Biology Chapter 17
Which blood types can have heterozygous genotypes associated with them?
Blood type AB Blood type A Blood type B
The three important ideas Mendel postulated concerning the transmission of traits from parents to offspring include:
-the two alleles of a gene separate during gamete formation so that each gamete receives a single allele per trait -traits exist in two forms - dominant and recessive -an individual carries two variants of genes per trait
Males inherit their X chromosome from their mother ______ of the time.
100%
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).
2,1
A Punnett square for a single trait should be set up as a ______ square (Not counting the squares for parental gametes).
2x2
The term multiple alleles refers to the presence of ______ or more alleles in the population.
3
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 is the end result of meiosis?
4 haploid cells
When two P generation individuals are crossed, the offspring constitute the
F1 generation.
True or false: Most traits are influenced by one gene.
False
Particulate inheritance was first proposed by
Gregor mendel
I-2
Heterozygous
II-1
Homozygous dominant
III-4
Homozygous recessive
Which blood type alleles are codominant to each other?
IA and IB
Select the best definition of a character.
A general feature of an organism
X-linked inheritance
A pattern of traits determined by genes that display a dominant/recessive relationship and are located on the x chromosome.
Epistasis
A type of gene interaction where the allele of one gene masks the effects of a dominant allele of another gene.
Which of the following characters is an example of codominance?
ABO blood type
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.
What explanation of inheritance suggests that hereditary traits are determined by discrete units that are transmitted from one generation to the next?
Particulate inheritance
Which gene plays a critical role in the developmental pathway that leads to maleness in humans?
SRY
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
What rule should be used to calculate the probability that independent events will occur together?
The product rule
What is the purpose of a testcross?
To determine the genotype of an individual with a dominant phenotype
IAi
Type A
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
Mendel's laws of inheritance are used in family planning to uncover in parents that may cause inherited disease in possible offspring.
alleles
Mendel used the garden pea to study inheritance because the pea plants were:
available in many varieties
haplodiploid
bee bee
Z-W
bird bird
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
heterozygous
half shaded
Meiosis results in the production of four daughter cells that each carry a single copy of one of the two original homologs.
haploid
haplodiploid system
haploid or diploid set of chromosomes
An individual with two identical alleles of a gene of a particular trait has a(n) genotype with respect to that gene.
homozygous
In a pedigree, a female and a male who mate are connected by a(n) ______ line.
horizontal
X-Y
human human
Pedigree analysis is typically used for studying:
human traits that follow simple Mendelian inheritance patterns
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
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
In an incomplete dominance pattern of inheritance, a heterozygous individual shows a(n) ______ phenotype.
intermediate
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
In a Punnett square, the symbols that make up the headings for the columns and rows correspond to the:
male and female gametes
In a recessive pattern of inheritance, two unaffected parents:
may produce affected or unaffected offspring
Consider two true-breeding individuals that differ in a single character. If these mate, their offspring are
monohybrids
The offspring of two true-breeding parents that differ in a single character are called single-trait hybrids, or
monohybrids
Most, or perhaps all, traits are influenced by ______ gene(s).
multiple
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
In genetic crosses, the term "hybrid" refers to:
offspring of a hybridization experiment
According to Mendel's law of segregation, the alleles of a gene segregate during gamete formation so that each gamete receives
one allele
Sex-linked genes are found on:
one sex chromosome but not the other
The concept of inheritance suggested that the determinants of hereditary traits are transmitted in discrete units from one generation to the next.
particulate
What type of plant did Mendel use for most of his work?
pea
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
Continuous phenotypic variation in quantitative traits is due to the combined effects of:
polygenic inheritance and environment
The ______ alignment of chromosomes in meiosis I leads to the independent assortment of alleles on different chromosomes.
random
Two unaffected parents produce an affected child. This is a characteristic of a(n) pattern of inheritance.
recessive
What pattern of inheritance is suspected when two unaffected individuals produce affected offspring?
recessive
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
When a cell prepares to divide, the homologs replicate so that each homolog consists of a pair of chromatids.
sister
males
square
What is the norm of reaction?
the phenotypic range displayed by individuals with a particular genotype under different environmental conditions
A two-factor cross is one in which an experimenter follows the inheritance of
two different characters.
Each parent carries alleles of a gene that will segregate from each other during gamete formation.
2
If a particular gene in a population has multiple alleles, how many alleles of that gene will a diploid individual possess?
2
The theory of inheritance states that inheritance patterns of traits can be explained by the transmission of chromosomes during meiosis and fertilization.
chromosome
Independent assortment of alleles of different genes can be explained by the random alignment of homologous pairs of during meiosis I.
chromosomes
females
circles
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
The ABO system is an example of which of the following?
codominance multiple alleles
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
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
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
The pattern of inheritance in which the expression of one gene masks the expression of another gene is known as .
epistasis
True or false: Heterozygous carriers of the CFTR allele exhibit the symptoms of cystic fibrosis.
f
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: Inheritance is the acquisition of traits by their transmission from offspring to parent.
false
affected
filled in
Siblings in a pedigree are notated in the order of their birth:
from left to right
X-O
fruit fly
The unit of heredity is the
gene
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
Mendel's "unit factors" that are passed intact from one generation to the next are now called
genes
What is the modern term for Mendel's "unit factors" that are passed on intact from one generation to the next?
genes
Which of the following are examples of quantitative traits in humans?
height metabolic rate skin color
Consider a testcross where the unknown parent is heterozygous. The offspring will be
heterozygotes and homozygotes
After DNA replication in a heterozygote, the two sister chromatids on a single chromosome contain:
identical alleles
dominance involves an intermediate phenotype in the heterozygote
incomplete
What is represented in pedigree analysis?
inheritance of an inherited trait over several generations in one family
A gene found on the X chromosome and not on the y chromosome is designated as an X- gene.
linked
Mendel's laws of inheritance are used in agriculture to develop commercially important
livestock crops
The of a gene is its physical location on a chromosome.
locus
The sex chromosomes refer to a distinctive pair of chromosomes that vary between and individuals.
male and female
Recessive X-linked alleles affect
males more than females.
