Cell Biology Final Exam Review
By definition, prokaryotic cells do not possess __________. (a) a nucleus (b) replication machinery (c) ribosomes (d) membrane bilayers
(a) a nucleus
The mitochondrial proteins found in the inner membrane are involved in the conversion of ADP to ATP, a source of energy for the cell. This process consumes which of the following substances? (a) oxygen (b) nitrogen (c) sulfur (d) carbon dioxide
(a) oxygen
Which of the following expressions accurately describes the calculation of pH? (a) pH = -log10[H+] (b) pH = log10[H+] (c) pH = -log2[H+] (d)pH = -log10[OH-]
(a) pH = -log10[H+]
The flow of genetic information is controlled by a series of biochemical reactions that result in the production of proteins, each with its own specific order of amino acids. Choose the correct series biochemical reactions from the options presented here. (a) replication, transcription, translation (b) replication, translation, transcription (c) translation, transcription, replication (d) translation, replication, transcription
(a) replication, transcription, translation
Aromatic carbon compounds such as benzene are planar and very stable. Double-bond character extends around the entire ring, which is why it is often drawn as a hexagon with a circle inside. This characteristic is caused by electron __________. (a) resonance (b) pairing (c) partial charge (d) stacking
(a) resonance
Oligosaccharides are short sugar polymers that can become covalently linked to proteins and lipids through condensation reactions. These modified proteins and lipids are called glycoproteins and glycolipids. Within a protein, which of the amino acids (shown in Figure Q2-30) is the most probable target for this type of modification? (a) serine (b) glycine (c) phenylalanine (d)methionine
(a) serine
Which of the following elements is least abundant in living organisms? (a) sulfur (b) carbon (c) oxygen (d)nitrogen
(a) sulfur
Indicate whether the following statements are true or false. A. Oxygen is toxic to certain procaryotic organisms. B. Mitochondria are thought to have evolved from anaerobic bacteria. C. Although bacteria use a variety of organic substances as food, bacteria are not able live on inorganic substances.
(a) true (b) false (c) true
The first task you are assigned in your summer laboratory job is to prepare a concentrated NaOH stock solution. The molecular weight of NaOH is 40. How many grams of solid NaOH will you need to weigh out to obtain a 500 ml solution that has a concentration of 10 M? (a) 800 g (b) 200 g (c) 400 g (d) 160 g
(b) 200 g
Changes in DNA sequence from one generation to the next may result in offspring that are altered in fitness compared with their parents. The process of change and selection over the course of many generations is the basis of __________. (a) mutation (b) evolution (c) heredity (d) reproduction
(b) evolution
Both DNA and RNA are synthesized by covalently linking a nucleotide 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) ionic interactions (b) hydrogen bonds (c) covalent bonds (d) van der Waals interactions
(b) hydrogen bonds
DNA and RNA are different types of nucleic acid polymer. Which of the following is true of DNA but not true of RNA? (a) It contains uracil. (b) It contains thymine. (c) It is single stranded. (d)It has 5′-to-3′ directionality
(b) it contains thymine
Which of the following organelles has both an outer and an inner membrane? (a) endoplasmic reticulum (b) mitochondrion (c) lysosome (d) peroxisome
(b) mitochondrion
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 Q2-28? (a) pyrophosphate (b) phosphoryl (c) carbonyl (d) carboxyl
(b) phosphoryl
The small molecule cyclic AMP (cAMP) takes about 0.2 second to diffuse 10 μm, on average, in a cell. Suppose that cAMP is produced near the plasma membrane on one end of the cell; how long will it take for this cAMP to diffuse through the cytosol and reach the opposite end of a very large cell, on average? Assume that the cell is 200 μm in diameter. (a) 4 seconds (b) 16 seconds (c) 80 seconds (d) 200 seconds
(c) 80 seconds
Which of the following statements is false? (a) ATP contains high-energy phosphoanhydride bonds. (b) ATP is sometimes called the "universal currency" in the energy economy of cells. (c) ATP can be incorporated into DNA. (d) ATP can be hydrolyzed to release energy to power hundreds of reactions in cells. (e)ATP comprises a sugar, phosphate groups, and a nitrogenous base
(c) ATP can be incorporated into DNA
Biological membranes are composed of specialized lipids that form bilayers. Which of the following is formed by unmodified fatty acids? (a) fat droplets (b) bilayers (c) micelles (d)planar lipid patches
(c) micelles
__________ are fairly small organelles that provide a safe place within the cell to carry out certain biochemical reactions that generate harmful, highly reactive oxygen species. These chemicals are both generated and broken down in the same location. (a) nucleosomes (b) lysosomes (c) peroxisomes (d)endosomes
(c) peroxisomes
A. thaliana, or Arabidopsis, is a common weed. Biologists have selected it over hundreds of thousands of other flowering plant species to serve as an experimental model organism because __________________. (a) it can withstand extremely cold climates (b) it can reproduce in 8-10 weeks (c) it produces thousands of offspring per plant (d) Both (b) and (c) are true.
