Over the past several decades, natural selection has caused populations of Staphylococcus aureus (an infectious wound bacterium) to evolve resistance to most antibiotics. If antibiotic use were stopped, what would you predict would happen to theseS. aureus populations? a. They will go extinct without the antibiotic b. the frequency of resistant forms will definately increase in these populations c. the populations will begin colonizing new environments d. the frequency of nonresistant forms will increase in these populations
the frequency of nonresistant forms will increase in these populations
The "heat" in chili peppers is due to a molecule called capsaicin. Suppose you breed chili peppers that have low amounts of capsaicin over many generations in order to make them milder (have less capsaicin). What process is occurring? A. environmental change b. heritable variation c. artificial selection d. natural selection
Can the atomic mass of an element change? A. no it is fixed. If it changes at all then you have formed a different element. B. yes, adding or losing electrons will substantially change the atomic mass. C. yes, adding or losing neutrons will change the atomic mass without forming a different element. d. yes. adding or losing protons will change the atomic mass without forming a different element.
c. yes. Adding or losing neutrons will change the atomic mass without forming a different element.\
Which one of the following is not a component of each monomer used to make proteins? A. a carboxyl group, COOH b. a phosphorous atom, P c. a side chain, R d. an amino functional group, NH2
b. a phosphorous atom, P
Suppose you discovered a new amino acid. Its R-group contains only hydrogen and carbon atoms. Predict the behavior of this amino acid. A. relative to the amino acids found in organisms, its interactions with water will be intermediate. B. it is hydrophilic c. relative to the amino acids found in organisms, its interactions with water will be very high d. it is hydrophobic
d. it is hydrophobic
What type of interaction is directly responsible for the formation of secondary structure? A. peptide bonds between nonadjacent amino acids b. peptide bonds between adjacent amino acids c. hydrogen bonds between sections of the polypeptide backbone d. hydrogen bonds between side chains of amino acids
c. hydrogen bonds between sections of the polypeptide backbone
Which statement accurately summarizes a difference between ribonucleotides and deoxyribonucleotides? A. in ribonucleotides the sugar is a pentose; deoxyribonucleotides have a hexose. B. ribonucleotides have a hydroxy,l group bonded to their 2' carbon; deoxyribonucleotides have an H at that same location C. ribonucleoties have a hydroxyl group bonded to their 3' carbon; deoxyribonucleotides have an H at that same location. D. Ribonucleotides contain only purines; deoxyribonucleotides contain only pyrimidines
B. Ribonucleotides have a hydroxyl group bonded to their 2' carbon; deoxyribonucleotides have an H at the same location
Which statement is most accurate regarding similarities and differences between proteins and nucleic acids? A. proteins and nucleic acids both have a sugar-phosphate backbone and are formed by condensation reactions. B. nucleic acids have directionality, proteins do not c. proteins and nucleic acids both have a backbone and are formed by condensation reactions. d. proteins are formed by hydrolysis reactions; nucleic acids are formed by condensation reactions
c. proteins and nucleic acids both have a backbone and are formed by condensation reactions
what is the major structural difference between starch and glycogen?
the amount of branching that occurs in the molecule
Compare the molecular formula of a carbohydrate (CH2O)n with that of carbon dioxide (CO2). What does the presence of hydrogen atoms in carbohydrates indicate? A. carbohydrates are more oxidized than co2 b. carbohydrates are more reduced than co2 c. every c atom in carbohydrate is bonded to 4 different atoms d. carbohydrates contain a carbonyl functional group
b. carbohydrates are more reduced than carbon dioxide
The term phospholipid can best be described by which of the following? A. a nonpolar lipid molecule that is made amphipathic by the addition of a phosphate b. a polar lipid molecule that fully repels water c. a nonpolar lipid molecule that is made polar by the addition of a phosphate d. a polar lipid molecule that fully interacts with water
a. a nonpolar lipid molecule that is made amphipathic by the addition of a phosphate
which statement most accurately explains why cholesterol and phospholipids are amphipathic but fats are not? A. cholesterol and phospholipids are primarily hydrophilic; fats are primarily hydrophobic. B. cholesterol and phospholipids are primarily hydrophobic; fats are primarily hydrophilic c. cholesterol and phospholipids contain both hydrophilic and hydrophobic regions; fats are primarily hydrophilic d. cholesterol and phospholipids contain both hydrophilic and hydrophobic regions; fats are primarily hydrophilic
c. cholesterol and phospholipids contain both hydrophobic regions; fats are primarily hydrophilic
what do phospholiipids and triglycerides have incommon? A. they both contain serine or some other organic compound b. they both have a phosphate c. they both have a glycerol backbone d. they both have three fatty acids.
