Unit 4 Biology Review

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In Mendel's time, most people believed that

characteristics of parents were blended in the offspring

Darwin did not know which mechanisms were responsible for the variation he saw


In his experiments with plants, Mendel removed which part of the plant to prevent unwantd fertilizations?


A locus is

the location of an allele on a chromosome

Various forms of a gene at a given locus are called


What indicates homozygous genotypes

AA and aa

What genotypes show dominant phenotypes

Aa and AA

Hybrid organisms produced from a cross between two pure-breeding organisms belong to which generation

F1 (first generation)

According to Mendel, what kind of genes "disappear" in F1 pea plants?


If R is dominant to r, the offspring of the cross of RR with rr will

display the same phenotype as the RR parent

Mendel found that pea plants expressing a recessive trait

were pure-breeding

If tall (D) is dominant to dwarf (d), and two homozygous varieties DD and dd are crossed, then what kind of offspring will be produced?

all tall

If tall (D) is dominant to dwarf (d), and two homozygous varieties DD and dd are crossed, then what kind of offspring will be produced?

all Dd

The F2 phenotypic ratio of a monohybrid cross is


If all offspring of a cross have the genotype Aa, the parents of the crosses would most likely be

AA x aa

Short hair (L) is dominant to long hair (l). If a short-haired animal of unknown origin is crossed with a long-haired animal and they produce one long-haired and one short-haired offspring, the results would indicate that

The short-haired animal was heterozygous

For Mendel's explanation of inheritence to be correct

which gametes combine at fertilazation had to be due to chance

The results of a testcross reveal that all offspring resemble the parent being tested. That parent necessarily is


The theory of segregation

explains the behavior of a pair of alleles during meiosis

If short hair (L) is dominant to long hair (l), then what fraction of the offspring produced by a cross of Ll ´ ll will be homozygous dominant?

none (no chance of this offspring)

Two brown dogs mated. Their offspring were five brown puppies and two white puppies. The most probable genotypes of the two brown dogs are

both Bb

Mendel's principle of independent assortment states that

Each hereditary unit is inherited separately from other hereditary units.

An individual with a genetic makeup of aa BB is said to be


If a child belonged to blood type O, he or she could not have been produced by which set of parents?

type AB mother and type O father

Susan, a mother with type B blood, has a child with type O blood. She claims that Craig, who has type A blood, is the father. He claims that he cannot possibly be the father. Further blood tests ordered by the judge reveal that Craig is AA. The judge rules that

Craig is right and doesn't have to pay child support.

If a child has an AB blood type, the parents

can have different blood types, but neither can be blood type O

Coat color in one breed of mice is controlled by incompletely dominant alleles so that yellow and white are homozygous, while cream is heterozygous. The cross of two cream individuals will produce

equal numbers of white and yellow mice, with twice as many creams as the other two colors

In incomplete dominance

One allele is not dominant to the other allele

In incomplete dominance

The genotype can be determinded by the phenotype

In incomplete dominance

The heterozygote is somewhat intermediate to the two homozygotes

In incomplete dominance

The intermediate phenotype may be the result of enzyme insufficiency

If a pure-breeding long-tail cat (LL) is crossed with a pure-breeding cat with no tail (rumpy, ll), and a cat with a short tail (stumpy) is produced, the simplest explanation is

an incompletely dominant gene

A gene that produces multiple effects is called a(n)

pleiotropic gene

Pleiotropic genes

influence more than one aspect of phenotype

Which of the following is not a known result of Marfan syndrome?

