Bio 111 Exam 3

Which of the sequences is not a palindrome? ATTATT GGATCC GGCGCGCC TTAATTAA ATTTAAAT

ATTATT

How many pairs of chromosomes does the human genome normally have? 6 23 38 46 15

23

The estimated number of genes in the human genome is: 250,000 400,000 15,000 40,000 25,000

25,000

Diploid somatic cells of elephants have 56 chromosomes. If nondisjunction of one of an elephant's chromosomes occurs in meiosis II, the resulting sperm are expected to have the chromosome complement: 28, 28, 28, 28 29, 29, 27, 27 29, 29, 28, 28 28, 28, 29, 27 56, 56, 57, 55

28, 28, 29, 27

Diploid somatic cells of elephants have 56 chromosomes. If nondisjunction of one of an elephant's chromosomes occurs in meiosis I, the resulting sperm are expected to have the chromosome complement: 29, 29, 27, 27 28, 28, 29, 27 28, 28, 28, 28 29, 29, 28, 28 56, 56, 57, 55

29, 29, 27, 27. Elephants have a diploid chromosome number of 28. Nondisjunction in the first meiotic division would produce only aneuploid gametes with either one extra chromosome or one too few.

In human cells, at the end of mitosis and after cytokinesis, how many chromatids have moved into each daughter cell? 23 46 22 92

46

In human cells, at the end of mitosis and after cytokinesis, how many chromatids have moved into each daughter cell? 46 23 92 22

46 Chromosomes are counted if they are derived from contributions from different parents. Thus, there are maternal and paternal homologs of each of the 23 human chromosomes and diploid cells have 46 chromosomes. Copies produced from DNA replication are not counted. They are just copies of either the maternal or paternal homolog, though they do increase the amount of DNA in the cell.

Which of the following is a palindrome? 5'-ATTATT-'3 5'-GGAAGG-'3 5'-CATTAC-3' 5'-AAGCTT-3'

5'-AAGCTT-3'

The lagging strand is the daughter strand that has its _____ end pointed toward the replication fork and is therefore synthesized _____. 5'; continuously 5'; in a series of segments 3'; continuously 3'; in a series of segments

5'; in a series of segments

At the start of mitosis, how many sister chromatids are present in a human cell? 23 46 12 92

92

What correctly describes the role of cell junctions? Desmosomes are cell junctions that form a seal or a barrier between cells Adherens junctions are cell junctions that anchor cells to other cells Tight junctions are cell junctions that anchor cells to the extracellular matrix Hemidesmosomes are cell junctions that anchor cells to other cells.

Adherens junctions are cell junctions that anchor cells to other cells

A couple has a baby that only has one X chromosome and no Y chromosome. This could have occurred because Maternal meiosis I Maternal meiosis II Paternal meiosis I Paternal meiosis II All of the above

All of the Above

Cell cycle checkpoints: can involve being blocked by tumor-suppressor proteins act as a brake on cell division if something is not right All of these choices are correct provide opportunities to check if the cell has carried out steps necessary for cell division.

All of these choices are correct

Many mutations in receptor kinases that lead to cancer allow the receptor to dimerize and become active, even in the absence of signaling molecules. An example is a mutant form of the EGF receptor kinase called Her2/neu. An antibody that prevents dimerization of Her2/neu receptor kinases is being tested for its effectiveness in stopping cancer. Which of the answer choices would be blocked if this antibody was bound to the EGF receptor? cellular response signal transduction All of these choices are correct receptor activation

All of these choices are correct

The extracellular matrix can influence the shape of a cell because: the cytoskeleton determines cell shape All of these choices are correct The extracellular matrix influences cell shape by interactions with cell adhesion molecules that bind to the cytoskeleton cell adhesion proteins on the plasma membrane attach to the extracellular matrix and cell adhesion proteins attach to the cell's cytoskeleton cell adhesion proteins on the plasma membrane attach to the extracellular matrix cell adhesion proteins attach to the cell's cytoskeleton.