c. they both have a glycerol backbone
sodium-potassium pumps: a. move 2 P ions and 3 Na ions while consuming an ATP for each cycle b. move 3 P ions and 2 Na ions while producing an ATP for each cycle
What type of functional group results when the alcohol group on glycerol reacts with the carboxylic acid group on a fatty acid? A. peptide bond b. glycosidic bond c. hydrocarbon d. ester
which statement most accurately sumarizes a feature of passive transport? A. it is a spontaneous process b. it involves no change in free energy c. no membraine protein are involved d. it makes the cell interior and exterior more different from one another
Mitochondria are separated into two compartments, the matrix and the intermembrane space, by their inner and outer membranes. How does the presence of two compartments contribute to the function of mitochondria? A. it enables mitochondrial DNA and ribosomes to remain seperated from the functional compartment of the mitochondria. b. the double-membrane feature of mitochondria is what enables them to glycosylate proteins c. the 2 compartments permit different but complementary functions to be accomplished in the organelle
what is the site of synthesis of proteins for export (secretion from the cell)? A. ribosomes that attach to the Golgi complex b. ribosomes that attach to the outer mitochondrial membrane c. ribosomes that attach to the endoplasmic reticulum d. free ribosomes
Mitochondrial DNA codes for about 13 proteins (depending on the species of organism). These 13 proteins account for a small proportion of the proteins present in mitochondria. The remaining proteins are coded for by nuclear DNA. What is the most likely explanation for how these proteins find their way to the mitochondria? a. mRNAs that are manufactured in the nucleus, but translated by mitochondrial ribosomes b. random transport vesicles c. signal sequences d. attachments of ribosomes to outer mitochondrial pores and direct deposition into the inner mitochondrial compartment
c. signal sequences
What can you infer about high-molecular-weight proteins that cannot be transported into the nucleus? A. they are foreign proteins b. they are defective proteins c. they lack nuclear localization signals (NLS) d. they have been tagged for destruction
Motor proteins require energy in the form of ATP. ATP hydrolysis results in a conformational change that allows the protein to move along microtubular tracks (pathways). What structural component of the motor protein contains the ATP binding site and, therefore, changes shape to enable movement? a. the stalk b. the portion of the molecule that binds to the vesicle being transported c. a location midway between the vesicle binding site and the protion of the molecule that binds to microtubular tracks d. the portion of the molecule that binds to the microtubular track along which the vesicle is being transported
What is a major difference in the extracellular matrix (ECM) between plant and animal cells? A. plant ecm components are released extracellularly by the gogli stacks, whereas lysosomes function in this capacity in animal cells b. Plant and animal ECMs are quite similar in structure and function. c. Plant ECM is composed primarily of proteins, whereas animal ECM is mainly carbohydrates. d. Plant ECM is primarily carbohydrate in nature, whereas animal ECM is largely protein based.
Which statement most accurately explains why ATP hydrolysis is highly exergonic? A. ATP contains the carbohydrate ribose, which stores a large amount of chemical energy b. energy is released when a phosphate group is added. C. there is a large increase in potential energy because charge repulsion is reduced, accompanied by a large increase in entropy. d. there is a large drop in potential energy because charge repulsion is reduced, accompanied by a large increase in entropy.
d. ****Potential energy drops because ATP's four negative charges become spread between two molecules as opposed to being clustered on one molecule; products are also more disordered than reactants.
