Unit 2 Exam Flashcards

1
Q

In a family that starts with you, your grandchildren would be the _____ generation.

A

F2

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2
Q

In a human pedigree that traces the inheritance of albinism, a filled square represents a _____.

A

Male with albinism

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3
Q

A person who has two identical alleles for a particular gene is _____ for that gene.

A

Homozygous

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4
Q

This pedigree shows the transmission of an autosomal recessive disease. If individuals III-2 and III-3 have an additional child, what is the probability that it will be an affected girl?

A

1/8

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5
Q

This pedigree shows the transmission of an autosomal recessive disease. What is the genotype of individual II-3 if the genes are represented by A/a?

A

Aa

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6
Q

Mendel called physical units responsible for the inheritance of traits “elementen.” The basis for his first law is that elementen _____.

A

Separate from each other as gametes form

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7
Q

For two genes on different chromosomes, the inheritance of one gene does not influence the chance of inheriting the other gene. This is called _____.

A

The law of independent assortment

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8
Q

For two traits A and B with two alleles each, the genotypes of the gametes that a double heterozygote would produce are _____.

A

AB, Ab, aB, ab

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9
Q

The phenotypic ratio expected from a dihybrid cross is _____.

A

9:3:3:1

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10
Q

Gregor Mendel is known for _____.

A

Breeding plants to demonstrate the logic behind inherited trait transmission

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11
Q

When Mendel crossed pure breeding peas having yellow seed color (YY) with pure breeding peas having green seed color (yy), all of the offspring had yellow seed color. These results mean that yellow seed color is the _____.

A

Dominant phenotype

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12
Q

The difference in mode of inheritance between Huntington disease and cystic fibrosis is that _____.

A

Huntington disease does not skip generations, but cystic fibrosis can

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13
Q

Destiny has distal symphalangism - her fingers and toes are stiff, with tiny nails. She looks it up and finds it is an autosomal dominant trait. Since her parents do not have it, she reasons that she has a new mutation. However, if she has children, each of them, assuming her partner does not have the condition, has a(n) _____ probability of inheriting the condition.

A

1/2

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14
Q

Which of the following analyses would be most effective in identifying a disease-causing gene variant inherited from a parent, or one that has arisen in the child?

A

Family exome analysis

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15
Q

Cystic fibrosis is autosomal recessive. This means that _____.

A

Both sexes can be affected and can “skip” generations through carriers

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16
Q

Which of the following genotypes is homozygous?

A

RR

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17
Q

In pea plants, the allele for tall (T) is dominant to the allele for short (t). The genotype for a short pea plant is _____.

A

tt

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18
Q

Which of the following is an illness caused by a mutation in mitochondrial DNA?

A

Leigh syndrome

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19
Q

Marbles is a Manx cat whose tail is so short that she appears not to have one. The genotype for short tail in Manx cats is heterozygous (Mm). Cats that are genotype mm have normal length tails, but cats that are genotype MM die before birth due to highly abnormal brains and spinal cords. Marbles has one copy of a dominant _____ allele.

A

Lethal

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20
Q

Some combinations of recessive alleles cause problems so severe that a fetus may cease to develop. Such lethal allele combinations appear to alter Mendelian ratios because _____.

A

Homozygotes for the lethal allele do not appear as a progeny class

21
Q

Different alleles that are both expressed in a heterozygote are _____.

A

Codominant

22
Q

Mitochondrial disorders tend to cause great fatigue because _____.

A

Muscle cells are normally filled with mitochondria

23
Q

Epistasis and multiple alleles differ in that _____.

A

Epistasis is an interaction between two genes, and multiple alleles are variants of the same gene

24
Q

Several members of the Fitzsimmons family have polydactyly, and they differ in their numbers of extra fingers and toes. Yet, certain relatives who should have extra digits don’t, such as Megan Fitzsimmons. She has two children, a son with two extra fingers and a daughter with an extra toe, and her father has an extra digit on each hand and foot. Polydactyly in this family is _____.

A

Variably expressive and incompletely penetrant

25
Q

Can a woman with blood type A have a child with blood type O with a man who is AB?

