17.2 The chromosome Theory of inheritance, Chapt 17 HW, 17.7, 17.6 Gene interaction, 17.5 Variations in inheritance patterns and their molecular basis, 17.4 Sex Chromosomes and X=linked inheritance patterns, Chapter 17.1, CHAPTER 17.0, 17.3 Pedigree...
What percentage of daughters would have hemophilia A if the parents included an affected father and a normal mother (not a carrier)? Hemophilia A is an X-linked recessive disorder.
0 %
A jar has six yellow marbles, one black marble and five red marbles. A person who cannot see the marbles is asked to pick one? What is the probability that it will be a black marble?
1/12
If a couple has four children, what is the probability that they will all be girls?
1/16
In pea plants, purple flowers are dominant to white flowers. If a heterozygous plant with purple flowers is testcrossed to a white plant, what phenotypic ratio will be observed in the offspring?
1/2 purple flowers and 1/2 white flowers
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
If a house cat has 76 total chromosomes, how many sister chromatids would a germ-line cell contain at the end of metaphase of meiosis I?
152
In pea plants, purple flowers are dominant to white flowers, and the purple and white alleles are represented with P and p, respectively. In a cross between two heterozygotes, what proportion of the offspring are expected to be purple?
3/4
If two parents who both have blood type AB have a child, what blood types are possible in the child?
A, B, and AB
Which of the following characters is an example of codominance?
ABO blood type
What would be a likely outcome if the alignment of maternal and paternal chromosomes during metaphase of meiosis did not adhere to Mendel's Law of Independent Assortment?
Alleles for genes would tend to be inherited together because chromosome pairs would align nonrandomly.
What does Mendel's law of segregation state?
Alleles of a gene segregate during gamete formation so that half the gametes receive one allele and half receive the second allele.
Continuous variation
An inheritance pattern produced by the additive interactions of several genes, along with environmental effects.
An inheritance pattern that occurs when the heterozygous individual expresses both alleles simultaneously. For example, a human carrying the A and B alleles for the ABO antigens of red blood cells produces both the A and the B antigens (has an AB blood type). Codominance
Codominance
The genetic material of a cell is the within chromosomes.
DNA
The genetic material that resides within chromosomes is
DNA
When two true-breeding plants that differ in a single character are crossed, the monohybrids display the_________ trait, and the ________________trait is masked.
Dominant Recessive
True Or False Each of the garden pea's visible characters has many different discrete variants. Hint: Variants are different forms of a trait.
False
True or false: In natural populations, mutant alleles are more common than wild-type alleles.
False
True or false: Most traits are influenced by one gene.
False
True or false: Sampling errors become larger with larger populations.
False
In the Punnett square shown here, what information belongs in the box that is circled?
Genotype Tt
Pedigree analysis is typically used for studying:
Human traits that follow simple inheritance patterns human traits that follow simple Mendelian inheritance patterns
Jerking movements, loss of mental abilities, and the onset of psychiatric problems between ages 30 and 50 are symptoms of
Huntington disease
In the following pedigree, match the individual with its most likely genotype?
I-2=Heterozygous II-1=Homozygous dominant III-4=Homozygous recessive
If a cross between heterozygotes for a single trait results in three distinct phenotypes, which of the following types of inheritance is the likely reason?
Incomplete dominance
In a two-factor cross, genes that are close together on a chromosome do not follow Mendel's law of __________________________
Independent assortment
The fact that maternal and paternal chromosome pairs align and orient randomly during metaphase of meiosis supports Mendel's
Law of Independent Assortment.
Who was the researcher who suggested particulate inheritance in the 1860s?
Mendel
The offspring of two true-breeding parents that differ in a single character are called single-trait hybrids, or
Monohybrids
What observation did Mendel make that refuted the notion of blending inheritance?
Monohybrids resembled one of the two parents rather than displaying an intermediate trait.
In humans, a male always receives an X chromosome from his____________________ and a Y chromosome from his _____________.
Mother Father
Does epistatic inheritance violate Mendel's laws of segregation and/or independent assortment?
No, epistatic inheritance does not violate Mendel's laws.
What explanation of inheritance suggests that hereditary traits are determined by discrete units that are transmitted frim one generation to the next?
Particular inheritance
What explanation of inheritance suggests that hereditary traits are determined by discrete units that are transmitted from one generation to the next?
Particulate inheritance
Most of Mendel's experiments were conducted using_______ plants
Pea
What type of plant did Mendel use for most of his work?
Pea
A(n) ___________________________analysis is the analysis of an inherited trait over several generations in one family.
Pedigree
Cross-fertilization involves placing________________________ from one plant onto the stigma of a flower on a different plant.
Pollen
How is cross-fertilization of a pea plant accomplished?
Pollen from one plant is transferred to the stigma of a different flower.
Most quantitative traits are affected by multiple genes and are therefore referred to as _______________traits.
Polygenic
A(n) ________________square can be used to predict the outcome of a simple genetic cross.
Punnett
In pea plants, round seeds are dominant to wrinkled seeds, and the round and wrinkled alleles are represented with R and r, respectively. What genotypes will have round seeds?
RR and Rr
Which gene plays a critical role in the developmental pathway that leads to maleness in humans?
SRY
Pattern baldness in humans occurs from an autosomal allele that is dominant in males and recessive in females. Sex-influenced inheritance
Sex-influenced inheritance
A cross in which only one character is studied is called a(n) ________________-_______________ cross.
Single-Factor Mono-Hybrid
In pea plants, a single gene controls pea texture. Smooth (S) peas are dominant over wrinkled (s) peas. A plant with smooth peas is crossed with a plant with wrinkled peas. Of the progeny, 252 are smooth and 247 are wrinkled. What are the genotypes of the parent plants?
Ss and ss
Role of Environment The scenario shows a distribution of plant height from genetically identical individuals plotted as a function of temperature. Check all that apply.
The genotype of the plant is likely altered by the environment.
What is the purpose of a testcross?
To determine the genotype of an individual with a dominant phenotype
True Or false Pea plants vary in several different visible characters or traits
True
True or False Each of the garden pea's visible characters has only two discrete variants.
True
True or False Homologous chromosomes begin to segregate into separate cells during anaphase of meiosis I.
True
True or False If meiosis proceeds correctly, four haploid daughter cells should result.
True
Mendel proposed that each individual carries___________________ forms of a gene for a given character, which are called alleles, and that the alleles of a gene separate during gamete formation so that each gamete receives______________________ allele(s).
Two One
Sex-linked genes in humans usually refer to genes found on the ______ chromosome.
X
Match the organisms with the correct mechanism of sex determination. X-Y Z-W X-O Environmental Haplodiploid
X-Y Humans The male is heterozygous for the sex chromosomes Z-W The make is homozygous for the sex chromosomes X-O Insects that are hemizygous for sex chromosomes Environmental In alligators, males are produced at intermediate temperature, females at low temperatures and a mixture of males and females at a high temperature Haplodiploid Male bees have half the number of chromosomes relative to female bees
Match each sex determination system with the correct factor that determines the sex of an individual.
