HW Flashcards by 镕璟谢

Why isn’t the mitochondrion classified as part of the endomembrane system?
A) It is a static structure.
B) Its structure is not derived from the ER or Golgi.
C) It has too many vesicles.
D) It is not involved in protein synthesis.
E) It is not attached to the outer nuclear envelope.

B) Its structure is not derived from the ER or Golgi

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The sodium‒potassium pump changes shape in response to
A) the binding of ions.
B) the hydrolysis of ATP and phosphorylation.
C) the release of Na+ ions outside the cell.
D) the influx of K+ ions.
E) secondary active transport.

B) the hydrolysis of ATP and phosphorylation.

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A localized group of organisms that belong to the same species is called a
A) biosystem.
B) community.
C) population.
D) ecosystem.
E) family.

C) population.

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Active transport moves molecules
A) in the same direction as diffusion moves them.
B) in a direction opposite to the one in which diffusion moves them.
C) into the cytoplasm.
D) toward the region with a higher pH.
E) toward the region of lower concentration of the molecule

B) in a direction opposite to the one in which diffusion moves them.

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A small dye molecule injected into a plant cell can pass into adjacent plant cells becuase of the presence of
A) plasmodesmata
B) a cell wall
C) the endoplasmic reticulum
D) nuclear pores
E) vacuoles

A) plasmodesmate

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Protein movement within a menbrane may be restricted by
A) a glycolipids and glycoproteins
B) cell fusion
C) the cytoskeleton
D) cell adhesion
E) peripheral membrane proteins

C) the cytoskeleton

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The drug 2,4-dinitrophenol (DNP) destroys the proton gradient across the inner mitochondrial membrane. What would be the effect of incubating isolated mitochondria in a solution of DNP?

a. Glycolysis would stop.
b. Mitochondria would show a burst of increased ATP synthesis.
c. Mitochondria would switch from glycolysis to fermentation.
d. ATP synthesis would decline.
e. O2 would no longer be reduced to H2O.

d. ATP synthesis would decline.

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Why does glucose oxidation occur in a series of steps?

a. One step wouldn’t allow the energy released to be harnessed efficiently.
b. Glucose cannot pass into the mitochondria and oxygen cannot enter the cytosol.
c. It doesn’t have to; it just happens to be that way.
d. Glycolysis evolved first and steps were just added over time.
e. Glucose is reduced, not oxidized.

a. One step wouldn’t allow the energy released to be harnessed efficiently.

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The following are true about membrane potential, except-

a) it is the voltage across the membrane
b) Neurons have a membrane potential of close to -70mV
c) In neurons, this membrane potential is critical to the generation of an action potential
d) the membrane allows ions to diffuse across freely

d) the membrane allows ions to diffuse across freely

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A water sample from a hot thermal vent contained a single-celled organism that had a cell wall
but lacked a nucleus. What is its most likely classification?
a) Eukarya
b) Archaea
c) Animalia
d) Protista
e) Fungi

b) Archaea

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Stanley Miller’s 1953 experiments assumed that early Earth’s atmosphere contained

a) hydrogen cyanide, formaldehyde, hydrogen gas, and water vapour.
b) ammonia, methane, hydrogen gas, and water vapour.
c) ammonia, methane, oxygen gas, and water vapour.
d) amino acids, methane, hydrogen cyanide, and water vapour.
e) methane, formaldehyde, ammonia, and carbon dioxide.

b) ammonia, methane, hydrogen gas, and water vapour.

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The amino acids of the protein keratin are arranged predominantly in an α helix. This
secondary structure is stabilized by
a) covalent bonds.
b) peptide bonds.
c) ionic bonds.
d) polar bonds.
e) hydrogen bonds.

e) hydrogen bonds.

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The covalent bond formed between two monosaccharides by way of dehydration is called a(n)

a) hydrogen bond.
b) sulphide bridge.
c) glycosidic link.
d) glucose bridge.
e) disaccharide link.

c) glycosidic link.

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Which of the following statements concerning unsaturated fats is true?

a) They are more common in animals than in plants.
b) They have double bonds in the carbon chains of their fatty acids.
c) They generally solidify at room temperature.
d) They contain more hydrogen than do saturated fats having the same number of carbon atoms.
e) They have fewer fatty acid molecules per fat molecule.

b) They have double bonds in the carbon chains of their fatty acids.

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A type of protein that functions by helping other proteins fold correctly is called a

a) hemoglobin.
b) denaturing protein.
c) chaperone.
d) renaturing protein.
e) foldzyme.

c) chaperone.

