biology 1610 exam 1

imagine you have discovered a new species of bacteria. To begin your investigation of this organism, you run an assay on the total nucleotide content of the bacterial DNA. If the cytosine content of DNA from the bacterial cells is 40%, what is the adenine content? 20% 10% Cytosine always pairs with guanine, so together they constitute 80% of bacterial DNA. The remaining 20% are equally divided between adenine and thymine. Hence, the adenine content of DNA of this bacterium is 10%. It is not possible to calculate this number for prokaryotes. 40% 60%

10%

A solution of pH 5 contains ___________ H+ than the same amount of solution at pH 3. 100 times more 10 times less 100 times less 2 times more 2 times less 10 times more

100 times less (10^2)

How many hydrogen atoms are present in a hydrocarbon chain of five carbons joined to each other by single covalent bonds? 10 12 You could add hydrogens to the structure 6 8

12

How many water molecules would be produced in making a polypeptide that is 14 amino acids long? 14 27 13 28

13

Potassium is important in neuron function and osmotic regulation. Find Potassium on the periodic table. The symbol is K .How many protons ______ and electrons __________ are in a Potassium atom? (uncharged).How many protons _______and electrons ___________ are in the Potassium ion (K+)?

19, 19, 19, 18

When full, the innermost electron shell of an atom contains _________ electrons, and the next shell contains ________ electrons.

2 8

In a DNA strand, successive nucleotides are linked by: 3'-5' phosphodiester bonds. base stacking.hydrogen bonds. peptide bonds. 2'-5' phosphodiester bonds.

3'-5' phosphodiester bonds

An organism's genome is analyzed and found to contain 18% guanine. What percentage of that organism's DNA is adenine?

32%

You have a solution with a Hydrogen Ion concentration of .000001. What is the pH of this solution? 7 6 8 3 5 4

6

Carbon as it appears on the periodic table is shown below. Match the statements below with the correct answers. Carbon has an atomic number of___________ and ___________ protons. In its uncharged form, carbon has ___________________ electrons

6, 6, 6

Which statement is true of DNA? Successive nucleotides in a strand are connected by hydrogen bonds. A purine always forms a complementary base pair with a pyrimidine. A phosphate group in a nucleotide is attached to the 3' carbon in ribose. The percentage of the purine A always equals the percentage of the purine G. It is used by ribosomes for translation.

A purine always forms a complementary base pair with a pyrimidine.

Use HONC 1-2-3-4 from covalent bond mnemonic from class. Which of the following hydrocarbons has a double bond in its carbon skeleton? (Hint: Draw out the molecules with the numbers of H and C shown in the formula. Focus on the HONC rules. Which of these molecules will have a double bond in it to meet the HONC rules.) C2H6 C2H4 C3H8 CH4

C2H4

Which of the molecules is classified as an organic molecule? NH3 (ammonia) NaCl (sodium chloride or salt) CO2 H2O (water) O2 (oxygen gas)

CO2

At physiological pH, the ionized state of the carboxyl (COOH) group in the R group of aspartic acid is: COOH. COOH+. COO-. The α-carboxylic acid group of amino acids is a weak acid, meaning that it releases a proton at physiological pH values. CO-O-.

COO-.

grobacterium is a bacterium that infects plants and causes them to form tumors. You are asked to determine how long a plant must be exposed to these bacteria to become infected. Which of the following is an appropriate CONTROL for the experiment? Use many plants to do the experiment.Expose the plant to Agrobacterium for only 1 minute.Expose the plant to another concentration of Agrobacterium for different lengths of time and measure tumors formed.Do not expose the plant to Agrobacterium and measure how many tumors are formed.

Do not expose the plant to Agrobacterium and measure how many tumors are formed

Agrobacterium is a bacterium that infects plants and causes them to form tumors. You are asked to determine how long a plant must be exposed to these bacteria to become infected. Which of the following experiments will provide the best data to address that question? Measure the number of tumors formed on plants, which are exposed to a known concentration of Agrobacterium solution for different lengths of time. Measure the concentration of Agrobacterium in different soil environments where the plants grow. Measure the number of tumors formed on a plant when exposed to various concentrations ofMeasure the number of tumors formed on plants, which are exposed to different concentrations of an Agrobacterium solution for different lengths of time.