X-Y system = presence or absence of the Y chromosome X-O system = ratio between X chromosomes and autosome sets haplodiploid system = haploid or diploid set of chromosomes Z-W system = presence or absence of the W chromosome
The sex chromosome makeup of a human female is _______and the sex chromosome makeup of a male is __________.
XX XY
Which of the following would be considered hemizygous?
XY
The SRY gene on the_______________________ chromosome is associated with the developmental pathway that leads to maleness.
Y
The______________ chromosome determines maleness in mammals.
Y
Which chromosome causes maleness in mammals?
Y
In the Z-W system in birds, females have the genotype ZW and males have the genotype __________
ZZ
In the Z-W system in birds, females have the genotype ZW and males have the genotype_____________
ZZ
When continuous traits are graphed with phenotype on the X axis and frequency of individuals with that phenotype on the Y axis, what type of curve results?
a bell-shaped curve, because there are many ways to arrive at a moderate value for the trait.
In a heterozygous individual each homolog will have
a different allele at the same locus.
Pea plants are self fertilizing which means that a female gamete is fertilized by
a male gamete from the same plant
What is an antigen?
a substance that can be recognized as foreign by the immune system
Height and skin pigmentation in humans are two examples of characters that are influenced by several genes that tend to interact in a(n) ______ way.
additive
Suppose multiple genes affect the same trait, and each gene contributes equally to the phenotype. This type of gene interaction is said to be
additive.
What is the modern term for what Mendel described as the two variant forms of a gene?
alleles
The law of independent assortment states that:
alleles of different genes assort independently during gamete formation
In recessive inheritance, two affected parents will
always produce affected offspring
When a trait is affected by more than one gene, all of which act to contribute to the outcome of the trait so that each gene potentially enhances its expression, this is called:
an additive interaction
The cellular division that changes the chromosome ploidy number from 2N to 1N occurs during
anaphase of Meiosis I
A substance that can be recognized as foreign by an animal's immune system is known as a(n)___________________ . In the case of blood groups, this substance was carbohydrates.
antigen
Human red blood cells have structures on their cell membranes known as surface________ . These are composed of glycolipids or glycoproteins.
antigens
Quantitative traits
are polygenic, encode genes for continuous traits, and are influenced by the environment.
The following pedigree is representative of
autosomal recessive inheritance
The paired chromosomes that are the same in both sexes are called
autosomes
Mendel used the garden pea to study inheritance because the pea plants were:
available in many varieties
In Mendel's experiments, the monohybrids resembled one of the two parents rather than displaying an intermediate trait. This observation refuted the notion of _________________________ inheritance that was popular at the time.
blending
Inheritance which suggested that parents make equal contribution to their offspring and that their genetic material joins together is called
blending inheritance
How do scientists evaluate the norm of reaction?
by exposing individuals with the same genotype to different environmental conditions
The study of sex chromosomes were pivotal in confirming the ___________ theory of inheritance
chromosome
The theory of inheritance states that inheritance patterns of traits can be explained by the transmission of chromosomes during meiosis and fertilization.
chromosome
The law of independent assortment is related to
chromosome alignment during meiosis
The law of independent assortment is related to:
chromosome alignment during meiosis
Independent assortment of alleles of different genes can be explained by the random alignment of homologous pairs of_____________ during meiosis I.
chromosomes
A situation where a single individual expresses two different alleles is referred to as
codominance
The phenomenon in which an individual expresses two different alleles of the same gene (as in blood type AB) is called
codominance
Traits that appear in every generation and affect males and females exhibit
dominant inheritance
Quantitative traits show a continuous range of phenotypes and often are influenced not only by multiple genes but also by the
environment
A heterozygous individual will have ______ numbers of gametes carrying the dominant allele and recessive allele.
equal
True or False inheritance of traits by transmission from offspring to parent
false
True or false: In a two-factor cross, genes that are close together on the same chromosome follow Mendel's law of independent assortment.
false
Starting with a 2n = 32 cell, at the end of meiosis II there will be
four cells; each n = 16
What is the end result of meiosis?
four haploid cells
Mendel's "unit factors" that are passed intact from one generation to the next are now called
genes
The combination of alleles that an individual has for a particular gene is the individual's:
genotype
The combination of alleles that an individual possesses, such as Tt or TT, is the individual's .
genotype
The term______________ describes the genetic composition of an individual for a particular gene.
genotype
The antigens on the surface of human red blood cells are made of:
glycoproteins and glycolipids
An individual with a dominant phenotype, may have a genotype of
heterozygous homozygous dominant
The offspring of hybridization experiments are referred to as
hybrids
The appropriate time to use the product rule is when dealing with events that are:
independent
The product rule states that the probability that two or more_________________ events will occur is equal to the product of their individual probabilities.
independent
A 9:3:3:1 ratio is obtained in the F2 generation of a dihybrid cross when alleles assort______________________ from one another.
independently
In an incomplete dominance pattern of inheritance, a heterozygous individual shows a(n) ______ phenotype.
intermediate
Recessive X-linked alleles affect
males more than females.
Males are more likely to display recessive X-linked traits than females because
males only have one copy of the X chromosome
The difference between a normal allele and one that causes disease is the result of
mutation
The phenotypic range exhibited by individuals with a particular genotype under differing environmental conditions is called the ___________of ______________ .
norm of reaction
Carriers of the cystic fibrosis allele are phenotypically
normal
Mendel's work involved quantitative experiments and careful analysis of the ______ of offspring carrying specific traits.
number
The formula for a probability that a random event will have a specific outcome is equal to the number of times an event occurs divided by the:
number of possible outcomes
In genetic crosses, the term "hybrid" refers to:
offspring of a hybridization experiment
Individuals with a dominant disorder usually have
one affected parent
According to Mendel's law of segregation, the alleles of a gene segregate during gamete formation so that each gamete receives:
one allele
In pea plants, smooth pods are dominant to constricted pods, and the smooth and constricted alleles are represented with S and s, respectively. What genotype will have constricted pods?
only ss
Human traits that follow simple Mendelian patterns are usually studied using
pedigree analysis
The larger a sample becomes, the ______ the sampling error becomes.
smaller
An individual with a dominant phenotype may be either homozygous or heterozygous. To determine the exact genotype of this individual a method called a(n)_______________ can be used.
testcross or test-cross
A heterozygous individual carries:
two different alleles of a given gene
For any given gene, the prevalent allele in a population is known as the_________ - ___________allele.
wild-type
What type of allele is defined as the prevalent allele in a population?
wild-type
Mendel's "unit factors" are now called _______________, and their variant forms are referred to as ________________.
