Question 1

When genes are located very close together on the same chromosome, ____.
A) gametes usually end up with the same combination of alleles as parental cells
B) gametes usually end up with unique combination of alleles
C) they are inherited separately
D) they often recombine during crossing over
E) offspring will look just like one parent

Accepted Answer

When genes are located very close together on the same chromosome, they are said to be in strong linkage. This means that they are less likely to undergo recombination during crossing over. Therefore, gametes usually end up with the same combination of alleles as parental cells.

Question 2

The switching between asexual and sexual reproduction by water fleas is controlled by ____.
A) epistasis
B) pleiotropy
C) incomplete dominance
D) codominant inheritance
E) environmental effects

Accepted Answer

The switching between asexual and sexual reproduction in water fleas is dependent on environmental cues such as food availability, population density, temperature, and photoperiod. These cues trigger the production of different hormones which then activate either sexual or asexual reproductive pathways. Therefore, the switching is controlled by environmental effects.

Question 3

In an autosomal dominant disorder such as Huntington's disease, two carrier parents have the probability of passing the gene onto ____ of their children.
A) 0  percent
B) 25  percent
C) 50  percent
D) 75  percent
E) 100  percent

Accepted Answer

The answer of In an autosomal dominant disorder such as...

Question 4

Narrative:
Achondroplasia, a hereditary form of dwarfism, is an autosomal dominant disorder; however homozygous dominant individuals either die before birth or very shortly thereafter. The homozygous recessive condition is normal. A dwarf couple decide to have children. Use this information to answer the following question:
Of the children of this couple who survive, what is the probability that they will be normal?
A) 0
B) ¼
C) 1/3
D) 2/3
E) ½

Accepted Answer

The couple are both heterozygous (Aa) for achondroplasia. The possible genotypes for their children are AA, Aa, Aa, and aa. The AA genotype is lethal, so only Aa and aa survive. Out of the surviving children, 1 out of 3 (aa) will be normal, giving a probability of 1/3.

Question 5

In a pedigree chart, a male who demonstrates the trait being studied is represented by a ____.
A) darkened square
B) darkened diamond
C) clear circle
D) clear square
E) darkened circle

Accepted Answer

In a pedigree chart, a square represents a male, and a darkened square indicates that the male has the trait being studied.

Question 6

Narrative:
Achondroplasia, a hereditary form of dwarfism, is an autosomal dominant disorder; however homozygous dominant individuals either die before birth or very shortly thereafter. The homozygous recessive condition is normal. A dwarf couple decide to have children. Use this information to answer the following question:
Of the children of this couple who survive, what is probability that they will be affected by achondroplasia?
A) 0
B) ¼
C) 1/3
D) 2/3
E) ½

Accepted Answer

Since achondroplasia is autosomal dominant, the parents are both heterozygous (Aa). The possible genotypes for their children are AA, Aa, and aa. The AA genotype is lethal, so only Aa (affected) and aa (normal) survive. Out of the surviving children, 2/3 will be Aa (affected) and 1/3 will be aa (normal).

Question 7

In the Bombay phenotype, a gene in the recessive condition blocks the expression of A and B red blood cell antigens. Thus, all A, B, and AB genotypes are expressed as the O phenotype. This is an example of ____.
A) complete dominance
B) polygeny
C) incomplete dominance
D) codominance
E) pleiotropy

Accepted Answer

The answer of In the Bombay phenotype, a gene in...

Question 8

A gene that produces multiple effects is called a(n) ____.
A) codominant gene
B) X-linked gene
C) epistatic gene
D) pleiotropic gene
E) incompletely dominant gene

Accepted Answer

A pleiotropic gene is a gene that produces multiple effects, such as a gene that determines both hair color and eye color. Codominant genes refer to genes in which both alleles are expressed equally, while X-linked genes are genes located on the X chromosome. Epistatic genes are genes that mask the effects of other genes, and incompletely dominant genes involve alleles that are not completely dominant or recessive.

Question 9

A pleiotropic gene ____.
A) acts on secondary sexual characteristics
B) influences multiple traits
C) is additive
D) produces lethal effects when homozygous
E) produces epigenetic effects

Accepted Answer

A pleiotropic gene influences multiple traits, meaning it has effects on several phenotypic traits. The other choices are not true for all pleiotropic genes.

Question 10

The probability of producing a normal child by two parents who are carriers for an autosomal recessive disorder is ____.
A) 0  percent
B) 25  percent
C) 50  percent
D) 75  percent
E) 100  percent

Accepted Answer

When both parents are carriers of an autosomal recessive disorder, there is a 75% chance of producing a child who is either a carrier or not affected at all, and a 25% chance of producing a child with the disorder. This is because each child has a 25% chance of inheriting two recessive alleles (one from each parent), a 50% chance of being a carrier like the parents (inheriting one recessive allele), and a 25% chance of inheriting two dominant alleles, resulting in not having the disorder. Therefore, the probability of producing a normal (either not affected or a carrier) child is 75%.

Question 11

An X-linked carrier is a ____.
A) homozygous dominant female
B) heterozygous female
C) homozygous recessive female
D) homozygous male
E) heterozygous male

Accepted Answer

An X-linked carrier is a female who carries one copy of a mutated gene on one of her X chromosomes, while the other X chromosome carries a normal copy of the gene. This makes her heterozygous for the gene in question. Since this is an X-linked condition, it means that the gene is located on the X chromosome. Homozygous dominant females (choice A) would not be carriers, as they would express the dominant trait. Homozygous recessive females (choice C) would have the condition themselves, as they would have two copies of the mutated gene. Homozygous males (choice D) would not be carriers, as they only have one X chromosome. Heterozygous males (choice E) cannot be carriers of X-linked conditions, as they only have one X chromosome and they will express any traits that are present on that chromosome.

