BI 108 Exam 1
The DNA sequence ATTCGTTCA is equivalent to which RNA sequence? - UAAGCAAGU - ATTCGTTCA - TAAGCAAGT - UGAACGAAU - AUUCGTUCA
AUUCGTUCA
There are a number of functional groups in biological molecules. Which statement about functional groups is accurate? - Hydroxyl groups are present only in carbohydrates. - Aldehyde groups are common in proteins. - Amino groups may be found in modified carbohydrates and in proteins. - Carboxyl groups are found in small molecules but not in macromolecules. - Sulfhydryl groups are important features of fats.
Amino group may be found in modified carbohydrates and in proteins
Many vitamins are essential to human health because they are precursors for coenzymes. Many are also compounds that human cells cannot synthesize themselves and so must be obtained through diet. What would happen if a person could not obtain one of these vitamins from a food source? - An enzyme would not fold properly, making it unable to catalyze a vital metabolic reaction. - An enzyme would lack a critical chemical component required as a participant in the enzyme's metabolic reaction. - An enzyme would lack a metal ion at its active site that enables the enzyme to carry out its catalytic mechanism. - An enzyme would lose its ability to bind substrates, making it unable to catalyze an essential chemical reaction. - An enzyme would lose its substrate specificity, causing it to catalyze many extra reactions that normally do not occur in a cell.
An enzyme would lack a critical chemical component required as a participant in the enzyme's metabolic reaction.
Which parameter is indicative of how far and in what direction a reaction will progress? - The concentration of reactants - The change in free energy of the reaction (ΔG) - The concentration of products - The change in enthalpy of the reaction (ΔH) - The overall size of the system in which the reaction occurs
The change in free energy of the reaction (ΔG)
Areas A and B are separated by a membrane that is permeable to a substance X. Which set of conditions will result in the greatest rate of diffusion of X into area A? - The concentration of X in A is 50 mM; the concentration of X in B is 60 mM. - The concentration of X in A is 10 mM; the concentration of X in B is 2 M. - The concentration of X in A is 5 mM; the concentration of X in B is 1 μM. - The concentration of X in A is 200 mM; the concentration of X in B is 250 mM. - The concentration of X in A is 1 M; the concentration of X in B is 500 mM.
The concentration of X in A is 10 mM; the concentration of X in B is 2 M
Which scenario supports Garrod's one-gene, one-enzyme hypothesis of metabolic disease causation? - The disease PKU is due to the failure to produce a functional variant of an enzyme. - A blood disease is due to a recessive allele in one of two genes. - A neurological disease is due to a dominant allele in a single gene. - Multiple genes contribute to the likelihood that a person will develop coronary heart disease. - ATCase, which catalyzes the first step in the pyrimidine biosynthetic pathway, is a 12-subunit complex constructed of catalytic and regulatory chains.
The disease PKU is due to the failure to produce a functional variant of en enzyme
Based on this figure, which statement is true? - Plants and bacteria do not share a common ancestor. - The diversity of organisms on Earth has increased since life arose. - Protists are prokaryotes. - Fungi are more closely related to plants than to animals. - Most of the species that were ever present on Earth have already been discovered
The diversity of organisms on Earth has increased since life arose
Which statement about ATP is false? - The synthesis of ATP is an endergonic reaction. - The hydrolysis of ATP to ADP and Pi is an exergonic reaction. - The phosphate bond energy of ATP cannot be harnessed for work. - ATP is a building block of RNA. - The phosphate bond energy of ATP may be transformed into light energy.
The phosphate bond energy of ATP cannot be harnessed for work.
To be metabolized, glucose must be converted to glucose 6-phosphate. However, the phosphorylation of glucose to form glucose 6-phosphate is endergonic with a positive ΔG. How do cells circumvent this problem? - The reaction is catalyzed by an enzyme, which allows the reaction to proceed by changing its ΔG. - The reaction is catalyzed by an enzyme, which allows the reaction to proceed by lowering its activation energy. - An enzyme raises the activation energy barrier to favor glucose 6-phosphate formation. - An enzyme changes the equilibrium constant for the reaction to favor glucose 6-phosphate formation. - The reaction is coupled to the hydrolysis of ATP, making the entire process exergonic.
The reaction is coupled to the hydrolysis of ATP, making the entire process exergonic.
Which interaction between atoms is the strongest? - Hydrophobic interactions - Ionic attraction - Covalent bonds - van der Waals forces - Hydrogen bonds
Covalent bonds
Which statement about chemical reactions is false? - They occur when atoms combine or change their bonding partners. - They may lead to the creation or destruction of energy. - They may go to completion. - They may lead to changes in forms of energy. - They convert reactants into products.