A

Yes, because of epistasis between the I and the H genes

26
Q

Mitochondrial DNA differs from nuclear DNA in that it _____.

A

Is poorer at DNA repair

27
Q

Marfan syndrome can be caused by mutations in either of two genes involved in the disorder, but mutations in one of the genes blocks activity of the other. This means that Marfan syndrome demonstrates _____.

A

Genetic heterogeneity and epistasis

28
Q

A man who has normal hearing and has a recessive deafness allele on chromosome 17 marries a woman who also has normal hearing and also has a recessive deafness allele, but this allele is on chromosome 3. The probability that their children will be deaf due to either of these mutated genes is closest to _____.

A

0%

29
Q

A and B are linked genes. In a study of 100 offspring, 94 had parental genotypes for A and B, while 6 were recombinants. A and B are _____ map units apart

A

6

30
Q

Hairlessness in dogs is inherited from a single dominant allele. Inheriting two dominant alleles is lethal for an embryo. Ralph and Penelope are both hairless dogs. What is the probability that Penelope will give birth to a puppy with hair?

A

1/3

31
Q

You identify a rare purple plumed parrot. When you cross the parrot to a true breeding white parrot, you get 1/2 white and 1/2 purple parrots. When you cross two purple parrots you get 1/3 white parrots and 2/3 purple parrots. Which of the following best explains this result?

A

The purple allele is lethal in the homozygous state

32
Q

A gene may have many alleles, but a person has only two alleles for a gene, because _____.

A

A gene can be altered in many ways, but a person has only two copies of any gene

33
Q

Children who have AIDS may have parents who have AIDS, but this is a result of viral infection, not inheritance of a mutation. This is an example of _____.

A

Phenocopy

34
Q

Amed has scaly skin due to the X-linked recessive condition ichthyosis. He is _____ for the trait.

A

Hemizygous

35
Q

Tamryn has a son who has Duchenne muscular dystrophy, which is inherited as an X-linked recessive trait. At a molecular level, the disease is due to lack of the protein dystrophin. Tamryn participates in a study that looks at dystrophin levels in various muscles. The study samples cells from 10 different muscles. The study finds that some cells make dystrophin and some do not. An explanation for this finding is that _____.

A

The X chromosome that bears the mutation is turned on in some cells but off in others

36
Q

Although both male and female sheep carry the genes for horn development, only male sheep grow horns. This is an example of _____.

A

A sex-limited trait

37
Q

A human male inherits _____.

A

An X chromosome from his mother and a Y chromosome from his father

38
Q

In cattle, mahogany spots are dominant in males and recessive in females. This trait is _____.

A

Sex-influenced

39
Q

A gene on the Y chromosome that determines maleness is _____.

A

SRY

40
Q

X inactivation is controlled by _____.

A

The XIST gene

41
Q

Sixteen-year-old Rhapsody has just learned that her younger brother Clyde is colorblind. Although she knows she has color vision because her cat, Juice, is clearly orange, and she reads that nearly all people with colorblindness are boys, she is concerned about her own sons one day. If she is a carrier for colorblindness, then the risk that a son of hers is colorblind is _____.

A

1/2

42
Q

Human males and females are roughly equivalent in terms of gene expression from the X chromosome because _____.

A

One of a female’s two X chromosomes is inactivated

43
Q

The Y chromosome was challenging to sequence because _____.

A

The sequence has many sites of high symmetry called palindromes

44
Q

A daughter can inherit an X-linked recessive disorder if _____.

A

Her mother is a carrier and her father has the disorder

45
Q

X-linked dominant traits are typically expressed _____.

A

Much more severely in males because they have only one X chromosome

46
Q

Unspecialized structures in embryos that develop into female sex organs are the _____.

A

Mullerian ducts

47
Q

What is true about the inheritance of the gene that causes Huntington disease?

A

If the mutant gene is inherited from one’s father, the disease progresses faster and with more severe symptoms

48
Q

In males, genes on the X chromosome are _____.

A

Expressed

49
Q

A boy developed signs of sexual maturity at age 3. A possible diagnosis is _____.

A

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency