BIO103 MOD 2 STUDY GUIDE (CH2&3)
Sulfur has six valence electrons. How many covalent bonds does a sulfur atom typically form? -3 -1 -5 -2 -4
2
In the accompanying figure, ionic bonds would form between the R groups of which amino acids? -1 and 3 -2 and 4 -3 and 5 -4 and 6 -3 and 6
2 AND 4
In the accompanying figure, hydrophobic interactions would occur between the R groups of which two amino acids? -1 and 4 -2 and 5 -3 and 6 -2 and 4 -3 and 5
3 AND 6
What is the purpose of a buffer? -To convert an acid to a base -To minimize the change in pH -To measure the acidity of a solution -To form a stable bond between atoms -To maintain a constant internal temperature
TO MINIMIZE THE CHANGE IN pH
A calorie is the amount of heat energy required to raise the temperature of 1 g of water 1 degree Celsius (C).
TRUE
A disaccharide is composed of two monosaccharides joined by a glycosidic bond.
TRUE
A phosphate group is weakly acidic.
TRUE
Cellulose is the main structural component of the walls that surround plant cells.
TRUE
Cyclic AMP is a type of nucleotide.
TRUE
Sugar dissolves readily in water because it is a(n) ____ substance. -hydrophilic -adhesive -hydrophobic -evaporative -cohesive
HYDROPHILIC
Analysis of a certain polymer shows that it contains phosphate groups, ribose groups, and pyrimidines. Based on this information, what statement best describes this compound? -It is an inorganic compound. -It is cylic AMP. -It is RNA. -It is DNA. -It is a polypeptide.
IT IS RNA
How many molecules are present in one mole of C6H12O6? (A) 6.02 × 10^23 molecules (B) 1.7 × 10^22 molecules (C) 1.3 × 10^10 molecules (D) 24 molecules (E) 1.7 × 10^10 molecules
A
Which lipid can be identified by its isoprene units? -Fats -Steroids -Carotenoids -Amino acids -Phospholipids
CAROTENOIDS
What is the functionality of regulatory proteins? -strengthen and protect cells and tissues -store nutrients -control the activities of proteins, genes, cells, and tissues -generate movement in cells and tissues -move substances between cells and across cell membranes
CONTROL THE ACTIVITIES OF PROTEINS, GENES, CELLS, AND TISSUES
The cohesiveness between water molecules is due largely to _________. -ionic bonds -hydrogen bonds -polar covalent bonds -nonpolar covalent bonds -hydrophobic interactions
HYDROGEN BONDS
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Most animals convert carotenoids to which vitamin? -Vitamin K -Vitamin A -Vitamin D -Vitamin E -Vitamin B
VITAMIN A
The chemical behavior of an atom is determined most directly by the: -atomic number -atomic weight -number of neutrons -number protons -number of valence electrons
number of valence electrons
Match the term with its description. (A) Sticking together of like molecules (B) Enables certain insects to walk on water (C) Tendency of water to move in narrow tubes (D) Sticking together of unlike molecules
(A) COHESION (B) SURFACE TENSION (C) CAPILLARY ACTION (D) ADHESION
What is the specific heat of water? -0.5 cal/g of water per degree Celsius -0.75 cal/g of water per degree Celsius -3 cal/g of water per degree Celsius -1 cal/g of water per degree Celsius -2 cal/g of water per degree Celsius
1 CAL/G OF WATER PER DEGREE CELSIUS
What is the approximate pH of ammonia? -7 -8 -2 -11 -4
11
What is the atomic mass of the atom identified as A in the accompanying figure? -2 amu -6 amu -8 amu -12 amu -18 amu
12 AMU
A salt is a compound in which the hydrogen ion of ____ is replaced by some other cation. -water -a base -an acid -an anion -a hydroxide ion
AN ACID
Which of the following would most likely form electrolytes in water? -glucose -a nonionic compound -an inorganic compound -an organic compound -ethanol
AN INORGANIC COMPOUND
What differentiates an organic compound from an inorganic compound? -An organic compound lacks isotopes. -An organic compound contains carbon. -An organic compound lacks valence electrons. -An organic compound is basic rather than acidic. -An organic compound contains two or more atoms.
