How can we help?

You can also find more resources in our Help Center.

91 terms

Bio Chapter 9 genesss

STUDY
PLAY
Which of the following statements dogs is false?
all dogs are descended from wolves
Which of the following statements best represents the theory of pangenesis developed by hippocrates?
Partivces called pangenes, which originate in each part of an organism's body, collect in the sperm or eggs and a passed on to the next generation
Which of the following statements regarding hypotheses about inheritance is false?
the blending hypothesis suggests that all of the offspring come either the mother or the father
Mendel conducted his most memorable experiments on
peas.
Varieties of plants in which self-fertilization produces offspring that are identical to the parents are referred to as
Tru-breeding
Which of the following statements regarding cross-breeding and hybridization is false?
The hybrid offspring of a cross are the P1 generation
A monohybrid cross is
a breeding experiment in which the parental varieties differ in only one character
Which of the following statements regarding genotypes and phenotypes is false?
An allele that is fully expressed is referred to as a recessive
Research since Mendel's time has established that the law of the segregation of genes during gametes formation
Applies to all sexually reproducing organisms
All the offsprings of a cross between a black-eyed mendelien and an orange-eyed memdelien have black eyes. What's the expected pheontypic ratio of a cross between two oranges-eyed mendeliens?
0 black-eyed :1 orange -eyed
The alleles of a gene are found at _____chromosomes
The same locus on homologous
The phenotypic ration resulting from a dihybrid cross showing independent assortment is expected to be
9:3:3:1
Mendel's law of independent assortment states that
each pair of alleles segregates independently of the other pairs of alleles during gamete formation
Imagine that we mate two black Labrador dogs with normal vision and find that three of the puppies are like the parents, but one puppy is chocolate with normal vision and another is black with PRA (progressive retinal atrophy, a serious disease of vision). We can conclude that
the alleles for color and vision segregate independently during gamete formation
A testcross is
a mating between an individual of unknown genotype and an individual heterozyous recessive for the trait of interest
Using a six sided die, what is the probability of rolling either a 5 or a 6?
1/6 +1/6 =1/3
Assumimg that the probability of having a female child is 50% and the probability of having a male cjild is also 50 what is the probability that a couple's first-born-child will be female and that their second child will be male?
25%
A carrier of a genetic disorder who does not show symptoms is most likely to be___ to transmit it to offspring
Heterozygous for the trait and able
Dr. Smith's parents have normal hearing. However, Dr. Smith has an inherited form of deafness. Deafness is a recessive trait that is associated with the abnormal allele d. The normal alleles at this locus, associated with normal hearing is D. Dr. Smith's parents could have which of the following genotypes?
Dd and Dd
Most genetic disorders of humans are caused by
recessive alleles
The vast majority of people afflicted with recessive disorders are born to parents who were
not affected at all by the disease
WHich of the following statements best explains why dominant alleles that cause lethal disorders are less common than recessive alleles that cause lethal disorders
Most individuals carrying a lethal dominant allele have the disorder and die before they reproduce, whereas individuals carrying a lethal recessive allele are more likely to be healthy and reproduce
Aminocentesis and chronic villus sampling allow for _____and_____ of the fetus so that it can be tested for abnormalities
Karyotyping ... Biochemical testing
Which of the following statements regaridng prenatal testing is false?
Chorionic viilus sampling is typically performed later in the pregnancy than amniocentesis
Which of the following statements regarding genetic testing is false?
Most human genetic diseases are treatable id caught early.
For most sexually reproducing organisms, Mendel's Lawa
Cannot strictly account for most patterns of inheritance.
Which of the following statements is false?
incomplete dominance supports the blending hypothesis
all the offspring of a cross between a red-flowered plant and a white -flowered plant have pink flowers. This means that the alleles for red flowers is_______to be the alleles for white flowers
incomplete dominance
Imagine that beak color is a finch species is controlled by a single gene. You mate a finch homozygous for orange (pigmented) beak with a finch homozygous for ivory (unpigmented) beak and get numerous offspring, all of which have a pale, ivory-orange beak. This pattern of color expression is most likely to be an example of
incomplete dominance
Which of the following is an example of incomplete donminance in humans?
hypercholesterolemia
the expression of both alleles for a trait in a heterozygous individual illustrates
codominance
A person with AB blood illustrates the principle of
codominance
Which of the following statements regarding sickle-cell disease is false?
Sickle-cell disease causes white blood cells to be sickle-shaped
Sickle-cell disease is an example of
codominace and pleiotropy
Which of the following terms refers to a situation where a single phenotypic character is determined by the a effects of two or more genes?
polygenic inheritance
The individual features of all organisms are the result of
genetics and the environment.
The chromosome theory of inheritance states that
the behavior of chromosomes during meiosis and fertilization accounts for patterns of inheritance.
Genes located close together on the same chromosomes are referred to as___genes and generally___
liked....do not sort independently during meiosis
Linked genes generally
do not follow the laws of independent assortment
You conduct a dihybrid cross and then testcross the generation.A ___ratio would make you suspect that the genes are limked
7:7:1:1
Crossing over___genes into assortments of __not found in the parents