Measure the number of tumors formed on plants, which are exposed to a known concentration of Agrobacterium solution for different lengths of time.

At physiological pH, the ionized state of the amino (NH2) group in the R group of lysine is: NH3+. At physiologic pH, the amino group gains a hydrogen. NH-. NH2. NH4++.

NH3+

Humans are often referred to as "carbon-based" life forms. Given that humans breathe oxygen, shouldn't humans be referred to as "oxygen-based" life forms? Yes, because oxygen is the most abundant element in human cells, not carbon. No, because oxygen is not an organic molecule. No, because humans exhale carbon dioxide No, because carbon is the most abundant element in human cells, not oxygen, Carbon is the most abundant element in living matter by dry biomass. Yes, because humans inhale oxygen.

No, because carbon is the most abundant element in human cells, not oxygen

The function of a protein is dependent upon the shape into which the chain of amino acids folds. Many noncovalent interactions are responsible for maintaining the protein's shape. Assume you have isolated a protein from an organism in its proper shape, and you have treated it with an enzyme that selectively targets and breaks only the peptide bonds in the proteins. Would the protein retain its shape under these conditions? -Yes; but the shape would be affected to a greater extent by changes in temperature. -Yes; because the noncovalent interactions that determine the shape of a protein are stronger than the peptide bonds. -No; while the noncovalent bonds determine the shape of a protein, the peptide bonds are required to hold the amino acids together. -The shape of the protein would be destroyed because most of the amino acids would exist as free monomers. The peptide bonds responsible for maintaining the primary structure of a protein are absolutely essential to the correct structure. -Yes; once noncovalent bonding determines the shape of a protein the peptide bonds are no longer necessary.

No; while the noncovalent bonds determine the shape of a protein, the peptide bonds are required to hold the amino acids together.

Let's say you feel very strongly that cigarette smoke does not increase the probability of getting cancer, and you base your view on something you read on the Internet. This is a good example of a(n): None of the other answer options are correct.hypothesis.theory.experiment.observation.

None are correct

Recall that a carbon atom behaves as if it possesses four valence electrons. Given this information, what is the most likely structural formula for carbon dioxide (CO2)? O=C=O Covalent bonds form when atoms share valence electrons. With four valence electrons, carbon can form four covalent bonds. With six valence electrons, oxygen can form two covalent bonds. Thus, each oxygen can form a double bond with carbon thereby completing the valence shells for the carbon and both oxygens. O-C=O O-C-O O=C-O

O=C=O

Which order accurately reflects the process of science as described in your textbook?

Observation -> question -> hypothesis formulation -> experiment -> support or refute hypothesis

biologist working in a lab adds a compound to a solution that contains an enzyme and substrate. This particular compound binds reversibly to the enzyme at the active site. Once the compound is bound to the enzyme, the rate of catalysis of substrate to product is greatly reduced. Which of the statements are true of the compound? The compound is an enzyme cofactor. The compound competes with the substrate for the active site of the enzyme. The compound is an allosteric activator. The compound is an allosteric inhibitor. The effect of the compound can be overcome by adding more substrate.

The compound competes with the substrate for the active site of the enzyme. The effect of the compound can be overcome by adding more substrate.

Consider the diagram. What is wrong with this diagram of secondary structure in a polypeptide chain? Hint: In the representation of β sheets as paired arrows, the convention is that the amino end is at the base of the arrow and the carboxyl end is at the tip. -The β sheet has an amino end and a carboxyl end. -The directionality of the polypeptide chain reverses orientation -between the arrows representing a β sheet. -β sheets cannot form when the arrows are pointed in the same -direction. -Nothing is wrong with the diagram.

The directionality of the polypeptide chain reverses orientation between the arrows representing a β sheet.

