CB exam 1
(Q007) During respiration, energy is retrieved from the high-energy bonds found in certain organic molecules. Which of the following, in addition to energy, are the ultimate products of respiration? a. CO2; H2O b. CH2OH; O2 c. CO2; O2 d. CH3; H2O
a. CO2; H2O
(Q008) The correct folding of proteins is necessary to maintain healthy cells and tissues. The presence of unfolded proteins are associated with some neurodegenerative disorders as Alzheimer's disease, Huntington's disease, and Creutzfeldt-Jakob disease (the specific faulty protein is different for each disease). What happens to these disease-causing, unfolded proteins? a. They form protein aggregates. b. They form structured filaments. c. They bind a different target protein. d. They are degraded.
a. They form protein aggregates.
(Q008) A base is a molecule that will ___________ a proton in water. a. accept b. repel c. donate d. neutralize
a. accept
(Q003) Complete the sentence with the best option provided below. The primary structure of a protein is the a. amino acid sequence. b. lowest energy conformation. c. amino acid composition. d. average size of amino acid side chains.
a. amino acid sequence.
(Q001) Select the answer that BEST completes the following statement: Chemical reactions in living systems occur in an __________ environment, within a narrow range of temperatures. a. aqueous b. extracellular c. optimal d. organic
a. aqueous
(Q014) The world of prokaryotes is divided into two domains (bacteria and archaea), each as different from each other as from eukaryotes. Select the observable characteristic that BEST separates archaea from bacteria. a. are found in extremely harsh environments b. are photosynthetic organisms c. can metabolize inorganic substances d. thrive in anaerobic conditions
a. are found in extremely harsh environments
(Q023) Which of the following choices BEST describes the role of the lysosome? a. clean-up, recycling, and disposal of macromolecules b. sorting of transport vesicles c. the storage of excess macromolecules d. transport of material to the Golgi apparatus
a. clean-up, recycling, and disposal of macromolecules
(Q007) Select the option that correctly finishes the following statement: A cell's genome a. contains all of a cell's DNA. b. is defined as all the genes being used to make protein. c. constantly changes, depending upon the cell's environment. d. is altered during embryonic development.
a. contains all of a cell's DNA.
(Q018) Catalysts are molecules that lower the activation energy for a given reaction. Cells produce their own catalysts, called a. enzymes. b. complexes. c. cofactors. d. proteins.
a. enzymes.
(Q031) Which of the following monomer building blocks is necessary to assemble selectively permeable boundaries around and inside cells? a. fatty acids b. nucleotides c. sugars d. amino acids
a. fatty acids
(Q014) Table 2-14 indicates the number and arrangement of electrons in the first four atomic electron shells for selected elements. On the basis of the information in the chart and what you know about atomic structure, which elements are chemically inert? a. helium; neon b. magnesium; calcium c. sodium; potassium d. carbon; sulfur
a. helium; neon
(Q042) Both DNA and RNA are synthesized by covalently linking a nucleoside triphosphate to the previous nucleotide, constantly adding to a growing chain. In the case of DNA, the new strand becomes part of a stable helix. The two strands are complementary in sequence and antiparallel in directionality. What is the principal force that holds these two strands together? a. hydrogen bonds b. ionic interactions c. van der Waals interactions d. covalent bonds
a. hydrogen bonds
(Q017) Which of the following organelles has both an outer and an inner membrane? a. mitochondrion b. endoplasmic reticulum c. peroxisome d. lysosome
a. mitochondrion
(Q014) Seed oils are often dehydrogenated and added back into processed foods. The new fatty acids have an increased number of carbon-carbon double bonds. The dehydrogenation reaction could also be described as a/an __________ reaction. a. oxidation. b. reduction. c. isomerization. d. protonation.
a. oxidation.
(Q044) Instead of studying one or two proteins or protein complexes present in the cell at any given time, we can now look at a snapshot of all proteins being expressed in cells being grown in specific conditions. This large-scale, systematic approach to the study of proteins is called a. proteomics. b. structural biology. c. systems biology. d. genomics.
a. proteomics.
