Exam 1 Review: Flashcards
A dominant allele causes freckles. A man has freckles but one of his parents does not have freckles. What is the man’s genotype?
A) Homologous
B) Heterozygous
C) Homozygous dominant
D) Heterologous
E) Homozygous recessive
B) Heterozygous
Cells that carry two sets of genetic information are:
A) Haploid
B) Diploid
C) Polyploid
D) Homologous
E) Paired
B) Diploid
The ability to roll the tongue is caused by a dominant allele. A woman is a “roller”, but one of her parents is not. What is the woman’s genotype?
A) Either homozygous recessive or homozygous dominant
B) It cannot be determined from this information
C) Heterozygous
D) Homozygous recessive
E) Homozygous dominant
C) Heterozygous
About 70% of Americans perceive a bitter taste from the chemical phenylthiocarbamide (PTC). The ability to taste this chemical results from a dominant allele (T) and not being able to taste PTC is the result of having two recessive alleles (t). Albinism is also a single locus trait with normal pigment being dominant (A) and the lack of pigment being recessive (a). A normally pigmented woman who cannot taste PTC has a father who is an albino taster. She marries a normally pigmented man, who is homozygous at the albinism locus, and who is a taster but who has a mother that does not taste PTC> Which of the following choices list ONLY possible genotypes of their children (all listed are possible)?
a) A/A; T/T — A/a; T/T — a/a’ T/T
b) A/A; T/t — A/a;T/t — a/a;T/t
c) A/A; t/t — A/a’ t/t — a/a; t/t
d) A/A; T/t — A/a; T/t — A/a; t/t
d) A/A; T/t — A/a; T/t — A/a; t/t
A form of a gene that has slightly different sequence than other forms of the same gene but encodes the same type of an RNA or protein is called a(n):
a) homologous chromosomes
b) homozygotes
c) allele
d) heterozygote
e) locus
c) allele
If a human trait is never passed from father to son, it is likely that this trait is:
a) dominant
b) recessive
c) autosomal
d) Y-linked
e) X-linked
e) X-linked
Hair color is determined in labrador retrivers by alleles at the B and E loci. A dominant allele B encodes black pigment, whereas a recessive allele b encodes brown pigment. Alleles at a second locus affect the deposition of the pigment in the shaft of the hair; dominant allele E allows dark pigment (black or brown) to be deposited, whereas recessive allele e prevents the deposition of dark pigment, causing the hair to be yellow. A black female labrador retriever was mated with a yellow male. Half of the puppies were black, and half were yellow. If the genotype of the black female parents was B/b;E/e, then what was the genotype of the other parent?
a) b/b;e/e
b) B/B;E/E
c) B/b;e/e
d) B/B;e/e
e) b/b;e/e
d) B/B;e/e
Whilde doing filedwork in Madagascar, you discover a new dragonfly species that has either red (R) o clear (r) wings. Inital crosses indicate that R is dominant to r. You preform three crosses using 3 different sets of red-winged parents with unknown genotypes and observe the following data:
Cross 1: 72 red-winged, 24-clear-winged
Cross 2: 12 red-winged
Cross 3: 96 red-winged
Which cross(es) is/are likely to have at least one parent with the genotype R/R?
a) cross 3
b) crosses 2 and 3
c) cross 2
d) crosses 1 and 2
e) cross 1
b) crosses 2 and 3
Is it better to have a large sample size in genetic crosses?
a) Yes, larger sample sizes mean there are more degrees of freedom
b) No, larger sizes lead to more errors in counting
c) No, larger sample sizes results in greater deviation from expected ratios
d) Yes, larger sample sizes can produce phenotypic ratios closer to the expected ratios
d) Yes, larger sample sizes can produce phenotypic ratios closer to the expected ratios
In Drosophila melanogaster, the level of expression of genes on the X chromosome in males is double. What phenomenon is this an example of?
a) paternal mitochondrial leakage
b) dosage compensation
c) extranuclear inheritance
d) genomic imprinting
b) dosage compensation
You discoer a new mutation in Drosophilia that causes an abnormal wing shape. When a male fly with this mutation is crossed to a homozygous normal female, the F1 are all wild-type phenotypically. The F2 flies consist of 1/2 phenotypically normal females, 1/4 phenotypically normal males, and 1/4 males with abnormal wings. What is the MOST likely explanation for the new mutant allele?
a) It is x-linked and recessive
b) It is y-linked
c) It is autosomal and dominant
d) Is is autosomal and recessive
e) It is x-linked and dominant
a) It is x-linked and recessive
A certain type of congenital (inherited) deafness in humans is caused by a rare autosomal dominant gene. A deaf man and a deaf woman with this form of deafness marry and have lots of children. Would you expect all of the children to be deaf, assuming Mendelian phenotype ratios?
No
In dogs, black coat color (B) is dominant over brown (b), and solid coat color (S) is dominant over white spotted coat (s). A cross between a black, solid female and a black, solid male produces only puppies with black, solid coats. This same female was then mated with a brown, spotted male. Half of the offspring from this cross were black and solid, and half of the offspring were black and spotted. What is the genotype of the brown spotted male?
a) b/b;s/s
b) B/B; S/s
c) B/B;S/s
d) B/B; S/S
e) B/b;S/S
a) b/b;s/s
The ability to curl one’s tongue into a U-shape is a genetic trait. Curlers always have at least one curler parent but noncurlers can have one or both parents who are curlers. Using C and c to symbolize the alleles that control this trait, what is the genotype of a non curler?
a) c/c
b) C/c
c) C/C or C/c
d) C/C
a) c/c
An allele for purple fur color in muppets (P) is dominant to an allele for white fur color (p). Heterozygotes for purple exhibit 50% penetrance. The following cross is carried out: P/p x p/p. What proportion of the progeny will be purple?
a) 1
b) 0.25
c) 0
d) 0.5
e) 0.125
b) 0.25
