Chapter 2 Flashcards by M A

Which subatomic particle has a negative charge?

A. Proton
B. Neutron
C. Electron
D. Nucleus

Electron
Why: Electrons carry a negative electrical charge.

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The valence shell of an atom is important because it:

A. Contains protons and neutrons
B. Determines how atoms bond
C. Stores genetic information
D. Produces energy

Determines how atoms bond
Why: The outer electrons control how an atom reacts with other atoms.

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A molecule formed by sharing electrons between atoms is held together by a:

A. Ionic bond
B. Hydrogen bond
C. Covalent bond
D. Metallic bond

Covalent bond
Why: Covalent bonds are formed when atoms share electrons.

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In an ionic bond, electrons are:

A. Shared equally
B. Shared unequally
C. Transferred from one atom to another
D. Not involved

Transferred from one atom to another
Why: One atom gives up electrons and another atom gains them.

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Water is a polar molecule because:

A. It has no electrical charge
B. Oxygen shares electrons equally with hydrogen
C. Oxygen pulls electrons more strongly than hydrogen
D. It has no hydrogen atoms

Oxygen pulls electrons more strongly than hydrogen
Why: This creates slight positive and negative charges in the molecule.

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A hydrogen bond forms due to attraction between:

A. Two positive charges
B. Two negative charges
C. Slightly positive and slightly negative regions
D. Neutral atoms

Slightly positive and slightly negative regions
Why: Opposite charges attract each other, even when the charges are weak.

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Which of the following is an example of an ionic compound?

A. H₂O
B. CO₂
C. NaCl
D. O₂

NaCl
Why: Sodium gives up an electron and chlorine gains one.

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Hydrogen bonds are best described as:

A. Strong bonds within a molecule
B. Weak attractions between molecules
C. Bonds that share electrons
D. Bonds that transfer electrons

Weak attractions between molecules
Why: Hydrogen bonds form from weak electrical attractions, not shared electrons.

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Why are hydrogen bonds important for life?

A. They create ATP
B. They help cells divide
C. They stabilize water and protein structure
D. They break down glucose

They stabilize water and protein structure
Why: Hydrogen bonds help water and proteins keep their shape and function.

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Which statement correctly compares ionic and covalent bonds?

A. Both involve sharing electrons
B. Ionic bonds transfer electrons; covalent bonds share electrons
C. Covalent bonds are weaker than hydrogen bonds
D. Ionic bonds occur only in water

Ionic bonds transfer electrons; covalent bonds share electrons
Why: The main difference is whether electrons are given away or shared.

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The atomic number of an atom is determined by the number of:
A) electrons
B) protons
C) neutrons
D) protons + neutrons
E) protons + electrons

protons
Why: The number of protons defines the element’s identity.

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Isotopes of an element differ in the number of:
A) protons
B) electrons
C) neutrons
D) electron clouds
E) electrons in energy shells

neutrons
Why: Isotopes have the same protons but different neutrons

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The mass number represents the number of:
A) protons
B) electrons
C) neutrons
D) protons + neutrons
E) neutrons + electrons

protons + neutrons
Why: Mass number counts all particles in the nucleus.

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The chemical behavior of an atom is determined by:
A) the number of protons
B) the number of neutrons
C) the outermost electron shell
D) the size of the atom
E) the mass of the nucleus

the outermost electron shell
Why: Chemical reactions depend on valence electrons.

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If an isotope of oxygen has 8 protons, 10 neutrons, and 8 electrons, its mass number is:
A) 26
B) 16
C) 18
D) 8
E) 12

18
Why: Mass number equals protons plus neutrons: 8 + 10 = 18.

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The mass of an atom is largely determined by the number of:
A) electrons
B) protons
C) neutrons
D) protons + neutrons
E) protons + electrons

protons + neutrons
Why: Most of an atom’s mass comes from its nucleus.

