chapter 2

Question 1

Define matter and list its three classical states.

Answer 1

Anything that takes up space & has mass. States: solid, liquid, gas.

Question 2

What is the difference between mass and weight?

Answer 2

Mass = amount of matter (kg, g). Weight = gravitational pull on mass (newtons; pounds).

Question 3

Describe an atom’s basic structure.

Answer 3

Central nucleus (protons + neutrons) surrounded by an electron cloud in energy-level shells.

Question 4

List the subatomic particles including their location, charge, and mass.

Answer 4

Proton: nucleus, +1, 1 amu. Neutron: nucleus, 0, 1 amu. Electron: shells, -1, ≈0 amu.

Question 5

What determines (a) atomic number and (b) atomic mass?

Answer 5

(a) # protons. (b) protons + neutrons (electrons negligible).

Question 6

Isotope vs. radioisotope.

Answer 6

Isotope = same protons, different neutrons. Radioisotope = isotope whose nucleus is unstable & emits radiation.

Question 7

List two medical uses and two dangers of radiation.

Answer 7

Uses: PET scans, thyroid-131 ablation. Dangers: DNA damage → cancer, radiation burns.

Question 8

What is the periodic table logic for reactivity?

Answer 8

Elements in the same column have the same # valence electrons ⇒ similar chemical properties/ionization.

Question 9

What are the four most abundant elements in humans?

Answer 9

O (oxygen), C (carbon), H (hydrogen), N (nitrogen).

Question 10

What is the difference between a molecule and a compound?

Answer 10

Molecule = ≥2 atoms covalently bonded. Compound = ≥2 different elements chemically combined (ionic or covalent).

Question 11

Define covalent, ionic, and hydrogen bonds in order of strength.

Answer 11

Covalent (share e–, strongest) > Ionic (opposite ions) > Hydrogen (weak attraction between δ+H and δ– atom).

Question 12

Give examples of single, double, and triple covalent bonds.

Answer 12

CH4 single; CO2 double; N2 triple.

Question 13

How does an Na+ ion form?

Answer 13

Na loses 1 e– → Na+.

Question 14

How does NaCl ionic bond form?

Answer 14

Cl gains 1 e– → Cl–; electrostatic attraction = NaCl.

Question 15

Polar vs. non-polar molecules.

Answer 15

Polar: unequal e– sharing, partial charges (H2O). Non-polar: equal sharing, no charge separation (O2).

Question 16

List the unique properties of water and their causes.

Answer 16

Polarity + H-bonds ⇒ excellent solvent, cohesion/adhesion, high heat capacity, high heat of vaporization.

Question 17

Define hydrogen bond.

Answer 17

Weak attraction between slightly + hydrogen and slightly – atom (O or N) on another molecule.

Question 18

Interpret the equation: 2H2 + O2 → 2H2O.

Answer 18

Reactants left; products right; coefficients = molecules; arrow reads ‘yields.’

Question 19

What do acids do in water? Provide an example.

Answer 19

Release H+ in water; e.g., HCl → H+ + Cl–.

Question 20

What do bases do in water? Provide an example.

Answer 20

Release OH– or accept H+; e.g., NaOH → Na+ + OH–.

Question 21

Describe the pH scale relationship.

Answer 21

Each unit = 10× [H+] change; lower pH ⇒ more acidic.

Question 22

Define buffer and give a blood example.

Answer 22

Chemical pair resists pH change. Carbonic acid–bicarbonate keeps blood near pH 7.4.

Question 23

Describe acid precipitation: formation and effects.

Answer 23

SO2/NOx + H2O → H2SO4/HNO3; harms forests, lakes, human lungs.

Question 24

Define macromolecule, monomer, and polymer.

Answer 24

Macromolecule = large polymer; polymer = chain of monomers via dehydration synthesis.

Question 25

What is dehydration synthesis vs. hydrolysis?

