Biology 181: Chapter 12
Which of the following plants was the main organism for Mendel's genetic experiments?
Pea
Which of these traits exhibit a dominant mode of inheritance?
Mid-digital hair Polydactyly Hypercholesterolemia
The inheritance patterns of many traits are (more or less) complex than simple Mendelian patterns.
More
Juvenile glaucoma is a hereditary disease that causes blindness due to the degeneration of nerves in which of the following?
Optic nerve
In terms of probabilities, the cross of a tall yellow seeded pea plant (TTYy) with a tall green seeded pea plant (Ttyy) is equivalent to which two monohybrid crosses?
TT x Tt and Yy x yy
A 9:3:3:1 ratio is obtained in the F2 generation of a dihybrid cross when alleles assort _______________ from one another.
independently, separately, distinctly, autonomously, or individually
Characteristics of albinism include
loss of pigment sun sensitivity
Albinism is an inherited condition in which the pigment ___________ is not produced due to the lack of the enzyme _____________.
melanin tyrosinase
A cross in which only a single trait is considered is called a(n) _______ cross or single factor cross.
monohybrid
In order to determine the likelihood of having a flipped coin come up on heads three times in a row, you would use the
multiplication rule
Of the following alleles for blood type, indicate which two alleles are codominant to each other.
IB IA
Which of the following statements about the number of alleles a gene can have is true?
In a population of organisms, a gene can be represented by more than two alleles.
In the monohybrid crosses performed by Mendel, the F1 plants always displayed ____.
one trait
A(n) Blank 1Blank 1 pudnitte , Incorrect Unavailable square can be used to predict the outcome of a simple genetic cross.
Punnett
Which of these blood phenotypes is NOT properly matched with the sugar exhibited on red blood cells?
Type O - have galactosamine and galactose
When the interaction of genes alters genetic ratios, this is called
epistasis
By convention, the phenotypic ratio from a Punnett square is written as
dominant:recessive
Sickle cell anemia is caused by a ________ allele because this mutation has more than one effect on the phenotype.
pleiotropic
An individual's total set of alleles for a particular trait is called his/her
genotype
The mutation that causes cystic fibrosis affects several traits and is, therefore, an example of a(n)
pleiotropic mutation.
An allele that has more than one effect on phenotype is called
pleiotropic.
The cross of an individual who has a dominant phenotype with an individual who is homozygous recessive for that gene is known as a
testcross
Examples of environmental influences on phenotype include
the pattern of coat color in Himalayan rabbits the pattern of coat color in Siamese cats
The classical assumptions of heredity would eventually lead to all members within a species having
the same appearance
A pea plant with green seeds is allowed to self hybridize. All of the resulting offspring plants produce green seeds as well. That plant is therefore considered to be a
true-breeding plant
If a particular gene in a population has multiple alleles, how many alleles of that gene will a diploid individual possess?
2
What was the ratio that Mendel observed between dominant and recessive traits in the F2 offspring of a monohybrid cross?
3 dominant:1 recessive
In a heterozygous individual, the probability of a recessive allele being present in a gamete is
0.5
Prior to Mendel's work, inheritance was viewed as traits being borne through which of the following fluids of the body?
Blood
The probability of genotypes in an independently assorted dihybrid cross is based on the probabilities of
two monohybrid crosses
A characteristic ______ segregation in the F2 generation is referred to as the Mendelian ratio for a monohybrid cross.
3:1
Which of these traits is NOT correctly matched with its mode of inheritance?
Red-green color blindness: dominant
The appropriate time to use the product rule is when dealing with events that are:
independent
The Blank 1Blank 1 mb , Incorrect Unavailable form of a trait is the one that is not expressed in the F1 generation of a monohybrid cross.
recessive
The ___________ form of a trait is the one that is not expressed in the F1 generation of a monohybrid cross.
recessive
Traits that exhibit continuous variation are also called
quantitative traits
What type of cross follows the simultaneous inheritance of two different traits?
Dihybrid cross
A parent with a genotype of RrYy can produce which of the following gametes?
rY Ry ry RY
One of the traits that Mendel studied in pea plant is plant height. Tall plants are dominant with respect to dwarf plants. If the gene for this trait is denoted by the letter "T", then the genotype of a dwarf pea plant is
tt
Which of the following is NOT one of the three main stages that Mendel conducted his experiments in?
Back crosses between F1 and P individuals
This generation is produced when the F1 monohybrids self fertilize:
F2
True or false: Crossing pure breed white flowered pea plants with pure breed purple flowered pea plants produced hybrid pea plants with purple flowers.