(d) both (b) and (c) are true
Figure below is an energy diagram for the reaction X→Y. Which equation below provides the correct calculation for the amount of free-energy change when X is converted to Y? (a) a + b - c (b) a - b (c) a - c (d) c - a
(d) c - a
Despite the differences between eucaryotic and procaryotic cells, procaryotes have proteins that are distantly related to eucaryotic actin filaments and microtubules. What is likely to be the most ancient function of the cytoskeleton? (a) cell motility (b) vesicle transport (c) membrane support (d) cell division
(d) cell division
The energy used by the cell to generate specific biological molecules and highly ordered structures is stored in the form of _____________. (a) Brownian motion (b) heat (c) light waves (d) chemical bonds
(d) chemical bonds
What unit of length would you generally use to measure a typical human cell? (a) centimeters (b) nanometers (c) millimeters (d) micrometers
(d) micrometers
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 Q2-22) form if dissolved in water? (a) 6 (b) 5 (c) 3 (d)4
(a) 6
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) CH3, H2O (c) CH2OH, O2 (d)CO2, O2
(a) CO2, H2O
If the isotope 32S has 16 protons and 16 neutrons, how many protons and how many neutrons will the isotope 35S have?
16 protons 19 neutrons
Arrange the following molecules in order with respect to their relative levels of oxidation (assign 5 to the most oxidized and 1 to the most reduced). _______ CH2O (formaldehyde) _______ CH4 (methane) _______ CHOOH (formic acid) _______ CH3OH (methanol) _______ CO2 (carbon dioxide)
3 1 4 2 5
Light + _________ + _________ → _________ + heat + sugars CO, CO2, O2, H2, H2O, N2, NO
H2O + CO2 ----- O2
Match each biological process with the model organism that is best suited or most specifically useful for its study, based on information provided in your textbook. You may list individual processes more than once. A. cell division B. development (multicellular) C. programmed cell death D. photosynthesis E. immunology _____ A. thaliana (Arabidopsis) _____ M. musculus (mouse) _____ S. pombe _____ C. elegans _____ S. cerevisiae _____ D. rerio (zebrafish) _____ D. melanogaster
B B A C A B A
Many of the mechanisms that cells use for maintenance and reproduction were first studied at the molecular detail in bacteria. Which bacterial species had a central role in advancing the field of molecular biology? (a) E. coli (b) D. melanogaster (c) S. pombe (d) C. elegans
(a) E. Coli
Indicate whether the following statements are true or false. A. A virus is a living organism. B. Cells of different types can have different chemical requirements. C. A human white blood cell is larger than a Paramecium cell.