genes alleles
Which of the following are examples of gene traits that interact additively
grain pigmentation in wheat weight in turkeys
Meiosis results in the production of four___________________ daughter cells that each carry a single copy of one of the two original homologs.
haploid
Graphs representing the distribution of continuous traits in a population are usually bell-shaped because:
multiple genotypes can produce the same phenotype
Sex-linked genes are found on
one sex chromosome but not the other
In pea plants, the allele T codes for tall plants and the allele t codes for short plants. If a plant is short, this would be considered its
phenotype
The characteristics of an organism that are the result of the expression of its genes is referred to as its _____________________
phenotype
Chickens that have the dominant allele of the frizzle gene (F_) have feathers that curl outward. Chickens that are ff have feathers that lie flat against their bodies. Chickens with F alleles—along with producing defective feathers—have higher metabolic rates, abnormal body temperatures, high blood flow capacity, and low egg-laying rates. This is an example of
pleiotropy
If "T" is a dominant allele for "tall," which of these would phenotypically describe a heterozygote (Tt)?
tall
In Mendel's experiments, he observed a 3:1 ratio between dominant and recessive traits in
the F2 generation of monohybrid crosses.
In Drosophila melanogaster, the sex is determined by the ratio between
the X chromosomes and its set of autosomes
According to the chromosome theory of inheritance, Mendel's laws can be explained by:
the behavior of chromosomes during meiosis
Theodor Boveri and Walter Sutton proposed:
the chromosome theory of inheritance
The effect of the amount of rainfall on the amount of fruit produced by a plant is an example of
the effects of environment on a phenotype
The effect of the amount of rainfall on the amount of fruit produced by a plant is an example of:
the effects of environment on a phenotype
Incomplete dominance can occur because
the heterozygote does not produce enough functional protein
The random alignment of different pairs of homologs during meiosis I explains
the law of independent assortment
The separation of homologous chromosomes during meiosis I explains:
the law of segregation
A male has hemophilia. Which parent provided the allele that causes this condition?
the mother
A single-factor cross is one in which an experimenter follows
the variants of only one character.
Two alleles may be codominant if:
they produce proteins that function slightly differently
In incomplete dominance, a cross of two heterozygotes produces ______ in the offspring.
three distinct phenotypes
A variant form of a character is called a(n)
trait
dominant
trait is displayed
recessive
trait is masked
In garden peas, tall (T) is dominant to short (t), and axial flowers (A) are dominant to terminal flowers (a). The two genes assort independently. If two heterozygous plants are crossed, what is the probability of obtaining an offspring that is short and terminal-flowered?
1/16
Tay-Sachs is an autosomal recessive condition that results from a mutation in a gene encoding the lysosomal enzyme, hexA,that normally degrades a specific type of lipid in brain cells. Failure to degrade the lipid results in degradation of brain neurons, and results in death in infancy or early childhood. Phil and Claire have a child with Tay-Sachs. What is the probability that their next two children will also have Tay-Sachs?
1/16
Cystic fibrosis is an autosomal recessive disorder. If two heterozygotes for the cystic fibrosis mutation have four children, what is the probability that all four children will have cystic fibrosis?
1/256
What is the probability of rolling a six-sided die and getting a 3?
1/6
The term multiple alleles refers to the presence of ______ or more alleles in the population.
3
X-linked inheritance
A pattern of traits determined by genes that display a dominant/recessive relationship and are located on the x chromosome.
What animal uses temperature rather than sex chromosomes to determine its sex?
Alligator
Codominance
An inheritance pattern that occurs when the heterozygote expresses both alleles simultaneously.
True or False Pea plants can be bred to generate offspring that possess only one variant of a trait.
True
True or False Sister chromatids separate during anaphase of meiosis II.
True
True or false: After several generations of self-fertilization of a true-breeding line, all of the offspring will have the same traits as the original parents.
True
True or false: Each character that Mendel selected to study was found in two discrete variants.
True
True or false: In humans, both males and females receive an X chromosome from their mothers
True
What is the molecular basis of codominance?
Two alleles encode proteins that function slightly differently from each other.
A cross that follows the simultaneous inheritance of two different characters is called a(n)______________ -______________ cross.
Two-Factor Di-Hybrid
Cells from the fruit fly Drosophila melanogaster contain four pairs of chromosomes. What is the number of possible chromosome orientations in that cell?
16
In incomplete dominance, what phenotypic ratio is expected from a cross of two heterozygotes?
1:2:1
Each parent carries_______________________ alleles of a gene that will segregate from each other during gamete formation.
2
In sweet peas, flower color is affected by an epistatic interaction between two genes. C (purple) is dominant to c (white), and P (purple) is dominant to p (white). However, cc masks P, and pp masks C, resulting in white flowers. In the cross CcPp x CcPp, what proportion of the offspring are expected to have white flowers?
7/16
A true-breeding pea plant with smooth green pods is crossed with a true-breeding plant with constricted yellow pods. The F1 offspring all have smooth green pods. If these F1 individuals are cross-fertilized, what proportion of the F2 offspring are expected to have smooth green pods?
9/16
What ratio is obtained in the F2 generation of a dihybrid cross when alleles assort independently from one another?
9:3:3:1
What phenotypic ratio is expected from a dihybrid cross involving two genes with epistatic interactions?
9:7
Flower color is an example of a(n)________________ in pea plants. Purple and white flower colors are examples of___________________________ .
Character Trait
Select all of the following that are principles of the chromosome theory of inheritance
Chromosomes are replicated and passed from parent to offspring and from cell to cell. Genes are found in the chromosomes. Gametes are haploid cells that combine to form a diploid cell during fertilization. During meiosis, the homologous pairs segregate independently and haploid gametes are produced. The nucleus of a diploid cell contains homologous pairs of chromosomes.
The unit of heredity is the
Gene
In alligators, the sex of an individual is determined by
In alligators, the sex of an individual is determined by:
Who hypothesize that traits could be modified by physiological events that those modification could be inherited by offspring?
Lamark
in the late 1700s,the French naturalist_________ hypnotized by physiological events and that those modifications could be inherited by their off sprint
Lamark
What rule should be used to calculate the probability that independent events will occur together?
The product rule
Place the steps of the Punnett square approach in the correct order. Start with the first step at the top.
Write down the genotype of both parents write down the possible gametes that each parent can make Fill in the possible genotype of offspring by combining the alleles of the gametes in the empty boxes determine the relative portions of genotypes in the offspring
Human males always inherit their ______ chromosome from their mother.
X
In humans, most sex-linked genes are found on the ________________ chromosome.