All of these choices are correct

What features of DNA make it possible to make recombinant DNA in the lab? All of these choices are correct The genetic code is the same for all organisms Two double helices from different sources can be ligated together Restriction enzymes cut DNA from all species

All of these choices are correct

Mitochondria contain their own double-stranded, circular DNA and replicate on their own. Why don't they suffer the same consequences as our cells in terms of limited division? Because mitochondrial DNA is circular, it does not shorten when it replicates Because they have high telomerase activity Because they have high telomerase activity, and their DNA is circular, so it doesn't shorten in replication Shortening of the DNA is only a problem with nuclear DNA; shortening of mitochondrial DNA is not catastrophic Since mitochondrial DNA only contains a few genes, it can last a lot longer

Because mitochondrial DNA is circular, it does not shorten when it replicates

You find a way to attach either a red or green fluorescent dye to nucleotides. Double-stranded DNA molecules with both strands labeled red fluoresce red, those with both strands labeled green fluoresce green, and those with one strand labeled red and the other green fluoresce yellow. You grow human cells in the presence of "red" nucleotides until both DNA strands of all chromosomes fluoresce red. You then allow one round of DNA replication in the presence of "green" nucleotides.What pattern of fluorescence do you expect to see in the sister chromatids of each chromosome? One chromatid will be red, and the other will be yellow One chromatid will be green, and the other will be yellow Both chromatids will be yellow One chromatid will be red, and the other will be green.

Both chromatids will be yellow

Which one of the choices is a characteristic shared by integrins and cadherins? Both are peripheral membrane proteins Both facilitate the adhesion of cells to extracellular matrix proteins Both are present in adherens junctions, desmosomes, and hemidesmosomes Both proteins have a cytoplasmic domain connected to the cytoskeleton.

Both proteins have a cytoplasmic domain connected to the cytoskeleton.

If a mutation occurred in the cadherin gene so that the cytoplasmic domain no longer attached to the cytoskeleton, which of the following would occur? Cadherins in desmosomes would no longer be anchored to intermediate filaments Cadherin cytoplasmic domain binds to microfilaments in adherens junctions and to intermediate filaments in desmosomes Cadherins in adherens junctions would no longer be anchored to microtubules Cadherins in hemidesmosomes would no longer be anchored to intermediate filaments Cadherins in desmosomes would no longer be anchored to microfilaments

Cadherins in desmosomes would no longer be anchored to intermediate filaments

Which is the function of cyclins? Cyclins activate kinases that regulate passage of cell cycle checkpoints Cyclins replicate DNA during S phase Cyclins function as tumor suppressor genes Cyclins remain in constant concentrations in the cell at all times.

Cyclins activate kinases that regulate passage of cell cycle checkpoints

Which is the function of cyclins? Cyclins remain in constant concentrations in the cell at all times Cyclins replicate DNA during S phase Cyclins function as tumor suppressor genes Cyclins activate kinases that regulate passage of cell cycle checkpoints

Cyclins activate kinases that regulate passage of cell cycle checkpoints

Which is the function of cyclins? Cyclins replicate DNA during S phase Cyclins remain in constant concentrations in the cell at all times Cyclins activate kinases that regulate passage of cell cycle checkpoints Cyclins function as tumor suppressor genes

Cyclins activate kinases that regulate passage of cell cycle checkpoints.

Actin microfilaments and tubulin-based microtubules are important components of the cytoskeleton that function during mitosis. Which process of cell division would be most affected if actin function was blocked? The mitotic spindle would not form The sister chromatids would not separate The chromosomes would not replicate Cytokinesis would not occur to divide the cytoplasm.

Cytokinesis would not occur to divide the cytoplasm.

What is the result of DNA ligase's action? DNA is condensed to chromosomes DNA transcription occurs DNA translation occurs DNA fragments are joined together DNA is broken up at specific sites

DNA fragments are joined together

Which enzyme is the first to bind to the DNA sequences at the origin of replication? DNA polymerase single-strand binding protein DNA helicase DNA primase DNA ligase

DNA helicase

Which of the enzymes is necessary to produce recombinant DNA? topoisomerase DNA ligase helicase Taq polymerase primase

DNA ligase

Transposable elements are: proteins that can move in and out of the nucleus None of the other answer options is correct DNA sequences that can insert themselves into RNA DNA sequences that can insert themselves into new positions within the genome proteins that can move between cells.