(a) False (b) True (c) False
The amino acids glutamine and glutamic acid are shown in Figure Q2-29. They differ only in the structure of their side chains (circled). At pH 7, glutamic acid can participate in molecular interactions that are not possible for glutamine. What types of interaction are these? (a) ionic bonds (b) hydrogen bonds (c) van der Waals interactions (d)covalent bonds
(a) Ionic bonds
Which of the following statements about amino acids is true? (a) Twenty-two amino acids are commonly found in proteins. (b) Most of the amino acids used in protein biosynthesis have charged side chains. (c) Amino acids are often linked together to form branched polymers. (d) All amino acids contain an NH2 and a COOH group
(a) all amino acids contain an NH2 and a COOH group
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) DNA (b) cell (c) organelle (d) protein
(a) cell
There are 20100 different possible sequence combinations for a protein chain with 100 amino acids. In addition to the amino acid sequence of protein, what other factors increase the potential for diversity in these macromolecules? (a) free rotation around single bonds during synthesis (b) noncovalent interactions sampled as protein folds (c) the directionality of amino acids being added (d)the planar nature of the peptide bond
(a) free rotation around single bonds during synthesis
Which of the following are examples of isomers? (a) glucose and galactose (b) alanine and glycine (c) adenine and guanine (d) glycogen and cellulose
(a) glucose and galactose
Each nucleotide in DNA and RNA has an aromatic base. What is the principal force that keeps the bases in a polymer from interacting with water? (a) hydrophobic interactions (b) hydrogen bonds (c) covalent bonds (d)van der Waals interactions
(a) hydrophobic interactions
In a folded protein, most of the nonpolar amino acids are buried inside the protein fold, whereas the polar and charged side chains are exposed to the components in the cytosol. This fold is more stable because of the expulsion of nonpolar atoms from contact with water, favoring the interaction of nonpolar atoms with each other. What is this fourth type of noncovalent interaction called? (a) hydrophobic interaction (b) hydrophilic interaction (c) apolar interaction (d) hydrocarbon interaction
(a) hydrophobic interactions
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) insect (b) bird (c) amphibian (d)mammal
(a) insect
Indicate whether the following statements are true or false. A. Membrane components in the cell are made in the endoplasmic reticulum. B. The Golgi apparatus is made up of a series of membrane-enclosed compartments through which materials destined for secretion must pass. C.Lysosomes are small organelles where fatty acid synthesis occurs.
(a) true (b) true (c) false
Because there are four different monomer building blocks that can be used to assemble RNA polymers, the number of possible sequence combinations that can be created for a RNA molecule made of 100 nucleotides is _______. (a) 100^4 (b) 4^100 (c) 4 × 100 (d) 100/4
(b) 4^100
Although there are many distinct prokaryotic species, most have a small range of shapes, sizes, and growth rates. Which of the following characteristics are not observed in prokaryotes? (a) a highly structured cytoplasm (b) endoplasmic reticulum (c) the ability to divide rapidly (d) a cell wall
(b) Endoplasmic Reticulum
Oxidation is the process by which oxygen atoms are added to a target molecule. Generally, the atom that is oxidized will experience which of the following with respect to the electrons in its outer shell? (a) a net gain (b) a net loss (c) no change (d) an equal sharing
(b) a net loss
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 breakdown nutrients in food can be described as _____________. (a) metabolic (b) catabolic (c) anabolic (d) biosynthetic
(b) catabolic
Brewer's yeast, apart from being an irreplaceable asset in the brewery and in the bakery, is an experimental organism used to study eucaryotic cells. However, it does face some limitations. Which of the processes below cannot be studied with yeast? (a) DNA replication (b) cell motility (c) exocytosis (d) cell division
(b) cell motility
The nucleus, an organelle found in eucaryotic cells, confines the __________, keeping them separated from other components of the cell. (a) lysosomes (b) chromosomes (c) peroxisomes (d) ribosomes
(b) chromosomes
Enzymes facilitate reactions in living systems. Figure below presents an energy diagram for the reaction X→Y. The solid line in the energy diagram represents changes in energy as the product is converted to reactant under standard conditions. The dashed line shows changes observed when the same reaction takes place in the presence of a dedicated enzyme. Which equation below indicates how the presence of an enzyme affects the activation energy of the reaction (catalyzed versus uncatalyzed)? (a) d - c versus b - c (b) d - a versus b - a (c) a + d versus a + b (d) d - c versus b - a