X
A general feature of an organism
best definition of a character
By convention, dominant alleles are written with a(n) _______ letter.
capital
Traits such as blood type in humans, white or purple flowers in sweet pea plants, and curly or normal wings in fruit flies are examples of _____________________traits, because the phenotypes do not overlap.
discrete
Traits with clearly defined phenotypic variants that can be sorted into distinct categories are known as _____________________ traits.
discrete
Traits with clearly defined phenotypic variants that can be sorted into distinct categories are known as______________ traits.
discrete
A 9:7 phenotypic ratio in a dihybrid cross is most consistent with:
epistasis
The pattern of inheritance in which the expression of one gene masks the expression of another gene is known as
epistasis
Quantitative traits are usually
polygenic
Continuous phenotypic variation in quantitative traits is due to the combined effects of:
polygenic inheritance and environment
The chance that an event will have a particular outcome is called
probability
That two unaffected individuals can produce an affected offspring exhibits
recessive inheritance
That two unaffected individuals can produce an affected offspring exhibits:
recessive inheritance
The critical element of Mendel's research focus was to use __________ strains that differed with regard to only one gene.
true-breeding
Mendel's Principle of Segregation states that
two alleles of a gene separate during gamete formation such that every gamete receives only one allele.
Two identical cells heterozygous for gene Q are undergoing meiosis. What is the probability that two haploid gametes selected from the products of meiosis both contain a recessive allele for gene Q?
0.25
Which of the following properties of the garden pea were advantageous for Mendel's studies of inheritance?
1. Capacity for self-fertilization or cross-fertilization 2.Ease of making crosses 3.Availability of many varieties with different traits
Red-green colorblindness in humans is caused by a sex-linked recessive allele. A colorblind man marries a woman with normal vision whose father was colorblind. The couple has a son. What is the probability that he is colorblind?
1/2
A pea plant with the genotype TtYy is crossed with a plant with the genotype ttYy. If the two genes are independently assorting, what is the probability that an offspring would be TtYY?
1/8
Males inherit their X chromosome from their mother ______ of the time.
100%
If a particular gene in a population has multiple alleles, how many alleles of that gene will a diploid individual possess?
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
In pea plants, when a true-breeding line with axial flowers is crossed with a true-breeding line with terminal flowers, all of the F1 offspring have axial flowers. What phenotypic ratio is expected in the F2 generation?
3 axial: 1 terminal
What ratio did Mendel observe in the F2 offspring in monohybrid crosses between true-breeding lines for dominant and recessive traits?
3 dominant : 1 recessive
In pea plants, purple flowers are dominant to white flowers, and axial flowers are dominant to terminal flowers. If a true-breeding plant with purple, axial flowers is crossed with a true-breeding plant with white, terminal flowers, what proportion of the F2 offspring will have purple, terminal flowers?
3/16 Reason: Purple is dominant and terminal is recessive. Therefore, we are looking for F2 plants that are dominant for one trait and recessive for the other. Thus, the answer is 3/16. Remember that the overall ratio is 9/16:3/16:3/16:1/16.
In a simple dominant/recessive relationship, the production of approximately ______ of the protein needed in the heterozygote is plenty for the individual to function typically.
50%
If two people who are both heterozygous for IA and i and who both have blood type A have a child, what blood types are possible in the child?
A and O
What is a phenotype?
A characteristic of an organism resulting from the expression of its genes
In Mendelian inheritance patterns, which of the following statements is accurate about recessive alleles? Check all that apply.
A recessive allele is a weaker form of a dominant allele A recessive allele will have an effect on an organism's phenotype if the individual is homozygous for the recessive allele
Epistasis
A type of gene interaction where the allele of one gene masks the effects of a dominant allele of another gene.
A die is a cube with six sides, with each side numbered 1, 2, 3, 4, 5, or 6. Match the probability of obtaining the number if one or two dice are rolled.
A. 5 with one die rolled 1/6 Correct B. 5 showing on either die when two are rolled (Hint: Each die roll is a mutually exclusive event.) 1/3 Correct C. 4 from the sum of the two dice rolled (Hint: Consider how many ways two dice can produce a 4.) 1/12 Correct D. Cat eyes or a 1 on each of the two dice rolled 1/36 Correct E. 1, 3, or 6 with one die (Hint: Rolling a 1, 3, or 6 are each mutually exclusive events.) 1/2
Imagine that fur length in a chinchilla species is a polygenic trait controlled by at least three genes. For each of these genes, long fur (PL, QL, or RL) has incomplete dominance over light (PS, QS, RS). A chinchilla homozygous for long fur is mated with a chinchilla that is homozygous for short fur. What will be true of their offspring?
All of their offspring will have intermediate-length fur.
Mendel postulated that every individual carries two genes for a given character. Furthermore, the gene for each character in his pea plant exists in two variant forms, and these forms are now called__________________
Alleles
Pedigree analysis is an approach to studying human genetics where an inherited trait is analyzed over the course of a few generations. Geneticists make use of a pedigree, or family tree, to understand how simple human traits are inherited—whether the mutant allele is dominant or recessive, autosomal or sex-linked. Shown below are three pedigrees. Match each pedigree with its corresponding form of inheritance. (Circles represent females, squares represent males, open shapes indicate the individual does not have the condition being studied, filled shapes indicate the individual has the condition.)
Autosomal sex-linked recessive autosomal recessive Let's look at each pedigree to see which mode of inheritance fits best. Pedigree 1: There are males and females who have the condition, so it is likely autosomal. Any individual who has the trait has a parent who also has the trait, so it is likely dominant. By analyzing parents and offspring, it could be recessive, but dominant is most likely. Pedigree 2: Almost every individual with this condition is male, so it is likely inherited in an X-linked recessive manner. Pedigree 3: There are males and females who have the condition, so it is likely autosomal. Individuals with the condition have parents who do not have the condition, so it is recessive. The parents are carriers (heterozygous).
the concept of ________inheritance propose that both parents make equal genetic contributions to their children and their genetic material blends together
Blending
Which blood types can have heterozygous genotypes associated with them?
Blood type A Blood type AB Blood type B
Which blood type results from a loss of function mutation in glycosyl transferase that prevents the enzyme from attaching a sugar to the carbohydrate tree of the surface antigen?
Blood type O
Who proposed the chromosome theory of inheritance?
Boveri and Sutton
In Drosophila, the breeding of a red-eyed female (Xw+,Xw+) fruit fly with a white-eyed male fruit fly (XwY) produces male and female offspring that only have red eyes. When these F1 red-eyed females and red-eyed males are mated, approximately 50% of offspring are red-eyed females, 25% red-eyed males and 25% white-eyed males. Based on these results, indicate if the following statements are true or false.
Eye color is found on the Y chromosome False Eye color is found on the X chromosome. True White eye color is dominant over red eye color. False Red eye color is dominant over white eye color. True Eye color inheritance is independent of the sex of individuals. False Eye color is an example of sex-linked inheritance. True
When two P generation individuals are crossed, the offspring constitute the
F1 generation.
