BIO103 MOD 2 STUDY GUIDE (CH2&3)

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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


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