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Which of the following statements best describes the termination of transcription in prokaryotes?

a) RNA polymerase transcribes through the polydenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase
b) RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from DNA and release the transcript
c) RNA polymerase transcribes through an intron, which causes the polymerase to let go of the transcript
d) once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome
e) RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA

b) RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from DNA and release the transcript

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In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA known as pre-mRNA?

a) ligase
b) RNA polymerase I
c) RNA polymerase II
d) RNA polymerase III

c) RNA polymerase II

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Which of the following is a function of a poly-A tail in mRNA?

a) it adds the modified guanine to the 3’ end of the mRNA
b) it indicates the site of translational termination
c) it is a sequence that codes for the binding of RNA polymerase to the DNA
d) it helps protect the mRNA from degradation by hydrolytic enzymes

d) it helps protect the mRNA from degradation by hydrolytic enzymes

Which of the following statements correctly describes alternative RNA splicing?

a) it is a mechanism that can increase the rate of transcription
b) it can allow the production of proteins of different sizes and functions from a single mRNA
c) it allows the production of similar proteins from different RNAs
d) it increases the rate of transcription

b) it can allow the production of proteins of different sizes and functions from a single mRNA

Accuracy in the translation of mRNA into the sequence of amino acids in a polypeptide depends on specificity in which of the following?
A) binding of ribosomes to mRNA
B) shape of the A and P sites of ribosomes
C) attachment of amino acids to tRNAs
D) bonding of the anticodon to the codon and the attachment of amino acids to tRNAs

D) bonding of the anticodon to the codon and the attachment of amino acids to tRNAs

Which of the following events in translation is the first to occur in eukaryotes?
A) elongation of the polypeptide
B) base pairing of activated methionine-tRNA to AUG of the messenger RNA
C) binding of the larger ribosomal subunit to smaller ribosomal subunits
D) covalent bonding between the first two amino acids
E) the small subunit of the ribosome recognizing and attaching to the 5’ cap of mRNA

E) the small subunit of the ribosome recognizing and attaching to the 5’ cap of mRNA

In eukaryotic cells, transcription cannot begin until

a) the two DNA strands have completely separated and exposed the promoter
b) several transcription factors have bound to the promoter
c) the 5’ caps are removed from the mRNA
d) the DNA introns are removed from the template

b) several transcription factors have bound to the promoter

Which of the following is not true of RNA processing?

a) exons are cut out before mRNA leaves the nucleus
b) nucleotides may be added at both ends of the RNA
c) ribozymes may function in RNA splicing
d) RNA splicing can be catalyzed by spliceosomes

a) exons are cut out before mRNA leaves the nucleus

Which of the following mutations would be most likely to have a harmful effect on an organism?

a) a deletion of three nucleotides near the middle of a gene
b) a single nucleotide deletion in the middle of an intron
c) a single nucleotide deletion near the end of the coding sequence
d) a single nucleotide insertion downstream of, and close to, the start of the coding sequence

d) a single nucleotide insertion downstream of, and close to, the start of the coding sequence

Comparative genomics has shown that A.) chimpanzees are human's closest living relative. B.) genes with new functions have been added over the course of evolution . C.) genes for enzymes of metabolism are similar in prokaryotes and eukaryotes. D.) Neanderthals, like humans, could vocalize through speech. E.) all of the above

E.) all of the above

Three temperature stages make up a single PCR cycle. These three stages (in order) are A.) denaturation, primer,annealing, synthesis. B.) synthesis, denaturation, primer annealing. C.) primer annealing, denaturation, synthesis. D.) denaturation, synthesis, primer annealing.

A.) denaturation, primer,annealing, synthesis.

Pharming is? A.)the use of expression vectors to modulate the expression of a gene in a specific tissue. B.) the production of medically useful products in plants or animals. C.) the use of reporter genes to identify bacteria with recombinant DNA. D.) a type of gene mutagenesis to study gene function. E.) a critical step in making GMOs.

B.) the production of medically useful products in plants or animals.

When comparing eukaryotic genomes and prokaryotic genomes, A.) eukaryotic genomes tend to have fewer regulatory sequences than prokaryotic genomes. B.) eukaryotic genomes have a single origin of replication on each chromosome. C.) the percentage of the genome devoted to coding sequence in eukaryotic genomes is lower than in prokaryotic genomes. D.) eukaryotic genomes have transposons but prokaryotic genomes do not. E.)eukaryotic genomes tend to be smaller than prokaryotic genomes.

C.) the percentage of the genome devoted to coding sequence in eukaryotic genomes is lower than in prokaryotic genomes.