Question 12

Geneticists use ____ to study the genetics of families through generations.
A) Punnett squares
B) pedigrees
C) karyotypes
D) DNA profiles
E) fossil analyses

Accepted Answer

Geneticists use pedigrees to study the inheritance patterns of genetic traits within families through multiple generations. Punnett squares are used to predict the possible phenotypes and genotypes of offspring from a genetic cross. Karyotypes are used to examine the number, size, and shape of chromosomes in a cell. DNA profiles are used to compare DNA samples from different individuals for forensic or paternity purposes. Fossil analyses are used to study ancient organisms and their evolutionary history.

Question 13

The ABO blood types have ____ different genotypes.
A) 4
B) 6
C) 8
D) 12
E) 16

Accepted Answer

The ABO blood types are determined by three alleles: A, B, and O. The possible genotypes and corresponding phenotypes are: AA and AO (type A), BB and BO (type B), AB (type AB), and OO (type O). There are 6 possible genotypes for ABO blood types.

Question 14

An autosomal recessive disorder ____.
A) requires that only one parent be a carrier
B) displays its symptoms in heterozygotes
C) is more frequent in males than females
D) requires that both parents are carriers
E) only affects females

Accepted Answer

Autosomal recessive disorders require that both parents are carriers in order for their offspring to inherit the disorder.

Question 15

Human eye color is an example of a trait that varies ____.
A) according to the geographical area
B) periodically
C) according to humidity
D) continuously
E) according to seasons

Accepted Answer

Human eye color varies continuously, meaning that it exists on a spectrum and can range from very light blue to very dark brown, with many shades in between. There is no set number of distinct eye colors, and individuals can even have a mixture of colors in their eyes. Eye color is determined by the amount and type of pigmentation in the iris, and this can vary within individuals and across populations. It is not influenced by factors such as geography, humidity, or seasons.

Question 16

In humans, skin color is controlled by several genes. Thus, skin color is a(n) ____ characteristic.
A) dominant
B) codominant
C) polygenic
D) pleiotropic
E) recessive

Accepted Answer

Skin color is controlled by multiple genes, with each gene contributing a certain amount to the overall phenotype. This is known as polygenic inheritance. Dominant, recessive, codominant, and pleiotropic inheritance involve single genes or a single gene affecting multiple traits, and do not apply to skin color.

Question 17

In a pedigree chart, a female showing the specific trait being studied is indicated by a ____.
A) clear square
B) darkened square
C) clear circle
D) darkened diamond
E) darkened circle

Accepted Answer

In pedigree charts, females are represented by circles and males by squares. A darkened shape indicates that the individual exhibits the specific trait being studied. Therefore, a darkened circle represents a female showing the specific trait.

Question 18

Six fingers on one hand would be classified as a(n) ____.
A) genetic disorder
B) disease
C) syndrome
D) genetic abnormality
E) illness

Accepted Answer

The answer of Six fingers on one hand would be...

Question 19

In Siamese cats, enzymes that code for dark fur color are only active in cooler temperatures. Thus, the tips of a Siamese cat's ears, feet, and tail are dark but not the warmer regions of its body core. This is an example of ____.
A) p leiotropy
B) environmental effects
C) epistasis
D) incomplete dominance
E) codominance

Accepted Answer

The fact that the enzymes that code for dark fur color are only active in cooler temperatures shows that environmental factors, specifically temperature, play a role in the expression of this trait. This is an example of environmental effects.

Question 20

Males are more commonly affected by X-linked recessive genetic disorders than females because ____.
A) females have two X chromosomes; therefore, they do not inherit recessive alleles
B) males have only one X chromosome; therefore, they express all recessive X-linked traits
C) males have only one X chromosome; therefore, they have multiple alleles for each X-linked gene
D) Y chromosomes cause X-linked gene mutations
E) males are genetically weaker than females

Accepted Answer

Males only have one X chromosome, so if they inherit a recessive X-linked allele, they will express the trait because there is no dominant allele on their other X chromosome to mask it. Females, on the other hand, have two X chromosomes, so even if they inherit a recessive X-linked allele, they may also inherit a dominant allele on their other X chromosome, masking the recessive trait.

Quiz 10: Patterns of Inheritance

When genes are located very close together on the same chromosome, ____.

The switching between asexual and sexual reproduction by water fleas is controlled by ____.

In an autosomal dominant disorder such as Huntington's disease, two carrier parents have the probability of passing the gene onto ____ of their children.

In a pedigree chart, a male who demonstrates the trait being studied is represented by a ____.

In the Bombay phenotype, a gene in the recessive condition blocks the expression of A and B red blood cell antigens. Thus, all A, B, and AB genotypes are expressed as the O phenotype. This is an example of ____.

A gene that produces multiple effects is called a(n) ____.

A pleiotropic gene ____.

The probability of producing a normal child by two parents who are carriers for an autosomal recessive disorder is ____.

An X-linked carrier is a ____.

Geneticists use ____ to study the genetics of families through generations.

The ABO blood types have ____ different genotypes.

An autosomal recessive disorder ____.

Human eye color is an example of a trait that varies ____.

In humans, skin color is controlled by several genes. Thus, skin color is a(n) ____ characteristic.

In a pedigree chart, a female showing the specific trait being studied is indicated by a ____.

Six fingers on one hand would be classified as a(n) ____.

In Siamese cats, enzymes that code for dark fur color are only active in cooler temperatures. Thus, the tips of a Siamese cat's ears, feet, and tail are dark but not the warmer regions of its body core. This is an example of ____.

Males are more commonly affected by X-linked recessive genetic disorders than females because ____.