LAB 8,9

Which of these crosses will only produce heterozygous offspring? (a) AA × aa (b) AA × Aa (c) Aa × Aa (d) aa × aa (e) Aa × aa

(a) AA × aa

In the follow reaction, which component is the substrate? Benzaldehyde + NBT-PMS + Aldehyde oxidase → Benzoic acid + blue products (a) Benzaldehyde (b) NBT-PMS (c) Aldehyde oxidase (d) Benzoic acid (e) Blue products

(a) Benzaldehyde

Which of the following statements is true of linkage? (a) The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them. (b) The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 100%. (c) All of the traits that Mendel studied-seed color, pod shape, flower color, and others-are due to genes linked on the same chromosome. (d) Linked genes are found on different chromosomes. (e) Crossing over occurs during prophase II of meiosis.

(a) The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.

How would one explain a testcross involving F1 dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced? (a) The two genes are closely linked on the same chromosome. (b) The two genes are linked but on different chromosomes. (c) Recombination did not occur in the cell during meiosis. (d) The testcross was improperly performed. (e) Both of the characters are controlled by more than one gene.

(a) The two genes are closely linked on the same chromosome.

What does a frequency of recombination of 50% indicate? (a) The two genes are likely to be located on different chromosomes. (b) All of the offspring have combinations of traits that match one of the two parents. (c) The genes are located on sex chromosomes. (d) Abnormal meiosis has occurred. (e) Independent assortment is hindered.

(a) The two genes are likely to be located on different chromosomes.

What is the reason that linked genes are inherited together? (a) They are located close together on the same chromosome. (b) The number of genes in a cell is greater than the number of chromosomes. (c) Chromosomes are unbreakable. (d) Alleles are paired together during meiosis. (e) Genes align that way during metaphase I of meiosis.

(a) They are located close together on the same chromosome.

The trait to be studied in this lab topic is the presence or absence of the enzyme __________ in the fruit fly. (a) aldehyde oxidase (b) carboxylase (c) ATPase (d) glyceraldehyde phosphatase (e) sucrase

(a) aldehyde oxidase

A true-breeding plant is one that is __________ for a particular trait, meaning that it has identical alleles for a particular trait. (a) homozygous (b) heterozygous (c) dominant (d) recessive (e) co-dominant

(a) homozygous

An individual with the genotype AaBb produces four different gametes in equal proportions. This is a demonstration of __________. (a) the chromosomal theory of inheritance (b) Mendel's law of independent assortment (c) linkage (d) crossing over (e) Mendel's principle of segregation

(b) Mendel's law of independent assortment

In the follow reaction, which component is the color indicator? Benzaldehyde + NBT-PMS + Aldehyde oxidase → Benzoic acid + blue products (a) Benzaldehyde (b) NBT-PMS (c) Aldehyde oxidase (d) Benzoic acid (e) Blue products

(b) NBT-PMS

When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result? (a) The gene involved is on the Y chromosome. (b) The gene involved is on the X chromosome. (c) The gene involved is on an autosome, but only in males. (d) Other male-specific factors influence eye color in flies. (e) Other female-specific factors influence eye color in flies.

(b) The gene involved is on the X chromosome.

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? (a) There is considerable genetic variation in garden peas. (b) Traits are inherited in discrete units, and are not the results of "blending." (c) Recessive genes occur more frequently in the F1 generation than do dominant ones. (d) Genes are composed of DNA. (e) An organism that is homozygous for many recessive traits is at a disadvantage.

(b) Traits are inherited in discrete units, and are not the results of "blending."

If true-breeding plants are cross-pollinated, under the Mendelian model the offspring will be __________. (a) homozygous (b) heterozygous (c) dominant (d) recessive (e) co-dominant

(b) heterozygous

The abdomen of the female fruit fly is __________ than in the male fruit fly. (a) smaller (b) larger

(b) larger

The adult female fruit fly is __________ than the male adult fruit fly. (a) smaller (b) larger

(b) larger

The best definition of a true-breeding plant is one that __________. (a) cannot be cross-fertilized (b) self-fertilizes to produce offspring identical to the parent c) produces sterile offspring when cross-fertilized (d) self-fertilizes to produce hybrid offspring (e) becomes sterile after three generations

(b) self-fertilizes to produce offspring identical to the parent

A(n) __________ gene is located on one sex chromosome, but not on the other. (a) autosomal (b) sex-linked

(b) sex-linked

The __________ trait is the one that is most commonly found in nature. (a) mutant (b) wild-type