(b) d - a versus b - a
The second law of thermodynamics states that the disorder in any system is always increasing. In simple terms, you can think about dropping NaCl crystals into a glass of water. The solvation and diffusion of ions is favored because there is an increase in _____________. (a) pH (b) entropy (c) ionic structure (d) stored energy
(b) entropy
Catalysts are molecules that lower the activation energy for a given reaction. Cells produce their own catalysts called _____________. (a) proteins (b) enzymes (c) cofactors (d) complexes
(b) enzymes
You wish to explore how mutations in specific genes affecting sugar metabolism might alter tooth development. Which organism is likely to provide the best model system for your studies and why? (a) horses (b) mice (c) E. coli (d) Arabidopsis
(b) mice
The cytoskeleton provides support, structure, motility, and organization, and it forms tracks to direct organelle and vesicle transport. Which of the cytoskeletal elements listed below is the thickest? (a) actin filaments (b) microtubules (c) intermediate filaments (d) none of the above (all the same thickness)
(b) microtubules
An element may have more than a one isotope. Isotopes have different atomic weights, but exhibit the same chemical behavior. Carbon-14 is an unstable isotope of carbon that decays very slowly. Compared to the common, stable carbon-12 isotope, carbon-14 has two additional ______________. (a) electrons (b) neutrons (c) protons (d) ions
(b) neutrons
Seed oils are often dehydrogenated and added back into processed foods as partly unsaturated fatty acids. In comparison with the original oil, the new fatty acids have additional double carbon-carbon bonds, replacing what were once single bonds. This process could also be described as _____________. (a) isomerization (b) oxidation (c) reduction (d) protonation
(b) oxidation
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) protonated (b) oxidized (c) hydrogenated (d) reduced
(b) oxidized
C. elegans is a nematode. During its development, it produces more than 1000 cells However, the adult worm only has 959 somatic cells. The process by which 131 cells are specifically targeted for destruction is called (a) directed cell pruning. (b) programmed cell death. (c) autophagy. (d)necrosis
(b) programmed cell death
The net distance a molecule travels as it diffuses through the cytosol is relatively short in comparison with the total distance it travels. This is because movement governed by diffusion alone is a ________________ process that is most effective for the dispersion of small molecules over short distances. (a) slow (b) random (c) regulated (d) complicated
(b) random
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) fat (b) sugar (c) protein (d)fiber
(b) sugar
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) sugars (c) amino acids (d) fatty acids
(c) amino acids
Zebrafish (Danio rerio) are especially useful in the study of early development because their embryos ______________. (a) are exceptionally large (b) develop slowly (c) are transparent (d) are naturally fluorescent
(c) are transparent
Mitochondria contain their own genome, are able to duplicate, and actually divide on a different timeline from the rest of the cell. Nevertheless, mitochondria cannot function for long when isolated from the cell because they are (a) viruses. (b) parasites. (c) endosymbionts. (d) anaerobes.
(c) endosymbionts
At first glance, it may seem that living systems are able to defy the second law of thermodynamics. However, on closer examination it becomes clear that although cells create organization from raw materials in the environment, they also contribute to disorder in the environment by releasing _____________. (a) water (b) radiation (c) heat (d) proteins
(c) heat
Chemical reactions that lead to a release of free energy are referred to as "energetically favorable." Another common way in which these reactions are described is _____________. (a) uphill (b) uncatalyzed (c) spontaneous (d) activated
(c) spontaneous
Oxidation and reduction states are relatively easy to determine for metal ions, because there is a measurable net charge. In the case of carbon compounds, oxidation and reduction depend on the nature of polar covalent bonds. Which of the following is the best way to describe these types of bond? (a) hydrogen bonds in a nonpolar solution (b) covalent bonds in an aqueous solution (c) unequal sharing of electrons across a covalent bond (d) equal sharing of electrons across a covalent bond
(c) unequal sharing of electrons across a covalent bond
