question

Who put forth the important biological principle that all cells come from cells?

answer

Virchow

question

Binary fission in bacterial cells involves ____________.

answer

distribution of a copy of the single parental chromosome to each daughter cell

question

A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain altogether?

answer

92

question

Chromatids are _____. (8.4)

answer

identical copies of each other if they are part of the same chromosome

question

A cell biologist carefully measured the quantity of DNA in grasshopper cells growing in cell culture. Cells examined during the G2 phase of the cell cycle contained 200 units of DNA. What would be the amount of DNA in one of the grasshopper daughter cells? (8.5)

answer

100 units

question

Chromatids form _____. (8.5)

answer

during the S phase

question

In some organisms such as certain fungi and algae, cells undergo mitosis repeatedly without subsequently undergoing cytokinesis. What would result from this? (8.5)

answer

large cells containing many nuclei

question

The function of the cell cycle is to produce daughter cells that _____. (8.5)

answer

are genetically identical to the parent cell (assuming no mutation has occurred)

question

Cytokinesis refers to _____. (8.5)

answer

division of the cell outside the nuclear material

question

At which point in the cell cycle do centrosomes begin to move apart to two poles of the cell in a dividing human liver cell? (8.6)

answer

prophase

question

The phase of mitosis during which the chromosomes move toward separate poles of the cell is _____. (8.6)

answer

anaphase

question

Single sister chromatids are found in cells at mitotic _____. (8.6)

answer

anaphase and telophase

question

Which one of the following does NOT occur during mitosis?

answer

Chromosomes replicate.

question

At which stage of mitosis are chromosomes lined up in one plane in preparation for their separation to opposite poles of the cell? (8.6)

answer

metaphase

question

The kinetochores _____. (8.6)

answer

are sites at which microtubules attach to chromosomes

question

In animal cell mitosis, the cleavage furrow forms during ___________. (8.7)

answer

cytokinesis

question

Which of these factors inhibits cell division? (8.8)

answer

being completely surrounded by other cells

question

Cells will usually divide if they receive the proper signal at a checkpoint in the ____ phase of the cell cycle.

answer

G1

question

Observations of cancer cells in culture support the hypothesis that cancer cells _____. (8.10)

answer

do not exhibit density-dependent inhibition

question

How many pairs of autosomes do humans have? (8.12)

answer

22

question

Which of the following is a normal human female? (8.12)

answer

XX

question

In humans, the __________ determines the sex of the offspring because __________. (8.12)

answer

male ... the male can contribute either an X or a Y chromosome

question

The diploid phase of the human life cycle begins with _____. (8.13)

answer

fertilization

question

In a cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing __________ chromosomes. (8.14)

answer

5

question

At the end of telophase I of meiosis and cytokinesis, there are _____. (8.14)

answer

two haploid cells

question

Synapsis occurs during _____. (8.14)

answer

prophase I

question

During anaphase I _____. (8.14)

answer

homologues separate and migrate toward opposite poles

question

Crossing over occurs during _____. (8.14)

answer

prophase I

question

An organism has a haploid chromosome number n = 4. How many tetrads will form during meiosis? (8.14)

answer

4

question

Synapsis of homologous pairs occurs only during prophase I of the first meiotic division? True or False?

answer

True

question

What is the function of meiosis? (8.14)

answer

to make cells with a haploid (half that of the parents) number of chromosomes

question

Mitosis and meiosis differ in several ways. Meiosis, but not mitosis, _____. (8.15)

answer

involves two bouts of cell division

question

Meiosis is more complicated than mitosis because it carries out more complicated functions. Meiosis must _____. (8.15)

answer

undergo two rounds of cytokinesis

question

Variation occurs when chromosomes are shuffled in _____. (8.16)

answer

meiosis

question

The major contribution of sex to evolution has been _____. (8.16)

answer

to provide a method that creates greater genetic variation.

question

Two chromosomes in a nucleus that carry genes for the same traits in the same loci, but specify different versions of the same traits, are called _____. (8.17)

answer

homologous chromosomes

question

Why is crossing over important? (8.18)

answer

It allows the exchange of genes between homologous chromosomes.