DNA sequences that can insert themselves into new positions within the genome

Which of the statements is true regarding chromosome replication in eukaryotes? In humans, it takes several days to replicate an entire chromosome During chromosome replication, multiple origins of replication form for all DNA in a cell None of the answer options is correct Replication bubbles remain distinct, isolated structures during chromosome replication and never fuse with one another Replication begins at one end of the chromosome and proceeds until it reaches the opposite end.

During chromosome replication, multiple origins of replication form for all DNA in a cell

Which of the statements is true regarding chromosome replication in eukaryotes? Replication bubbles remain distinct, isolated structures during chromosome replication and never fuse with one another During chromosome replication, multiple origins of replication form for all DNA in a cell In humans, it takes several days to replicate an entire chromosome None of the answer options is correct Replication begins at one end of the chromosome and proceeds until it reaches the opposite end

During chromosome replication, multiple origins of replication form for all DNA in a cell

A cell that is not actively dividing is in what phase of the cell cycle? S G1 M G2 G0

G0

If a cell underwent mitosis, and its daughter cells were immediately exposed to chemicals that damaged the DNA, at which stage of the cell cycle checkpoint would you predict the cell would arrest? G1 checkpoint G2 checkpoint M checkpoint G1, G2, or the M checkpoints

G1 checkpoint DNA damage that occurs at the beginning of G1 would be detected and cause the cell cycle to arrest at the G1 checkpoint

At which stage of the cell cycle could you see sister chromatids with a microscope? G2 S M G1

M Chromosomes condense during mitotic prophase and are fully condensed at metaphase. At both of these stages, they are visible through a microscope. Prophase and metaphase are both parts of mitosis, which occurs in M phase.

A baby is born with the sex-chromosomes XYY. Both parents have the normal number of chromosomes (46). In which meiotic division (I or II; material or paternal) did the nondisjunction occur? Maternal meiosis I Maternal meiosis II Paternal meiosis I Paternal meiosis II All of the above

Paternal meiosis II

Which of the statements is true regarding telomeres? Telomeres contain non-essential genes that are not necessary for cell survival Telomeres are repaired to the same extent in germ cells and somatic cells Telomeres are enzymes that repair telomerases, which cap the end of linear chromosomes Telomeres are typically only a few base pairs in size Telomeres contain repeated base sequences.

Telomeres contain repeated base sequences.

How do CDKs promote cell division? They cause cyclin levels to increase and decrease They regulate the activity of cyclins.They bind to DNA They change the ability of microtubules to polymerize They phosphorylate proteins that allow passage through cell cycle checkpoints

They phosphorylate proteins that allow passage through cell cycle checkpoints

How do CDKs promote cell division? They bind to DNA They cause cyclin levels to increase and decrease They phosphorylate proteins that allow passage through cell cycle checkpoints They regulate the activity of cyclins They change the ability of microtubules to polymerize

They phosphorylate proteins that allow passage through cell cycle checkpoints Cyclin-dependent kinases (CDKs) have that name because they are kinases whose activation depends upon cyclin binding. When cyclin levels rise, the kinases are activated to phosphorylate and activate proteins required by the next phase of the cell cycle.

Why are single-stranded binding proteins necessary for DNA replication? They provide the energy necessary to separate the two strands of DNA None of the answer options is correct They prevent the two parental strands from coming together again They direct where replication will start They direct the primase where to lay down the primer.

They prevent the two parental strands from coming together again

Why are single-stranded binding proteins necessary for DNA replication? They provide the energy necessary to separate the two strands of DNA They direct the primase where to lay down the primer They prevent the two parental strands from coming together again They direct where replication will start None of the answer options is correct

They prevent the two parental strands from coming together again.