ΔG° indicates the change in the standard free energy as a reactant is converted to product. Given what you know about these values, which reaction below is the most favorable? (a) ADP + Pi → ATP ΔG° = +7.3 kcal/mole (b) glucose 1-phosphate → glucose 6-phosphate ΔG° = -1.7 kcal/mole (c) glucose + fructose → sucrose ΔG° = +5.5 kcal/mole (d) glucose → CO2 + H2O ΔG° = -686 kcal/mole
(d)
You have a concentrated stock solution of 10 M NaOH and want to use it to produce a 150 ml solution of 3 M NaOH. What volume of water and stock solutions will you measure out to make this new solution? (a) 135 ml of water, 15 ml of NaOH stock (b) 115 ml of water, 35 ml of NaOH stock (c) 100 ml of water, 50 ml of NaOH stock (d) 105 ml of water, 45 ml of NaOH stock
(d) 105 ml of water, 45 ml of NaOH stock
Avogadro's number, calculated from the atomic weight of hydrogen, tells us how many atoms or molecules are in mole. The resulting base for all calculations of moles and molarity (how many molecules are present when you weigh out a substance or measure from a stock solution) is the following: 1 g of hydrogen atoms = 6 ´ 1023 atoms = 1 mole of hydrogen Sulfur has a molecular weight of 32. How many moles and atoms are there in 120 grams of sulfur? (a) 3.75 and 6 × 1023 (b) 32 and 6 × 1023 (c) 1.75 and 1.05 × 1024 (d)3.75 and 2.25 × 1024 o
(d) 3.75 and 2.25 x 10^24
Biologists cannot possibly study all living species. Instead, they try to understand cell behavior by studying a select subset of them. Which of the following characteristics are useful in an organism chosen for use as a model in laboratory studies? (a) amenability to genetic manipulation (b) ability to grow under controlled conditions (c) rapid rate of reproduction (d) all of the above
(d) all of the above
Choose the answer that best fits the statement. Cholesterol is an essential component of biological membranes. Although it is much smaller than the typical phospholipids and glycoplipids in the membrane, it is a(n) _________________ molecule, having both hydrophilic and hydrophobic regions. (a) polar (b) oxygen-containing (c) hydrophobic (d)amphipathic
(d) amphipathic
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 of by which external materials are captured inside vesicles and brought into the cell? (a) degradation (b) exocytosis (c) phagocytosis (d) endocytosis
(d) endocytosis
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(n) ______________ ion. (a) hydroxide (b) ammonium (c) chloride (d) hydronium
(d) hydronium
Chloroplasts are found only in eucaryotic cells that carry out photosynthesis: plants and algae. Plants and algae appear green as a result of the presence of chlorophyll. Where is chlorophyll located in the chloroplast? (a) in the first, outer membrane (b) in the space between the first and second membranes (c) in the second, inner membrane (d) in the third, innermost membrane
(d) in the third, innermost membrane
The __________ __________ is made up of two concentric membranes and is continuous with the membrane of the endoplasmic reticulum. (a) plasma membrane (b) Golgi network (c) mitochondrial membrane (d) nuclear envelope
(d) nuclear envelope
Which of the following characteristics would not support the idea that the ancestral eucaryote was a predator cell that captured and consumed other cells? (a) dynamic cytoskeleton (b) large cell size (c) ability to move (d) rigid membrane
(d) rigid membrane
Macromolecules in the cell can often interact transiently as a result of noncovalent interactions. These weak interactions also produce stable, highly specific interactions between molecules. Which of the factors below is the most significant in determining whether the interaction will be transient or stable? (a) the size of each molecule (b) the concentration of each molecule (c) the rate of synthesis (d) surface complementarity between molecules
(d) surface complementarity between molecules
Cell biologists employ targeted fluorescent dyes or modified fluorescent proteins in both standard fluorescence microscopy and confocal microscopy to observe specific details in the cell. Even though fluorescence permits better visualization, the resolving power is essentially the same as that of a standard light microscope because the resolving power of a microscope is limited by the __________ of light. (a) absorption (b) intensity (c) filtering (d) wavelength
(d) wavelength
An ionic bond between two atoms is formed as a result of the ______________. (a) sharing of electrons (b) loss of a neutron from one atom (c) loss of electrons from both atoms (d) loss of a proton from one atom (e) transfer of electrons from one atom to the other
(e) transfer of electrons from one atom to the other
A. If 0.5 mole of glucose weighs 90 g, what is the molecular weight of glucose? B. What is the concentration, in grams per liter (g/l), of a 0.25 M solution of glucose? C.How many molecules are there in 1 mole of glucose?