They may lead to the creation or destruction of energy
Nucleotides are joined together in a single strand of DNA - by hydrogen bonds. - by carbon-carbon bonds. - by hydrophobic interactions. - by glycosidic linkages. - by phosphodiester bonds.
by phosphodiester bonds.
The synthesis of complex molecules is _______, whereas their degradation is _______. Synthesis occurs with _______ in entropy. - endergonic; exergonic; an increase - endergonic; exergonic; a decrease - exergonic; endergonic; no change - exergonic; endergonic; an increase - endergonic; exergonic; no change
endergonic; exergonic; a decrease
The data indicate that the overall CO2 concentration is _______, with yearly fluctuations due to _______. - variable; precipitation - increasing; ocean absorption - increasing; photosynthesis - decreasing; precipitation - decreasing; photosynthesis
increasing; photosyntehsis
An organism - must reproduce to ensure survival of its kind. - cannot do biological work. - always contains more than one cell. - can evolve. - can be generated from nonliving materials.
must reproduce to ensure survival of its kind
Hydrocarbons are _______ and _______, whereas salts are _______ and _______. - nonpolar; hydrophobic; polar; hydrophilic - nonpolar; hydrophilic; polar; hydrophobic - nonpolar; hydrophobic, nonpolar, hydrophilic - polar; hydrophilic; nonpolar; hydrophobic - polar; hydrophobic; nonpolar; hydrophilic
nonpolar; hydrophobic; polar; hydrophilic
Nucleotides are composed of - one or more amino acids. - nucleic acids. - one or more phosphates, a sugar, and a base. - a base and at least one phosphate. - fatty acids and a base.
one or more phosphates, a sugar, and a base
Covalent bond formation depends on the ability of atoms to _______ other atoms. - share one or more pairs of electrons with - donate electrons to - receive electrons from - share neutrons with - donate protons to
share one or more pairs of electrons
Which statement about diffusion is false? - Simple diffusion depends on specific carrier or channel proteins. - Facilitated diffusion does not require ATP. - Molecules move from areas of greater concentration to areas of lesser concentration. - Diffusion continues until the molecular concentrations are in equilibrium. - Diffusion occurs as the result of the random movement of molecules.
simple diffusion depends on specific carrier or channel proteins
Which statement disagrees with the second law of thermodynamics? - The disorder of a system and its surroundings decreases overall with time. - Chemical energy may be converted to light energy. - Only a portion of the total energy of a system is available to do work. - Potential energy may be used to do work. - During energy conversion, some energy can be lost as heat.
the disorder of a system and its surroundings decreases overall with time
Comparison of the same gene and its product in two different animal species revealed that the amino acids are 98 percent identical but the nucleotides are only 86 percent identical. What accounts for the much higher amino acid identity than nucleotide identity? - The genetic code is redundant. - The genetic code differs between species. - The researchers sequenced different template strands. - The genetic code is nonredundant. - The genetic code is ambiguous.
the genetic code is rebundant
An mRNA sequence is 5′-CAGUUACGA...UAAGC-3′ ([...] denotes intervening sequences). What is the sequence of the template strand of DNA? - 5′-CAGUUACGA...UAAGC-3′ - 5′-CAGTTACGA...TAAGC-3′ - 3′-CAGUUACGA...UAAGC-5′ - 3′-GTCAATGCT...ATTCG-5′ - 5′-GTCAATGCT...ATTCG-3′
- 3′-GTCAATGCT...ATTCG-5′
Given that Avogadro's number is 6.02 × 1023, how many molecules of KCl are there in 10-13 liter of a 1 M KCl solution? - 6.02 × 1036 - 6.02 × 1010 - 6.02 × 10-10 - 6.02 × 103 - 6.02 × 1013
- 6.02 × 1010
If the coding region of an mRNA is 2,400 nucleotides long, how many codons does it have? - 600 - 800 - 1,200 - 2,400 - 7,200
800
Which step is thought to have occurred, according to endosymbiotic theory? - A dependent prokaryotic cell was engulfed by an independent prokaryotic cell, allowing the dependent cell to survive within the independent host cell. - A dependent prokaryotic cell was engulfed by another dependent prokaryotic cell, allowing each cell to survive with the help of the other. - An independent prokaryotic cell was engulfed by a dependent prokaryotic cell, allowing the dependent host cell to survive with the help of the engulfed cell. - An independent prokaryotic cell was engulfed by another independent prokaryotic cell, after which the engulfed cell lost certain functions and became dependent on the host cell. - An independent prokaryotic cell was engulfed by another independent prokaryotic cell, and both continued activities independent of one another.
An independent prokaryotic cell was engulfed by another independent prokaryotic cell, after which the engulfed cell lost certain functions and became dependent on the host cell.