(b) wild-type

A true-breeding plant that produces yellow seeds is crossed with a true-breeding plant that produces green seeds. The F1 plants have yellow seeds. What is the expected phenotypic ratio of seed color of the offspring of an F1 × F1 cross? (a) 1:2:1 (b) 2:1 (c) 3:1 (d) 9:3:3:1 (e) 1:1

(c) 3:1

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? (a) 0% (b) 25% (c) 50% (d) 75% (e) 100%

(c) 50%

What do we mean when we use the terms monohybrid cross and dihybrid cross? (a) A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents. (b) A monohybrid cross produces a single progeny, whereas a dihybrid cross produces two progeny. (c) A di-hybrid cross involves organisms that are heterozygous for two characters and a monohybrid cross involves only one. (d) A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations. (e) A monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio.

(c) A di-hybrid cross involves organisms that are heterozygous for two characters and a monohybrid cross involves only one.

In the follow reaction, which component is the enzyme? Benzaldehyde + NBT-PMS + Aldehyde oxidase → Benzoic acid + blue products (a) Benzaldehyde (b) NBT-PMS (c) Aldehyde oxidase (d) Benzoic acid (e) Blue products

(c) Aldehyde oxidase

A true-breeding plant that produces yellow seeds is crossed with a true-breeding plant that produces green seeds. The seeds of all of the offspring are yellow. Why? (a) The yellow allele is recessive to the green allele. (b) All of the offspring are homozygous yellow. (c) The yellow allele is dominant to the green allele. (d) The alleles are co-dominant. (e) Yellow is an easier color to produce.

(c) The yellow allele is dominant to the green allele.

An alternate form of a gene is called a(n) __________. (a) gene (b) autosome (c) allele (d) chromosome (e) sexosome

(c) allele

Alleles are described as __________. (a) homologous chromosomes (b) environmental factors that affect gene expression (c) alternate versions of a gene (d) Punnett squares (e) alternate phenotypes

(c) alternate versions of a gene

Mendel crossed true-breeding purple-flowered plants with true-breeding white-flowered plants, and all of the resulting offspring produced purple flowers. The allele for purple flowers is __________. (a) segregated (b) monohybrid (c) dominant (d) recessive (e) independent

(c) dominant

Only one allele needs to be present to be expressed if that allele is __________. (a) homozygous (b) heterozygous (c) dominant (d) recessive (e) co-dominant

(c) dominant

A mating between a true-breeding purple-flowered pea plant and a true-breeding white-flowered pea plant would produce a(n) __________. (a) true-breeding variety (b) inbred organism (c) hybrid (d) P generation (e) F2 generation

(c) hybrid

Mendel accounted for the observation that traits that had disappeared in the F1 generation reappeared in the F2 generation by proposing that __________. (a) new mutations were frequently generated in the F2 progeny, "reinventing" traits that had been lost in the F1 (b) the mechanism controlling the appearance of traits was different between the F1 and the F2 plants (c) traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1 (d) the traits were lost in the F1 due to dominance of the parental traits (e) members of the F1 generation had only one allele for each trait, but members of the F2 had two alleles for each trait

(c) traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1

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? (a) 1/16 (b) 3/16 (c) 3/8 (d) 1/2 (e) 9/16

(d) 1/2

18. If two genes are inherited independently of each other, then a cross between an individual that is heterozygous for the two genes and a homozygous recessive individual will yield offspring in a __________ phenotypic ratio. (a) 9:3:3:1 (b) 3:1 (c) 1:1:1:1 (d) 2:2:1:1 (e) There is not enough information to answer the question.

(d) 2:2:1:1

Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties? (a) No genes interacted to produce the parental phenotype. (b) Each allele affected phenotypic expression. (c) The traits blended together during fertilization. (d) One phenotype was completely dominant over another. (e) Different genes interacted to produce the parental phenotype.

(d) One phenotype was completely dominant over another.