Answer 25

Dehydration synthesis: remove H2O to link monomers. Hydrolysis: add H2O to break polymers.

Question 26

List the four major macromolecule classes.

Answer 26

*Carbohydrates*, *lipids*, *proteins*, *nucleic acids*.

Question 27

What is the carbohydrate monomer and three key polysaccharides?

Answer 27

Monomer = monosaccharide (glucose). Key polysaccharides: *glycogen*, *starch*, *cellulose*.

Question 28

Describe fatty acid structure and the difference between saturated and unsaturated.

Answer 28

Long hydrocarbon + COOH. Saturated = no C=C, solid (butter). Unsaturated = ≥1 C=C kink, liquid (olive oil).

Question 29

What are the components of a triglyceride and its function?

Answer 29

Glycerol + 3 fatty acids; function: long-term energy, insulation, cushioning.

Question 30

Define trans fats and their health impact.

Answer 30

Hydrogenated unsaturated fats with trans C=C; raise LDL, increase heart-disease risk.

Question 31

List five key lipid functions.

Answer 31

*Energy storage*, *membranes (phospholipids, cholesterol)*, *insulation*, *hormone precursors*, *vitamin absorption*.

Question 32

Describe the phospholipid structure and its role in membranes.

Answer 32

Glycerol + 2 FA tails (hydrophobic) + phosphate head (hydrophilic) → bilayer barrier.

Question 33

What is the basic skeleton of a steroid and give three examples.

Answer 33

4 fused carbon rings; examples: *cholesterol*, *estrogen*, *testosterone*.

Question 34

What are the sources and roles of cholesterol?

Answer 34

Endogenous liver synthesis & diet (animal fats); roles: membrane fluidity, steroid hormone/vitamin D precursor.

Question 35

What is the protein monomer and its four functions?

Answer 35

Amino acid; functions: *structural*, *transport*, *enzymes*, *movement/signaling*.

Question 36

List the levels of protein structure.

Answer 36

1° sequence aa; 2° α-helix/β-sheet H-bonds; 3° 3-D folding R-group interactions; 4° multiple subunits assembly.

Question 37

Define denaturation and its causes.

Answer 37

Loss of 3-D shape ⇒ loss function; causes: *heat*, *pH*, *chemicals*.

Question 38

What is the role of enzymes and how do they speed up reactions?

Answer 38

Biological catalyst lowers activation energy; aligns substrates at active site → ES complex.

Question 39

Define active site and enzyme-substrate complex.

Answer 39

Specific pocket where substrate binds; ES complex undergoes transition → product + free enzyme.

Question 40

Cofactor vs. coenzyme.

Answer 40

Cofactor = non-protein helper (metal ion/organic); organic cofactors = coenzymes (vitamins).

Question 41

Explain the equation E + S ⇌ ES → E + P.

Answer 41

Enzyme + substrate bind reversibly → complex → converted to product; enzyme reusable.

Question 42

What are the types of nucleic acids and their overall functions?

Answer 42

DNA: genetic blueprint; RNA: expresses blueprint (protein synthesis).

Question 43

Describe the structure of a nucleotide.

Answer 43

Pentose sugar, phosphate group(s), nitrogenous base.

Question 44

Compare DNA and RNA in terms of sugar, bases, and strands.

Answer 44

DNA: deoxyribose, A-T-C-G, double helix. RNA: ribose, A-U-C-G, single strand.

Question 45

What is the composition of ATP and its role?

Answer 45

Adenine + ribose + 3 phosphates; high-energy phosphate bond hydrolysis powers cellular work.

Question 46

Define heat capacity vs. heat of vaporization in water.

Answer 46

Capacity: energy to raise temp 1 °C; vaporization: energy to convert to gas; both high in water due to H-bonds.

Question 47

Define solvent, solute, and solution; give a biological example.

Answer 47

Solvent dissolves (water), solute dissolved substance (NaCl), solution mixture (blood plasma ions).