Biochem 4 Flashcards

Proteins are best described as:
A. Linear amino acid chains
B. Branched lipid polymers
C. Paired nucleotide helices
D. Cyclic monosaccharide rings

In these notes, proteins primarily support:
A. DNA replication fidelity
B. Membrane potential generation
C. Molecular transport and scaffolding
D. Steroid hormone synthesis

With cooling, water responds by:
A. Decreases hydrogen bonding
B. Breaks covalent bonds
C. Eliminates dipole forces
D. Increases hydrogen bonding

In body fluids, water most directly functions as a:
A. Structural polymer
B. Solvent medium
C. Enzymatic catalyst
D. Lipid emulsifier

The extracellular compartment comprises:
A. Cytosol and organelles
B. Interstitial fluid, blood, lymph
C. Bone, muscle, fat
D. Nucleus and mitochondria

Water is dipolar because it has:
A. Equal electron sharing
B. Pure ionic bonding
C. Uneven electron distribution
D. No partial charges

Water dissociation yields:
A. Na+ and Cl-
B. Ca2+ and CO3--
C. H2 and O2
D. H+ and OH-

pH is the:
A. Ratio of acid to base
B. Negative log of [H+]
C. Log of hydroxide
D. Measure of buffer amount

An acid is a substance that:
A. Releases hydrogen ions
B. Accepts hydrogen ions
C. Releases hydroxide ions
D. Accepts hydroxide ions

A base is a substance that:
A. Releases hydrogen ions
B. Releases carbon dioxide
C. Accepts hydrogen ions
D. Accepts hydroxide ions

When a strong acid is added to water, it:
A. Forms a stable buffer
B. Does not dissociate
C. Accepts protons rapidly
D. Dissociates and releases H+

A weak acid is characterized by its:
A. Dissociation constant Ka
B. Always complete dissociation
C. Fixed pH in water
D. Always negative charge

pH, Ka, and dissociation are related by:
A. Nernst equation
B. Henderson–Hasselbalch equation
C. Michaelis–Menten equation
D. Gibbs–Helmholtz equation

A buffer is a mixture of:
A. Two strong acids
B. Hydrogen and hydroxyl gases
C. Protein and lipid micelles
D. Undissociated acid and conjugate base

The acid form after losing its proton is the:
A. Parent acid
B. Carbonic acid
C. Conjugate base
D. Undissociated acid

A buffer’s greatest capacity occurs when pH is:
A. Near the pKa
B. Far below pKa
C. Far above pKa
D. Independent of pKa

Buffer effectiveness depends on:
A. Temperature and pressure
B. Volume and viscosity
C. pKa–pH relation, concentration
D. Osmolarity and hemoglobin

The major source of acid from normal metabolism is:
A. Phosphate
B. Carbon dioxide
C. Bicarbonate
D. Chloride

Normal metabolism generates:
A. Ketones only
B. CO2 only
C. Inorganic acids only
D. CO2, metabolic, inorganic acids

CO2 reacting with water produces:
A. Carbonic acid
B. Lactic acid
C. Hydrochloric acid
D. Phosphoric acid

Bicarbonate, phosphate, and hemoglobin act as:
A. Enzymes
B. Buffers
C. Hormones
D. Transporters

Respiratory removal of carbonic acid occurs via:
A. Excreting NH4+ in urine
B. Sweating bicarbonate
C. Expiring CO2
D. Storing H+ in bone

Renal excretion of acid occurs mainly as:
A. H2O
B. CO2
C. HCO3-
D. NH4+

Reference range for blood pH is:
A. 7.36–7.44
B. 7.20–7.28
C. 7.10–7.18
D. 7.52–7.60

Complete reduction of molecular O2 requires:
A. Four electrons
B. Two electrons
C. One electron
D. Three electrons

Obese patients tend to have lower % body water because:
A. Glycogen holds little water
B. Fat holds little water
C. Bone holds little water
D. Muscle holds little water

Extracellular water is found mainly in:
A. Cytosol and organelles
B. Nucleus and mitochondria
C. Bone and adipose
D. Plasma and interstitial fluid

Transcellular water is best described as:
A. Majority intracellular volume
B. Specialized extracellular fluid portion
C. Entire interstitial compartment
D. Entire lymphatic compartment

In water, shared electrons are attracted to the ___, creating a ___.
A. Oxygen, partial negative
B. Hydrogen, partial negative
C. Oxygen, partial positive
D. Hydrogen, partial positive