True
Prior to the work of Mendel, inheritance was viewed as resulting from
blending of traits from an offspring's parents.
A(n) Blank 1Blank 1 recessive , Incorrect Unavailable cross follows the simultaneous inheritance of two different characters.
dihybrid, two-factor, or 2-factor
The form of a trait that is always expressed when crossing two true-breeding parents in a monohybrid cross is called
dominant
Consider a testcross where the unknown parent is heterozygous. The offspring will be
heterozygotes and homozygotes
The results of a testcross indicate that all of the offspring have a dominant phenotype. The genotype of the parent in question must be
homozygous dominant
Quantitative traits are usually
polygenic
To calculate the probability that if a woman has four children, they will all be girls, you should use the
product rule
The Blank ___________ form of a trait is the one that is not expressed in the F1 generation of a monohybrid cross.
recessive
An example of a ___________ cross is using pollen from a green-seeded pea plant to fertilize a yellow-seeded pea plant and then using pollen from a yellow-seeded pea plant to fertilize a green-seeded pea plant.
reciprocal
Which of the following is NOT a component of Mendel's five-element model (please note that the answers use the modern term gene instead of factor)?
the two alleles are usually the same
Prior to the 20th century, the two main ideas that provided the basis for most thinking about heredity were
traits are transmitted directly from parents to offspring heredity occurs within species
A hybridization experiment involves mating
two individuals with different characteristics to each other
A Punnett square has rows and columns which represent gametes made by males and females. At the intersection of each row and column we combine the corresponding gametes to produce the genotype of a potential
zygote or offspring
In a homozygous recessive individual the probability of the dominant allele being present is
0
In the cross of Pp x Pp four outcomes are possible: PP, Pp, pP, and pp. The probability of being heterozygous is ________.
1/2
When performing a monohybrid cross, Mendel noticed that not all individuals in the F2 generation were true breeding. What proportion were not?
1/2 of the F2 individuals exhibiting the dominant form were not true breeding.
In a certain plant, fruit color is affected by an epistatic interaction between two genes. The fruit is red in the presence of at least one dominant allele of either or both gene A or gene B, and white when there are no dominant alleles present. What proportion of the offspring of a cross of AaBb x AaBb plants is expected to be red?
15/16
How many possible allele combinations (consider all possible combinations, even those that are identical) are produced in the offspring of heterozygous parents in a dihybrid cross?
16
A 3:1 phenotypic ratio in the F2 generation of a monohybrid cross represents this genotypic ratio:
1:2:1
One of the parents in a dihybrid cross has the genotype AABb. How many types of gametes can this parent produce?
2
A Punnett square for a single trait should be set up as a ______ square (Not counting the squares for parental gametes).
2 x 2
How many potential phenotypes can result from a dihybrid cross when the traits assort independently from one another?
4
This ratio is obtained in the F2 generation of a dihybrid cross when alleles assort independently from one another.
9:3:3:1
An individual with genotype Aa can produce which gamete(s)?
A and a
Which of the following is an example of a testcross?
AaBb x aabb
In pea plants, the allele T encodes for tall plants, while the allele t encodes for dwarf plants. If a true-breeding tall pea plant is crossed with a true-breeding dwarf pea plant what are the expected genotypes of the offspring?
All Tt
The trait for round (R) peas is dominant over the trait wrinkled (r) peas. What would happen if true-breeding round peas are crossed with true-breeding wrinkled peas?
All offspring will have round peas.
In a monohybrid cross, when there are a pair of alternate forms of a trait, in which generation is one of the traits latent, or present but not expressed?
F1
In a typical monohybrid cross, all of the offspring in which generation will exhibit a single trait without blending?
F1
True or false: Mendel found that plants exhibiting the recessive trait were usually not true-breeding.
False
True or false: Mendel's observations did not support the independent assortment hypothesis.
False
What distinguished Mendel's results from earlier investigators?
He quantified his results.
Pedigree analysis is typically used for studying:
Human traits that follow simple inheritance patterns
Which of the following traits is NOT described correctly?
Huntington disease: wasting away of muscles during childhood
What type of experiment involves mating two individuals with different characteristics to each other? One individual provides females gametes, while the other provides male gametes.
Hybridization
Choose the two dominant alleles in the human ABO blood group system.
IA IB
A mismatched blood transfusion may lead to agglutination in the blood due to a reaction carried out by which system of the body?
Immune system
Which of the following conditions is inherited due to a dominant allele?