A number of mutations have been described in G proteins that have profound effects on their activity. For example, some mutations greatly increase the affinity of the G protein for GDP, making it very difficult for GDP to be exchanged for GTP. Other mutations prevent the hydrolysis of GTP to GDP. For each of the statements that describe a malfunction in cellular response, indicate the type of mutation that is responsible.The MAP kinase pathway is continually activated, even in the absence of a signaling molecule. Which type of mutation could be responsible for this malfunction in cellular response? a Ras mutant that cannot hydrolyze GTP to GDP a Ras mutant with high GDP affinity Neither of the other answer options is correct

a Ras mutant that cannot hydrolyze GTP to GDP

An epithelial tissue is defined as: a network of cells that use chemical communication a few cells embedded into an extensive extracellular matrix a collection of contractile cells a collection of cells that lines cavities or outside surfaces.

a collection of cells that lines cavities or outside surfaces

The extracellular matrix is: a network of proteins and polysaccharides inside the cell that keep organelles in place a network of proteins found in the cellular membrane that allow for substances to enter the cell a network of proteins and polysaccharides outside the cell that play a role in structural support a network of channel proteins found in the cellular membrane that allow for communication.

a network of proteins and polysaccharides outside the cell that play a role in structural support

A researcher is using a small molecule inhibitor that prevents phosphorylation as a tool to manipulate a signaling pathway. What is the most likely target of this small molecule inhibitor? a G protein-coupled receptor a G protein α subunit a phosphatase a receptor kinase a ligand-gated ion channel

a receptor kinase

If we did not heat the PCR reaction, how else could we get it to work? add ligase and ATP add helicase and ATP add RNA primase add telomerase

add helicase and ATP

A couple has a baby that only has one X chromosome and no Y chromosome. This could have occurred because: there was nondisjunction of homologous chromosomes in meiosis I in the mother. Meiosis in the father was normal. All of these choices are correct there was nondisjunction of sister chromatids in meiosis II of the father. Meiosis in the mother was normal. there was nondisjunction of the paired X and Y chromosomes in meiosis I in the father. Meiosis in the mother was normal. there was nondisjunction of the sister chromatids in meiosis II in the mother. Meiosis in the father was normal.

all of these choices are correct

The microtubules that form the mitotic spindle extend out from the centrosome. Where would you expect to find the plus (fast-assembling) end of a spindle microtubule? away from the centrosome and away from the kinetochore toward the centrosome and away from the kinetochore away from the centrosome and toward the kinetochore toward the centrosome and toward the kinetochore

away from the centrosome and toward the kinetochore

Nucleoids, structures composed of supercoils of DNA that form multiple loops, are found in: insects bacteria protists plants yeast

bacteria

Which cytoskeletal elements are capable of assembling and disassembling in the cell? ntermediate filaments only both microtubules and microfilaments microfilaments only microtubules only

both microtubules and microfilaments

Dynein motor proteins use the energy from ATP to: carry vesicles along a microtubule within a cell in a minus-to-plus direction carry vesicles along a microfilament within a cell in a minus-to-plus direction carry vesicles along a microtubule within a cell in a plus-to-minus direction carry vesicles along a microfilament within a cell in a plus-to-minus direction slide along microfilaments to contract muscle cells.

carry vesicles along a microtubule within a cell in a plus-to-minus direction

The amount of _____ is fairly constant throughout the cell cycle, but the amount of _____ varies. cyclin-dependent kinase; DNA DNA; cyclinscyclin-dependent kinases; cyclins cyclins; DNA

cyclin-dependent kinases; cyclins

Which type of organism packages its DNA in the form of nucleosomes? eukaryotes archaea bacteria All of these choices are correct.

eukaryotes

In a person with the genotype XXY, we can tell that nondisjunction must have taken place in the mother and not the father. false true

false

It is always true that the larger the organism, the larger genome it will have. true false

false

If a restriction site of AatII is 5′-GACGTC-3′ then 3′-GACGTC-5′ is also an AatII restriction site. true false

false Sequence written from 3' to 5' should be complementary to the sequence written from 5' to 3', not identical to it. The correct sequence from 3' to 5' would be 3'-CTGCAG-5'.