A hydrogen bond is a:
A. Covalent electron sharing
B. Ionic attraction between ions
C. Hydrophobic solute clustering
D. Weak H-to-electronegative bond

Each water molecule is typically hydrogen-bonded to:
A. Two neighbors
B. Four neighbors
C. Six neighbors
D. Eight neighbors

What dissolves easily in water?
A. Neutral lipids and sterols
B. Nonpolar hydrocarbons
C. Polar organics, inorganic salts
D. Noble gases and waxes

Hydrogen bonds between water and polar solutes continuously:
A. Permanently lock solutes
B. Dissociate and reform
C. Convert to covalent bonds
D. Prevent water channel flow

Water’s high heat of fusion allows it to:
A. Boil at low heat
B. Rapidly change temperature
C. Resist temperature change
D. Have low specific heat

With heat input, water responds by:
A. Decreases hydrogen bonding
B. Increases hydrogen bonding
C. Forms ionic lattices
D. Eliminates dipole forces

With cooling, water responds by:
A. Decreases hydrogen bonding
B. Breaks covalent bonds
C. Eliminates dipole forces
D. Increases hydrogen bonding

“Electrolytes” here refers to:
A. Proteins and lipids
B. Bicarbonate and inorganic ions
C. Glucose and urea
D. Vitamins and hormones

Major electrolytes in ECF are:
A. K+ and phosphate
B. Ca2+ and Mg2+
C. Na+ and Cl-
D. H+ and lactate

Major electrolytes inside cells are:
A. K+ and phosphates
B. Na+ and chloride
C. Calcium and bicarbonate
D. Glucose and urea

Hydration shells primarily surround:
A. Neutral gases
B. Lipid droplets
C. Proteins only
D. Anions and cations

Osmolality is proportional to:
A. Sodium concentration only
B. Total solute concentration
C. Plasma proteins only
D. Fluid volume only

Osmotic pressure is the:
A. Force moving solute outward
B. Force creating ion gradients
C. Force keeping water equal sides
D. Force measuring membrane thickness

When water is lost into urine, blood volume water is resupplied by:
A. Interstitial fluid refill
B. Intracellular fluid refill
C. Bone mineral release
D. Transcellular fluid refill

Ka for a weak acid (HA) is:
A. Ka = [A-]/[HA]
B. Ka = [H+]/[HA]
C. Ka = [HA]/[H+][A-]
D. Ka = [H+][A-]/[HA]

The midpoint of a titration curve is:
A. pH equals pKa
B. pH equals pOH
C. pH equals 7.00
D. pH equals Ka

The bicarbonate buffer system primarily occurs in:
A. Red blood cells
B. Intracellular fluid
C. Extracellular fluid
D. Mitochondrial matrix

The hemoglobin buffer system primarily occurs in:
A. Extracellular fluid
B. Red blood cells
C. Blood plasma only
D. Interstitial fluid only

The phosphate buffer system occurs in:
A. All cell types
B. Red blood cells only
C. Extracellular fluid only
D. Plasma only

The initial acid–base effect of aspirin is:
A. Metabolic alkalosis
B. Respiratory acidosis
C. Metabolic acidosis
D. Respiratory alkalosis

Aspirin is a weak acid. When aspirin binds H⁺ (is protonated), it exists primarily in which chemical form?
A. Salicylate
B. Acetic acid
C. Acetylsalicylic acid
D. Salicylic acid

Salicylate interferes most with production of:
A. Nuclear DNA
B. Cytosolic NADH
C. Mitochondrial ATP
D. Hemoglobin heme

Salicylate may also impair:
A. Platelet ADP receptors
B. Renal function
C. Pulmonary surfactant
D. Hepatic bile flow

Carbonic anhydrase accelerates:
A. HCO3- → CO2
B. Lactate → pyruvate
C. NH3 → NH4+
D. CO2 + H2O → H2CO3

Carbonic acid dissociates into:
A. Na+ and Cl-
B. H+ and HCO3-
C. H+ and OH-
D. CO2 and H2O

In these notes, the pKa of carbonic acid is:
A. 6.1
B. 4.8
C. 3.8
D. 7.4

Carbonic anhydrase is not found in:
A. Plasma and interstitial fluid
B. Renal tubular cells
C. Red blood cells
D. Gastric parietal cells