A. 180 grams B. 45 g/L C. 6.02 x 10^23
Model Organisms: A. programmed cell death B. chloroplast function C. immunology D. development of a multicellular tissue
A. C. Elegans B. Arabidopsis C. Mouse D. Drosophilia
Indicate whether the statements below are true or false. A. Electrons are constantly moving around the nucleus of the atom, but they can move only in discrete regions. B. There is no limit to the number of electrons that can occupy the fourth electron shell. C. Atoms with unfilled outer electron shells are especially stable and are therefore less reactive. D.Covalent bonds are formed when electrons are either shared or transferred between atoms $v
A. True B. False C. False D. False
A. DNA- animal plant bacterial B. Nucleus- animal plant bacterial C. Plasma Membrane- animal plant bacterial D. Chloroplast- animal plant bacterial E. Cell Wall- animal plant bacterial F. Lysosome- animal plant bacterial G. Mitochondrion- animal plant bacterial H. Golgi Apparatus- animal plant bacterial
A. animal plant bacterial B. animal plant C. animal plant bacterial D. plant E. plant bacterial F. animal plant G. animal plant H. animal plant
Given what you know about the differences between procaryotic cells and eucaryotic cells, rate the following things as "good" or "bad" processes to study in the model organism, E. coli. A. formation of the endoplasmic reticulum B. DNA replication C. how the actin cytoskeleton contributes to cell shape D. how cells decode their genetic instructions to make proteins E. how mitochondria get distributed to cells during cell division
A. bad B. good C. bad D. good E. bad
Match each term related to the structure of nucleic acids (A-I) with one of the descriptions provided. A. base B. glycosidic bond C. nucleoside D. nucleotide E. phosphoanyhydride bond F. phosphoester bond G. ribose H. phosphodiester bond I. deoxyribose ____ the linkage between two nucleotides ____ the linkage between the 5′ sugar hydroxyl and a phosphate group ____ the nitrogen-containing aromatic ring ____ five-carbon sugar found in DNA ____ sugar unit linked to a base ____ linkage between the sugar and the base ____ linkages between phosphate groups ____ sugar linked to a base and a phosphate ____five-carbon sugar found in RNA A
H F A I C B E D G
Cells can be very diverse: superficially, they come in various sizes, ranging from bacterial cells such as Lactobacillus, which is a few __________________ in length, to larger cells such as a frog's egg, which has a diameter of about one __________________. Despite the diversity, cells resemble each other to an astonishing degree in their chemistry. For example, the same 20 __________________ are used to make proteins. Similarly, the genetic information of all cells is stored in their __________________. Although __________________ contain the same type of molecules as cells, their inability to reproduce themselves by their own efforts means that they are not considered living matter. amino acids; micrometer(s); viruses; DNA; millimeter(s); yeast; fatty acids; plants; meter; plasma membranes
micrometer millimeter amino acids DNA viruses
By definition, catalysis allows a reaction to occur more __________________. Chemical reactions occur only when there is a loss of __________________ energy. Enzymes act more __________________ than other catalysts. A catalyst decreases the __________________ energy of a reaction. activation free slowly chemical bond kinetic unfavorable completely rapidly favorable selectively
rapidly free selectively activation
Which of the following statements are true or false? A. The second law of thermodynamics states that the total amount of energy in the Universe does not change. B. The ultimate source of energy for living systems is chlorophyll. C. CO2 gas is fixed in a series of reactions that are light-dependent. D. H2 is the most stable and abundant form of hydrogen in the environment.
A. False B. False C. False D. False
Indicate whether the following statements are true or false. A. Primitive plant, animal, and fungal cells probably acquired mitochondria after they diverged from a common ancestor. B. Protozoans are single-celled eucaryotes with cell morphologies and behaviors that can be as complex as those of some multicellular organisms. C. Animal, plant, fungal, and bacterial cells all possess cell walls.