Which are the two main lineages of prokaryotes that diverged early in life's history? - Archaea and Eukarya - Bacteria and Eukarya - Protista and Bacteria - Eukarya and Protista - Bacteria and Archaea
Bacteria and Archaea
Fatty acids are - carboxylic acids with long hydrocarbon tails. - linked to glycerol in fats by phosphodiester bonds. - saturated hydrocarbons. - large polymers of monosaccharides. - generally present in water-soluble proteins.
Carboxylic acids with long hydrocarbon tails
The villi of the small intestine are lined with epithelial cells that absorb nutrients from digested food on one side and transfer these nutrients into the blood on the other side. Which cell shown in the figure would be most efficient as an epithelial cell in the intestinal villi, and why? (cell A is a smaller cube and cell B is larger) - Cell B because it has a greater volume than cell A. - Cell A because its volume is greater than its surface area. - Cell B because it has a greater surface area than cell A. - Cell A because it has a larger surface area-to-volume ratio than cell B. - Cell B because it has a larger overall size than cell A.
Cell A because it has a larger surface area-to-volume ratio than cell B
Five statements about cell membranes are given. Which statement can be used to explain the importance of the cell membrane to cell survival? - The cell membranes of prokaryotes and eukaryotes have the same basic structure. - Cell membranes are composed of a phospholipid bilayer embedded with proteins. - Cell membranes are selectively permeable with respect to molecules and ions. - The cell membrane is so small that it is best viewed with an electron microscope. - The cell membrane expands or shrinks by the addition or removal of phospholipid molecules.
Cell membranes are selectively permeable with respect to molecules and ions.
Which statement correctly describes a difference between DNA and RNA? - DNA is single-stranded, whereas RNA is double-stranded. - DNA occurs in the nucleus, whereas RNA only occurs outside the nucleus. - DNA contains a ribose, whereas RNA contains a deoxyribose. - DNA is replicated, whereas RNA is translated. - DNA contains four nucleotides, whereas RNA contains three
DNA is replicated, whereas RNA is translated
Of the following types of ecosystems, which one does not receive its energy from the sun? - Tundra - Coral reefs - Deep-sea hydrothermal vents - Mid-ocean depths, where organisms feed on detritus from above - Forest soils, where organisms feed on soil detritus
Deep-sea hydrothermal vents
Which property of water contributes most to the ability of fish in lakes to survive very cold winters? - Strong cohesive forces - High heat capacity - Density differences at different temperatures - High surface tension - High heat of vaporization
Density differences at different temperatures
Which statement about isotopes is false? - Isotopes vary in the number of neutrons but not the number of protons. - Radioisotopes are unstable and spontaneously emit radiation. - Isotopes have the same atomic number but not the same atomic weight. - Isotopes have virtually the same chemical reactivity. - Deuterium is an isotope of hydrogen containing one proton and two neutrons.
Deuterium is an isotope of hydrogen containing one proton and two neutrons
A researcher poses the hypothesis that plants grow tallest under a full spectrum of visible light. The researcher runs an experiment in which she plants seeds of the same plant species in pots and places different groups of pots under different lighting conditions. Group 1 receives the full spectrum of visible light, while groups 2 through 6 receive narrow ranges of visible wavelengths of light. All lighting conditions are at the same intensity. The researcher observes that the plants growing tallest are those exposed to blue light. After making these observations, which step is she most likely to carry out next? - Run a control trial to be sure that a valid conclusion can be made based on the results. - Discard her original hypothesis and formulate a new one. - Design a follow-up experiment to change soil type and water conditions simultaneously as tests of these variables on plant growth. - Discard her question that asks what factors influence plant growth and why. - Repeat the experiment at a different level of light intensity
Discard her original hypothesis and formulate a new one.
In some cases, a single amino acid substitution can cause a protein to lose its biological activity. In other cases, a single amino acid substitution causes no change to a protein's biological activity. Which statement can best be used as evidence to support an explanation for these observations? - Amino acids are covalently linked through peptide bonds to form the primary structure of a protein. - Amino acids found in the proteins of living organisms have many similarities, including an alpha-amino group and an alpha-carboxyl group. - Amino acids occur as optical isomers, but only one isomer of each is found in the proteins of most of the organisms on Earth. - Noncovalent interactions between atoms in a polypeptide chain stabilize the secondary, tertiary, and quaternary levels of its structure. - Each amino acid side chain has properties that are very different from those of some side chains and very similar to those of others.
Each amino acid side chain has properties that are very different from those of some side chains and very similar to those of others.
Which statement can be used to explain how the first law of thermodynamics relates to biological systems? - Biological systems must take in energy from the surroundings to be able to build complex molecules from smaller precursor molecules. - In any biological system, the total energy includes the usable energy that can do work and the unusable energy that is lost to disorder. - Energy moves in and out of biological systems and is transformed from one type to another, but no energy is destroyed or created in the process. - The amount of energy that a biological system has available to do work is always less than the original amount of energy taken in by the system from its surroundings. - In a biological system, free energy continually decreases with repeated energy transformations.