Major buffers maintaining ICF pH are:
A. Phosphate anions and proteins
B. Bicarbonate and hemoglobin
C. Sodium and chloride
D. Lactate and ketones

Hydrogen ion transport helps maintain:
A. Constant urine pH
B. Constant gastric pH
C. Constant intracellular pH
D. Constant plasma pH

If a cell becomes more acidic, exchange moves:
A. HCO3- in; Cl- out
B. Na+ in; H+ in
C. H+ out; K+ in
D. H+ out; Na+ in

If a cell becomes too alkaline, exchange moves:
A. HCO3- in; Cl- out
B. HCO3- out; Cl- in
C. H+ in; Na+ out
D. NH4+ out; H+ in

A major source of nonvolatile acid is:
A. Carbonic acid
B. Lactic acid
C. Sulfuric acid
D. Acetic acid

Sulfuric acid is generated by:
A. Sulfates + sulfur amino acids
B. Glucose oxidation
C. Fatty acid beta-oxidation
D. Ketone dissociation

Major contributor to urinary buffering, not blood:
A. Bicarbonate
B. Hemoglobin
C. Phosphate
D. Ammonium

Gastric HCl is secreted by ___ to:
A. Parietal cells; denature proteins
B. Chief cells; emulsify fats
C. G cells; activate pepsin
D. Enterocytes; absorb glucose

Gastric acid is neutralized in small intestine by:
A. Bile acids secretion
B. Mucus release
C. Pancreatic bicarbonate secretion
D. Gastrin release

DKA most directly reflects:
A. Acid loss in urine
B. Acid accumulation, type 1
C. CO2 retention, COPD
D. Excess bicarbonate, vomiting

A patient suspected of salicylate toxicity is most likely to have:
A. Lower abdominal pain
B. Respiratory stimulation
C. Chest tightness
D. Peripheral edema

Which symptom is NOT listed for salicylate toxicity?
A. Nausea
B. Headache
C. Upper abdominal distress
D. Tinnitus

Because solutes can only be excreted dissolved in water, renal water loss is primarily determined by the amount of water needed to:
A. Dilute excreted solutes
B. Replace sweat losses
C. Maintain plasma proteins
D. Raise blood pressure

A buffer works best within:
A. Three pH of pKa
B. One pH of pKa
C. Five pH of pKa
D. Ten pH of pKa

pKa is calculated as:
A. log Ka
B. -log pH
C. -log Ka
D. log[H+]

Normal metabolism generates which set?
A. CO2 and bicarbonate only
B. Lactate and bicarbonate only
C. CO2 and phosphate only
D. Lactate, ketones, sulfuric HCl, CO2

CO2 reacting with water forms:
A. Carbonic acid
B. Hydrochloric acid
C. Sulfuric acid
D. Lactic acid

Salicylate overdose causes respiratory alkalosis by:
A. Suppressing medullary drive
B. Reducing CO2 production
C. Blocking renal ammoniagenesis
D. Stimulating medullary respiratory center

Salicylate raises CO2 and lactate mainly because:
A. ATP falls; glycolysis rises
B. ATP rises; glycolysis falls
C. CO2 excretion stops
D. Lactate oxidation accelerates

Salicylate may worsen metabolic acidosis by:
A. Increasing bicarbonate generation
B. Increasing chloride retention
C. Renal dysfunction accumulates strong acids
D. Decreasing ketone production

Henderson–Hasselbalch equation is:
A. pH = -log[H+]
B. pH=pKa+log(A-/HA)
C. Ka=[HA]/[H+][A-]
D. pKa = -log pH

When a weak acid is 50% dissociated:
A. pH equals pKa
B. pH equals 7.40
C. pH equals pOH
D. pH equals Ka

Total body water distribution is:
A. 40% ICF; 60% ECF
B. 70% ICF; 30% ECF
C. 50% ICF; 50% ECF
D. 60% ICF; 40% ECF

In these notes, “ICF” components include:
A. Transcellular fluid only
B. Urine and sweat
C. Plasma and interstitial
D. RBC cytosol only

ED rehydration for uncomplicated dehydration uses:
A. 0.9% saline
B. 5% dextrose
C. 3% saline
D. 0.45% saline

High filtrate glucose and ketones causing polyuria is:
A. SIADH
B. Osmotic diuresis
C. Nephritic syndrome
D. Diabetes insipidus

Ka best represents a weak acid’s:
A. Buffer capacity
B. Tendency to donate H+
C. Ability to bind OH-
D. Rate of oxidation