A woman's doctor tells her to gargle with salt water. She stirs a tablespoon of salt into a cup of warm water and watches the salt dissolve. Why does the salt dissolve in water? -The partial positive charges on hydrogen atoms in water molecules are attracted to sodium ions, and the partial negative charges on oxygen atoms in water molecules are attracted to chlorine ions -The partial positive charges on hydrogen atoms in water molecules are attracted to sodium ions -The partial positive charges on hydrogen atoms in water molecules are attracted to chlorine ions, and the partial negative charges on oxygen atoms in water molecules are attracted to sodium ions. -The partial negative charges on oxygen atoms in water molecules are attract-ed to chlorine ions -The partial negative charges on chlorine atoms are attracted to positive charges on hydrogen atoms in water molecules.

The partial positive charges on hydrogen atoms in water molecules are attracted to chlorine ions, and the partial negative charges on oxygen atoms in water molecules are attracted to sodium ions.

Several chemical properties make water uniquely suited for its role as a central "molecule of life". Which statement is false? -Water is a good solvent of polar molecules and ions -The structure of a water molecule is stabilized by hydrogen bonds -Hydrogen bonding leads to high cohesiveness between water molecules -Water molecules are always polar -Water resists temperature changes.

The structure of a water molecule is stabilized by hydrogen bonds

Consider the diagram. What is wrong with this diagram of secondary structure in a polypeptide chain? -The β sheet has two amino ends. -Nothing is wrong with the diagram. -The directionality of the polypeptide chain reverses orientation between the arrows representing a β sheet. -β sheets cannot form when the arrows are pointed in opposite directions.

The β sheet has two amino ends.

Which statements are true of an inhibitor that binds the active site of an enzyme? Select all that apply. These inhibitors are structurally similar to the normal substrate of an enzyme. These inhibitors are a kind of allosteric regulator that decreases enzyme activity. Adding more substrate can reduce the effect of these inhibitors. These inhibitors increase the rate of enzyme activity. These inhibitors compete with the substrate for the active site of the enzyme.

These inhibitors are structurally similar to the normal substrate of an enzyme. Adding more substrate can reduce the effect of these inhibitors. These inhibitors compete with the substrate for the active site of the enzyme.

ne of your friends is arguing that viruses are alive. What information would you provide to convince him that viruses can't be considered alive? Viruses cannot carry out metabolic reactions on their own.Viruses contain either RNA or DNA but not both.Viruses are much more closely related to archaeons than bacteria.Viruses typically have protein coats and no plasma membrane.

Viruses cannot carry out metabolic reactions on their own

22. Which of the following is NOT a component of a nucleotide? one or more phosphate groups a five-carbon sugar a nitrogen-containing base All of these choices are correct a carboxyl group

a carboxyl group

A mutation takes place in a protein-coding gene that changes one codon resulting in a single amino acid replacement. Which type of replacement is least likely to result in a disruption of protein structure and function? -a hydrophobic amino acid to a hydrophilic amino acid -a polar amino acid to a polar amino acid -an acidic amino acid to a basic amino acid -a polar amino acid to a hydrophobic amino acid -a hydrophilic amino acid to a hydrophobic amino acid

a polar amino acid to a polar amino acid

You are working at NASA studying new life forms found in the Cueva de Villa Luz caves. You have collected an unknown specimen that appear to be 0.5 micron in size, have a cell membrane and ribosomes. This specimen could be... (B) prokaryote(C) a eukaryoteA, B, or C(A) a virus(D) an archeaeither B or C or D

a prokaryote

Carbohydrates and proteins are two types of macromolecules. Which functional characteristic of proteins distinguishes them from carbohydrates? large amount of stored information tendency to make cell membranes hydrophobic None of the other answer options is correct. efficient storage of usable chemical energy ability to catalyze biochemical reactions

ability to catalyze biochemical reactions

The interactions between amino acids are major factors in determining the shape of a protein. These interactions can be affected by the environment surrounding a protein. Which factor would have an effect on the shape of a protein? -the concentrations of ions present in the environment -whether the other molecules in the environment are predominantly hydrophilic or hydrophobic -the pH of the environment -the temperature of the environment -All of these choices are correct.

all are correct

Which of the examples are cellular life forms: yeast, bacteria, plant, animal? All are cellular except yeast Only plants and animals are cellular All of these choices are correct All are cellular except bacteria

all are correct

The strands in a double helix of DNA are: antiparallel. complementary. All of these choices are correct. wound around each other with 10 base pairs per turn. held together via hydrogen bonds.