Chromosomes that are not sex chromosomes are called __________. (a) centrosomes (b) allosomes (c) non-sexosomes (d) autosomes (e) dominant

(d) autosomes

An individual who is homozygous __________. (a) expresses the dominant trait (b) carries two different alleles for a gene (c) is a carrier of a genetic disorder (d) carries two copies of the same allele for a gene (e) expresses the recessive trait

(d) carries two copies of the same allele for a gene

Males are more often affected by sex-linked traits than females because __________. (a) male hormones such as testosterone often alter the effects of mutations on the X chromosome (b) female hormones such as estrogen often compensate for the effects of mutations on the X chromosome (c) X chromosomes in males generally have more mutations than X chromosomes in females (d) males are hemizygous for the X chromosome (e) mutations on the Y chromosome often worsen the effects of X-linked mutations

(d) males are hemizygous for the X chromosome

Two alleles must be present for a __________ trait to be expressed. (a) incomplete (b) heterozygous (c) dominant (d) recessive (e) co-dominant

(d) recessive

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? (a) 1 (b) 1/2 (c) 1/4 (d) 1/6 (e) 0

(e) 0

Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F1 males will have cinnabar eyes? (a) 0% (b) 25% (c) 50% (d) 75% (e) 100%

(e) 100%

Round seeds (R) are dominant to wrinkled seeds (r), and yellow seeds (Y) are dominant to green seeds (y). What is the expected phenotypic ratio of a cross between an RrYy and an rryy individual? (a) 1:2:1 (b) 9:3:3:1 (c) 3:1 (d) 6:5:4:1 (e) 1:1:1:1

(e) 1:1:1:1

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? (a) tt (b) Hh (c) HhTt (d) T (e) HT

(e) HT

The activity of the enzyme aldehyde oxidase is controlled by the __________ gene. (a) Hox (b) tinman (c) dunce (d) rutabaga (e) aldox

(e) aldox

In the wild-type Drosophila fly for eye color (sepia+), the eye color is __________. (a) white (b) black (c) gray (d) yellow (e) red

(e) red

Round seeds (R) are dominant to wrinkled seeds (r), and yellow seeds (Y) are dominant to green seeds (y). What is the expected phenotypic ratio of a cross between an RrYy and an rryy individual?

1:1:1:1

A true-breeding plant that produces yellow seeds is crossed with a true breeding plant that produces green seed. The f1 plants have yellow seeds. What is the expected phenotypic ratio of seed color of the offspring of and f1 X f1 cross

3:1

__________Alternate versions of a gene

Alleles

Dominant

An allele that masks the expression of another allele (A)

Recessive

An allele whose expression is masked by another allele (a)

Allele

An alternate form of a gene

Monohybrid

An individual heterozygous for a particular gene

Dihybrid

An individual who is heterozygous for two particular genes

A true-breeding plant that produces yellow seeds is crossed with a true-breeding plant that produces green seeds. The seeds of all of the offspring are yellow; therefore the yellow allele is_______to the green allele.

Dominant

Only one allele needs to be present to be expressed if that allele is __________.

Dominent

If true-breeding plants are cross-pollinated, under the Mendelian model the offspring will be __________.

Heterozygous

An individual who_________carries two copies of the same allele for a gene

Homozygous

Thomas Morgan's choice of Drosophila melanogaster has been proven useful even today. Which of the following has/have continued to make it a most useful species? I. its four pairs of chromosomes II. a very large number of visible as well as biochemically mutant phenotypes III. easy and inexpensive maintenance IV. short generation time and large number of offspring

I. its four pairs of chromosomes, IV. short generation time and large number of offspring

Heterozygous

Possessing different alleles of a gene (Aa)

Homozygous

Possessing identical alleles of a gene (AA)

Two alleles must be present for a __________ trait to be expressed.

Recessive

According to Mendels law of ___________ gametes have only one copy of each allele

Segregation

Genotype

The allele combination in an individual

F1

The first filial generation; offspring

Wild type

The most common phenotype or allele for a gene in a population.

Phenotype

The observable expression of an allele combination

P1

The parental generation

F2

The second filial generation; offspring of offspring

The best definition of a ________ plant is one that self-fertilizes to produce offspring identical to the parent

True-Breeding

Chromosomes that are not sex chromosomes are called_______

autosomes

Thomas Morgan's choice of Drosophila melanogaster has been proven useful even today. One of these characteristics is that it has 4 pairs_______

chromosomes

The______that two genes are on a chromosome, the lower the probability that a crossover will occur between them

closer

According to Mendel's law of segregation, __________. (a) two alleles segregate into each gamete (b) homologous chromosomes move to the same gamete (c) more gametes carrying the dominant allele are produced than gametes carrying the recessive allele (d) gametes have one copy of each allele (e) gametes are diploid

d) gametes have one copy of each allele

Males are more often affected by sex-linked traits than females because males are_____ for the X chromosome

hemizygous

A dihybrid cross involves organisms that are___________ for two characters and monohybrid cross involves only one

heterozygous

A mating between a true-breeding purple-flowered pea plant and a true-breeding white-flowered pea plant would produce a(n) __________.

hybrid