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The weakest bond between two atoms is the:
A) ionic
B) covalent
C) polar
D) nonpolar
E) hydrogen

hydrogen
Why: Hydrogen bonds are weaker than other bonds.

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The smallest stable units of matter are:
A) atoms
B) molecules
C) protons
D) neutrons
E) electrons

atoms
Why: Atoms are the smallest units that retain the properties of matter.

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The reaction A + B + energy → AB is an example of a(n):
A) exergonic
B) endergonic
C) equilibrium
D) decomposition
E) exchange

endergonic
Why: Endergonic reactions absorb energy to occur

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Ionic bonds are formed when:
A) atoms share electrons
B) electrons are completely transferred
C) a pair of electrons is shared unequally
D) hydrogen forms bonds with negative atoms
E) two or more atoms lose electrons simultaneously

electrons are completely transferred
Why: One atom gives and another takes electrons.

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If a pair of electrons is unequally shared between two atoms, a(n):
A) single covalent bond
B) double covalent bond
C) triple covalent bond
D) polar covalent bond
E) hydrogen bond

polar covalent bond
Why: Unequal sharing creates a molecule with partial charges.

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AB → A + B is decomposition; A + B → AB is:
A) exchange
B) synthesis
C) combustion
D) replacement
E) metabolism

synthesis
Why: Synthesis reactions combine substances to form a new compound.

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When atoms complete their outer electron shell by sharing electrons, they form:
A) ionic bonds
B) covalent bonds
C) hydrogen bonds
D) anions
E) cations

covalent bonds
Why: Sharing electrons fills the outer shell.

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Chemical reactions that yield energy, such as heat, are:
A) endergonic
B) activated
C) exergonic
D) neutral
E) thermonuclear

exergonic
Why: Exergonic reactions release energy

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All of the following are true concerning enzymes, except: A) are proteins B) function as biological catalysts C) lower activation energy D) affect only the rate of a reaction E) are consumed during the reaction

are consumed during the reaction Why: Enzymes are not used up; they speed up reactions.

The term ________ means each enzyme catalyzes only one type of reaction: A) saturation B) specificity C) inertia D) activation E) monoreactive

specificity Why: Enzymes are specific to one reaction type.

How would the lack of a cofactor for an enzyme affect its function? A) Function not altered B) Function slower C) Function faster D) Cannot function E) Ceases after maximum rate

Cannot function Why: Some enzymes need cofactors to work

Which of the following statements about water is not correct? A) Composed of polar molecules B) Responsible for much of body mass C) Has a relatively low heat capacity D) Can dissolve many substances E) Contains hydrogen bonds

Has a relatively low heat capacity Why: Water actually has a high heat capacity.

During ionization, water molecules disrupt ionic bonds to produce ions called: A) cations B) anions C) acids D) electrolytes E) counterions

electrolytes Why: Ions in solution that conduct electricity are electrolytes

Oppositely charged ions in solution are prevented from combining by: A) heat capacity B) hydration spheres C) nonpolar nature of water D) free radicals E) hydrogen bonding

hydration spheres Why: Water surrounds ions and keeps them apart.

Which property of water helps keep body temperature stabilized? A) kinetic energy B) lubrication C) surface tension D) reactivity E) thermal inertia

thermal inertia Why: Water resists temperature changes due to high heat capacity.

Each amino acid differs from another in the: A) number of central carbon atoms B) size of amino group C) number of carboxyl groups D) nature of the side chain E) number of peptide bonds

nature of the side chain Why: The side chain (R group) gives amino acids unique properties.

A solution containing equal H⁺ and OH⁻ ions is: A) acidic B) basic C) neutral D) alkaline E) in equilibrium

neutral Why: Equal hydrogen and hydroxide ions make the solution neutral.

If a substance has a pH greater than 7, it is: A) neutral B) acidic C) alkaline D) a buffer E) a salt

alkaline Why: pH above 7 indicates a basic solution.