Energy moves in and out of biological systems and is transformed from one type to another, but no energy is destroyed or created in the process
Olive oil melts at a lower temperature than beef fat because - oils contain glycerol, whereas fats do not. - fats contain more saturated fatty acids than oils do. - fats contain more unsaturated fatty acids than oils do. - oils are made by plants, whereas fats are made by animals. - olive trees naturally occur in warmer climates than beef cattle do.
Fats contain more saturated fatty acids than oils do
In 1928, British bacteriologist Alexander Fleming made an accidental discovery. He noticed that a fungus had contaminated one of the agar plates he had streaked with a bacterial species to be studied. The fungus prevented the bacteria from growing in the immediate area surrounding the fungus. Upon further investigation, Fleming found that the fungus produced a substance that was the agent responsible for killing the bacteria. He called this substance penicillin. Given this information, which statement best explains why Fleming's discovery is relevant to the general public today? - Fleming's attention to detail diverted his efforts to investigate bacteria and likely robbed humanity of important discoveries that he would have otherwise made. - Fleming's discovery enabled the development of chemical substances as antibiotics to treat deadly bacterial infections. - Fleming's work revealed the ability of bacteria to mutate, which necessitates the constant search for new antibiotics. - Fleming's research spawned new questions about the ecological interactions between fungi and bacteria. - Fleming's sloppiness in the lab serves as a reminder to all researchers that sterile technique is critical to preventing unwanted fungal growth on bacterial plates.
Fleming's discovery enabled the development of chemical substances as antibiotics to treat deadly bacterial infections.
Isotopic analysis of biological samples can be a useful tool in the study of - how a drug moves through the body. - life-spans of ancient animals. - social patterns of ancient people. - the genetic makeup of dinosaurs. - the mating preferences of a bird species.
How a drug moves through the body
What property of organelles and other subcellular structures is used to separate them using the lab technique known as cell fractionation? - Mass - Charge - Composition - Density - Shape
Mass
Which statement about RNA is false? - Transfer RNA functions in translation. - Ribosomal RNA functions in translation. - RNAs are produced by transcription. - Messenger RNAs are produced on ribosomes. - DNA codes for mRNA, tRNA, and rRNA.
Messenger RNAs are produced on ribosomes
The "building blocks" of polysaccharides are _______, and these blocks are covalently linked together by _______ bonds. - glycerol and fatty acids; ester - amino acids; peptide - monosaccharides; glycosidic - phospholipids; ester - disaccharides; glycosidic
Monosaccharides; glycosidic
A student calculates the amount of plant biomass produced by a field during one season. He defines this as the gross primary production of the field. Is this correct, and why or why not? - Yes; it represents the total amount of energy received from the sun and stored by plants. - Yes; it represents the total amount of energy available to consumers, which is the GPP. - Possibly; it represents the production that could be measured, but not necessarily all production. - No; it represents net primary production, because it does not measure energy lost during respiration. - No; it represents net primary production, which includes both available production and energy lost as heat
No; it represents net primary production, because it does not measure energy lost during respiration
Which gas is not thought to have been added to the atmosphere by extensive volcanic eruptions early in Earth's history? - Hydrogen sulfide - Nitrogen - Sulfur dioxide - Carbon dioxide - Oxygen
Oxygen
Which shows the elements carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and phosphorus (P) in decreasing order by the number of covalent bonds they usually form? - C > P > N > O > H - P > O > C > N > H - P > C > N > O > H - P > C > O > N > H - P > C > O > H > N
P > C > N > O > H
Which are biological examples of potential energy (PE) and kinetic energy (KE)? - PE = concentration gradient; KE = chemical bonds - PE = muscle contraction; KE = electrical charge imbalance - PE = chemical bonds; KE = ion movement across a membrane - PE = electrical charge imbalance; KE = concentration gradient - PE = protein conformational change; KE = muscle contraction
PE = protein conformational change; KE = muscle contraction
Which finding can be used to justify the claim that living organisms are dynamic? - Microscopic examination of tissue removed from a multicellular organism reveals cells as the underlying basic units of structure. - Combustion of living plants results in formation of carbon dioxide and water along with a great deal of heat. - Examination of fossilized remains of dinosaurs indicates that these organisms share some anatomical features with modern birds. - Elemental analysis of living tissue reveals the presence of many elements in trace quantities. - Radioisotopic tracing shows that living organisms transform glucose and oxygen to carbon dioxide and water.
