unit 5 mcq test

heredity

which of the following statements about genes is incorrect? A) Genes correspond to segments of DNA.

B) Many genes contain the information needed for cells to synthesize enzymes and other

proteins.

C) During fertilization, both the sperm and the ovum contribute genes to the resulting fertilized

egg.

D) One gene only is used in a specific cell type.

E) Genetic differences can result from changes in the DNA called mutations.

D) One gene only is used in a specific cell type.

How do the two members of a pair of homologous chromosomes differ from each other?

A. their length

B. the identity and relative position of the genes present on each of the chromosomes

C. their staining patterns

D. the position of the centromere within each of the chromosomes

E. the precise sequence of the DNA within each of the chromosomes

E. the precise sequence of the DNA within each of the chromosomes

By examining a karyotype, it is possible to determine…

A) which of two related plant forms is a gametophyte, and which is a sporophyte.

B) the sex of an animal.

C) the age of a fungus.

D) A and B only

E) A, B, and C

D) A and B only: which of two related plant forms is a gametophyte, and which is a sporophyte and the sex of an animal.

The human X and Y chromosomes are

a. are almost entirely homologous, despite their different names.

b. include genes that determine an individual's sex.

c. are of approximately equal size and number of genes.

d. are both present in every somatic cell of males and females alike.

e. include only genes that govern sex determination.

b. include genes that determine an individual's sex.

Which of these statements is false?
A. At sexual maturity, ovaries and testes produce diploid gametes by meiosis.
B. Sexual life cycles differ with respect to the relative timing of meiosis and fertilization.
C. In humans, each of the 22 maternal autosomes has a homologous paternal chromosome.
D. Single, haploid (n) sets of chromosomes in ovum and sperm unite during fertilization, forming a diploid (2n), single-celled zygote.
E. In humans, the 23rd pair, the sex chromosomes, determines whether the person is female (XX) or male (XY).

A. At sexual maturity, ovaries and testes produce diploid gametes by meiosis.

which of the following is the term of a human cell that contains 22 pairs of autosomes and two X chromosomes

a. an unfertilized egg

b. a sperm cell

c.a male somatic cell

d. a female somatic cell

e. an unfertilized egg cell and a female somatic cell

d. a female somatic cell

In animals, meiosis results in gametes, and fertilization results in

A) spores.

B) gametophytes.

C) zygotes.

D) sporophytes.

E) clones.

C) zygotes.

After telophase I of meiosis, the chromosomal makeup of each daughter cell is

A. diploid, and the chromosomes are each composed of two chromatids

B. haploid, and the chromosomes are each composed of two chromatids

C. diploid, and the chromosomes are each composed of a single chromatid

D. haploid, and the chromosomes are each composed of a single chromatid

B. haploid, and the chromosomes are each composed of two chromatids

How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis?

A.
They have twice the amount of cytoplasm and half the amount of DNA.

B.
They have half the number of chromosomes and half the amount of DNA.

C.
They have the same number of chromosomes and half the amount of DNA.

D.
They have half the number of chromosomes and one-fourth the amount of DNA.

E.
They have half the amount of cytoplasm and twice the amount of DNA.

D.

They have half the number of chromosomes and one-fourth the amount of DNA.

Which of the following is true of the process of meiosis?

A) Four autosomes result

B) Four diploid cells result

C) Two diploid cells result

D) Four chiasmata result

E) Four haploid cells result

E) Four haploid cells result

crossing over occurs during which phase of meiosis

a) prophase 1

b) anaphase 1

c) telophase 1

d) prophase 2

e) metaphase 2

a) prophase 1

You have in your possession a microscope slide with meiotic cells on it and a light microscope. What would you look for if you wanted to identify metaphase I cells on the slide?
A) a visible nuclear envelope
B) separated sister chromatids at each pole of the cell
C) tetrads lined up at the center of the cell
D) a synaptonemal complex
E) a cleavage furrow

C) Tetrads lined up at the center of the cell

For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes based on the independent assortment of chromosomes during meiosis?

about 8 million

Independent assortment of chromosomes is a result of _____.

the random way each pair of homologous chromosomes lines up at the metaphase plate during meiosis I

Which of the following statements about crossing over is incorrect?

A) Crossing over combines sections of the maternal and paternal chromosomes.

B) Crossing over plays a role in both sexual and asexual reproduction.

C) There are on average one to three crossover events per chromosome.

D) Crossing over increases the extent of genetic variation beyond what is possible through independent assortment alone.

E) Crossing over results in recombinant chromosomes

B) Crossing over plays a role in both sexual and asexual reproduction.

What name is given to the process that restores the diploid number of chromosomes?

fertilization

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.

Telophase I

Homologous chromosomes migrate to opposite poles during _____.

Anaphase I

Synapsis occurs during..

prophase 1

In a cell in which 2n=6, the independent assortment of chromosomes during meiosis can by itself give rise to ___ genetically different gametes.

eight

1) Pea plants were particularly well suited for use in Mendel's breeding experiments for all of the following reasons except that:
A) Peas show easily observed variations in a number of characters, such as pea shape and flower color.
B) It is possible to control matings between different pea plants.
C) It is possible to obtain large numbers of progeny from any given cross.
D) Peas have an unusually long generation time.
E) Many of the observable characters that vary in pea plants are controlled by single genes.

D) Peas have an unusually long generation time.

A plant with purple flowers is allowed to self-pollinate. Generation after generation, it produces purple flowers.
This is an example of
A) hybridization.
B) incomplete dominance.
C) true-breeding
D) the law of segregation.
E) polygenetics.