all choices are correct

The atom: -has negatively charged particles circling around a positively charged nucleus -is the unit of composition for elements -is the basic unit of matter -All of these choices are correct -contains protons, neutrons, and electrons.

all of these choices are correct

roteins can be used for which cellular roles? structural support All of these choices are correct. cell signaling. cell communication biological catalysis

all of these choices are correct

In the metabolic pathway illustrated, the reactant (substrate A) is converted equally to one of two end products, E or G. Use the diagram of the pathway to answer the question. Letters indicate the substrates and products, and numbers indicate the enzymes. In this pathway, the intermediate, C, is a substrate for both enzyme 3 and enzyme 5 and is converted with equal efficiency to D and F.If end product G inhibits enzyme 5, what would you expect to observe as the amount of G increases in the cell? an increase in the production of C a decrease in the production of D an increase in the production of B an increase in the production of E The description of the metabolic pathway states that enzymes 3 and 5 operate at equal efficiency. Thus, if enzyme 5 is inhibited, all of the substrate C would go to enzyme 3 and onward to the pathway branch that results in E. an increase in the production of G

an increase in the production of E

In the metabolic pathway illustrated, the reactant (substrate A) is converted equally to one of two end products, E or G. Use the diagram of the pathway to answer the question. Letters indicate the substrates and products, and numbers indicate the enzymes. In this pathway, the intermediate, C, is a substrate for both enzyme 3 and enzyme 5 and is converted with equal efficiency to D and F. If end product G inhibits enzyme 3, what would you expect to observe as the amount of G increases in the cell? an increase in the production of G an increase in the production of B an increase in the production of E an increase in the production of D an increase in the production of C

an increase in the production of G

How might an enzyme inhibitor slow down the action of an enzyme without binding to the active site? by lowering the activation energy by changing the shape of the substrate by binding to another site on the enzyme and changing its shape by binding the substrate

by binding to another site on the enzyme and changing its shape

Which one of the elements is found in every organic molecule? oxygen sulfur phosphorus carbon nitrogen

carbon

When carrying out a controlled experiment, it is important to: change multiple variables at once to see the full effect of the variables change only one variable at a time All of these choices are correct subject different groups to different conditions

change only one variable at a time

a pair of shared valence electrons is referred to as a(n): covalent bond hydrophobic effect hydrogen bond ionic bond

covalent bond

Complete the matching exercise below by choosing the CORRECT description of each bond type in aqueous solution. a1.electrons shared by atoms c2.an interaction of a partially positive hydrogen atom and an electronegative atom b3.an interaction between oppositely charged ions

covalent bond hydrogen bond ionic bond

In the metabolic pathway illustrated, the reactant (substrate A) is converted equally to one of two end products, E or G. Use the diagram of the pathway to answer the questions Letters indicate the substrates and products, and numbers indicate the enzymes. In this pathway, the intermediate, C, is a substrate for both enzyme 3 and enzyme 5 and is converted with equal efficiency to D and F. If end product E inhibits enzyme 1, which outcome would you expect to observe? an increase in the production of Ga decrease in the production of E and G Inhibition of an enzyme that occurs early in a pathway will decrease all subsequent reactions. an increase in the production of Aa decrease in the production of E, but no change in the production of G

decrease in the production of E and G

The unfolding of a protein by heat or chemical treatment is referred to as: disaggregation. depolymerization. uncoupling. hydrolysis. denaturation.

denaturation

induction

deriving general principles from specific results

A region of a protein that folds in a particular way, and that carries out a specific function, is referred to as a folding

domain

A major difference between eukaryotic cells and prokaryotic cells is that: eukaryotic cells have a nucleus and prokaryotic cells do not.neither eukaryotic cells nor prokaryotic cells have a nucleus.both eukaryotic cells and prokaryotic cells have a nucleus.prokaryotic cells have a nucleus and eukaryotic cells do not.