A. False B. True C. False
Indicate whether the statements below are true or false. If a statement is false, explain why it is false. A. nonolar interactions" is simply another way of saying "van der Waals attractions." B. Condensation reactions occur in the synthesis of all the macromolecules found in cells. C. All proteins and RNAs pass through many unstable conformations as they are folded, finally settling on one single, preferred conformation. D.When nonpolar molecules are placed in an aqueous solution, the water molecules surrounding the nonpolar surface become completely disordered
A. False B. True C. True D. False
Which of the following statements are true or false? If a statement is false, explain why it is false. A. Enzymes lower the free energy released by the reaction that they facilitate. B. Enzymes lower the activation energy for a specific reaction. C. Enzymes increase the probability that any given reactant molecule will be converted to product. D. Enzymes increase the average energy of reactant molecules
A. False; lower activation energy B. True C. True D. False; decreases
Indicate whether the statements below are true or false. If a statement is false, explain why it is false. A. A disaccharide consists of a sugar covalently linked to another molecule such as an amino acid or a nucleotide. B. The hydroxyl groups on monosaccharides are reaction hotspots and can be replaced by other functional groups to produce derivatives of the original sugar. C. The presence of double bonds in the hydrocarbon tail of a fatty acid does not greatly influence its structure. D.Glycerol is a three-carbon compound that connects the fatty acid tails with the polar head group in phospholipids
A. False; sugar has to be linked to another sugar B. True C. False; it does D. True
Match the type of microscopy on the left with the corresponding description provided below. There is one best match for each. A. confocal B. transmission electron C. fluorescence D. phase contrast E. scanning electron F. bright-field ____ uses a light microscope with an optical component to take advantage of the different refractive indexes of light passing through different regions of the cell. ____ employs a light microscope and requires that samples be fixed and stained in order to reveal cellular details. ____ requires the use of two sets of filters. The first filter narrows the wavelength range that reaches the specimen and the second blocks out all wavelengths that pass back up to the eyepiece except for those emitted by the dye in the sample. ____ scans the specimen with a focused laser beam to obtain a series of two-dimensional optical sections, which can be used to reconstruct an image of the specimen in three-dimensions. The laser excites a fluorescent dye molecule, and the emitted light from each illuminated point is captured through a pinhole and recorded by a detector. ____ has the ability to resolve cellular components a small as 2 nm. ____ requires coating the sample with a thin layer of a heavy metal to produce three-dimensional images of the surface of a sample.
D- Phase contrast F- Bright field C- Fluorescence A- Confocal B- Transmission electron E- Scanning electron
Whereas ionic bonds form a(n) __________________, covalent bonds between atoms form a(n) __________________. These covalent bonds have a characteristic bond __________________ and become stronger and more rigid when two electrons are shared in a(n) __________________. Equal sharing of electrons yields a(n) __________________ covalent bond. If one atom participating in the bond has a stronger affinity for the electron, this produces a partial negative charge on one atom and a partial positive charge on the other. These __________________ covalent bonds should not be confused with the weaker __________________ bonds that are critical for the three-dimensional structure of biological molecules and for interactions between these molecules. charge length polar covalent molecule salt double bond noncovalent single bond ionic nonpolar weight
Salt Molecule Length Double bond Nonpolar Polar Noncovalent
Eucaryotic cells are bigger and more elaborate than procaryotic cells. By definition, all eucaryotic cells have a __________________, usually the most prominent organelle. Another organelle found in essentially all eucaryotic cells is the __________________, which generates the chemical energy for the cell. In contrast, the __________________ is a type of organelle found only in the cells of plants and algae, and performs photosynthesis. If we were to strip away the plasma membrane from a eucaryotic cell and remove all of its membrane-enclosed organelles, we would be left with the __________________, which contains many long, fine filaments of protein that are responsible for cell shape and structure and thereby form the cell's __________________. chloroplast cytosol nucleus chromosome endoplasmic reticulum ribosomes cytoskeleton mitochondrion
nucleus mitochondrion chloroplast cytosol cytoskeleton