Radioisotopic tracing shows that living organisms transform glucose and oxygen to carbon dioxide and water
Which structure is not surrounded by one or more membranes? - Ribosome - Chloroplast - Mitochondrion - Peroxisome - Vacuole
Ribosome
Which lab procedure is the best to use to determine whether a newly discovered single-celled organism is prokaryotic or eukaryotic? - Search for the presence of membrane-bound structures within the cell, using transmission electron microscopy. - Determine the molecular makeup of the organism's cell membrane, using chemical analysis. - Stain cells with a ribosome-specific stain, and then use light microscopy to assess whether ribosomes are present or absent in the cells. - Use biochemical methods to determine whether the organism has a cell wall and is also capable of carrying out photosynthesis. - Use analytical techniques to determine the number of genes encoded in the organism's DNA.
Search for the presence of membrane-bound structures within the cell, using transmission electron microscopy.
Refer to the figure below showing active transport of amino acids from the intestine into cells lining the small intestine, followed by passive transport into the blood. Based on this figure, what terms would be used to describe the mechanism of uptake of amino acids into intestinal cells? - Primary active transport; antiporter - Primary active transport; uniporter - Secondary active transport; uniporter and antiporter - Primary active transport; symporter - Secondary active transport; symporter and antiporter
Secondary active transport; symporter and antiporter
Of the statements below, which best explains why the study of water is relevant to the study of living organisms? - Water is produced when amino acids polymerize to form proteins and when nucleotides polymerize to form RNA and DNA. - Ninety-six percent of water on Earth is found in the oceans, 1 percent is found in bays and estuaries, and 3 percent is found in freshwater locations. - An average rainstorm drops about 100,000 liters of water over 1 acre of land. - Sixty percent of an adult human's body weight is due to water, with two-thirds of this water located inside cells and one-third outside cells. - Water is the only compound on Earth that can be found as a gas, a liquid, and a solid in different natural settings.
Sixty percent of an adult human's body weight is due to water, with two-thirds of this water located inside cells and one-third outside cells.
Certain types of cells have very low levels of metabolic activity for long time periods, but then rapidly shift to grow and divide. To undergo this shift, these cells must activate anabolic pathways. Which is one way they are able to accomplish this? - Large molecules influence metabolic flux through competitive inhibition effects on enzymes. - Small molecules affect metabolic flux through allosteric effects on enzymes. - Anabolic enzymes inhibit catabolic enzymes. - Cells begin directing all of their energy toward reactions with negative ΔGs. - Cells only synthesize anabolic enzymes and cease synthesizing catabolic enzymes.
Small molecules affect metabolic flux through allosteric effects on enzymes
Consider two enzyme reaction solutions. Solution 1 has a ratio of enzyme to substrate of 1:100. Solution 2 has a ratio of enzyme to substrate of 100:1. Both solutions contain the same quantity of enzyme. Which reaction gives the greater reaction rate, and why? - Solution 1, because the enzyme has much more available substrate than in solution 2. - Solution 1, because the enzyme has much less available substrate than in solution 2. - Solution 2, because the enzyme is saturated in this solution but not in solution 1. - Solution 2, because the enzyme is not saturated in this solution but is saturated in solution 1. - Both have the same reaction rate, because they contain the same quantity of enzyme.
Solution 1, because the enzyme has much more available substrate than in solution 2.
A strain of Neurospora is able to grow on minimal medium. When substance A is added to the medium, however, the strain cannot grow. Supplying a small amount of substance B has no effect on the strain, but it cannot reverse the effect of substance A. Supplying a small amount of substance C, by contrast, enables the strain to grow with substance A. Which of the following statements best explains these facts? - Substance A is a toxin that the strain cannot break down, and substance B is an enzyme that breaks down substance A. - Substance A is a toxin that the strain cannot break down, and substance C is an enzyme that breaks down substance A. - The strain has the capacity to produce substance C. - Substance A is a mutagen. - Substance C is a mutagen.
Substance A is a toxin that the strain cannot break down, and substance C is an enzyme that breaks down substance A.
Why is the pH of a 0.1 M solution of acetic acid in water higher than that of a 0.1 M solution of HCl in water? - HCl is a weaker acid than acetic acid. - The acetic acid does not fully ionize in water, whereas HCl does. - HCl does not fully ionize in water, whereas acetic acid does. - Acetic acid is a better buffer than HCl. - Acetate (ionized acetic acid) is a strong base.
The acetic acid does not fully ionize in water, whereas HCl does.
Which statement best explains the shape of this curve? (an S shapped curve) - The enzyme has multiple active sites. As the enzyme binds substrate at one site, its affinity for binding substrate at other active sites increases. - The enzyme has a single active site. As the enzyme binds substrate, the activity of the enzyme stalls until it can clear the active site. - The enzyme has multiple active sites. As the substrate concentration increases, all sites must be equally bound for the reaction to proceed. - The enzyme has multiple active sites. Substrate binding at each of the sites is dependent upon the temperature of the reaction. - The enzyme has a single active site. Substrate binding at this particular site occurs within a narrow pH range, termed the equivalence point.