The aortic connective tissue becomes too thick and rigid

All of the genes located on a given chromosome comprise a

linkage group

If two genes are on the same chromosome,

They are in the same linkage group

Genes that are located on the same chromosome

tend to be inherited together

Genes that are located on the same chromosome

usually appear together in the gamete

Genes that are located on the same chromosome

are said to be linked

Genes that are located on the same chromosome

may be separated during crossing over

Genes on the same chromosome are separated from each other by

crossing over

Children born to light-skinned women exposed to high levels of sunlight have a heightened risk of birth defects because

UV radiation breaks down folate

This may be influenced by the enviroment

ability of plants to grow

This may be influenced by the enviroment

shape of Daphnia heads

This may be influenced by the enviroment

how people handle stress

This may be influenced by the enviroment

fur color in Himalayan rabbits

A bell-shaped curve of phenotypic variation is a representation of

continuous variation

Melanin pigment can be present in which eye colors

blue, hazel, brown

Green pod, purple flower, yellow seed coat, dwarf plant, axial flower position - Of these, which is not a dominant trait?

dwarf plant

Homozygous, carrier, heterozygotes, hybrid, Aa - Of these, which is not a heterozygoous condition?


pure breeding, homozygous, heterozygous, carrier, phenotype - Of these, which is not discriptive of gene makeup?


Chromosomes other than those involved in sex determination are known as


Sex chromosomes

determine sex

Sex chromosomes

vary from one sex to another

Sex chromosomes

carry some genes that have nothing to do with sex

Sex chromosomes

were unknonw to Mendel

Designates a normal human female


Designates a normal human male


The SRY gene is found on

the human Y chromosome

______ males have two of the same sex chromosomes


A karyotype

is a visual display of chromosomes arranged according to size

Chemical used to keep chromosomes from separating during metaphase


Karyotyping involves taking pictures of chromosomes during


achondroplasia, cysitic fibrosis, huntingtong disease, marfan syndrom, progeria - Of these, which is no an autosomal dominant genetic disorder?

Cysitc Fibrosis (autosomal recessive genetic disorder)

A normal woman mated with a man with achondroplasia whose father was normal. What is the chance that this mating will produce offspring with achondroplasia?

0.50 (50 percent)


is an autosomal recessive inheritance and must be homozygous to be expressed

A normal woman whose father had galactosemia mated with a normal man whose mother also was galactosemic. What is the chance that they will have galactosemic children?

0.25 (25 percent)

Progeria is caused by a(n)

spontaneous dominant mutation

A colorblind man and a woman with normal vision whose father was colorblind have a son. Colorblindness, in this case, is caused by an X-linked recessive gene. If only the male offspring are considered, the probability that their son is colorblind is

0.50 (50 percent)

A colorblind man and a woman with normal vision whose father was colorblind have a daughter. Colorblindness, in this case, is caused by an X-linked recessive gene. The probability that their daughter is colorblind is

0.50 (50 percent)

Red-green colorblindness is an X-linked recessive trait in humans. A colorblind woman and a man with normal vision have a son. What is the probability that the son is colorblind?

100 percent

Red-green colorblindness is an X-linked recessive trait in humans. What is the probability that a colorblind woman and a man with normal vision will have a colorblind daughter?

0 percent

If a daughter expresses an X-linked recessive gene, she inherited the trait from

both parents

A human X-linked recessive gene may be

passed to daughters from their fathers and to sons from their mothers

An X-linked carrier is a

heterozygous female

Colorblindness is an X-linked trait in humans. If a colorblind woman marries a man with normal vision,

Their sons will be colorblind; daughters will be carriers

A woman heterozygous for colorblindness (an X-linked recessive allele) marries a man with normal color vision. What is the probability that their first child will be colorblind?

25 percent

Queen Victoria

was a carrier of hemophilia


is rare in the human population


is more common among men


was common in English royalty


is an X-linked recessive trait

A chromosome's gene sequence that was ABCDEFG before modification and ABCDLMNOP afterward is an example of


A chromosome's gene sequence that was ABCDEFG before modification and ABCDCDEFG afterward is an example of


A chromosome that has been broken and rejoined in a reversal sequence has undergone


A chromosome's gene sequence that was ABCDEFG before damage and ABCFG after is an example of


A chromosome's gene sequence that was ABCDEFG before damage and ABFEDCG after is an example of


Cri-du-chat is caused by a(n)


Human chromosomes differ from chimpanzee chromosomes mainly by


The condition occurring when an organism has a 2n + 1 chromosome composition is known as


Down syndrome involves trisomy


The sex chromosome composition of a person with Turner syndrome is


The sex chromosome composition of a person with Klinefelter syndrome is


A genetic abnormality that may result in low fertility males with mental retardation or breast enlargement is


Males who tend to be taller than average and show mild mental retardation may have the _____ chromosome complement


Nondisjunction involving the X chromosomes may occur during oogenesis and produce two kinds of eggs. If normal sperm fertilize these two types, which of the following pairs of genotypes are possible?