eukaryotic cells have a nucleus and prokaryotic cells do not

For a folding domain that forms a sort of "fist" with certain amino acid R groups buried within and other R groups facing out, the hydrophobic R groups mainly face "out" and the hydrophilic R groups mainly face "in." false true

false

In a protein-coding region of DNA, any mutation that replaces a single nucleotide for another will replace any amino acid with any other amino acid. true false

false

Most proteins retain metabolic activity when denatured. true false

false

you are studying a protein that you call Protein X. There is an aspartic acid at a key position in Protein X that is important in the folding and stabilization of that protein. If this aspartic acid is changed to a different amino acid, which one of the amino acid substitutions is most likely to allow the protein to fold normally? arginine glutamic acid glycine threonine serine

glutamic acid

Which of the statements is true regarding glycine? Glycine is similar to tyrosine in terms of structure and chemical properties. Glycine is special because it contains a -SH group important in protein folding. Glycine is a large, polar amino acid. Glycine is an asymmetric amino acid. Glycine increases the flexibility of the peptide backbone.

glycine increases the flexibility of the peptide backbone.

A pair of atoms joined by a polar covalent bond: mixes well with nonpolar solvents has the charge spread evenly across both atoms has a slight positive charge on one atom and a slight negative charge on the other is unlikely to form hydrogen bonds with water.

has a slight positive charge on one atom and a slight negative charge on the other

Two major types of protein secondary structures are referred to as: residual and permanent. elementary and primary. amino and carboxyl. helix and sheet.

helix and sheet

Which bonds rely on the attraction of positive and negative charges? Select all that apply. covalent bonds hydrogen bonds ionic bonds

hydrogen and ionic bonds

Secondary structure is characterized by which type of interactions? -hydrogen bonding within the peptide backbone -hydrogen bonding between R groups of amino acids -the covalent bond between an amino nitrogen and a carboxyl carbon -ionic bonding between an acidic R group and a basic R group -a covalent bond between two cysteines

hydrogen bonding within the peptide backbone

A young girl is staring at the raindrops running down her window. She notices that the raindrops remain more or less intact, even as they cascade down the windowpane. This is a result of: covalent bonds between water molecules hydrogen bonds between water molecules oxygen bonds between water molecules ionic bonds between water molecules polar covalent bonds between water molecules.

hydrogen bonds between water molecules

ou have an aqueous solution with a pH of 8.0. You add sodium chloride to a concentration of 1 gram per 100 milliliters. What happens to the pH? It stays the same It depends on the temperature It goes down It goes up.

it stays the same

Which of the organic molecules are commonly used for energy storage? lipids and carbohydrates carbohydrates, nucleic acids, and lipids proteins and nucleic acids nucleic acids and lipids proteins, carbohydrates, and lipids

lipids and carbohydrates

when an electron gains energy it:

moves further away from the nucleus of the atom

in double-stranded DNA, the sugar-phosphate backbones are: on the inside, separated by grooves of equal size. on the inside, separated by grooves of unequal size. on the outside, separated by grooves of equal size. on the outside, separated by grooves of unequal size.

on the outside, separated by grooves of unequal size.

In a double-stranded DNA molecule, the strands are said to be antiparallel because: only one of them is a template strand. each purine of one strand pairs with a pyrimidine of another. they form an uneven pair of grooves on the outside of the molecule. one strand runs in 5' to 3' direction and the other in 3' to 5'.

one strand runs in 5' to 3' direction and the other in 3' to 5'.

he [H+] of a solution changes from .000001 to .000000001. Did the pH increase or decrease? What did the pH change to? pH increased to 1000 pH increased to 9 pH decreased to 3 pH decreased to 1000

pH increased to 9

Which of the elements would most likely have bonding properties similar to nitrogen (N)

phosphorus

State what specific types of bonds are formed in the molecules shown below. (Electro-negativities of the atoms are listed). c1.PO4 (electronegativity of P is 2.19, O is 3.44) b2.CH3(electronegativity of C is 2.5 and H is 2.1) a3.KBr (electronegativity of K is 0.8, Br is 2.96) c4.HCl (electronegativity of H is 2.1, Cl is 3.2)

polar nonpolar ionic polar

Using the periodic table provided, select the element that would be found in least abundance in a living cell.