(Q002) The variations in the physical characteristics between different proteins are influenced by the overall amino acid compositions, but even more important is the unique amino acid a. sequence. b. number. c. bond. d. orientation.
a. sequence.
(Q018) Mitochondria perform cellular respiration, a process that uses oxygen, generates carbon dioxide, and produces chemical energy for the cell. Which answer below indicates a correct pairing of the material "burned" and the form of energy produced during cellular respiration? a. sugar, ATP b. sugar, fat c. fat, ADP d. fat, protein
a. sugar, ATP
(Q033) The biosynthetic pathway for the two amino acids E and H is shown schematically in Figure 4-33. You are able to show that E inhibits enzyme V, and H inhibits enzyme X. Which biosynthetic product is most likely the inhibitor of enzyme T? a. B b. C c. H d. E
b. C
(Q010) Molecular chaperones can work by creating an "isolation chamber." What is the purpose of this chamber? a. This chamber serves to transport unfolded proteins out of the cell. b. This chamber serves to protect unfolded proteins from interacting with other proteins in the cytosol, until protein folding is completed. c. The chamber acts as a garbage disposal, degrading improperly folded proteins so that they do not interact with properly folded proteins. d. This chamber is used to increase the local protein concentration, which will help speed up the folding process.
b. This chamber serves to protect unfolded proteins from interacting with other proteins in the cytosol, until protein folding is completed.
(Q012) Prokaryotic cells do not possess a. replication machinery. b. a nucleus. c. membrane bilayers. d. ribosomes.
b. a nucleus.
(Q003) Proteins are important architectural and catalytic components within the cell, helping to determine its chemistry, its shape, and its ability to respond to changes in the environment. Remarkably, all of the different proteins in a cell are made from the same 20 __________. By linking them in different sequences, the cell can make protein molecules with different conformations and surface chemistries, and therefore different functions. a. nucleotides b. amino acids c. fatty acids d. sugars
b. amino acids
(Q002) When there is an excess of nutrients available in the human body, insulin is released to stimulate the synthesis of glycogen from glucose. This is a specific example of a/an __________ process, a general process in which larger molecules are made from smaller molecules. a. metabolic b. anabolic c. catabolic d. biosynthetic
b. anabolic
(Q001) Chemical reactions carried out by living systems depend on the ability of some organisms to capture and use atoms from nonliving sources in the environment. The specific subset of these reactions that break down nutrients in food can be described as a. anabolic. b. catabolic. c. biosynthetic. d. metabolic.
b. catabolic.
(Q001) Living systems are incredibly diverse in size, shape, environment, and behavior. It is estimated that there are between 10 million and 100 million different species. Despite this wide variety of organisms, it remains difficult to define what it means to say something is alive. Which of the following can be described as the smallest living unit? a. organelle b. cell c. protein d. DNA
b. cell
(Q016) Which of the following is NOT a feature commonly observed in β sheets? a. extended polypeptide backbone b. coiled-coil patterns c. antiparallel regions d. parallel regions
b. coiled-coil patterns
(Q033) Which of the following are examples of isomers? a. alanine and glycine b. glucose and galactose c. adenine and guanine d. glycogen and cellulose
b. glucose and galactose
(Q025) The pH of an aqueous solution is an indication of the concentration of available protons. However, you should not expect to find lone protons in solution; rather, the proton is added to a water molecule to form a/an __________ ion. a. hydroxide b. hydronium c. ammonium d. chloride
b. hydronium
(Q036) Drosophila melanogaster is a/an __________. This type of animal is the most abundant of all animal species, making it an appropriate choice as an experimental model. a. bird b. insect c. mammal d. amphibian
b. insect
(Q011) When elemental sodium is added to water, the sodium atoms ionize spontaneously. Uncharged Na becomes Na+. This means that the Na atoms have been a. hydrogenated. b. oxidized. c. reduced. d. protonated.
b. oxidized.