Plants from two different true-breeding P generation lines are crossed to one another and produce offspring. These offspring are allowed to self-fertilize, which results in production of the:
F2 generation
True Or false Pea plants have characters or traits that show blending and are not readily distinguishable.
False
True or False . Pea plants can generate offspring that possess a single variant of a trait.
False
True or False If one of the four daughter cells is diploid instead of haploid with regards to a certain chromosome, the embryo will always spontaneously abort.
False
True or False The four daughter cells resulting from meiotic division of sex cells should contain more than one copy of each chromosome.
False
True or false: All inheritance patterns of genes that segregate and assort independently show transmission of these genes from parents to offspring that are consistent with Mendelian inheritance.
False
True or false: Epistatic inheritance violates Mendel's law of independent assortment.
False
True or false: Heterozygous carriers of the CFTR allele exhibit the symptoms of cystic fibrosis.
False
True or false: In all animals that have a Y chromosome, the presence of the Y chromosome results in male development
False
True or false: In dominant inheritance, affected parents always have affected offspring
False
True or false: When multiple alleles of a gene exist, each individual may inherit more than two alleles.
False
In humans, the allele for freckles is dominant (F) and the allele for no freckles is recessive (f). An individual who is heterozygous for freckles would have which of the following genotypes?
Ff
What is broadly defined as a unit of heredity?
Gene
Mendel proposed that a unit factor, now called a ____________________, codes for a character, and each individual carries two variant forms, now called_____________ , of the unit factor for a given character.
Gene Alleles
The phenomenon that occurs when a trait is controlled by two or more genes, each with two or more alleles, is called what?
Gene interaction
What is the modern term for Mendel's "unit factors" that are passed on intact from one generation to the next?
Genes
The pedigree shown below is from a family with albinism. Albinism is a genetic condition that occurs when the body is unable to make or distribute melanin, a pigment that gives color to skin, hair, and the iris of the eye. The pedigree shown below is from a family with albinism. Analyze the pedigree to determine whether albinism is inherited in a dominant or recessive fashion, and then apply the correct genotypes to individuals I-1, I-2, II-2, and II-5.
Given what you now know, what information is most likely to produce the correct answer? How is albinism inherited? Both males and females have the condition, so it is likely autosomal. Individuals who have albinism have parents who do not have the condition, so it is recessive. If it were dominant, affected individuals would have at least one affected parent. So, we can work on the fact that the condition is autosomal recessive. In an autosomal recessive condition, what is the genotype of a person who has the condition (II-2). II-2 is homozygous recessive, and had to get a recessive allele from each parent. Each parent has to have a recessive allele, but since they do not have the condition, they also have to have a dominant allele. I-1 and I-2 are carriers. Can we determine the genotype of II-5? She does not have albinism, so has to have a dominant allele. But is she homozygous dominant or is she heterozygous? Drag the correct genotypes to the appropriate boxes.
Consider a newly discovered organism that is bioluminescent. Scientists studying this animal have discovered that there are two enzymes necessary for the animal to glow, encoded by the bright and red genes. Furthermore, scientists have confirmed that for bioluminescence to be displayed, an individual must have at least one copy of the dominant allele for each gene, (B and R). Match the genotypes with their correct phenotypes, glowing or nonglowing.
Glowing BBRR BBRr BbRR BbRr Non-glowing BBrr Bbrr bbRR bbRr bbrr
A diploid parent cell with genes H, T, and Q has a maternal genotype HTQ and paternal genotype htq. What would be the most likely daughter cell genotype if independent assortment does NOT occur?
HTQ
In pea plants, yellow seeds (Y) are dominant to green seeds (y) and round seeds (R) are dominant to wrinkled seeds (r). The genes for seed color and seed shape are on different chromosomes. Two true-breeding parents, one with yellow round peas and the other with green wrinkled peas, are crossed. Which of the following is/are accurate regarding the resulting F1 plants? Check all that apply.
Half the F1 plants have the genotype YYRR and half have the genotype yyrr. The F1 plants have the following phenotypes—yellow round, yellow wrinkled, green round, green wrinkled—in equal proportions. All of the F1 plants have yellow round seeds. Half of the F1 plants have yellow round seeds and half have green wrinkled seeds. All of the F1 plants have green wrinkled seeds. The F1 plants make only YR and yr gametes.
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
Which blood type alleles are codominant to each other?
IA and IB
Which two blood type alleles encode enzymes with slightly different active sites that attach different sugars to the carbohydrate tree of the surface antigen?
IA and IB
Match the following blood type genotypes with phenotypes.
IAi = Type A IBIB = Type B ii = Type O IAIB = Type AB
Of the following alleles for blood type, indicate which two alleles are codominant to each other.
IB IA
Individuals who are homozygous for the normal gene that encodes an enzyme for metabolizing phenylalanine have low levels of this amino acid, while individuals heterozygous for the mutated gene have intermediate levels of phenylalanine, and individuals homozygous for the mutated gene have very high levels of phenylalanine, and therefore exhibit phenylketonuria. Incomplete dominance
Incomplete dominance
Huntington's disease (HD) is an incurable, fatal neurological disease. It is inherited in an autosomal dominant manner. The median age of diagnosis of HD is about 38 years. Jonathan is a 28-year-old individual whose mother had HD. Neither his father nor his much older brother who is 45 years old show any signs of HD. Which statements is/are accurate with regards to Jonathan and his family? Check all that apply.
Jonathan's mother has the genotype Hh. Jonathan's father has the genotype Hh. Jonathan's older brother has the genotype hh.
In humans, long eyelashes (L) are dominant to short eyelashes (l). On the left are three boxes, each containing one possible genotype for eyelash length. Match the terms/phrases on the right with their correct genotype(s); some labels may be used more than once, and some labels may not be used at all.
LL All offspring will have king eyelashes when crossed with Ll genotype Homozygous dominant will have long eyelashes Ll Heterozygous Will have long eyelashes ll Homozygous recessive will have short eyelashes
Which of Mendel's laws states that alleles of different genes assort independently of each other during gamete formation?
Law of independent assortment
The_____________________ of a gene is its physical location on a chromosome.
Locus
In the haplodiploid sex determination system used by bees, unfertilized eggs develop into________________ , and fertilized eggs develop into_______________ .
Male Female
Indicate if the conditions described would result in the development of a human male or a female individual.
Male Two X chromosomes and a Y chromosome One normal X chromosome and an X chromosome with an SRY gene insertion Four X chromosomes and a Y chromosome one each of the X and Y Chromosome Female only one X chromosome One X chromosome and Y chromosome with the DRY gene deleted An individual with only one X chromosome and a Y chromosome with an SRY gene mutation
The sex chromosomes refer to a distinctive pair of chromosomes that vary between________ and___________ individuals.
Male = XY Female= XX
Recessive alleles are expressed more frequently in__________ than in__________ .
Males Females
The pattern of inheritance that deals with genes that segregate and assort independently is described by the term__________________ inheritance.