silicon

Aquaclear is a new general herbicide for aquatic plants. It is effective against freshwater but not saltwater plants. It works by breaking down the cell walls of the plants and the freshwater plants die because their cells accumulate large concentration of the herbicide which causes them to.... (Hint: Think osmosis. When solute (herbicide) concentration is high inside the cells water concentration is low) shrink and cease to function swell and burst are crushed by the weight of the plant remain the same size but malfunction

swell and burst

The fully folded structure of a functional protein composed of a single polypeptide chain is referred to as: secondary. quaternary. tertiary. primary.

tertiary

he structural diversity of carbon-based molecules is determined by which properties? Select all the apply. the ability of carbon to form four covalent bonds the ability of carbon's covalent bonds to rotate freely the orientation of carbon's bonds in the form of a tetrahedron the ability of carbon to ionize and interact with other ions carbon's strong electronegativity results in polar covalent bonds

the ability of carbon to form four covalent bonds the ability of carbon's covalent bonds to rotate freely the orientation of carbon's bonds in the form of a tetrahedron

Which choice is an example of a hydrogen bond? -the bond that forms between two hydrogen atoms within different water molecules -the bond that forms between a hydrogen atom in one water molecule and an oxygen atom in another water molecule -the bond that forms between two hydrogen atoms within the same water molecule -the bond that forms between a hydrogen and oxygen atom within the same water molecule -the bond that forms between two oxygen atoms within different water molecules

the bond that forms between a hydrogen atom in one water molecule and an oxygen atom in another water molecule

A folding domain of a polypeptide chain has a primary structure containing 5 phenylalanine residues, where F represents the side chain of phenylalanine. Consider the possible folding orientations.If this domain folds in one of the two orientations shown, which is more likely, the one on the left or the one on the right? the one on the left Hydrophobic side chains tend to associate in the interior of proteins away from the cytosol. the one on the right

the one on the left

Which statement accurately describes a polar covalent bond? -the interaction of an atom with very high electronegativity and an atom with very low electronegativity -None of the other answer options is correct -the interaction of a hydrogen atom connected to an atom with a high electronegativity and an electronegative atom of another molecule -the unequal sharing of electrons between an atom with a partial positive charge and an atom with a partial negative charge -the equal sharing of electrons between atoms of identical or similar electronegativities

the unequal sharing of electrons between an atom with a partial positive charge and an atom with a partial negative charge

An explanation supported by a large body of observations and experimentation is referred to as a(n): supposition.hypothesis.prediction.investigation.theory.

theory

A 0.9% NaCl solution is isotonic (aka same concentration) to red blood cells. Which of these describes the results if red blood cells are placed into a 9% solution of NaCl? (Hint: Think osmosis. Draw it out. Show salt and water and figure out where there is more water and then how water will move.) They will swell but not burst They will shrink None of the above Nothing will happen They will burst

they will shrink

What are the functions of an enzyme? Select all that apply. to lower the activation energy for the reaction to increase the rate of a specific reaction to allow a reaction to be reversible to alter the equilibrium of a specific reaction to alter the ΔG of a specific reaction

to lower the activation energy for the reaction to increase the rate of a specific reaction

Deoxyribonucleic acid is used for: (Select all that apply.) transmission of information cell-to-cell communication storage of information biological catalysis.

transmission of information storage of information

Amino acids with hydrophobic R groups are most often found in the interior of folded proteins. true false

true

In the sequence 5'-AGGCCT-3', an available phosphate group would be found at the nucleotide labeled "A." false true

true

Part of the reason why salt dissolves in water is that hydrogen bonds form between water molecules and chlorine ions. True False

true

Nitrogen and phosphorus are in the same column of the periodic table. They have similar properties in bonding with other molecules because they have the same number of: paired electrons electrons electron shells valence electrons

valence electrons

Many salmon return to the place where they were born to spawn (reproduce). You hypothesize that they use visual cues to find their way back. To test your hypothesis, you blind salmon and then examine whether or not they are able to return to their birthplace. You find that they are able to find their way back. From this experiment, you: have proven your hypothesis.have rejected your hypothesis.can't determine whether your hypothesis is supported or not.developed a theory about the role of vision in salmon navigation.supported your hypothesis.

you have rejected your hypothesis