(Q003) Self-replication of living cells occurs through the catalytic action of a. DNA. b. proteins. c. nucleotides. d. RNA.
b. proteins.
(Q012) The three-dimensional coordinates of atoms within a folded protein are determined experimentally. After researchers obtain a protein's structural details, they can use different techniques to highlight particular aspects of the structure. What visual model best displays a protein's secondary structures (α helices and β sheets)?
b. ribbon
(Q022) Photosynthesis enables plants to capture the energy from sunlight. In this essential process, plants incorporate the carbon from CO2 into high-energy __________ molecules, which the plant cell mitochondria use to produce ATP. a. fiber b. sugar c. protein d. fat
b. sugar
(Q019) β sheets can participate in the formation of amyloid fibers, which are insoluble protein aggregates. What drives the formation of amyloid fibers? a. extension of β sheets into much longer β strands b. β-sheet stabilization of abnormally folded proteins c. formation of biofilms by infectious bacteria d. denaturation of proteins containing β sheets
b. β-sheet stabilization of abnormally folded proteins
(Q026) Larger molecules have hydrogen-bonding networks that contribute to specific, high-affinity binding. Smaller molecules such as urea can also form these networks. How many hydrogen bonds can urea (Figure 2-26) form if dissolved in water? a. 3 b. 4 c. 6 d. 5
c. 6
Q041) Activated carriers are small molecules that can diffuse rapidly and be used to drive biosynthetic reactions in the cell. Their energy is stored in a readily transferable form such as high-energy electrons or chemical groups. Which of the molecules below donates a chemical group rather than electrons? a. NADH b. NADPH c. ATP d. FADH2
c. ATP
(Q007) Which of the following is UNLIKELY to be hydrophilic? a. a molecule with a lot of polar covalent bonds b. a molecule that forms hydrogen bonds with water c. a molecule with primarily nonpolar covalent bonds d. a salt that is held together with ionic bonds
c. a molecule with primarily nonpolar covalent bonds
(Q001) Polypeptides are synthesized from amino acid building blocks. The condensation reaction between the growing polypeptide chain and the next amino acid to be added involves the loss of a. a carboxylic acid group. b. a carbon atom. c. a water molecule. d. an amino group.
c. a water molecule.
(Q044) All of the biological molecules listed below contain high-energy phosphate bonds. Which one is the key driver of most phosphorylation reactions and the transfer of metabolic energy? a. creatine-P b. glucose-P c. adenosine-P3 d. acetyl-P
c. adenosine-P3
(Q006) A molecule with a lot of polar covalent bonds is likely to a. be hydrophobic. b. form ionic bonds. c. be highly soluble in water. d. contain only atoms with low electronegativity.
c. be highly soluble in water.
(Q016) The nucleus, an organelle found in eukaryotic cells, confines the __________, keeping them separated from other components of the cell. a. peroxisomes b. lysosomes c. chromosomes d. ribosomes
c. chromosomes
(Q029) Substances that release protons when they dissolve in water are acids. Which of the following household substance is acidic? a. hand soap b. bleach c. coffee d. water
c. coffee
(Q018) Coiled-coils are typically found in proteins that require an elongated structural framework. Which of the following proteins do you expect to have a coiled-coil domain? a. myoglobin b. insulin c. collagen d. porin
c. collagen
(Q048) NADH and NADPH are activated carrier molecules that function in completely different metabolic reactions. Both carry two additional __________ and one additional __________. This combination can also be referred to as a hydride ion. a. hydrogens; electron. b. protons; electron. c. electrons; proton. d. electrons; phosphate.
c. electrons; proton.