The enzyme has multiple active sites. As the enzyme binds substrate at one site, its affinity for binding substrate at other active sites increases.
Enzyme Y is a component of a metabolic pathway and is inhibited by a metabolite produced at the end of that particular metabolic pathway. Which statement would not be true regarding this enzyme? - This enzyme regulates the pathway through a feedback inhibition mechanism. - This enzyme may also be activated by metabolites of another pathway. - Levels of this enzyme may be regulated at the level of transcription of its gene. - This enzyme uses competitive inhibition as a mechanism for its regulation by downstream metabolites in the pathway. -This enzyme is very likely involved in the first commitment step of the metabolic pathway mentioned in the question.
This enzyme uses competitive inhibition as a mechanism for its regulation by downstream metabolites in the pathway.
A research group hypothesizes that diet influences the distribution of bacterial species inhabiting the human digestive system. The researchers define two populations with very different diets—one in England and another in Africa—for sample collection. They take fecal samples from each group and measure the percentage of each species of bacteria present in the samples. How is this investigation classified and why? - This investigation is a controlled investigation because it was carried out using defined study populations. - This investigation is a controlled investigation because controlled methods were used for the collection and analysis of fecal samples. - This investigation is a comparative study because it compares a characteristic of two different groups that could be influenced by many variables. - This investigation is both a controlled and comparative study because it controls all but one variable influencing two study groups and then compares how that variable differs. - This investigation is a comparative study because it tests a hypothesis that was formulated by comparing the diets of two populations.
This investigation is a comparative study because it compares a characteristic of two different groups that could be influenced by many variables.
How might a researcher study the presence of a specific protein in cells from different tissues of the body? - Slice cells into thin sections, use electron microscopy to take many images of structures inside the cells, and search for the protein in the images. - Observe the protein in living cells, using light microscopy techniques that preserve cells in the living state. - Treat cells with a dye that selectively binds to the protein of interest, and look for evidence of this dye in cells, using light microscopy. - Use scanning electron microscopy to search for the protein in the three-dimensional surfaces of whole cells. - Use a general protein stain to treat cells before preparing them for bright-field microscopy, and then search for evidence of this dye in the samples.
Treat cells with a dye that selectively binds to the protein of interest and look for evidence of this dye in cells, using light microscopy
Sweating is a useful cooling device for humans because water - absorbs a great deal of heat in changing from its liquid state to its gaseous state. - absorbs a great deal of heat in changing from its solid state to its liquid state. - can exist in three states at temperatures common on Earth. - is an outstanding solvent. - ionizes readily.
absorbs a great deal of heat in changing from its liquid state to its gaseous state
The average net primary production (NPP) per square meter is greatest in the _______ ecosystem, and the greatest contribution to Earth's total primary production is made by the _______ ecosystem. - tropical rainforest; tropical rainforest - algal beds and coral reefs; algal beds and coral reefs - tropical rainforest; open ocean - algal beds and coral reefs; open ocean - open ocean; open ocean
algal beds and coral reefs; open ocean
The primary structure of proteins is the _______. The primary structure contains the information necessary for the formation of a secondary structure, including the _______ and the _______. Secondary structure of proteins is stabilized by the formation of _______ bonds. - amino acid sequence; β pleated sheet; α helix; disulfide - α helix; amino acid sequence; β pleated sheet; hydrophobic - amino acid sequence; α helix; β pleated sheet; hydrogen - amino acid sequence; α helix; β pleated sheet; peptide - β pleated sheet; α helix; amino acid sequence; hydrogen
amino acid sequence; α helix; β pleated sheet; hydrogen
Replication is the synthesis of _______, while transcription is the synthesis of _______. - an RNA copy of DNA; an exact copy of DNA - an exact copy of DNA; proteins - an exact copy of RNA; an exact copy of DNA - proteins; an RNA copy of DNA - an exact copy of DNA; an RNA copy of DNA
an exact copt of DNA; an RNA copy of DNA
In the scientific method, a hypothesis is - the basis for making predictions. - formulated solely by speculation. - a final answer to a question. - formulated by statistical analysis of data. - an alternative to an experiment.
basis for making predictions
The recent increase in atmospheric CO2 levels is mainly a result of an increase in - gross primary productivity. - the biomass of the biosphere. - the absorption of infrared radiation escaping from Earth. - cellular respiration by the exploding human population. - the burning of fossil fuels and wood.