None of these

What would be the least satisfactory organism for genetic research?


In a pedigree chart, a male showing the specific trait being studied is indicated by

darkened square

In a pedigree chart, a female who does not deomonstrate the trait being studied is represented by

clear circle

What is not inherited as an autosomal recessive

Marfan's syndrome

More common in males


How soon after conception is the best time for amniocentesis

8-12 weeks

Amniocentesis involves sampling

the fetal cells floating in the amniotic fluid

Amniocentesis is

used in prenatal diagnosis to detect chromosomal mutations and metabolic disorders in embryos

Chroionic villus sampling can be performed as early as _____ weeks after conception


Preimplantation diagnosis

relies on in-vitro fertilization

What membrane helps form the placenta and can yield cells for early prenatal diagnosis


symptoms of phenylketonuria (PKU) may be minimized or suppressed by a diet low in


Phenotypic treatments

may increase the number of defective genes in the population

What does not provide evidence that genes are located on chromosomes

enviromental factors may influence gene expression

What is not a related condition in which abnormal numbers of chromosomes are present

complete chromosome set

What organism is not widely used in genetic research


What condition is not caused by chromosomal nondisjunction

Huntington disorder

Inhibits microtuble assembly; prevents chromosome movement


a piece of the chromosome is inadvertently left out during the repair process


a repeat of a particular DNA sequence in the same chromosome or in nonhomologous ones


a chromosome segment that has been cut out and rejoined at the same place, but backward


(2n-1) a gamete deprived of a chromosome


a chromosome segment is permanently transferred to a nonhomologous chromosome


(2n+1) three chromosomes of the same kind are present in a set of chromosomes


Nondisjunction of the twenty first chromosomal pair

Down syndrome

autosomal recessive inheritence


x-linked recessive inheritance


nondisjunction of the sex chromosome

turner syndrome

autosomal recessive inheritance


autosomal dominant inheritance

huntingtons disease

x-linked recessive inheritance


autosomal recessive inheritence

sickle cell

Johann Miescher is credited with

discovering nucleic acids

The significance of Fred Griffith's experiment in which he used two strains of Streptococcus pneumoniae is that

it demonstrated that harmless cells had become permanently transformed through a change in the bacterial hereditary system

What is NOT true about Fred Griffiths experiment

mice injected with heat-killed S bacteria die

Which scientisits identified the transforming substance involved in changing R bacteria to S


Bacteriophages are


the significance of the experiments in which 32p and 35s were used is that

it demonstrated that radioactively labeled bacteriophages transfer their DNA but not their protein coats to their host bacteria

Nucleic acid contains


Hershey and Chase discovered that 35s and not 32p had been incorporated into the hereditary system of the bacteria

this statement is False

Experiment that determined DNA, not protein, was the hereditary material

Hershey and Chase

Sulfur is

found in proteins but not nucleic acids

The building blocks of nucleic acids are


amino acids, nucleotides, 5-carbon sugars, phosphate, nitrogenous bases - Of these, which does not belong?

amino acids

In the pairing of two nucleotides within the double helix

hydrogen bonds are used, adenine and thymine bind together, purines bind with pyrimidines, double ring nitrogenous bases connect to single ring bases - all of these

a nucleotide may contain

purine, pentose, phosphate group, pyrimidine

Rosalind Franklins research contribution was essential in

establishing most of the principal structural features of DNA

James Watson and Francis Crick

established the double-stranded nature of DNA
established the principle of base pairing
explained how DNA's structure permitted it to be replicated
proposed the concept of the doube-helix

In the bonding of nitrogenous bases

guanine is paired with cytosine

The DNA molecure could be compared to a


In DNA complementary base pairing occurs between

adenine and thymine

Adenine and guanine are

double ringed purines

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