeds and the A1 allele leads to small dots on lentil seeds. If A1 and A2 alleles were related by incomplete dominance, what would be the phenotype of F1 seeds? spots and dots on lentil seeds either spots or dots on lentil seeds marking that are between the size of spots and dots

marking that are between the size of spots and dots

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? roan × roan red × white red × roan white × roan

roan x roan

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

one phenotype was completely dominant over another.

Mendel accounted for the observation that traits which had disappeared in the F1 generation reappeared in the F2 generation by proposing that 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. the traits were lost in the F1 due to blending of the parental traits. members of the F1 generation had only one allele for each character, but members of the F2 had two alleles for each character. new mutations were frequently generated in the F2 progeny, "reinventing" traits that had been lost in the F1.

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