AN ORGANIC COMPOUND CONTAINS CARBON
What is the difference between an electrically neutral atom and an ion? -An atom must have an equal number of neutrons and electrons, while an ion does not. -An ion has an equal number of protons and electrons, while an atom has an unequal number. -An atom has an unequal number of neutrons and protons, while an ion has an equal number. -An ion has an unequal number of protons and electrons, while a neutral atom has an equal number. -An atom has its electrons in orbitals, while an ion has its electrons in its nucleus.
An ion has an unequal number of protons and electrons, while a neutral atom has an equal number.
Which of the following solutions has a pH value of 9.0? -Beer -Blood -Bleach -Seawater -Rainwater
BLEACH
How can we identify a particular element? -by its number of protons -by its number of electrons -by its number of neutrons -by its shape of valence shells -by its amount of energy levels
BY ITS NUMBER OF PROTONS
_______________________ are isomers that are mirror images of each other. -Enantiomers -Disaccharides -Geometric isomers -Amino groups -Structural isomers
ENANTIOMERS
What type of protein accelerates the thousands of different chemical reactions that take place in an organism? -enzyme -amino acid -transport protein -regulatory protein -protective protein
ENZYME
As water boils and turns to steam, what happens to the hydrogen bonds? -The hydrogen bonds break. -The hydrogen bonds strengthen. -The hydrogen bonds generate additional bonds. -The hydrogen bonds form a crystalline lattice structure. -The hydrogen bonds continually break and rejoin
THE HYDROGEN BONDS BREAK
A molecule of a saturated triacylglycerol contains: -the maximum number of double bonds between carbons in the fatty acid chains -the maximum number of triple bonds between carbons in the fatty acid chains -the maximum number of hydrogen atoms in the fatty acid chains -fatty acid chains with both amino and carboxyl groups -alternating single and double bonds between carbons in the fatty acid chains
THE MAXIMUM NUMBER OF HYDROGEN ATOMS IN THE FATTY ACID CHAINS
What is the difference between the two atoms in the accompanying figure? -their electrical charge -the number of electrons -the number of protons -the number of neutrons -the number of valence shells
THE NUMBER OF NEUTRONS
Match the molecule with the appropriate word or phrase. (A) most are nonpolar (B) cellulose (C) has 20 different types of monomers (D) a beta-pleated sheet is one typical structure (E) monomers are joined by a glycosidic linkage (F) contains purines and pyrimidines (G) may contain thymine (H) cholesterol
(A) LIPID (B) CARBOHYDRATE (C) PROTEIN (D) PROTEIN (E) CARBOHYDRATE (F) NUCLEIC ACID (G) NUCLEIC ACID (H) LIPID
What is the OH− concentration of a solution having a pH of 2? (A) 1 × 10^-12 (B) 1 × 10^-10 (C) 1 × 10^-7 (D) 1 × 10^-2 (E) 1 × 10^-1
A
Which of the following describes an amphipathic molecule? -A phospholipid with two polar ends -A phospholipid with two hydrophobic ends -A steroid with a hydrophilic functional group -A steroid with a hydrophobic functional group -A phospholipid with both a hydrophobic end and a hydrophilic end
A PHOSPHOLIPID WITH BOTH A HYDROPHOBIC END AND A HYDROPHILIC END
What is the difference between a stable isotope and a radioisotope? -A stable isotope emits light. -A radioisotope emits radiation. -A stable isotope emits radiation. -A stable isotope absorbs radiation. -A radioisotope has an unequal number of protons and electrons.
A RADIOISOTOPE EMITS RADIATION
Which element forms the backbone of organic molecules? -magnesium -iron -chlorine -sodium -carbon
CARBON
You isolate a compound that is insoluble in water, has alternating single and double bonds and has a bright orange color. You correctly conclude that this compound is a: -protein -nucleic acid -polysaccharide -steroid -carotenoid
CAROTENOID
Glucose and fructose are ____ because they have identical molecular formulas but their atoms are arranged differently. -polar -tertiary -enantiomers -structural isomers -geometric isomers
STRUCTURAL ISOMERS
Which functional group in cysteine residues can form bridges that help stabilize a protein's tertiary structure? -amino -carbonyl -hydroxyl -phosphate -sulfhydryl
SULFHYDRYL
Which event illustrates evaporative cooling? -a tea kettle whistling -sweat evaporating from the skin -ice cubes floating in a glass of water -a fish not freezing in an ice-covered pond -salt dissolving in a pot of water with potatoes
SWEAT EVAPORATING FROM THE SKIN
Hemoglobin consists of 574 amino acids arranged in four polypeptide chains.
