Kinkle Biology Exam 3 (Clicker)

Each chromosome has a ___________, a point of constriction that bind specific proteins and holds two sister chromatids together.

centromere

What is occurring during S phase of the cell cycle?

DNA synthesis

What part of he cell cycle do cells spend most of their time?

Interphase

Chromosomes start to condense & the spindle starts to form in which phase of the Mitosis?

prophase

Plant cells typically achieve cytokinesis by

forming a cell plate across the middle of the cell.

The two copies of each chromosome in body cells are called

homologous chromosomes.

During which phase of the cell cycle are mitochondria and chloroplasts distributed equally among daughter cells?

There is no mechanism to distribute mitochondria and chloroplasts equally among daughter cells.

The bacterial genome exist as a

single, circular, double stranded DNA molecule.

A chromatid is

one-half of a newly replicated eukaryotic chromosome.

Mature nerve cells are incapable of cell division. These cells are probably in what phase of the cell cycle

G1

What is essentially the reverse of prophase?

Telophase

Cytokinesis occurs right after

Telophase

Animal cells typically achieve cytokinesis by

Forming a cleavage furrow that pinches the cell into two.

The initiation of the S phase and the M phase of the cell cycle depends on a pair of molecules called _______ and _______.

Cdks; cyclin

Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called

cyclins.

Which is the first and primary checkpoint in the cell cycle where a cell will be caused to exit the cycle if this point is not passed?

G1/S

Why do neurons and some other specialized cells divide infrequently?

They have been shunted into G0.

When cyclin binds Cdk, what can occur?

kinase activation can occur

Which of the following statements about cyclin-dependent kinases (Cdks) or cyclin is false?
A) Different Cdks act at different points in the
cell cycle.
B) A Cdk can catalyze the phosphorylation of
other proteins.
C) Cdks use ATP as a substrate.
D) Cyclin is made continuously during the cell
cycle.

Cyclin is made continuously during the cell cycle.

If you wanted to convert a proto-oncogene to an oncogene, what methods would you choose?

genetic damage

What best explains the way that an abnormal p53 causes normal cells to become cancer cells? The abnormal p53 protein....

fails to carry out DNA repair.

During which phase of mitosis do the two sister chromatids become individual chromosomes?

anaphase

Cyclin-dependent kinase (Cdk) is _____.

an enzyme that attaches phosphate

The success of DNA replication is assessed during the ______ phase.

G2

Name the protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active?

Cdk

Which of the following statements best fits as an analogy for a cell with a mutation in a tumor-suppressor gene?
A) The gas pedal of a car gets stuck while
pushed down.
B) The gas pedal of a car does not work at all.
C) The brake pedal of a car gets stuck while
pushed down.
D) The brake pedal of a car does not work at
all.

The brake pedal of a car does not work at all.

Meiosis is used primarily

to produce haploid gametes

At the end of meiosis and cytokinesis, each of the four resulting cells contains

one full set of chromosomes, each a single chromatid.

Crossing over involves the exchange of genetic material between

homologous chromosomes

A particular cell has half as much DNA as other cells in a mitotically active tissue. The cell in question is most likely in

G1

Which statement best explains the way that an abnormal p53 causes normal cells to become cancer cells? The abnormal p53 protein
A) fails to carry out DNA repair.
B) triggers too many cells to grow.
C) damages the normal DNA.
D) stimulates the death of normal cells.

fails to carry out DNA repair

You are studying meiosis in an organism that has 28 chromosomes as its diploid number. How many chromosomes will each nucleus have after meiosis I, but before cytokinesis?

14

You are studying meiosis in an organism that has 28 chromosomes as its diploid number. How many chromosomes will the cell have after meiosis II, but before cytokinesis?

28

What is true of sister chromatids?

They are replicated chromosomes still joined together at the centromere
They are nearly identical in mitotic chromosomes

At the end of the first meiotic division, each chromosome consists of

two chromatids

Which of the following is not true of homologous chromosome pairs?
1 They come from only one of the individual's parents
2 They usually contain slightly different versions of the same genetic information
3 They segregate from each other during meiosis I
4 They synapse during meiosis I

They come from only one of the individual's parents

Which of the following is not true of sister chromatids?
They arise by replication during S phase
They segregate from each other during each mitotic anaphase
They usually contain nearly identical versions of the same genetic information
They segregate from each other during meiosis I

They segregate from each other during meiosis I

One difference between mitosis and meiosis I is that

homologous chromosome pairs synapse during meiosis but not during mitosis

Meiosis and mitosis are both processes that involve nuclear division. What is the difference between the two?