recombines linked ...alleles
The mechanism that "breaks" the linkage between linked genes is
crossing over
Which of the following kinds of data could be used to map the relative position of three genes on a chromosome?
the frequencies with which the corresponding traits occur together in offspring?
What is the normal complement of sex chromosomes in a human male?
one X chromosome and one Y chromosome
The sex chromosome complement of a normal human male is
XY
How many sex chromosomes are in a human gamete?
one
How is sex determined in most ants and bees?
by the number of chromosomes
Given the sex determination system in bees, we can expect that
Females bees will produce eggs by meiosis, while male bees will produce sperm by mitosis
What is meant by the statement that "male bees are fatherless"?
Male bees develop from unfertilized eggs
Any gene located in a sex chromosome
is called a sex-linked gene.
Recessive X-linked traits are more likely to be expressed in a male fruit fly than a female fruit fly because
the male's phenotype results entirely from single Xlinked gene.
A color blind woman marries a man who is not color blind. All of thier sons, nut none of their daughter, are color-blind. Which of the following statement correctly explains results?
The gene for color version is linked to the X chromosome
Sex-linked conditions are more common in men then in women because
Men need to inherit only one copy of the recessive allele for the condition to be fully expressed.
According to scientists, about what percentage of men currently living in Central Asia may be descended from Monogolian ruler Genghis Khan>
8%
Female inheritance patterns cannot be analyzed by simply studying the X chromosome because
the X Chromosomes is obtained from both father and mother
character
a heritable feature
trait
a distinguishing characteristic or quality
true-breeding
plants that produce offspring of the same variety when they self pollinate
hybridization
the mating, or crossing, of two varieties
P generation
The first set of parents crossed in which their genotype is the basis for predicting the genotype of their offspring, which in turn, may be crossed
F1 generation
the generation resulting immediately from a cross of the first set of parents
F2 generation
The second filial generation, which is comprised of offspring(s) resulting from a cross of the members of F1 generation.
alleles
alternate versions of a gene
dominant allele
in a heterozygote, the allele that is fully expressed in the phenotype
recessive allele
in a heterozygote, the allele that is completely masked in the phenotype
law of segregation
Mendel's fist law, stating that allele pairs separate during gamete formation, and then randomly reform as pairs during the fusion of gametes at fertilization
punnett square
a diagram used in the study of inheritance to show the results of random fertilization
homozygous
having two identical alleles for a certain trait
heterozygous
having two different alleles for a given genetic character
phenotype
the physical and physiological traits of an organism
genotype
the genetic makeup of an organism
testcross
breeding of an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype. the ration of phenotypes in the offspring determines the unknown genotype
monohybrid
an organism that is heterozygous with respect to a singke gene of interest. results from a cross between parents homozygous for different alleles.
dihybrid
an organism that is heterzygous with respect to two genes of interest. results from a cross between parents double homozygous for different alleles
law of independent assortment
Mendel's second law stating that each allele pair segregates independently during gamete formation; applies when genes for two characteristics are located on different pairs of homologous chromosomes
incomplete dominance
a type of inheritance in which F1 hybrids have an appearance that is intermediate between the phenotypes of the parental varieties
complete dominance
a type of inheritance in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable
codominance
a phenotypic situation in which the two alleles affect the phenotype in separate, distinguishable ways
pleiotropy
the ability of a single gene to have multiple effects
epistasis
a phenomenon in which one gene alters the expression if another gene that is independently inherited
quantitative character
a heritable feature in a population that varies continuously as a result of environmental influences and the additive effect of two or more genes
polygenic inheritance
an additive effect of two or more gene loci on a single phenotypic character
norm of reaction
the range of phenotypic probabilities for a single genotype, as influenced by the environment
multifactorial
a type of phenotypic character influenced by the genetic and environmental factors
pedigree
a family tree describing the occurrence of heritable characters in parents and offspring across as many generations as possible
cystic fibrosis
a genetic disorder that occurs in people with two copies of a certain recessive allele; characterized by an excessive secretion of mucus and consequent vulnerability to infection; fatal if untreated
tay-sachs disease
a human genetic disease caused by a dysfunctional enzyme that fails to break down brain lipids of a certain class; seizures, blindness, and degeneration of motor and mental performance usually become manifest in a few months after birth
sickle-cell disease
a human genetic disease of red blood cells caused by the substitution of a single amino acid in the hemoglobin protein; it is the most common inherited disease among African Americans
huntington's disease
a human genetic disease caused by a dominant allele; characterized by uncontrollable body movements and the degeneration of the nervous system; usually fatal 10-20 years after the onset of symptoms
amniocentesis
a technique for determining genetic abnormalities in a fetus by the presence of certain chemicals or defective fetal cells in the amniotic fluid,obtained by aspiration from a needle inserted into the uterus
chorionic villus sampling (CVS)
a form of prenatal diagnosis to determine genetic abnormalities in the fetus. It entails getting a sample of the placental tissue and testing it.