TRUE
Molecular chaperones mediate the folding of other protein molecules.
TRUE
The carboxyl group can exist in either an ionized or nonionized form.
TRUE
The tetrahedron shape of a methane molecule is the result of orbital hybridization.
TRUE
What does the accompanying figure represent? -an acid and a base -two different ions -a cation and an anion -two different elements -two isotopes of the same element
TWO ISOTOPES OF THE SAME ELEMENT
Which of the following fatty acids include one or more adjacent pairs of carbon atoms joined by a double bond? -saturated fatty acids -monounsaturated fatty acids -unsaturated fatty acids -polyunsaturated fatty acids -trans fatty acids
UNSATURATED FATTY ACIDS
___________ in the muscle cell are required for muscle contraction. -Sodium ions -Potassium ions -Calcium ions -Chloride ions -Magnesium ions
CALCIUM IONS
A beta-pleated sheet is an example of a protein's tertiary structure.
FALSE
A chemical formula shows the types and numbers of atoms in a molecule and their arrangement.
FALSE
A combination of adhesive and cohesive forces accounts for surface tension.
FALSE
A pyrimidine is a double-ring molecule.
FALSE
A solution having a pH of 8 is slightly acidic.
FALSE
An example of an anion is K+.
FALSE
An inorganic compound is one that contains carbon.
FALSE
By definition, geometric isomers are mirror images of each other.
FALSE
Condensation and hydrolysis reactions are catalyzed by the same enzymes.
FALSE
Since a carbon atom has 4 valence electrons, it can complete its valence shell by forming a total of 4 hydrogen bonds.
FALSE
Which organic compound is not only responsible for energy storage, but can also provide thermal insulation? -Lipids -Proteins -Nucleic acids -Carbohydrates -Monosaccharides
LIPIDS
Which element activates many enzymes and is needed in blood and other tissues of animals? -magnesium -iron -sulfur -chlorine -sodium
MAGNESIUM
The products of the process in the accompanying figure are: -enzymes -amino acids -monosaccharides -molecules of glycerol -representative of a glycoside linkage
MONOSACCHARIDES
A liquid with a pH of 7 is considered a(n) ____ solution. -basic -neutral -acidic -hydrophilic -hydrochloric
NEUTRAL
Isotopes differ from each other with respect to the number of: -protons only -electrons only -neutrons only -both protons and electrons -both neutrons and protons
NEUTRONS ONLY
The following amino acid would be characterized as ____ based on the chemical properties of its side chain. -basic -acidic -nonpolar -hydrophilic -electrically charged
NONPOLAR
Which pair matches the correct macromolecule with the bond that joins its subunits? -protein−ester linkage -steroid−peptide bond -polysaccharide−peptide bond -triacylglycerol−glycosidic linkage -nucleic acid−phosphodiester linkage
NUCLEIC ACID-PHOSPHODIESTER LINKAGE
When a nucleic acid undergoes hydrolysis, the resulting subunits are: -fatty acids -amino acids -nucleotides -carotenoids -monosaccharides
NUCLEOTIDES
Unlike lipids, hydrophilic functional groups typically contain ____ atoms, which make them more soluble in water. -carbon -oxygen -hydrogen -nitrogen -phosphate
OXYGEN
Which component is the OXIDIZING AGENT in the following chemical reaction? 4 Fe + 3 O2 → 2 Fe2O3 -rust -iron -water -oxygen -hydrogen
OXYGEN
Which of the following is a common oxidizing agent? -carbon monoxide -lithium -oxygen -zinc -iron
OXYGEN
Which of the following atoms can form five covalent bonds? -oxygen -phosphorus -hydrogen -carbon -nitrogen
PHOSPHORUS
Which carbohydrate is the most structurally complex? -polymer -monomer -phospholipid -polysaccharide -monosaccharide
POLYSACCHARIDE
At which level of protein structure are peptide bonds most important? -primary -secondary -tertiary -quaternary -globular
PRIMARY
A base is defined as a(n) _____ acceptor. -neutron -electron -proton -anion -cation
PROTON
The primary difference between the amino acids commonly found in proteins is in their: -R or variable groups -number of potassium groups -number of phosphate groups -number of carbonyl groups -number of asymmetric carbons
R OR VARIABLE GROUPS
The molecular fragment, represented in the accompanying figure is: -ATP -RNA -DNA -a nucleotide -a polysaccharide
RNA
A steroid consists of carbon atoms arranged in four attached rings. How many carbon atoms do three of the rings contain? -six carbon atoms -five carbon atoms -three carbon atoms -seven carbon atoms -two carbon atoms
SIX CARBON ATOMS
Which atom would most likely be involved in an ionic bond? -hydrogen -helium -oxygen -nitrogen -sodium
SODIUM
It takes one calorie of heat to raise the temperature of one gram of water by one degree Celsius at sea level. This is referred to as the ____ of water. -specific heat -heat of fusion -homeostasis -vaporization -heat of transformation
SPECIFIC HEAT
Specific heat refers to the amount of energy required to change 1 gram of a substance from the liquid phase to the vapor phase.