C) true-breeding

The f1 offspring on mendels classic pea cross always looked like one of the 2 parental varieties because..

one allele was dominant

what is a genetic cross between an individual showing a dominant phenotype but an unknown genotype…

test cross

Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. What does this suggest?

A. that the parents were both heterozygous for a single trait

B. that each offspring has the same alleles for each of two traits

C. that the trait shows incomplete dominance

D. that a blending of traits has occurred

E. that the parents were true-breeding for contrasting traits

A. that the parents were both heterozygous for a single trait

Which of the following is false, regarding the law of segregation?
Select one:
a. It states that each of two alleles for a given trait segregate into different gametes.
b. It can be explained by the segregation of homologous chromosomes during meiosis.
c. It can account for the 3:1 ratio seen in the F2 generation of Mendel's crosses.
d. It can be used to predict the likelihood of transmission of certain genetic diseases within families.
e. It is a method that can be used to determine the number of chromosomes in a plant.

e. It is a method that can be used to determine the number of chromosomes in a plant.

Mendel accounted for the observation that traits that had disappeared in the F1 generation reappeared in the F2 generation by proposing that__.

traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1

In certain plants, the tall trait is dominant to the short trait. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short

0%

Tallness (T) in snapdragons is dominant to dwarfness (t), while red (R) flower color is dominant to white (r). The heterozygous condition results in pink (Rr) flower color.

6:3:3:2:1:1

a cross between a true-breeding sharp-spines cactus and a spineless cactus would most likely all be

sharp spined, assuming that sharp spines are a dominant trait over spinelessness.

A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r, respectively. A third gene for the MN blood group has co dominant alleles M and N.

Which of the following is a possible phenotype for the father?

B positive

Which of the following is an example of polygenic inheritance?

Skin pigmentation in humans

individuals with this disorder are unable to metabolize certain lipids, affecting brain development. Affected individuals die in early childhood

tay-sachs disease

Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by which of the following?

environmental factors such as soil pH

the allele for blue hydrangea being completely dominant

the knowledge that multiple alleles are involved

the alleles being codominant

environmental factors such as soil pH

All the offspring of a cross between a black eyed Mendelian and an orange eyed Mendelian have black eyes. What is the expected phenotypic ratio of a cross between two orange eyed Mendeliens?

0 black eyed: 1 orange eyed

all the offspring of a cross between a red flowered plant and a white flowered plant have pink flowers. this means that the allele for red flowers is for white flowers.

incomplete dominant

Chromosomes and genes share all of the following characteristics except that

A) they are both present in pairs in all diploid cells.

B) they both undergo segregation during meiosis.

C) their copy numbers in the cell decrease after meiosis, and increase during fertilization.

D) they are both copied during the S phase of the cell cycle.

E) they both pair up with their homologues during prophase of mitosis.

E) they both pair up with their homologues during prophase of mitosis.

When Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?

A) The gene involved is on the Y chromosome.

B) The gene involved is on the X chromosome.

C) The gene involved is on an autosome, but only in males.

D) Other male-specific factors influence eye color in flies.

E) Other female-specific factors influence eye color in flies.

B) The gene involved is on the X chromosome.

Males are more often affected by sex-linked traits than females because...

a. males are hemizygous for the X chromosome.

b. male hormones such as testosterone often alter the effects of mutations on the X chromosome.

c. female hormones such as estrogen often compensate for the effects of mutations on the X.

d. X chromosomes in males generally have more mutations than X chromosomes in females.

e. mutations on the Y chromosome often worsen the effects of X-linked mutations.

a. males are hemizygous for the X chromosome.

What is the chromosomal system for determining sex in mammals?

X-Y

most Calico cats are female because?

a male inherits only one of the two x-linked genes controlling hair color

a man who carries an x-linked allele will pass it on to?

all of his daughters

A Barr body is normally found in the nucleus of which kind of human cell?

C) Somatic cells of a female only

One possible result of chromosomal breakage can be that a fragment reattaches to the original chromosome in a reverse orientation. This is called___.

inversion

what do all human males inherit from their mother?

mitochondrial DNA and an X chromosome

If a chromosome lacks certain genes, what has most likely occurred?

deletion

Genes (alleles) that are located on the same chromosome and are often inherited together and are said to be

linked

Alternate forms of the same gene are called _____.

alleles

A pedigree analysis for a given disorder's occurrence in a family shows that, although both parents of an affected child are normal, each of the parents has had affected relatives with the same condition. The disorder is then which of the following?

A) Maternally inherited

B) Recessive

C) Incompletely dominant

D) Dominant

E) A new mutation

B) Recessive

Expressions of a trait such as yellow versus green seeds are referred to as:

a. varieties

b. phenotypes

c. genotypes

d. factors

e. allele

b. phenotypes

In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?

tortoiseshell females; black males

Which of the following is true regarding linkage maps? They

C) are a genetic map based on recombination frequencies.

What is the mechanism for the production of genetic recombinants?

crossing over and independent assortment

What does a frequency of recombination of 50% indicate?

A) The genes are located on sex chromosomes.

B) The two genes are likely to be located on different chromosomes.

C) All of the offspring have combinations of traits that match one of the two parents.

D) Independent assortment is hindered.

E) Abnormal meiosis has occurred

B) The two genes are likely to be located on different chromosomes.

New combinations of linked genes are due to which of the following?

crossing over

how would one explain a test cross involving F1 dihybrid flies in which more parental type….

the two genes are linked and present on the same chromosome.