Mitosis is nuclear division, resulting in diploid somatic cells. Meiosis is nuclear division, resulting in haploid gametes.

Diploid organisms use meiosis for the development of gametes. Meiosis consists of how many rounds of nuclear division?

Two

Between the two divisions of meiosis there is

no S phase

At the end of cytokinesis II of meiosis, each of the four resulting cells contains

one full set of chromosomes, each a single chromatid.

Which of the following statements about crossing over is false?
a) Crossing over takes place between non-sister chromatids.
b) Crossing over takes place between sister chromatids.
c) Recombination nodules may be observed.
d) Sites of crossing over are called chiasmata.

Crossing over takes place between sister chromatids

The totality of the alleles present in an organism is called its

genotype

When the two haploid gametes contain two different alleles of a given gene, the resulting offspring is called

heterozygous

Mendel referred to the trait that was expressed in the hybrid, F1 or first filial generation as

dominant.

One of the main reasons genes assort independent of one another is that

they are on different chromosomes.

An allele that is present but unexpressed is

recessive.

True breeding plants will...

produce the same offspring when crossed for many generations

It has been found that at a certain locus of the human genome, 200 different alleles exist in the population. Each person has at most _______ alleles at this locus

2

Let P = purple flowers and p = white, and T = tall plants and t = dwarf. What combinations of gametes could be produced by a heterozygote for both the traits

PT, Pt, pT, pt

In dogs, erect ears and barking while following a scent are due to dominant alleles; droopy ears and silence while following a scent are due to recessive alleles. A dog homozygous dominant for both traits is mated to a droopy-eared, silent follower. The expected F1 phenotypic ratios should be

16:0

In white tigers, the absence of fur pigmentation is caused by a recessive allele. This allele also causes the tigers to be cross-eyed. If two tigers heterozygous for this allele mate and produce offspring, what percentage can be expected to be white and/or cross-eyed

25% will be white and the same 25% will be cross-eyed

In cocker spaniels, black color (B) is dominant over red (b), and solid color (S) is dominant over spotted (s). If the offspring between BBss and bbss individuals are mated with each other, what fraction of their offspring will be expected to be black and spotted?

3⁄4

Crossing spherical-seeded pea plants with wrinkled-seeded pea plants resulted in progeny that all had spherical seeds. This indicates that the wrinkled-seed trait is

recessive

Which of the following statements about Mendelian genetics is false?
a) Alternative forms of genes are called alleles
b) A locus is a gene's location on its chromosome
c) Only two alleles can exist for a given gene in a population
d) A genotype is a description of the alleles that represent an individual's genes

Only two alleles can exist for a given gene in a population

In pea plants, the gene for yellow seeds, Y, is dominant to the allele for green seeds, y. A plant with green seeds must have the genotype

yy

Which statement about an individual that is homozygous for an allele is false?
Each of its cells possesses two copies of that allele
Each of its gametes contains one copy of that allele
It is true-breeding with respect to that allele
Its parents were necessarily homozygous for that allele

Its parents were necessarily homozygous for that allele

Let P = purple flowers and p = white, and T = tall plants and t = dwarf. Of the 16 possible gamete combinations in the dihybrid cross, how many would be the phenotype white, tall

3

A person with cystic fibrosis must have:

Two CTFR genes that are not working correctly

A person without cystic fibrosis must have:

One dominant CTFR gene and one recessive CTFR gene
or
Two dominant CTFR genes

An individual with cystic fibrosis must have parents that:

Both have at least one recessive gene.

The likelihood that a child will inherit cystic fibrosis if his or her parents each have one recessive gene is approximately:

1 in 4 (25%)

The likelihood that a child will inherit cystic fibrosis if his or her parents both have cystic fibrosis is approximately

4 in 4 (100%)

The phenotypic ratio for a testcross with a homozygous individual and a heterozygous individual is ______.

1:1

A dominant allele K is necessary for normal hearing. A dominant allele M on a different locus results in deafness no matter which other alleles are present. If a kkMm individual is crossed with a Kkmm individual, _______ percent of the offspring will be deaf

75

If a trait not expressed in the F1 generation reappears in the F2 generation, the inheritance of the trait in question is a(n) example of

dominance and recessiveness

In a simple Mendelian monohybrid cross, true-breeding tall plants are crossed with short plants, and the F1 plants, which are all tall, are allowed to self-pollinate. What fraction of the F2 generation are both tall and heterozygous?