(Q028) Lysozyme is an enzyme that specifically recognizes bacterial polysaccharides, which renders it an effective antibacterial agent. Into what classification of enzymes does lysozyme fall? a. protease b. isomerase c. hydrolase d. nuclease
c. hydrolase
(Q008) Your body extracts energy from the food you ingest by catalyzing reactions that essentially "burn" the food molecules in a stepwise fashion. What is another way to describe this process? a. solvation b. dehydration c. oxidation d. reduction
c. oxidation
(Q041) The variety and arrangement of chemical groups on monomer subunits contribute to the conformation, reactivity, and surface of the macromolecule into which they become incorporated. What type of chemical group is circled on the nucleotide shown in Figure 2-41? a. carboxyl b. carbonyl c. phosphoryl d. pyrophosphate
c. phosphoryl
(Q037) The phosphorylation of a protein is typically associated with a change in activity, the assembly of a protein complex, or the triggering of a downstream signaling cascade. The addition of ubiquitin, a small polypeptide, is another type of covalent modification that can affect the protein function. Ubiquitylation often results in a. membrane association. b. nuclear translocation. c. protein degradation. d. protein secretion.
c. protein degradation.
(Q039) Cells require one particular monosaccharide as a starting material to synthesize nucleotide building blocks. Which of the monosaccharides below fills this important role? a. ribulose b. fructose c. ribose d. glucose
c. ribose
How many bonds are made by a carbon atom? a. 3 b. 1 c. 2 d. 4
d. 4
(Q003) Given the periodic table below, how many electrons does an oxygen atom have? a. 2 b. 4 c. 16 d. 8
d. 8
(Q011) One of the key features of living systems is the use of energy to create and maintain order. A good example is found in the folding of newly synthesized proteins. Which activated carrier molecule is used by chaperone proteins to support protein folding? a. FADH2 b. NADPH c. NADH d. ATP
d. ATP
(Q034) Which species was the key model organism for the advancement of molecular biology (understanding DNA replication, decoding the DNA to make proteins, etc.)? a. C. elegans b. D. melanogaster c. S. pombe d. E. coli
d. E. coli
(Q024) The equilibrium constant (K) for the reaction Y→X can be expressed with respect to the concentrations of the reactant and product molecules. Which of the expressions below shows the correct relationship between K, [Y], and [X]? a. K = [X] - [Y] b. K = [Y]/[X] c. K = [Y] * [X] d. K = [X]/[Y]
d. K = [X]/[Y]
(Q007) Protein folding can be studied using a solution of purified protein and a denaturant (urea), a solvent that interferes with noncovalent interactions. Which of the following is observed after the denaturant is removed from the protein solution? a. The polypeptide adopts a new, stable conformation. b. The polypeptide forms solid aggregates and precipitates out of solution. c. The polypeptide remains denatured. d. The polypeptide returns to its original conformation.
d. The polypeptide returns to its original conformation.
(Q004) The energy used by the cell to generate specific biological molecules and highly ordered structures is stored in the form of a. heat. b. Brownian motion. c. light waves. d. chemical bonds.
d. chemical bonds.
(Q024) The cell constantly exchanges materials by bringing nutrients in from the external environment and shuttling unwanted by-products back out. Which term describes the process by which external materials are captured inside transport vesicles and brought into the cell? a. phagocytosis b. exocytosis c. degradation d. endocytosis
d. endocytosis
(Q001) The function of a(n) _________ cell, which has a long, branched structure, requires many connections to be made with neighboring cells. a. yeast b. fat c. egg d. nerve
d. nerve
(Q002) All living cells a. need to replicate within another cell. b. are nearly the same size. c. have the same overall shape. d. share the same basic chemistry.
d. share the same basic chemistry.
(Q012) A covalent bond between two atoms is formed as a result of the a. transfer of electrons from one atom to the other. b. loss of electrons from both atoms. c. loss of a proton from one atom. d. sharing of electrons
d. sharing of electrons
(Q020) Polar covalent bonds are formed when the electrons in the bond are not shared equally between the two nuclei. Which one of these molecules contains polar bonds? a. methane b. propane c. molecular oxygen d. water
d. water