The most likely way for proteins to acquire new functions is via ``` A.) retrotransposons. B.) gene duplication. C.) biased gene conversion. D.) concerted evolution. E.) bioprospecting. ```

B.) gene duplication.

Which of the following enzymes perform opposite functions? (a) RNA polymerase and DNA ligase (b) DNA polymerase and DNA ligase (c) Restriction endonuclease and DNA ligase (d) Restriction endonuclease and DNA polymerase (e) Reverse transcriptase and restriction endonuclease

Which of the following statements regarding recombinant DNA is false? (a) Complementary sticky ends can form hydrogen bonds with each other. (b) Restriction enzymes can create DNA fragments with "blunt ends." (c) Restriction enzymes cut DNA at palindromic sequences. (d) Restriction enzymes can create DNA fragments with "sticky ends." (e) A single restriction enzyme can cut DNA sequences at several different recognition sites.

(e) A single restriction enzyme can cut DNA sequences at several different recognition sites.

If a mutation has a visible effect at 26°C, but no visible effect at 20°C, then 20°C is the _______ temperature and 26°C is the _______ temperature. Select one: a. restrictive; permissive b. conditional; restrictive c. restrictive; conditional d. permissive; restrictive e. permissive; conditional

d. permissive; restrictive

Which of the following techniques involves the manipulation of single-stranded DNA? Select one: a. PCR amplification b. DNA restriction enzyme digestion c. Gel electrophoresis d. Restriction digestion e. Allele-specific oligonucleotide hybridization

e. Allele-specific oligonucleotide hybridizatione.

In a gel electrophoresis experiment, researchers notice that one band has migrated much farther on the gel than the others. They conclude that it is _______ than the others. Select one: a. more negatively charged b. a longer fragment c. more abundant d. a shorter fragment e. less negatively charged

d. a shorter fragment

If cells in the process of dividing are subjected to Coro of drugs interferes with the formation of spend apparatus in which stage will mitosis be arrested Select one: a. anaphase b. prophase c. telophase d. cytokinesis e. metaphase

e. metaphase

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. the measured DNA levels range from 3 to 6 picograms nucleus in which stage of the cell cycle does a nucleus contains 6 picograms of DNA Select one: a. S phase. b. M phase. c. G1 phase. d. G0 phase. e. G2 phase

e. G2 phase

In an alpha helix, the coiling is stabilized by a. hydrogen bonding of the N–H groups on one amino acid and the C=O groups on another. b. the hydrophobic nature of the R chains, which causes the chain to coil with the R groups inward. c. repulsion of the R chains from each other, causing the coil to form with the R groups on the outside. d. disulfide bond formation between cysteines that are regularly spaced along peptide chains. e. the N–C–C repeat of the peptide backbone, allowing for regularly spaced peptide bonds between chain segments.

a. hydrogen bonding of the N–H groups on one amino acid and the C=O groups on another.

7. The binding of a molecule at a regulatory site of an enzyme changes the geometry of the active site and loss of enzymatic activity. This molecule binding is freely reversible. This is an example of a. noncompetitive inhibition. b. passive enzymatic regulation. c. competitive inhibition. d. irreversible inhibition. e. covalent modification.

a. noncompetitive inhibition.

14. Which process occurs when O2 is unavailable to a cell? a. Fermentation b. The citric acid cycle c. Pyruvate oxidation d. Formation of H2O by the electron transport chain e. Oxidative phosphorylation

a. Fermentation

20. In DNA replication, on the _______, the exposed (or synthesized) DNA 3 end gets farther and farther away from the fork as replication proceeds. a. lagging strand b. leading strand c. Okazaki fragments d. primer e. sliding DNA clamp

a. lagging strand

21. The modified base inosine contributes to a. the wobble effect. b. the fidelity function. c. mRNA processing. d. the formation of peptide bonds in translation. e. proteolysis.

a. the wobble effect.

Stop codons a. only enter the A site. b. do not enter any of the sites on the ribosome. c. enter the A and the P sites. d. enter the A and the E sites. e. enter the A, P, and E sites.

a. only enter the A site.

33. In what way are iPS and embryonic stem cells most similar? a. Their cell potency b. The way cells are harvested c. The likelihood of immune rejection d. The use of microarrays used in making them e. The ethical considerations

a. Their cell potency

40. What role do spacers play in the CRISPR–CAS9 system found in many bacteria? a. Identification of natural enemies b. Destroying natural enemies c. DNA repair d. Increasing gene expression e. Decreasing gene expression

a. Identification of natural enemies