Mendelian simple Mendelian
What type of inheritance involves genes that segregate and assort independently?
Mendelian inheritance
Which of these is commonly used to predict the results of simple genetic crosses?
Punnett square
Red-green colorblindness in humans is caused by a sex-linked recessive allele. A color-blind man marries a woman with normal vision whose father was color-blind. Complete the Punnett square to answer the following questions: What is the probability that they will have a color-blind daughter? (X = wild type allele, Xc = color blind allele)
Red-green colorblindness is a sex-linked recessive trait; the gene for color vision is on the X chromosome. A male who has a defective allele will be colorblind. A female will be colorblind if she has two defective alleles, and will be a carrier if she is heterozygous. The father is colorblind, so he has a defective allele. His genotype is XCY. Why does he exhibit a recessive condition when he is not homozygous recessive? The mother is not colorblind, so she has to have at least one normal X, she is X_. We are told that her father was colorblind, so her father was XcY. She would get an Xc from her father, so her genotype is XXC. What are the results of an XCY x XXC cross?
The characters that Mendel studied in pea plants included pod color and shape,_______________ color and shape,______________ color and position, and plant __________________.
Seed Flower Height
A person with Tay-Sachs disease is homozygous for a mutated form of the hexosaminidase A gene (Tay-Sachs allele). This results in little production of the functional hexosaminidase A enzyme, leading to poor lipid metabolism, excess brain lipid deposition and eventual death. Individuals who are heterozygous for the Tay-sachs allele, produce enough of the hexosaminidase enzyme for proper lipid metabolism, and hence do no exhibit the disease. Simple Mendelian inheritance
Simple Mendelian inheritance
Which of the following complex inheritance patterns are correctly matched to their description?
Simple Mendelian: Pattern determined by alleles pair displaying dominant/recessive relationship located on autosome. Epistasis: The alleles of one gene mask the effect of the alleles of another gene.
Tay-Sachs is an autosomal recessive condition that results from a mutation in a gene encoding the lysosomal enzyme, hexA, that normally degrades a specific type of lipid in brain cells. Failure to degrade the lipid results in degradation of brain neurons. Match the statements about Tay Sachs and the hex A enzyme to the appropriate genotype. T = dominant allele; t = recessive allele
TT Make normal amount of HexA Does not have Tay Sachs Tt Make 1/2 the normal amount of HexA Does not have Tay Sachs but is a carrier tt Makes no HexA enzye Has Tay sachs
What theory states that the inheritance patterns of traits can be explained by the transmission of chromosomes during meiosis and fertilization?
The chromosome theory of inheritance
The inheritance of the ABO blood group in humans is illustrated in the table. Check all that apply.
The gene for blood type shows a complete dominance inheritance pattern. The gene for blood type shows an incomplete dominance inheritance pattern. The gene for blood type has only two different alleles. The gene for blood type has multiple (> 2) alleles. A person with type O blood will have compatibility with blood from a type A donor. Hint: Antibodies attack antigens or foreign molecules that are not naturally produced by the individual.
Muscular dystrophy (MD) is a group of disorders that involve muscle weakness and loss of muscle tissue. Duchenne muscular dystrophy (DMD) is a rapidly-worsening form of MD. DMD is caused by a defect in the dystrophin gene. The dystrophin protein is a vital part of a protein complex involved in muscle support and structure. DMD is much more common in boys than in girls ( about 1/3500 boys have DMD, girls rarely have DMD). Which statements about DMD are ACCURATE? Check all that apply.
The gene for dystrophin is likely on an autosome. If a female has a defective dystrophin allele, she will likely have a normal allele to act as a "back up". DMD is an autosomal dominant trait. A man who has DMD will pass the defective allele to all of his sons, and those sons will have DMD.
In pea plants, yellow seeds (Y) are dominant to green seeds (y) and round seeds (R) are dominant to wrinkled seeds (r). The genes for seed color and seed shape are on different chromosomes. Two true-breeding parents, one with yellow round peas and the other with green wrinkled peas, are crossed. What are the genotypes of the parents, and what kind of gametes will they produce?
The genotype of the plant with yellow round seeds will be YYRR and produce YR gametes, while the genotype of the plant with green wrinkled seeds will be yyrr and produce yr gametes.
Which of the following are examples of environmental effects on phenotype?
The number of seeds eaten by a bird affects its weight. The amount of sunlight experienced by a sunflower affects the number of seeds produced.
In Labrador retrievers, black coat (B) is dominant to brown coat (b) and normal vision (N) is dominant to blindness (n). The genes for coat color and blindness are on separate chromosomes. You cross a dog that is heterozygous for coat color and vision with a blind brown dog. Which statements are TRUE about this scenario? Check all that apply.
The probability of getting a brown blind puppy is 1/16 The probability of getting a brown puppy is ½. Because blindness is recessive, the probability of getting a blind puppy is ¼. A black blind puppy that results from this cross could have the genotype BBnn. Because two traits are being followed, the phenotypic ratio of offspring will be 9:3:3:1.
True or false: In humans, both males and females receive an X chromosome from their mothers.
True
True or false: In most species of flowering plants, the same plant produces both male and female gametophytes
True
True or false: To study the norm of reaction, scientists subject individuals with the same genotypes to different environmental conditions.
True
The probability of a couple having either a boy or a girl is ½. However, many families have more boys than girls and vice versa. Why is the observed ratio of boys to girls in typical families different than the predicted ratio?
Two of the answers are correct. There is a large random sampling error due to the small size of human families and the sex of each child is determined independently.
Polygenic Inheritance: Connecting Genotype, Phenotype, and Environment Phenotype is not often determined by one gene (i.e., metabolic rate is determined by the combination of multiple genes). In addition to an organism's genotype, the environment can influence phenotype. A rabbit breeder has established that rabbit body weight is determined by the combination of three genes as well as ambient temperature during the first four weeks after birth. The three genes involved in the determination of body weight are gene A (fat deposition), gene B (appetite), and gene C (gastric motility). Each gene can occur in heavy and light alleles (indicated by upper case and lower case letters, respectively). If a rabbit is heterozygous for each gene (Aa, Bb, Cc), the rabbit is an intermediate weight. If a rabbit is homozygous for all of the light genes (aa, bb, cc), the rabbit is lightweight. If a rabbit is homozygous for all of the heavy genes (AA, BB, CC), the rabbit is heavyweight. Additionally, rabbits reared at low temperatures during early development will deposit additional fat, making them heavier, whereas rabbits reared at high temperatures will not deposit as much adipose tissue. Arrange the following genotype and ambient temperature combinations from heaviest to lightest weight rabbits.
What do you already know about how genes and environment influence phenotype? What other information is related to the question? When multiple genes contribute to a single phenotype, such as mouse body size, a spectrum of phenotypes can be observed. The variation can increase when environment also affects the same phenotype.