Juvenile glaucoma
Which person followed up Kölreuter's work by crossing garden peas in 1820s?
Knight
This law states that in a dihybrid cross, the segregation of different allele pairs is independent.
Law of independent assortment
Which of these are not reasons that Mendel chose to study the garden pea:
Long generation time They were inexpensive to buy
Which of following crosses is crossing two variations of a single trait?
Monohybrid cross
Mutations in how many genes cause the symptoms of cystic fibrosis?
One
Choose statements that correctly refer to components of Mendel's five-element model (please note that the answers use the modern term gene instead of factor).
Parents transmit genes to offspring. Alternative forms of genes are called alleles. The presence of an allele doesn't ensure that it will be expressed. The two alleles remain discrete.
A trait that has multiple genes contributing to its expression is known as which of the following?
Polygenic trait
Which of these is commonly used to predict the results of simple genetic crosses?
Punnett square
The following pedigree is representative of which type of inheritance?
Recessive
Which of the following are examples of environmental effects on phenotype?
The amount of sunlight experienced by a sunflower affects the number of seeds produced. The number of seeds eaten by a bird affects its weight.
How can two pea plants be cross-fertilized?
The male parts of flowers on one plants are removed and pollen from the other plant is introduced.
Mendel's work involved quantitative experiments and careful analysis of the offspring carrying specific traits. He paid the most attention to which of the following?
The numbers of every different type of offspring
Choose the 4 reasons that contributed to Mendel selecting the garden pea as his experimental subject.
There were a large number of pure varieties. Garden peas can self-fertilize. Earlier investigators had produced hybrid peas. The garden pea had a relatively short generation time.
Which term is used to refer to plant varieties in which offspring produced from self-fertilization remain uniform from one generation to the next.
True-breeding
Which of the following is an example of a monohybrid cross?
White and purple flowers
When a polygenic trait is studied, individuals can be grouped in different categories based on their traits and the number of individuals per category can then be plotted to produce a histogram. The bell shaped histogram typically approaches
a normal distribution
Assuming independent assortment, which of the following are examples of gametes produced by an AaBb individual?
ab AB
In order to predict the outcome of mutually exclusive events, this rule should be used:
addition
A nonfunctional allele for tyrosinase is characteristic of the genetic condition called
albinism
The law of independent assortment states that in a dihybrid cross, the of each gene assort independently.
alleles
In a monohybrid cross, the F2 generation is produced by
allowing the F1 generation to self-fertilize
Mendel's observations supported the independent __________ hypothesis.
assortment
When continuous traits are graphed in the form of a histogram with the phenotype on the X-axis, and the frequency of individuals with that phenotype on the Y-axis, a __________-shaped curve results.
bell
When Mendel crossed white-flowered and purple-flowered plants the hybrid offspring in the first __________ generation, or F1 generation, were all ___________ (what color?).
filial purple
When two consecutive events occur, each one with its own probability (that does not depend on the the probability of the other event), we say that the two events are
independent
A 9:3:3:1 ratio is obtained in the F2 generation of a dihybrid cross when alleles assort ____________ from one another.
independently, separately, distinctly, autonomously, or individually
An experimental cross where only a single characteristic is considered (for example, flower color) is called
monohybrid
Events that cannot occur at the same time are called
mutually exclusive
In a _____________ distribution, the values of a variable are distributed around a mean within a certain spread, which indicates the amount of variation in the variable.
normal
This analysis is appropriate for studying traits, such as genetic diseases, that follow simple Mendelian patterns:
pedigree
The physical appearance or other observable characteristic of an individual is called his/her
phenotype
Human height is an example of a trait that has a continuous distribution of phenotypes. Human height is therefore an example of inheritance.
polygenic
Continuous phenotypic variation results from
polygenic inheritance and independent segregation of genes
Before Mendel performed his experiments with peas, scientists had observed that alternative forms of traits could be distributed among the progeny of a mating. This process is called
segregation or segregating
Before Mendel performed his experiments with peas, scientists had observed that alternative forms of traits could be distributed among the progeny of a mating. This process is called .
segregation or segregating
Before Mendel performed his experiments with peas, scientists had observed that alternative forms of traits could be distributed among the progeny of a mating. This process is called _______.
segregation or segregating
Coat color in Siamese cats and Himalayan rabbits is influenced by
temperature
In order for Mendel's simple ratios to hold true, the following assumption must be made:
that the traits are inherited independently
In Mendel's experiments, he observed a 3:1 ratio between dominant and recessive traits in
the F2 generation of monohybrid crosses.