FALSE
The atomic mass determines the identity of an element.
FALSE
The valence shell of hydrogen or helium is unstable when it contains two electrons.
FALSE
When atoms react to form an ionic bond, electrons are shared between those atoms.
FALSE
When glucose and fructose undergo condensation, maltose is produced as a product.
FALSE
How many covalent bonds are formed by carbon atoms, producing a wide variety of molecular shapes and sizes? -Six -Two -Three -Four -Seven
FOUR
What carbohydrate energy storage molecule is found in animal liver and muscle cells? -starch -cellulose -a fatty acid -glycogen -cholesterol
GLYCOGEN
Which of the following is sometime referred to as animal starch? -cellulose -sugars -starch -fatty acid -glycogen
GLYCOGEN
Which of the following is a purine base found in nucleotides? -uracil -steroid -guanine -cytosine -thymine
GUANINE
The covalent bond between a hydrogen atom and the oxygen atom in water is formed when: -hydrogen gains an electron from oxygen -hydrogen and oxygen share an electron pair -hydrogen and oxygen both lose electrons from their outer shells -hydrogen and oxygen both gain electrons in their outer shells -hydrogen loses an electron from oxygen
HYDROGEN AND OXYGEN SHARE AN ELECTRON PAIR
Which component BECOMES oxidized in the following chemical reaction? 4 Fe + 3 O2 → 2 Fe2O3 -rust -iron -water -oxygen -hydrogen
IRON
What are compounds that have the same molecular formulas but different structures and different molecules? -Thiols -Monomers -Hexoses -Amyloplasts -Isomers
ISOMERS
Which of the following is a covalent compound? -potassium chloride -methane -lithium bromide -magnesium oxide -sodium fluoride
METHANE
Assume that the shaded portions of the molecule in the accompanying figure each represent different polypeptide chains. What does this represent? -Cellulose -A carotenoid -An amino acid -A steroid hormone -The quaternary structure of a protein
THE QUARTERNARY STRUCTURE OF A PROTEIN
Which statement about van der Waal interactions is FALSE? -They are very strong. -They are attractive forces. -They operate over very short distances. -They form between nonpolar molecules. -They involve transient regions of positive and negative charges.
THEY ARE VERY STRONG
Nitrogen has five electrons in its valence shell. How many electrons does it need to gain to complete its valence shell? -one -two -three -seven -eight
THREE
Which of the following describes the tertiary structure of a protein molecule? -bonding of two amino acids to form a dipeptide -folding of a peptide chain to form an alpha helix -association of several polypeptide chains by weak bonds -order in which amino acids are joined in a peptide chain -three-dimensional shape of an individual polypeptide chain
THREE-DIMENSIONAL SHAPE OF AN INDIVIDUAL POLYPEPTIDE CHAIN
What is the purpose of regulatory proteins? -To store nutrients -To defend against foreign invaders -To catalyze a specific chemical reaction -To control the expression of specific genes -To strengthen and protect cells and tissues
TO CONTROL THE EXPRESSION OF SPECIFIC GENES