An important buffer in body fluids is: A) NaCl B) NaOH C) HCl D) NaHCO₃ E) H₂O

NaHCO₃ Why: Bicarbonate maintains pH balance in the body.

Which has a greater concentration of hydrogen ions, pH 5 or pH 4? A) pH 4 B) pH 5 C) Both equal D) pH 9 E) Not enough info

pH 4 Why: Lower pH means more hydrogen ions.

Carbohydrates, lipids, and proteins are classified as: A) organic molecules B) inorganic molecules C) acids D) salts E) bases

organic molecules Why: They all contain carbon.

The alpha-helix and pleated sheet are examples of: A) primary B) secondary C) tertiary D) quaternary E) pentanary

secondary Why: These are common folded protein structures

Molecules that store and process genetic information are: A) proteins B) nucleic acids C) carbohydrates D) lipids E) steroids

nucleic acids Why: DNA and RNA store and transfer genetic info.

The chemical shorthand used to describe chemical compounds and reactions effectively is known as _____. A. Molecular formula B. Chemical notation C. Molecular weight D. Mass number

Chemical notation Why: Chemical notation is the system used to represent compounds and reactions efficiently.

Most organic molecules in a cell are replaced at intervals ranging from hours to months. This average time is _____. A. Catabolic rate B. Turnover time C. Rate of incorporation D. Clotting time

Turnover time Why: Turnover time refers to how long molecules remain before being replaced.

Which kind of bond holds atoms in a water molecule together? What attracts water molecules to one another? A. Polar covalent bonds; hydrogen bonds B. Ionic bonds; charge interactions C. Hydrogen bonds; charge interactions D. Covalent bonds; hydrogen bonds

Polar covalent bonds; hydrogen bonds Why: Oxygen and hydrogen share electrons unequally (polar covalent), and separate water molecules attract via hydrogen bonds.

Both oxygen and neon are gases at room temperature. Oxygen combines readily with other elements, but neon does not. Why? A. Neon has 8 electrons in its valence shell; oxygen has only 6 B. Neon cannot undergo bonding due to its polarity C. Neon is exergonic D. Neon’s molecular weight is too low

Neon has 8 electrons in its valence shell; oxygen has only 6 Why: Neon’s full valence shell makes it chemically stable and nonreactive.

What is a mole and why is it useful to describe elements in terms of moles? A. 6.02 × 10²³ / easier to keep track of relative numbers of atoms B. A quantity with a weight in grams equal to atomic weight / same number of atoms C. Total number of neutrons and protons D. Nuclei emit radiation E. Both A and B

Both A and B Why: A mole equals 6.02 × 10²³ particles and allows comparison of quantities across elements

Why are enzymes needed in our cells? A. To promote chemical reactions B. For reactions to proceed under life-compatible conditions C. To lower activation energy requirements D. All of the above

All of the above Why: Enzymes speed reactions, lower activation energy, and allow life to function at normal body conditions.

How does an antacid help decrease stomach discomfort? A. Reduces buffering capacity B. Decreases stomach pH C. Reacts a weak acid with a stronger one D. Neutralizes acid using a weak base

Neutralizes acid using a weak base Why: Antacids counter stomach acid by neutralization.

In cells, glucose is converted into two three-carbon molecules and releases energy. How would you classify this reaction? A. Endergonic B. Exergonic C. Decomposition D. Both B and C

Both B and C Why: Energy is released (exergonic) and the molecule is broken down (decomposition).

Which property of water accounts for the cooling effect of perspiration? A. Solubility B. Reactivity C. High heat capacity D. Lubrication

High heat capacity Why: Water absorbs large amounts of heat as it evaporates, cooling the body.

Which notation describes dehydration synthesis and why? A. A-B-C-H + HO-D-E → A-B-C-D-E + H₂O; removal of water B. A-B-C-D-E + H₂O → A-B-C-H + HO-D-E; bond broken C. AB → A + B D. AB + CD → AD + CB

A Why: Dehydration synthesis forms a larger molecule by removing water.