question

Each cell in an individual with Down syndrome contains ____ chromosomes. (8.20)

answer

47

question

During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as _____. (8.21)

answer

nondisjunction

question

Which one of the following is Turner syndrome? (8.22)

answer

XO

question

The basic difference between Mendel's particulate theory of inheritance and the previous blending theory was that the blending theory, but not the particulate theory, maintained that _____. (9.1)

answer

after a mating, genes of the two parents are mixed in the offspring and lose their individual identities

question

Phenylketonuria is an autosomal recessive disorder. Using P and p to represent the alleles, what is the genotype of a phenylketonuric person? (9.3)

answer

pp

question

In a cross between two heterozygotes (Aa), the next generation will be _____. (9.3)

answer

in the ratio 1:1 homozygotes to heterozygotes

question

In Mendel's monohybrid cross of purple-flowered and white-flowered peas, all members of the F1 generation were of the __________ phenotype because their genotype was __________ for the flower-color gene. (9.3)

answer

purple-flowered ... heterozygous

question

An allele is _____. (9.3)

answer

an alternative version of a gene

question

Homologous pairs of chromosomes frequently _____. (9.4)

answer

contain different alleles

question

An AABb individual is mated with another AABb individual. The possible number of genetically different kinds of offspring is _____. (9.5)

answer

3

question

What is indicated when a single-character testcross yields offspring in a 1:1 phenotypic ratio? (9.6)

answer

The parent with the dominant phenotype was heterozygous.

question

If each parent can produce 100 genetically distinct gametes, how many genetically distinct offspring can two parents produce? (9.7)

answer

10,000

question

Tay Sachs disease runs in Rebecca's family. On a family pedigree, she saw a shaded circle. This represented _____. (9.8)

answer

a female with Tay Sachs

question

When two average-height parents give birth to a child exhibiting achondroplastic dwarfism, it is most likely due to a new mutation. This is because _____. (9.9)

answer

achondroplasia is caused by an allele that is always expressed, so the parents couldn't have the allele

question

A red bull is crossed with a white cow and all of the offspring are roan, a shade between red and white. This is an example of genes that are _____. (9.12)

answer

incompletely dominant

question

A single allele that controls more than one character is said to be _____. (9.14)

answer

pleiotropic

question

The genetic test that is used to determine whether someone possesses a potentially harmful recessive allele is referred to as _____ testing. (9.17)

answer

carrier testing

question

Sturtevant's genetic mapping _____. (9.21)

answer

orders genes on a chromosome based on recombination frequencies

question

The Y chromosomes of mammals contain genes that code for ____________. (9.22)

answer

"maleness" and few other traits

question

In an important experiment, radioactively labeled bacteriophages were allowed to infect bacteria. In the first trial, the phages contained radioactive DNA, and radioactivity was detected in the bacteria. Next, other phages containing radioactive protein were allowed to infect bacteria, and radioactivity was not detected in the bacteria. These experiments led to the conclusion that _____. (10.1)

answer

the genes of this phage were made of DNA

question

What technique was most helpful to Watson and Crick? (10.3)

answer

X-ray crystallography

question

The information in DNA is contained in _____. (10.3)

answer

the sequence of nucleotides along the length of one strand of the DNA molecule

question

Which one of the following statements does NOT apply to the Watson-Crick model for DNA? (10.3)

answer

The two strands of the helix are held together by covalent bonds.

question

During the replication of DNA molecules _____. (10.5)

answer

both strands of a molecule act as templates

question

Two new strands of DNA molecules grow as bases are added by the enzyme _____. (10.5)

answer

DNA polymerase

question

What enzyme joins DNA fragments? (10.5)

answer

DNA ligase

question

Monomers for the synthesis of DNA are called _____. (10.5)

answer

nucleotides

question

A polymerase constructs a new strand alongside each old one by pairing complementary nucleotides. True or false?

answer

True

question

Who of the following formulated the one gene-one enzyme hypothesis? (10.6)

answer

Beadle and Tatum

question

Information is transferred from the nucleus to the cytoplasm of eukaryotic cells in the form of _____. (10.7)

answer

nucleic acids

question

A particular ____ carry the information for making a specific polypeptide, but ____ can be used to make any polypeptide. (10.7)

answer

gene and mRNA ... a ribosome and tRNA

question

Each amino acid in a protein is coded for by three bases in the DNA. True or false?

answer

True

question

There are six different codons signaling for the placement of the amino acid leucine in a protein. Because of this, we say that the code is _____. (10.8)

answer

redundant

question

A terminator in mRNA synthesis is _____. (10.9)

answer

a specific nucleotide sequence in DNA that signals a stop

question

Which one of the following catalyzes the linkage between nucleotides to form RNA? (10.9)

answer

RNA polymerase

question

A cell biologist found that two different proteins with largely different structures were translated from two different mRNAs. These mRNAs, however, were transcribed from the same gene in the cell nucleus. Which mechanism below could best account for this? (10.10)

answer

Exons from the same gene could be spliced in different ways to make different mRNAs.