burning of fossil fuels and wood
Receptor-mediated endocytosis is the mechanism for transport of - integral membrane proteins. - cholesterol. - clathrin. - ions. - all macromolecules
cholesterol
The speed and direction of ions as they move through channels in the cell membrane are determined by the - size and charge of the ions. - number of channel proteins present. - concentration gradient. - ability of the ions to bind water. - thickness of the cell membrane.
concentration gradient
For a covalent bond to be polar, the two atoms that form the bond must have - differing atomic weights. - differing numbers of neutrons. - differing melting points. - differing electronegativities. - similar electronegativities.
differing electronegativities
Osmosis is a specific form of - secondary active transport. - pinocytosis. - diffusion. - movement of water by carrier proteins. - active transport.
diffusion
Ribozymes are RNA molecules that have enzymatic activity. This conflicts with the belief of early molecular biologists that - the flow of information in gene expression goes in one direction. - the flow of information in gene expression goes in both directions. - DNA information can be propagated into information in proteins, but information in proteins cannot be propagated into information in DNA. - each enzyme is a polypeptide. - each enzyme was encoded by one gene
each enzyme is a polypeptide
The cell membrane - encloses a distinct chemical environment. - catalyzes chemical reactions. - carries genetic information. - is usually formed of protein molecules. - exists due to the specific gravity of water.
encloses a distinct chemical environment
The structure of a biological membrane is best described by the _______ model. - fatty acid - phospholipid bilayer - fluid mosaic - hydrophilic core - plasma membrane
fluid mosaic
Suppose the reaction A → B has a large negative ΔG. The reaction would proceed _______, at equilibrium _______ would be present, and _______. - from A to B; mostly B; insufficient information is given to predict the rate of the reaction - from B to A; mostly A; the reaction would be slow - from A to B; mostly B; the reaction would be fast - from A to B; mostly B; the reaction would be slow - There is not enough information to answer the question.
from A to B; mostly B; insufficient information is given to predict the rate of the reaction
Carbohydrates play a role in the biological membrane as recognition sites for other cells and molecules. They covalently bind to a protein in the membrane to form - lipid proteins. - transmembrane proteins. - plasma bilayers. - phospholipids. - glycoproteins.
glycoproteins
Polar molecules... - have electric charges that are unequally distributed. - have the ability to form ions when dissolved in water. - have electric charges that are equally distributed. - have bonds with an overall negative charge. - have bonds with an overall positive charge.
have electric charges that are unequally distributed
All carbohydrates - are polymers. - are simple sugars. - are found in biological membranes. - have the general structure (C1H2O1)n or CnH2nOn. - are more soluble in nonpolar solvents than in water.
have the general structure (C1H2O1)n or CnH2nOn.
If a cell has an increased need for a particular molecule already present in a higher concentration within the cell than in the extracellular fluid, the cell might use active transport, which usually moves molecules - from inside to outside the cell. - in a direction opposite to the one in which diffusion moves them. - in the same direction as diffusion moves them. - in a direction that tends to bring about equilibrium. - toward higher pH.
in a direction opposite to the one in which diffusion moves them
Vitamin B12 is an essential vitamin that humans must acquire from their diets. Within the small intestine, vitamin B12 is taken up by receptor-mediated endocytosis as shown in the figure. The protein labeled IF binds to vitamin B12 molecules in the intestinal lumen, forming a complex. This complex is recognized by the IF receptor present on intestinal cells and stimulates endocytosis when it binds. Vitamin B12 by itself does not bind to the receptor. Individuals known to carry a mutation in either the IF protein or the IF receptor are represented in the table, along with observations about whether symptoms of vitamin B12 deficiency are present. If a drug molecule could be produced that would bind to vitamin B12 and stimulate uptake by intestinal cells, which individual(s) would be expected to benefit, based on the information given? - Individuals 2 and 3 only - Individual 1 only - Individuals 1 and 2 only - Individual 3 only - Individual 2 only
individual 2 only
_______ proteins are embedded in biological membranes while _______ proteins are associated with surface regions of biological membranes. - Cytoskeletal; integral - Extracellular; peripheral - Peripheral; extracellular - Transmembrane; integral - Integral; peripheral
integral; peripheral
Phagocytosis, pinocytosis, and receptor-mediated endocytosis all involve - the presence of receptor proteins. - invagination of the plasma membrane. - the export of macromolecules. - the intake of specific fluids by the cell. - the intake of large particles.
invagination of the plasma membrane
Which effector of enzyme activity is least likely to be utilized by cells? - Allosteric inhibitors - Allosteric activators - Competitive inhibitors - Noncompetitive inhibitors - Irreversible inhibitors
irreversible inhibitors
Which is a reason to use statistics to evaluate data? - It provides a way for proving that your hypothesis is correct. - It makes it possible to avoid having to consider the null hypothesis. - It facilitates the exclusion of data that do not fit your hypothesis. - It accounts for variation in scientific measurements. - It enables you to predict experimental results.