Why might adding inorganic phosphate to a reaction mixture where glycolysis was rapidly proceeding help sustain the metabolic pathway? A. the metabolic intermediates of glycolysis are phosphorylated b. it increases the energy levels of the electrons that are transfered to the electron transport chain where ATP is produced. c. it would increase the oxygen sypply available for aerobic respiratioin because each phosphate group has four oxygen atoms as constituents d. it would increase the amount of glucose available for catabolism.
which of the following events takes place in the electron transport chain? A. the breakdown of an acetyl group to carbon dioxide b. substrate-level phosphorylation c. breakdown of glucose into 2 pryvate molecules. D. the extraction of nrg from hi-nrg electrons remaining from glycolysis and the Krebs cycle
The energy of electron transport serves to move (translocate) protons to the outer mitochondrial compartment. How does this help the mitochondrion to produce energy? A. The protons receive electrons from the NAD+ and FAD that are accepted by electrons in glycolysis and the Krebs cycle. b. The translocation of protons sets up the electrochemical gradient that drives ATP synthesis in the mitochondria. c. The hydrogen ions (protons) are transferred to oxygen in an energy-releasing reaction. d. The protons pick up electrons from the electron transport chain on their way through the inner mitochondrial membran
In the energy-yielding phase of glycolysis, energy is extracted in the form of a. NADH b. pyruvate c. ATP and NADH d. ATP
What is the function of the reactions in a fermentation pathway?
to generate NAD+ and NADH, so glycolysis can continue
Most of the CO2 from the catabolism of glucose is released during ______ a. glycolisis b. the Krebs cycle c. chemiosmosis d. electron transport
The process of photosynthesis probably originated in: a. prokaryotes b. in fungi c. three separate times d. in plants
The proteins of the electron transport chain active in the light-dependent reactions a. are part of the reaction centre of photosystem I b. are membrane proteins present in the thylakoid c, have hydrophilic exterior surfaces d. are free proteins present in the thylakkoid lumen
As electrons are passed through the system of electron carriers associated with photosystem II, they lose energy. What happens to this energy? A. it is used to phosphorylate NAD+ to NADPH, the molecule that accepts electrons from photosystem I. b. it exciteds electrons of the reaction center of photosystem I. c. it is used to establish and maintain a proton gradient d. it is lost as heat
the electrons of photosystem II are excited and transferred to electron carriers. From which molecule or structure do the phososystem II replacement electrons come?
The light-independent reactions of plants function to make organic molecules using carbon dioxide as a carbon source. What is the electron source that helps reduce carbon dioxide to sugars and other organic molecules?
How does carbon fixation differ between C3 and C4 plants?
Rubisco is the primary enzyme that catalyzes carbon fixation in C3 plants, and phosphoenolpyruvate carboxylase can catalyze carbon fixation in C4 plants.
what is a major difference between meiosis II and mitosis? A. homologues align on the metaphase plate in meiosis II b. sister chromatids separate in mitosis and homologues separate in meiosis II c. in meiosis II sister chromatids separate d. crossover takes place in meiosis II
what is a major difference between mitosis and meiosis I? a. dna replication takes place prior to mitosis, but not before meiosis I. b. only meiosis I results in daughter cells that contain identical genetic information c. sister chromatids separate in mitosis, and homologues separate in meiosis I. d. sister chromatids separate in mitosis and homologues separate in meiosis II
which of the following would enable you to detect aneuploidy? A. karyotyping b. autosomy c. syngamy d. synapsis
different ratios occur in crosses with single gene pairs or two gene pairs. What type of ratios are likely to occur in crosses dealing with a single gene pair? A. 1:1:1:1, 1:4:6:4:1 b. 9:3:3:1, 1:2:1 c. 3:1, 1:1, 1:2:1, d. 4:1, 1:1, 1:4:1
In humans, xeroderma pigmentosum is a disorder of the nucleotide excision repair mechanism. These individuals are unable to repair DNA damage caused by ultraviolet light. Which of the following are the most prominent types of mutations in individuals suffering from xeroderma pigmentosum? a. methylation of purines b. telomere shortening c. mismatch errord d. pyrimidine dimers
d. pyrimidine dimers
Imagine that you've set up a genetic screen to identify E. coli mutants that cannot metabolize the amino acid tryptophan. Beginning with a master plate containing many colonies, you prepare replica plates on medium with glucose or tryptophan as the only energy source. You would look for colonies that _____. a. can grow only on the plates with glucose b. can grow on both types of media c. cannot grow on either type of media d. can grow only on the plates with tryptophan
a. can grow only on the plates with glucose
Catabolite activator protein (CAP) activity is controlled by the cAMP at the _____ level. A. translational b. post-translational c. transcriptional