The term refers to the presence of three or more alleles in the population.
multiple alleles
Normal alleles become abnormal alleles through the process of
mutation
The difference between a normal allele and one that causes disease is the result of
mutations
The phenotypic range exhibited by individuals with a particular genotype under differing environmental conditions is called the of .
norm of reaction
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
A(n) analysis is the analysis of an inherited trait over several generations in one family.
pedigree
Human traits that follow simple Mendelian patterns are usually studied using:
pedigree analysis
A cross that follows the simultaneous inheritance of two different characters is called a(n) -cross.
two factor
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
unaffected
unshaded
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
Place the steps of the Punnett square approach in the correct order. Start with the first step at the top.
write down genotypes write down possible fill in determine
In humans, the term sex-linked genes usually refers to -linked genes.
x
Mendel chose to study characters of pea plants that occurred in:
two discrete variants
Select all of the following that are principles of the chromosome theory of inheritance.
-Genes are found in the chromosomes. -The nucleus of a diploid cell contains homologous pairs of chromosomes. -Chromosomes are replicated and passed from parent to offspring and from cell to cell. -During meiosis, the homologous pairs segregate independently and haploid gametes are produced. -Gametes are haploid cells that combine to form a diploid cell during fertilization.
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.
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
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.
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
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
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
continuous variation
An inheritance pattern produced by the additive interactions of several genes, along with environmental effects.
Codominance
An inheritance pattern that occurs when the heterozygote expresses both alleles simultaneously.
Which of the following properties of the garden pea were advantageous for Mendel's studies of inheritance?
Availability of many varieties with different traits Capacity for self-fertilization or cross-fertilization Ease of making crosses
The genetic material of a cell is the within chromosomes.
DNA
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
The pattern of inheritance that deals with genes that segregate and assort independently is described by the term inheritance.
Mendelian
What type of inheritance involves genes that segregate and assort independently?
Mendelian inheritance
Who hypothesized that traits could be modified by physiological events and that those modifications could be inherited by offspring?
Lamarck
In the late 1700s, the French naturalist hypothesized that traits could be modified by physiological events and that those modifications could be inherited by offspring.
Lamark
Which of Mendel's laws states that alleles of different genes assort independently of each other during gamete formation?
Law of independent assortment
Who was the researcher who suggested particulate inheritance in the 1860s?
Mendel
Which of these is commonly used to predict the results of simple genetic crosses?
Punnett square
Flower color is an example of a(n) in pea plants. Purple and white flower colors are examples of .
character trait
IAIB
Type AB
IBIB
Type B
ii
Type O
The concept of inheritance proposes that both parents make equal genetic contributions to their children and that their genetic material blends together.
blending
The explanation of inheritance which suggested that parents make equal contributions to their offspring and that their genetic material joins together is called:
blending inheritance
A general feature of an organism, such as plant height or flower color, is called a(n) ______.
character
Genes found exclusively on the X chromosome are called:
X-linked
In the X-O sex determination system, which of the following genotypes could be found in a female? Select all that apply.
XX XXY
The sex chromosome makeup of a human female is and the sex chromosome makeup of a male is .
XX and XY
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 X
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
Pea plants are self fertilizing which means that a female gamete is fertilized by:
a male gamete from the same plant
In a pedigree, parents are connected to their offspring by:
a vertical line
The law of independent assortment states that:
alleles of different genes assort independently during gamete formation
environmental
alligator alligator
In recessive inheritance, two affected parents will:
always produce affected offspring
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
Z-W system
presence or absence of the W chromosome
X-Y system
presence or absence of the Y chromosome
The chance that an event will have a particular outcome is called
probability
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
X-O system
ratio between X chromosomes and autosome sets
A trait that causes a disease will occur more frequently in males than females if the trait is
recessive and X-linked
That two unaffected individuals can produce an affected offspring exhibits:
recessive inheritance
The limitations of pedigree analysis as compared to breeding experiments include:
sample size too small
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
Mendel's focus on ________ genes was pivotal in establishing the science of genetics because it allow Mendel to formulate basic laws of inheritance.
single
A cross in which only one character is studied is called a(n) - cross.
single factor
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
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 by:
the behavior of chromosomes during meiosis the effect of the environment on gene expression
The separation of homologous chromosomes during meiosis I explains:
the law of segregation
If a true-breeding line is allowed to self-fertilize for several generations, the resulting offspring will have:
the same traits as the parents
A single-factor cross is one in which an experimenter follows
the variants of only one character.
A variant form of a character is called a(n) .
trait
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
The critical element of Mendel's research focus was to use __________ strains that differed with regard to only one gene.
true-breeding