A cell in prophase I of meiosis has _____ as much DNA as each of the daughter cells following cytokinesis of meiosis II. four times twice half one quarter

four times

A cell in prophase I of meiosis has _____ as much DNA as each of the daughter cells following cytokinesis of meiosis II. four times half one quarter twice

four times Meiosis starts with a diploid genome that has replicated to make four copies. After two divisions without another DNA replication event between the divisions, each final cell has one copy of the genome.

In contrast to linear DNA replication, circular DNA replication typically: has a single origin of replication occurs only at a single replication fork All of these choices are correct does not produce a replication bubble does not produce Okazaki fragments

has a single origin of replication

Ras is a type of G protein because it: All of these choices are correct responds to the activation of G protein-coupled receptors is only active when it binds GTP triggers the formation of cyclic AMP (cAMP).

is only active when it binds GTP.

Can it be determined from the data in the table which eukaryotic species has the largest genome? Can it be determined which species has the greatest number of chromosomes? yes; yes yes; no no; no no; yes

no; no

The C-value paradox states that genome size: is negatively correlated with the complexity of the organism is uncorrelated with the complexity of the organism differs in reproductive cells and nonreproductive cells is positively correlated with the complexity of the organism

is uncorrelated with the complexity of the organism

The fact that DNA replication occurs in virtually the same way in all organisms reflects: the universal genetic code the fact that mutations are generally harmful its multiple origins in different lineages of organisms its origin early in the history of life the laws of thermodynamics.

its origin early in the history of life

Gel electrophoresis separates DNA fragments based on: nucleotide sequence replication rate length mutations primers

length

Homologous pairs of chromosomes separate during: mitosis only meiosis II only meiosis II and mitosis meiosis I and mitosis meiosis I only

meiosis I only

Myosin is a motor protein that associates with: intermediate filaments microtubules microfilaments vimentin

microfilaments

Cells with cilia rely mainly on _____ to facilitate their movement. intermediate filaments microfilaments microtubules

microtubules

Microtubules and microfilaments are said to be "dynamic" elements of the cytoskeleton. In this case, "dynamic" means that: microtubules and microfilaments are assembled, disassembled, and then reassembled again in a regulated manner microtubules and microfilaments are constantly changing and are never in the same place for very long once individual microfilaments and microtubules have formed, they can change shape and move around inside the cell.

microtubules and microfilaments are assembled, disassembled, and then reassembled again in a regulated manner

Microfilaments increase in length: more quickly at one end than the other by assembling outward from the centrosome in cycles of slower polymerization following rapid depolymerization if free tubulin dimers are available All of these choices are correct.

more quickly at one end than the other

The polymerase chain reaction (PCR) is used to generate: multiple copies of whole chromosomes single copies of whole chromosomes a single copy of a targeted region of DNA multiple copies of a targeted region of DNA multiple copies of whole chromosomes and a targeted region of DNA

multiple copies of a targeted region of DNA

The point at which DNA synthesis is initiated is called the: primer primase replication fork origin of replication start codon

origin of replication

DNA is wrapped around histones, which contain many copies of the positive amino acids lysine and arginine. These positive amino acids neutralize the negative charge of the _____ of the DNA wrapped around the histone. ribose sugar All of these choices are correct hydroxyl group phosphate group nitrogenous base

phosphate group

What is the function of kinase protein? move cargo toward the + end of the microtubule move cargo toward the - end of the microtubule connect two microtubule in motile cilia phosphorylate another protein

phosphorylate another protein

In nerve cells, the centrosome is located near the nucleus. Vesicles move from near the nucleus to the end of long extensions (axons) along microtubules. Based on these two facts, it is possible to conclude that these vesicles are moving in the _____ direction on the microtubule using the motor protein _____. plus end; dynein minus end; kinesin plus end; kinesin minus end; dynein

plus end; kinesin

Crossing over occurs during which step in meiosis? prophase I metaphase I anaphase I prophase II

prophase I

Within a nucleoid, the supercoiled DNA loops are held together by: nucleosomes proteins homologous chromosomes nucleoidal RNAs tubulin

proteins

According to the figure shown, phosphate groups play a key role in receptor kinase activation by: All of these choices are correct providing binding sites to recruit and activate signal-transduction proteins activating the receptor so that the receptor is capable of binding its signal activating the dimerization of the receptor kinase proteins in the membrane activating receptor kinase activity