In humans, the term sex-linked genes usually refers to ______________ -linked genes.
X
Match each sex determination system with a representative species
X-Y = human X-O = fruit fly Z-W = bird haplodiploid = bee environmental = alligator
Genes found exclusively on the X chromosome are called
X-linked
A women who is heterozygous for the recessive hemophilia gene does not exhibit the disease. Her sons, but not daughters, inherit the disease. X-linked inheritance
X-linked inheritance
What inheritance pattern is exhibited by hemophilia A?
X-linked recessive inheritance
The genotype of a human female is
XX
In the X-O sex determination system, which of the following genotypes could be found in a female? Select all that apply.
XX XXY : Reason: In the XO system, the ratio of X chromosomes to autosomes (not the presence of absence of the Y chromosome) determines sex. In this system, XX and XXY would be female, while XY and X would be male.
In what system does the Y chromosome determine maleness?
XY
In the X-O system, which operates in many insects, females are XX and males are either
XY Reason: In some XO sex determination systems, such as that in Drosophila, the males are XY. The Y chromosome does not contribute to the sex-determination system. The ratio of X chromosomes to autosomes determines gender in this system. X
Consider a diploid cell that contains genes Y, R, and Z on separate chromosomes. What is the likely genotype of a daughter cell if the parent cell with genotype YyRRZz undergoes meiosis?
YRZ
YY Yy yy
YY = Homozygous for the green allele Yy = Heterozygous for the yellow and green alleles yy = Homozygous for the yellow allele
Cystic fibrosis is the most common lethal genetic disease among Caucasians. Individuals with cystic fibrosis produce a mutated chloride (Cl-) channel protein that results in abnormal ion and water transport across epithelia such as those lining the lung, often making it difficult to breathe. Cystic fibrosis is inherited in an autosomal recessive manner; individuals who are heterozygous for the cystic fibrosis allele are carriers but do not exhibit the disease. Drag the individual crosses shown below to their appropriate phenotypic outcome. (Wild type [normal] allele = F; Cystic fibrosis allele = f.)
You are being asked to determine the outcome of five different crosses! How many (if any) offspring of each cross will have CF; how many will be normal? You can perform 5 different Punnett squares to determine the ratios. Another way to solve at least some of the crosses is to look at the parents. If any parent of a cross is FF, all offspring will have at least one F (regardless of the other parent's genotype) and will be normal. If both parents are ff, what does that mean for the offspring? If both parents are heterozygous—you may want to do a Punnett square for this one.
Mendel's laws of inheritance are used in family planning to uncover in parents that may cause inherited disease in possible offspring.
alleles
Mendel's laws of inheritance are used in family planning to uncover______________ in parents that may cause inherited disease in possible offspring.
alleles
Gregor Mende
carried out his experiments in an abbey garden. conducted research that proved that the "blending hypothesis" was the correct explanation of how heredity worked. discovered the basic principles of hereditary.
A general feature of an organism, such as plant height or flower color, is called a(n) ______.
character
The ABO system is an example of which of the following?
codominance multiple alleles
The phenomenon in which an individual expresses two different alleles of the same gene (as in blood type AB) is called
codominance Co-dominance
Mendel's laws of inheritance are used in agriculture to develop commercially important
crops livestock
The major role meiosis plays in chromosomal inheritance is to
double the amount of DNA and reduce the chromosome number in daughter cells from 2N to 1N.
In pea plants, green pods are dominant to yellow pods. The genotype of a plant with green pods must be:
either homozygous dominant or heterozygous
Match the ways to denote individuals on a pedigree
females = circles Males = squares affected individuals = shaded unaffected individuals = not shaded presumed heterozygotes = half shaded
Nondisjunction of chromosome 1 occurs in a cell undergoing meiosis II. At the end of meiosis, what would you expect to see in the four gametes?
four daughter cells, two normal, one that is missing chromosome 1, one with two copies of chromosome 1
In humans, the allele for freckles is dominant (F) and the allele for no freckles is recessive (f). An individual who is heterozygous for freckles would have which of the following phenotypes?
freckles
Siblings in a pedigree are notated in the order of their birth
from left to right
The term______________________ describes the genetic composition of an individual for a particular gene.
genotype
Hemophilia A is a recessive X-linked disorder. If a mother is a heterozygous carrier of the disease allele and the father is unaffected, what proportion of the offspring are likely to be affected?
half of the sons and none of the daughters
An individual with only one copy of a particular gene is said to be
hemizygous
Which of the following diseases displays an X-linked recessive pattern of inheritance?
hemophilia A
Consider a testcross where the unknown parent is heterozygous. The offspring will be
heterozygotes and homozygotes
An individual who carries two different alleles of a gene is termed ___________with respect to that gene
heterozygous
In pea plants, tall is dominant to short. When a tall plant of unknown genotype is testcrossed with a short plant, half of the offspring are tall, and half are short. What was the genotype of the tall parent?
heterozygous
If an individual is_______________________ for a particular gene, then the two chromosomes in a homologous pair will have a different allele at the locus for the gene.
heterozygous or heterozygote
The accuracy of probability calculations increases with
higher sample size.
An individual with two identical alleles of a gene of a particular trait has a(n) ___________ genotype with respect to that gene.
homozygous
An individual with two identical alleles of a gene of a particular trait has a(n)__________________ genotype with respect to that gene.
homozygous
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
homozygous dominant heterozygous homozygous recessive
homozygous dominant = TT heterozygous = Tt homozygous recessive = tt
In a pedigree, a female and a male who mate are connected by a(n) ______ line.
horizontal
After DNA replication in a heterozygote, the two sister chromatids on a single chromosome contain:
identical alleles
In a pedigree, what is the correct order to list siblings?
in order of birth, from left to right
_______________dominance involves an intermediate phenotype in the heterozygote
incomplete
If a heterozygote displays a phenotype that is intermediate between the two homozygous individuals, then the trait must operate by
incomplete dominance
If heterozygous parents are crossed, a 1:2:1 phenotypic ratio will be observed in the offspring when which of the following types of heredity is involved?
incomplete dominance
If pure red snapdragons are crossed with pure white snapdragons the F1 generation offspring are all pink, and the F2 consists of 1/4 red, 1/2 pink, and 1/4 white flowers. What type of inheritance is this?
incomplete dominance
The heterozygote does not produce enough of the functional protein to produce the wild type trait in:
incomplete dominance
There are __________ patterns of genes that segregate and assort independently that do not display_______________ a dominant/recessive relationship.
inheritance simple
What is represented in pedigree analysis?
inheritance of an inherited trait over several generations in one family
In some situations, a single character is controlled by two or more different genes, each with two or more alleles. This phenomenon is called gene
interaction
What are the symptoms of the dominant disorder Huntington disease?
