Ch 15 Flashcards
The acquisition of traits by their transmission from parent to offspring is called
inheritance
Mendel used the garden pea to study inheritance because the pea plants were:
easy to cross
A variant form of a character is called a(n) ______, and a variant form of a gene is called a(n) ______.
trait; allele
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 offspring of hybridization experiments are referred to as
hybrids.
True or false: Inheritance is the acquisition of traits by their transmission from offspring to parent.
False
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
Which of the following properties of the garden pea were advantageous for Mendel’s studies of inheritanc
True-breeding strains were available.
Many varieties with different traits were available.
Pea plants can be self-fertilized or cross-fertilized.
Character
A general feature of an organism
Trait
A specific variant of a feature of an organism
Gene
A genetic determinant that is passed intact from one generation to the next
Allele
A variant form of a genetic determinant
A single-factor cross is one in which an experimenter follows
the variants of only one character.
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
Consider two true-breeding individuals that differ in a single character. If these mate, their offspring are
monohybrids
In genetic crosses, the term “hybrid” refers to:
offspring of a hybridization experiment
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
When two P generation individuals are crossed, the offspring constitute the
F1 generation.
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/ allels
dominant
trait is displayed
recessive
trait is masked
A cross in which only one character is studied is called a___ ____
single factor gene
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
The offspring of two true-breeding parents that differ in a single character are called single-character hybrids, or ____
Monohybrids
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
In Mendel’s experiments, he observed a 3:1 ratio between dominant and recessive traits in
the F2 generation of monohybrid crosses.
In pea plants, yellow seeds are dominant to green seeds, and the yellow and green alleles are represented with Y and y, respectively. Match each genotype with the correct description of alleles.
YY = Homozygous for the yellow allele
Yy = Heterozygous for the yellow and green alleles
yy = Homozygous for the Green allele
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
In the Punnett square shown here, what information belongs in the box that is circled?
Genotype Tt
Mendel’s “unit factors” are now called _______________, and their variant forms are referred to as ________________.
genes / alleles
What ratio is obtained in the F2 generation of a dihybrid cross when alleles assort independently from one another?
9:3:3:1
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
The law of independent assortment states that:
alleles of different genes assort independently during gamete formation
The combination of alleles that an individual possesses, such as Tt or TT, is the individual’s
genotype
According to the chromosome theory of inheritance, Mendel’s laws can be explained by:
the behavior of chromosomes during meiosis
A Punnett square for a single trait should be set up as a ______ square (Not counting the squares for parental gametes).
2 x 2
The separation of homologous chromosomes during meiosis I explains:
the law of segregation
A 9:3:3:1 ratio is obtained in the F2 generation of a dihybrid cross when alleles assort _____ from one another
independently
The ______ alignment of chromosomes in meiosis I leads to the independent assortment of alleles on different chromosomes.
random
Which of Mendel’s laws states that alleles of different genes assort independently of each other during gamete formation?
Law of independent assortment
Pedigree analysis is typically used for studying:
human traits that follow simple inheritance patterns
Which of the following 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.
Traits that appear in every generation and affect males and females equally are characteristic of:
dominant inheritance
What aspect of chromosome behavior during meiosis explains Mendel’s law of segregation?
Separation of homologous chromosomes during meiosis I
In a recessive pattern of inheritance, two unaffected parents:
may produce affected or unaffected offspring
Independent assortment of alleles of different genes can be explained by the random alignment of homologous pairs of ____________ during meiosis I.
chromosomes
True or false: In dominant inheritance, affected parents always have affected offspring.
False
Human traits that follow simple Mendelian patterns are usually studied using:
pedigree analysis
The pattern of inheritance that deals with genes that segregate and assort independently is described by the term_______ inheritance.
mendelian
Some heterozygotes up-regulate expression of the dominant allele to compensate for the lack of function in a ___ allele.
recessive
A trait that appears to skip generations and is present at an equal frequency in males and females exhibits:
recessive inheritance
Pleiotropy occurs because
- the expression of a single gene can affect cell function in more than one way
- a gene may be expressed in different cell types in a multicellular organism
- a gene may be expressed at different stages of development
In recessive inheritance, two affected parents will:
always produce affected offspring
In an incomplete dominance pattern of inheritance, a heterozygous individual shows a(n) ______ phenotype.
intermediate
Individuals with a dominant disorder usually have:
one affected parent
In incomplete dominance, a cross of two heterozygotes produces ______ in the offspring.
three distinct phenotypes
What type of inheritance involves genes that undergo segregation and independent assortment?
Mendelian inheritance
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%
How do scientists evaluate the norm of reaction?
By exposing individuals with the same genotype to different environmental conditions
_______ is a phenomenon that occurs because a single gene can be expressed in multiple cell types or at several stages of development.
pleiotropy
Five sex determination systems are presented here. Match each with its representative species.
X-Y ------ humans X-O ----- fruit fly Z-W ----- bird haplodiploid ---- bee environmental --- alligator
________ dominance involves an intermediate phenotype in the heterozygote.
incomplete
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
Which chromosome causes maleness in mammals?
Y
The pattern of inheritance that deals with genes that segregate and assort independently is described by the term _________ inheritance
Mendelian
Genes found on one sex chromosome but not the other are called ______ - _______ genes.
sex linked
True or false: To study the norm of reaction, scientists subject individuals with the same genotypes to different environmental conditions.
True
Recessive X-linked alleles affect
Recessive X-linked alleles affect
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
In humans, a male always receives an X chromosome from his ______ and a Y chromosome from his _______
mom and dad