providing binding sites to recruit and activate signal-transduction proteins

Which of the examples is a transgenic organism? a human who was given a blood-clotting factor produced in bacterial cellsa rat with rabbit hemoglobin genesa a bacterium that has received genes by conjugation a fern grown in cell culture from a single fern root cell a human treated with insulin produced by bacteria

rat with rabbit hemoglobin genes

Nicotine from cigarette smoke acts as a ligand and associates with specific proteins on the surface of cells in the brain, causing feelings of pleasure and well-being. Select the appropriate event in the cellular response to nicotine.The opening of an ion channel as a result of nicotine binding is an example of: termination receptor activation receptor binding signal transduction response

receptor activation

In recombinant DNA experiments, ______ is used to cut pieces of DNA, and ______ joins these segments. DNA ligase; helicaseDNA ligase; a restriction enzyme RNA polymerase; a restriction enzyme DNA polymerase; DNA ligasea restriction enzyme; DNA ligase

restriction enzyme; DNA ligase

What is the name of the class of enzymes that recognizes and cuts a specific sequence of DNA? restriction enzymes helicases topoisomerases DNA polymerases primases

restriction enzymes

Reproduction by mitotic cell division: involves the formation of gametes results in two daughter cells that are genetically identical does not require the replication of chromosomes reduces the number of chromosomes by half

results in two daughter cells that are genetically identical

Reproduction by mitotic cell division: reduces the number of chromosomes by half results in two daughter cells that are genetically identical does not require the replication of chromosomes involves the formation of gametes.

results in two daughter cells that are genetically identical

A mutation occurs that prevents a receptor kinase from dimerizing. What would be the effect on signaling? ligand can still bind to the receptor so signaling will not be affected target genes/enzymes will not be activated activation of signaling pathway in the absence of ligand signal transduction pathway will remain active after ligand dissociates

target genes/enzymes will not be activated

Suppose you carry out a DNA-editing experiment using CRISPR in which the editing template DNA has strands labeled with the heavy nitrogen isotope 15N. The experiment is carried out in the presence of the normal light isotope 14N. Then the expected distribution of the isotope in the strands in the edited region of the target DNA would be: that both strands are labeled with 15N that both strands are labeled with 14N that only one strand is labeled with 14N and the other strand with 15N.

that both strands are labeled with 14N

What feature of double-stranded DNA makes it necessary to have a leading strand and a lagging strand during replication? the antiparallel orientation of the strands the negative charge on the sugar-phosphate backbone the base stacking of the bases the hydrogen bonding between bases

the antiparallel orientation of the strands The base stacking, the negative charge on the sugar-phosphate backbone, and the hydrogen bonding between bases are the same in both strands. The only feature that differs between strands in double-stranded DNA is their orientation; the strands are antiparallel. DNA polymerase can add nucleotides only to 3' end of newly synthesized molecule.

Mitotic cell division is considered asexual because: this form of cell division is most similar to binary fission the daughter cells get different mixes of maternal and paternal chromosomes the daughter cells formed are genetically different the daughter cells receive DNA from one parent cell, and the daughter cells are genetically identical

the daughter cells receive DNA from one parent cell, and the daughter cells are genetically identical

Energy is required in order to add a nucleotide to the growing strand of DNA during replication. From where does that energy come? DNA ligase primase helicase the incoming nucleotide DNA polymerase

the incoming nucleotide

During PCR, where does the energy come from that adds the nucleotide to the growing DNA strand? Taq polymerase ATP the incoming nucleotides the primers the elevated temperature of the PCR reaction

the incoming nucleotides

Okazaki fragments are found on _____ strand of DNA. the lagging the parental both the leading and lagging the leading

the lagging

Okazaki fragments are found on _____ strand of DNA. the leading the lagging the parental both the leading and lagging

the lagging

The centrosome is: a region of the chromosome where sister chromatids are attached to each other a region of the chromosome where kinetochores attach the microtubule organizing center for the mitotic spindle a region of the chromosome where microtubules attach to chromosomes during mitosis.