1⁄2

A test cross can be used to do all of the following except

identify the chromosome on which a gene is located

Yellow-seeded plants might be homozygous or heterozygous. We could find out which by crossing these plants with

true breeding green-seeded plants.

Height and eye colors are two examples of continuous variation in humans. Whereas in pea plants the tall allele is dominant over the short allele, there are no intermediate heights in peas. Which of the following is the best explanation for the differences described above?

Many genes, rather than one gene for a characteristic, control some variations in species.

In the ABO blood type system,

A and B are codominant

In Mendel's experiments, if the allele for tall (T) plants was incompletely dominant over the allele for short (t) plants, what offspring would have resulted from crossing two Tt plants?

1/4 tall; 1/2 intermediate height; 1/4 short

In a typical Mendel experiment on pea-seed color, if the dominant yellow seed-bearing plant was crossed with the recessive green seed-bearing plant, the F2 generation will show what ratio of each kind?

3 yellow: 1 green

Traits that are carried on the X chromosome are said to be ________________.

sex-linked

If an XY human had a deletion of the SYR gene, they would

develop as a female.

In humans, the male has an X and Y sex chromosome. The human female has two X chromosomes. In birds, the female has a Z and a W sex chromosome while the male has two Z chromosomes. Which of the following statements is accurate about which parent controls the sex of the offspring?

In humans the male controls the sex of the offspring, and in birds the female controls the sex.

Irene and William are having their first child. Irene knows her blood type is A, but William does not know his blood type. However, William knows that his mother and father were B. Their first child is a boy named Gregory. Gregory has type O blood. Irene and William do not understand how this happened. You could explain this to them using which of the following choices?

Irene's genotype is AO, and William's genotype is BO; thus, Gregory expresses the phenotype of O

Y-linked genes include a gene that produces hairy pinnae (the external ear). A male with hairy pinnae will pass this trait

only to his sons

Cleft chin is a sex-linked dominant trait. A man with a cleft chin marries a woman with a round chin. What percent of their female progeny will show the cleft chin trait?

100

What percent of their male progeny will show the cleft chin trait?

0

It is predictable that about half of the human babies born will be male and half will be female because

of the segregation of the X and Y chromosomes during male meiosis

Linked genes are genes that

are found on the same chromosome

How is genetic linkage related to the principle of independent assortment?

If two loci are linked then they do not assort independently

White eyes is a recessive sex-linked trait in fruit flies. If a white-eyed female fruit fly is mated to a red-eyed male, their offspring should be

all white-eyed males, all red-eyed females

If a female was a carrier for sex-linked color blindness, what percentage of her male children would also be color blind?

50%

Organisms generally have many more genes that assort independently than the number of chromosomes. This phenomenon is due to

crossing over.

In sex-linked inheritance of a recessive gene, all

male offspring who receive the mutant X chromosome would show the trait.

In a two-point cross to map genes A and B, you obtained 98 recombinant flies out of a total of 730 progeny. How far apart are these genes?

13.4 cM

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?

8

In tomatoes, tall is dominant to short, and smooth fruits are dominant to hairy fruits. A plant homozygous for both dominant traits is crossed with a plant homozygous for both recessive traits. The F1 progeny are tested and crossed with the following results: 78 tall, smooth fruits; 82 dwarf, hairy fruits; 22 tall, hairy fruits; and 18 dwarf, smooth fruits. These data indicate that the genes are

linked and show 20 percent recombination

Huntington's disease is caused by an autosomal dominant allele. It is a lethal disease, but it persists in the human population. Which of the following statements best describes why?

Huntington's disease presents symptoms in humans after many have already reproduced; therefore, they are unaware that they passed on Huntington's disease

Generally, mitochondrial genes are inherited through _______

Maternal inheritance

In humans, if a non-disjunction event led to an individual with a genotype of XXY, they would

be male because they have a Y chromosome

A same-sex couple wants to have a child in which they both contribute genetically to the offspring. Assuming it was technically possible to replace the DNA found in a sperm with female DNA, or DNA found in the egg with male DNA, what other scientific obstacle must be overcome?

genetic imprinting

Which of the following is not a component of nucleic acids?

protein

Fourteen percent of the DNA nucleotides from a certain organism contain T. What amounts of the other bases would you expect to be present in this particular DNA?

14 % A, 36 % C, 36 % G

The two strands across from each other in a single DNA molecule are

complementary.

The chemical bond connecting one nucleotide with the next one along a single nucleic acid chain is called a

phosphodiester bond.

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

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