it accounts for variation in scientific measurements
Which statement about starch is false? - It may be partially branched. - It is a polymer of glucose. - It is formed by the condensation of monomers. - It has properties very similar to those of cellulose. - It can be digested by humans.
it has properties very similar to those of cellulose
A biologist discussing the discovery of horseshoe crab fossils that date to 445 mya mentions that these fossils were the ancestors of horseshoe crabs living today. Which biological principle does this illustrate? - The fundamental unit of life is the cell. - All organisms on Earth share a common ancestor. - Life is continuous. - All living organisms are composed of cells. - Evolution explains the diversity of living organisms on Earth today.
life is continuous
Cholesterol is soluble in chloroform, a nonpolar organic solvent, but it is not soluble in water. Based on this information, cholesterol belongs to what class of biological macromolecules? - Oligosaccharides - Carbohydrates - Proteins - Enzymes - Lipids
lipids
The binding of a substrate to an enzyme - is always covalent. - is irreversible. - is nonspecific. - may involve hydrogen bonds and van der Waals interactions. - does not induce shape changes in the enzyme.
may involve hydrogen bonds and van der Waals interactions
The cytoskeleton consists of - cilia, flagella, and microfilaments. - cilia, microtubules, and microfilaments. - internal cell walls. - microtubules, intermediate filaments, and microfilaments. - calcified microtubules.
microtubules, intermediate filaments, and microfilaments.
All lipids are - triglycerides. - polar. - hydrophilic. - polymers of fatty acids. - more soluble in nonpolar solvents than in water.
more soluble in nonpolar solvents than in water
Enzymes increase the rate of a reaction in all of the following ways except - orienting substrates. - inducing strain on the substrate. - reacting chemically with the substrate. - donating a proton to the substrate. - permanently binding the substrate.
permanently binding the substrate
Based on its structure, a triglyceride is most closely related to a - wax. - phospholipid. - fat-soluble vitamin. - steroid. - carotenoid.
phospholipid
The organisms that produced the oxygen gas in Earth's early atmosphere were - anaerobic eukaryotes. - aerobic eukaryotes - completely unlike modern organisms. - aerobic prokaryotes. - photosynthetic prokaryotes
photosynthetic prokaryotes
If all the lysosomes within a cell suddenly ruptured, what would be the most likely result? - Proteins in the cytosol would break down. - More proteins would be made. - The DNA in mitochondria would break down. - The mitochondria and chloroplasts would divide. - There would be no change in cell function.
proteins in the cytosol would break down
The major factor limiting cell size is the - volume of water in the cytoplasm. - need for energy. - presence of membrane-enclosed organelles. - ratio of surface area to volume. - composition of the cell membrane.
ratio of surface area to volume
Some proteins on the surface of a mammalian cell contain carbohydrates. These proteins are synthesized by _______ and the sugars are added in the _______. - mitochondrial ribosomes; smooth endoplasmic reticulum - ribosomes on the rough endoplasmic reticulum; Golgi apparatus - cytoplasmic ribosomes; smooth endoplasmic reticulum - the Golgi apparatus; rough endoplasmic reticulum - cytoplasmic ribosomes; plasma membrane
ribosomes on the rough endoplasmic reticulum; Golgi apparatus
Fatty acids have hydrophilic heads and hydrophobic tails. This allows them to - self-organize into a single layer surrounding a sphere of water. - form a double-layered membrane with heads facing out and a layer of water between the tails. - act as catalysts for chemical reactions. - act as information carriers for protocells. - self-organize into a double layer surrounding a sphere of water.
self-organize into a double layer surrounding a sphere of water.
A biologist hypothesizes that keeping mice on a restricted diet with minimal calories will increase their aggression. The biologist designs an experiment in which 100 mice are to be housed in individual cages under similar conditions and diets. He then plans to place pairs of mice together in the same cage to observe their interactions. What is true about this study design? - The study is not controlled. - The study is well designed since it uses a large sample of mice. - The study includes too many variables. - The study is flawed because the hypothesis is not testable. - The study is unnecessary because the results are obvious
the study is not controlled
In the double-stranded structure of DNA, - the two strands are held together by covalent bonds. - the monomers in each strand are linked together by hydrogen bonds. - both strands run in the same direction. - the two strands are held together by hydrogen bonds. - the monomers in each strand are linked together by ionic bonds.
the two strands are held together by hydrogen bonds
A unicellular organism adapted to living in salt water is placed in a freshwater tank. What is the likely outcome? - Water moves into the cell, causing it to burst. - Water moves out of the cell, causing it to shrivel. - Water moves out of the cell until the organism can adapt. - Water moves into the cell until the organism can adapt. - Water and salt move in opposite directions until the organism can adapt
water moves into the cell causing it to burst