the microtubule organizing center for the mitotic spindle

Consider a cell in which one of the proteins or enzymes involved in DNA replication is altered in a way that results in an increased rate of single-base changes in the newly synthesized DNA strand. Which function of which protein is most likely disrupted in this situation? the strand separation function of single-stranded binding protein the unwinding function of helicase the proofreading function of DNA polymerase the fragment joining function of DNA ligase the winding stress relief function of topoisomerase II

the proofreading function of DNA polymerase The most likely function disruption that would produce an increased base incorporation error rate is that of the proofreading function of DNA polymerase. Of incorrectly incorporated nucleotides, 99% are corrected by the proofreading function.

Which of these events includes a checkpoint in the cell cycle? the transition from G1 to S phase All of these events include a checkpoint in the cell cycle the transition from S phase and the completion of DNA synthesis to G2 phase the transition from anaphase to telophase

the transition from G1 to S phase There are three checkpoints in the cell cycle: the transition from G₁ to S phase, the transition from G₂ to M phase, and the transition from meta-phase to anaphase during M phase.

Anatoxin-a is a structural analog of acetylcholine which has an extremely high affinity for the acetylcholine receptor. It is a rapidly acting poison; when administered, death occurs within minutes due to nonstop contractions of respiratory and cardiac muscle. Which is true? -there is no enzyme present in the neuromuscular junction which can break down anatoxin-a - anatoxin-a prevents neurons from releasing acetylcholine - acetylcholine receptors remain closed when treated with anatoxin-a -high levels of acetylcholine would counteract the effects of anatoxin-a

there is no enzyme present in the neuromuscular junction which can break down anatoxin-a

Which of the cell junctions is involved in creating a barrier between cells? tight junction adherens junction desmosome

tight junction

Which of the cell junctions is involved in creating a barrier between cells? tight junction desmosome adherens junction

tight junction

0. One application of GMOs is to engineer mice that have particular diseases that scientists wish to study. false true

true

One application of GMOs is to engineer mice that have particular diseases that scientists wish to study. false true

true

Synthesis of nucleic acids always occurs in the 5′ → 3′ direction. false true

true

Synthesis of nucleic acids always occurs in the 5′ → 3′ direction. true false

true

Transposable elements make up about 50% of the DNA in the human genome. true false

true

Trisomy 21 (Down syndrome) is one of only a few examples of an autosomal trisomy in humans in which the fetus develops to term and is born alive. falsetrue

true

A daughter strand of DNA produced during chromosome replication can be composed of leading and lagging strands from different replication bubbles. true false

true Within a single replication bubble, the same daughter strand is the leading strand at one replication fork and the lagging strand at the other replication fork. This happens because the replication forks in each replication bubble move away from each other. When two replication bubbles fuse, the leading strand from one meets the lagging strand from the other and are joined by DNA ligase.

A skin cell in G2 of interphase has _____ as much DNA as it had in G1. exactly one-fourth twice half four times

twice

If DNA were replicated in a conservative manner, what would the Meselson-Stahl experiment have shown after one round of replication in light N? One band intermediate in density one band, heavy density two bands, one heavy and one light two bands, one intermediate and one light two bands, one intermediate and one heavy

two bands, one heavy and one light

Forensic technicians unearth a skeleton from a shallow grave. They extract a tiny amount of DNA from the pulp found in the teeth. How could they obtain sufficient DNA for an analysis of the victim's genes? subject the DNA to gel electrophoresis subject the DNA to restriction enzymes None of the other answers is correct use the polymerase chain reaction use a nucleic acid probe

use the polymerase chain reaction

At night time, Zebrafish embryos change the color of the melanophore cells in their skin to a darker shade by: using kinesin motor proteins to move pigment granules inward toward the center of the cell using dynein motor proteins to move pigment granules outward from the center of the cell using kinesin motor proteins to move pigment granules outward from the center of the cell using dynein motor proteins to move pigment granules inward toward the plus end of microtubules using dynein motor proteins to move pigment granules inward toward the center of the cell

using kinesin motor proteins to move pigment granules outward from the center of the cell