question

Usually, in eukaryotic genes _____. (10.10)

answer

both introns and exons are transcribed, but the RNA transcribed from introns does not leave the nucleus

question

Which one of the following statements correctly describes mRNA processing in eukaryotes? (10.10)

answer

Introns are cut out and the resulting exons are spliced together.

question

A base-substitution mutation in a germ cell line is likely to have NO effect on phenotype if the substitution _____. (10.10)

answer

occurs in an intron

question

In a eukaryotic cell, transcription takes place _____. (10.10)

answer

in the nucleus

question

The bonds that hold tRNA molecules in the correct three-dimensional shape are _____. (10.11)

answer

hydrogen bonds

question

During translation in a eukaryotic cell _____. (10.12)

answer

polypeptides are synthesized at ribosomes, according to instructions carried by mRNA

question

The P site of a ribosome does which one of the following? (10.12)

answer

It holds the growing polypeptide chain.

question

Which one of the following processes does NOT take place in the nucleus? (10.12)

answer

translation

question

The first amino acid inserted into a new polypeptide chain in eukaryotic cells is always _____. (10.13)

answer

methionine

question

During translation, amino acid chain elongation occurs until _____. (10.14)

answer

the ribosome encounters "stop" codons

question

During the process of translation, ____ matches an mRNA codon with the proper amino acid. (10.14)

answer

transfer RNA

question

Imagine an error occurring during DNA replication in a cell, so that where there is supposed to be a T in one of the genes, there is instead a G. What effect will this probably have on the cell? (10.16)

answer

One of its kinds of proteins might contain an incorrect amino acid.

question

The phage reproductive cycle that kills the bacterial host cell is a _____ cycle. (10.17)

answer

lytic

question

A prophage is a(n) _____. (10.17)

answer

viral genetic material that has been incorporated into a bacterial cell's chromosome

question

A microbiologist analyzed chemicals obtained from an enveloped RNA virus—similar to a mumps virus—that infects monkeys. He found that the viral envelope contained a protein characteristic of monkey cells. Which of the following is the most likely explanation? (10.18)

answer

The virus gets an envelope when it leaves the host cell.

question

Which of these is classified as an emerging virus that can have a direct impact on human health? (10.20)

answer

Ebola

question

A bacterium can make the amino acid glycine or absorb it from its surroundings. A biochemist found that glycine binds to a repressor protein and causes the repressor to bind to the bacterial chromosome, turning off an operon. If it is like other operons, the presence of glycine will result in the _____. (11.1)

answer

cessation of the synthesis of glycine

question

Operons _____. (11.1)

answer

function in frequently changing environments

question

Experiments involving _____ have demonstrated that differentiated cells contain all of the genetic information found in undifferentiated cells. (11.3)

answer

nuclear transplantation

question

In frogs, when the nucleus of an intestinal cell of a tadpole is transferred to an egg whose nucleus has been removed (nuclear transplantation), some of the eggs will develop into normal tadpoles. This demonstrates _____. (11.3)

answer

that these cells have retained all of their genetic potential

question

In eukaryotes, DNA packing seems to affect gene expression primarily by _____. (11.4)

answer

controlling access to DNA

question

One of the functions of nucleosomes, structures in the nucleus, is to _____. (11.4)

answer

wrap the DNA to organize it and make it more compact so that a large amount of DNA can fit into a cell nucleus

question

Regions of noncoding DNA within a gene are called _____. (11.7)

answer

introns

question

Following transcription, mechanisms that regulate gene expression may include the __________. (11.8)

answer

initiation of translation, breakdown of RNA, and activation of a protein

question

Why, of all cell types, do embryonic stem (ES) cells have greatest potential for use in the treatment of disease? (11.12)

answer

They are undifferentiated cells that have the potential to differentiate into all of the different specialized cells of the body.

question

An animal's head-to-tail axis is established by _____ (11.13)

answer

egg cell mRNA

question

The cellular response of a signal-transduction pathway that activates a transcription factor would be _____. (11.14)

answer

the synthesis of mRNA

question

Which of these genes inhibit cell division? (11.16)

answer

tumor-suppressor gene

question

A cancer cell _____. (11.16)

answer

does not respond to the signals that control cell division

question

Most human cancers are __________. (11.18)

answer

caused by the accumulation of mutations

question

_____ is the leading cause of death in the United States. (11.20)

answer

Heart disease

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