jerking movements loss of mental abilities psychiatric problems
The results of pedigree analysis are less definitive than breeding experiments because the small size of human families results in
large sampling errors
The results of pedigree analysis are less definitive than breeding experiments because the small size of human families results in:
large sampling errors
It is ______ common to find Y-linked genes as compared to X-linked genes
less
When two genes are located close to one another on a chromosome, they tend to be transmitted together. This phenomenon is known as
linkage
Which phenomenon describes the presence of two genes very close to each other on the same chromosome, and which are transmitted together as a unit?
linkage
A gene found on the X chromosome and not on the y chromosome is designated as an X-_________________ gene.
linked
The physical location of a gene on a chromosome is called the gene's:
locus
A mutation that creates a ______ allele is likely to decrease or eliminate the synthesis or functional activity of a protein.
loss-of-function
Which of the following organs are affected by cystic fibrosis
lungs pancreas intestine sweat glands
Match the appropriate sexes according to the haplodiploid system in bees:
male = unfertilized haploid egg female = fertilized diploid egg
In a Punnett square, the symbols that make up the headings for the columns and rows correspond to the:
male and female gametes
What sex chromosomes are found in male and female birds?
male birds have ZZ; female birds have ZW
In a recessive pattern of inheritance, two unaffected parents
may produce affected or unaffected offspring
Homologous chromosomes separate from one another during:
meiosis I
meiosis I= homologous pairs segregate meiosis II= sister chromatids separate
meiosis I= homologous pairs segregate meiosis II= sister chromatids separate
Epistatic interactions often arise because two or more proteins may be part of a(n) ______________pathway leading to the formation of a single product.
metabolic
Which of the following are examples of quantitative traits in humans?
metabolic rate height skin color
Consider two true-breeding individuals that differ in a single character. If these mate, their offspring are
monohybrids
Probability calculations become accurate as the sample size increases.
more
Sons receive X-linked recessive alleles from their ______ who are carriers.
mothers
Most, or perhaps all, traits are influenced by ______ gene(s).
multiple
The term___________ ________refers to the presence of three or more alleles in the population.
multiple alleles
Alleles that have been altered by mutations are called _______________ alleles.
mutant
Normal alleles become abnormal alleles through the process of
mutation
Recessive X-linked traits are more common in males than females because males have only _________________ copy(ies) of the X chromosome.
one
The concept o __________________________ inheritance suggested that the determinants of hereditary traits are transmitted in discrete units from one generation to the next.
particulate
Traits that show continuous variation over a range of phenotypes are known as ______ traits.
quantitative
Mendel's proposed his laws of inheritance based on
quantitative experiments
The ______ alignment of chromosomes in meiosis I leads to the independent assortment of alleles on different chromosomes.
random
Loss of function alleles decrease or eliminate protein function and are usually:
recessive
Lowercase letters are used to represent ________________alleles.
recessive
Those who have a homozygous_________________ genotype will exhibit the symptoms of cystic fibrosis, including abnormalities of the pancreas, intestine, sweat glands, and lungs.
recessive
What pattern of inheritance is suspected when two unaffected individuals produce affected offspring?
recessive
Two unaffected parents produce an affected child. This is a characteristic of a(n )_________________ pattern of inheritance.
recessive autosomal recessive
A trait that causes a disease will occur more frequently in males than females if the trait is
recessive and X-linked
Some heterozygotes up-regulate expression of the dominant allele to compensate for a lack of function in a(n) _____________allele.
recessive or defective
Alleles that are ________ are expressed more frequently in _______
recessive; males
The limitations of pedigree analysis as compared to breeding experiments include
sample size too small
The deviation between the observed and expected outcomes is referred to as the random
sampling error
What are the seven characters that Mendel studied in pea plant
seed color seed shape flower color pod color flower position pod shape height
Mendel's law of_________________ is the idea that the two alleles of a gene separate during the formation of eggs and sperm so that every gamete receives only one allele.
segregation
In pea plants, a female gamete is normally fertilized by a male gamete from the same plant. This process is called ______________________-fertilization.
self
What aspect of chromosome behavior during meiosis explains Mendel's law of segregation?
separation of homologous chromosomes during meiosis I
The __________________chromosomes are a pair of chromosomes that are different in males and females.
sex
Genes found on one sex chromosome but not the other are called___________ -___________ genes
sex-linked
Mendel's focus on ________ genes was pivotal in establishing the science of genetics because it allow Mendel to formulate basic laws of inheritance
single
Mendel's focus on ________ genes was pivotal in establishing the science of genetics because it allow Mendel to formulate basic laws of inheritance.
single
In meiosis, when a cell prepares to divide, the homologs replicate so that each homolog consists of a pair of _______________________chromatids.
sister
During meiosis II,_____________________ __________________ separate from one another.
sister chromatids
Most species of flowering plants have a single diploid plant called a(n) __________________ that produces male and female gametophytes.
sporophyte
Epistasis is the pattern of inheritance in which
the alleles of one gene mask the expression of the alleles of another gene
According to the chromosome theory of inheritance, Mendel's laws can be explained b
the behavior of chromosomes during meiosis
Random sampling error is the deviation between:
the observed and expected outcomes
What is the norm of reaction?
the phenotypic range of a genotype influenced by the environment the phenotypic range displayed by individuals with a particular genotype under different environmental conditions
If two events are independent of each other, then the probability that they will both occur is equal to:
the product of their individual probabilities
What determines an individual's sex in Drosophila melanogaster?
the ratio between the X chromosomes and the autosomes
If a true-breeding line is allowed to self-fertilize for several generations, the resulting offspring will have:
the same traits as the parents
The three important ideas Mendel postulated concerning the transmission of traits from parents to offspring include:
traits exist in two forms - dominant and recessive the two alleles of a gene separate during gamete formation so that each gamete receives a single allele per trait an individual carries two variants of genes per trait
What distinctive patterns of genes on sex chromosomes helped geneticists show that particular genes are located on particular chromosomes?
transmission
True or False Pea plants that differ with respect to a specific character or trait can be cross-fertilized.
true
True or false: Of the gametes produced by a heterozygous individual, half will contain the dominant allele and half will contain the recessive allele.
true
A two-factor cross is one in which an experimenter follows the inheritance of
two different characters.
Mendel chose to study characters of pea plants that occurred in:
two discrete variants
An individual who is homozygous for a given gene carries
two identical alleles of the gene
An individual who is homozygous for a given gene carries:
two identical alleles of the gene
A hybridization experiment involves mating
two individuals of the same species with different characteristics
Epistatic inheritance may occur when
two proteins are involved in the same cellular function
Epistatic inheritance may occur when:
two proteins are involved in the same cellular function
A linkage group is a set of adjacent genes that are transmitted together as a
unit
Several genes that are close together on a chromosome and transmitted together as a_________________ make up a linkage group.
unit
Which of the following are examples of gene traits that interact additively?
weight in turkeys grain pigmentation in wheat