Which lipids would you find in human cell membranes? A. Cholesterol B. Glycolipids C. Phospholipids D. All of the above

All of the above Why: All three are membrane components.

When two monosaccharides undergo dehydration synthesis, which molecule is formed? A. Polypeptide B. Disaccharide C. Eicosanoid D. Polysaccharide

Disaccharide Why: Two monosaccharides join to form a disaccharide.

Organic molecules with a 1:2:1 ratio of C:H:O belong to which class and function how? A. Lipids; energy B. Proteins; movement C. Nucleic acids; inheritance D. Carbohydrates; energy

Carbohydrates; energy Why: This ratio is characteristic of carbohydrates.

Why is cholesterol important in the human body? A. Forms prostaglandins B. Maintains membrane rigidity and hormone production C. Component of eicosanoids D. Stores lipid-soluble vitamins

B Why: Cholesterol stabilizes membranes and is used to make steroid hormones.

What are similarities of phospholipids and glycolipids? A. Hydrophobic hydrocarbon tails B. Help form membranes C. Made of phosphate and glycogen D. A and B

A and B Why: Both are membrane lipids with hydrophobic tails.

Protein makes up what percentage of human body mass? A. 1 B. 10 C. 20 D. 80

20 Why: Proteins account for about one-fifth of body mass.

How might a change in an enzyme’s active site affect function? A. Increased activity B. Decreased activity C. Inhibited activity D. All of the above

All of the above Why: Changes in shape affect substrate binding in different ways.

Proteins are chains of which molecules? A. Saccharides B. Fatty acids C. Amino acids D. Nucleic acids

Amino acids Why: Amino acids are protein monomers.

How does boiling affect protein structure? A. Denatures protein B. Forms quaternary structure C. Rearranges primary structure D. Alters R groups

A Why: Heat denatures proteins by unfolding them.

Why is it significant that keratin/collagen are fibrous and hemoglobin/myoglobin are globular? A. Fibrous proteins are tough and structural B. Fibrous proteins only work in solution C. Globular proteins function in solution D. A and C

A and C Why: Structure determines function and solubility.

Which statement about DNA is FALSE? A. Encodes protein information B. Controls physical characteristics C. Assembles amino acids directly D. Regulates metabolism

C Why: DNA provides instructions but does not assemble amino acids itself.

Which molecule contains ribose, nitrogenous bases, and phosphate groups? A. DNA B. ATP C. Protein D. RNA

RNA Why: RNA contains ribose sugar (DNA has deoxyribose).

Why does salt solution conduct electricity but sugar does not? A. Electricity requires ions B. Sugar forms colloids C. Electricity absorbed by glucose D. Salt is hydrophobic

A Why: Salt dissociates into ions; sugar does not.

What molecule is produced by phosphorylation of ADP? A. ATPase B. ATP C. ADP D. UTP

ATP Why: Adding a phosphate to ADP forms ATP.

Wine has a pH of 3 and tomatoes a pH of 4. This means: A. Wine is closer to neutral B. Wine has 10× more H⁺ C. Tomatoes are basic D. Wine has 100× more H⁺

B Why: Each pH unit equals a tenfold change in hydrogen ion concentration.

What is Avogadro’s number? A) The atomic mass of an element B) The mass of one mole C) The number of particles in one mole D) The number of protons in an atom

C Why: Avogadro’s number = 6.02 × 10²³ particles It is a COUNT, not a weight.

One mole of any substance contains: A) 1 gram B) A variable number of atoms C) 6.02 × 10²³ particles D) The atomic number

C Why: A mole is defined as Avogadro’s number of particles, no matter the substance.

One mole of oxygen gas (O₂) contains: A) 2 atoms B) 6.02 × 10²³ atoms C) 6.02 × 10²³ molecules D) 12 grams

C Why: O₂ exists as molecules, not single atoms.

Chapter 2 Flashcards

(67 cards)