A higher Ka generally means the acid:
A. Dissociates less in water
B. Dissociates more in water
C. Becomes a stronger base
D. Becomes more hydrophobic

Normal arterial blood pH is:
A. 7.10–7.20
B. 7.26–7.34
C. 7.36–7.44
D. 7.46–7.54

Intracellular pH normally ranges:
A. 6.9–7.4
B. 7.36–7.44
C. 7.8–8.2
D. 6.0–6.5

“Typical” intracellular pH is about:
A. 6.9
B. 7.1
C. 7.4
D. 7.6

Carbonic acid (H2CO3) dissociates into:
A. H+ and Cl-
B. Na+ and HCO3-
C. H+ and HCO3-
D. CO2 and H2O

In blood, carbonic acid “can’t buffer” because:
A. Too little dissolved CO2
B. Almost fully dissociated
C. No bicarbonate present
D. No hemoglobin present

When base removes H+, H2CO3 shifts to:
A. H+ and HCO3-
B. CO2 and H2O
C. H+ and CO3--
D. NH4+ and HCO3-

As base is added, dissolved CO2 + H2O replenishes:
A. NH3
B. HCO3-
C. H2CO3
D. H2PO4-

Dissolved CO2 availability is adjusted mainly by:
A. Liver gluconeogenesis rate
B. Breathing rate and CO2 expiry
C. Sweat rate and sodium loss
D. Renal albumin excretion

RBCs contain high amounts of:
A. Carbonic anhydrase
B. Acetylcholinesterase
C. Lipoprotein lipase
D. Catalase only

Carbonic anhydrase is absent from:
A. RBC cytosol
B. Renal tubules
C. Blood plasma and interstitial
D. Gastric mucosa

In RBCs, released H+ is buffered by:
A. Albumin
B. Hemoglobin
C. Bicarbonate
D. Phosphate only

Anion exported from RBC for chloride is:
A. Lactate
B. Phosphate
C. Sulfate
D. Bicarbonate

Plasma/interstitial buffering capacity comes from:
A. Bicarbonate and carbonic acid
B. Hemoglobin and phosphate
C. Lactate and ketones
D. Sodium and chloride

Blood buffering capacity includes:
A. Only phosphate buffers
B. Only carbonic acid
C. Albumin and side chains
D. CO2 in alveoli

Interstitial protein buffering is limited because:
A. Proteins cannot accept H+
B. Protein concentration is low
C. Proteins are membrane-bound
D. Proteins are rapidly degraded

Major ICF buffer in these notes is:
A. Bicarbonate
B. Hemoglobin
C. Phosphate anions
D. Carbonic acid

Examples of ICF phosphate buffers include:
A. ATP, G6P, H2PO4-
B. NaCl, KCl, CaCl2
C. CO2, H2CO3, HCO3-
D. Albumin, globulin, fibrinogen

Major intracellular buffer in RBCs is:
A. Phosphate
B. Bicarbonate
C. Lactate
D. Sulfate

In these notes, phosphate is higher in:
A. Interstitial than blood
B. Blood than interstitial
C. Plasma than intracellular
D. CSF than blood

Many ICF proteins buffer via:
A. Histidine residues
B. Tryptophan residues
C. Phenylalanine residues
D. Leucine residues

Metabolic anions leave cells together with:
A. OH-
B. CO2
C. H+
D. NH3

Sulfuric acid arises from metabolism of:
A. Lysine and leucine
B. Tyrosine and tryptophan
C. Cysteine and methionine
D. Alanine and glycine

Nonvolatile acids are excreted mainly via:
A. Lungs
B. Sweat glands
C. Urine
D. Saliva

With cooling, water responds by:
A. Decreases hydrogen bonding
B. Breaks covalent bonds
C. Eliminates dipole forces
D. Increases hydrogen bonding

Urinary pH buffering range listed is:
A. 3.0–4.0
B. 4.5–5.0
C. 5.5–7.0
D. 7.2–7.6

Minimum urinary pH listed is:
A. 5.0
B. 5.5
C. 6.0
D. 7.0

Acid secretion includes all EXCEPT:
A. Phosphate
B. Ammonium
C. Uric acid
D. Creatinine

NH3 is kept low in blood because:
A. It is renal-limited
B. It is neurally toxic
C. It is insoluble
D. It is rapidly exhaled

As tubules secrete H+ into urine, they return:
A. Chloride to blood
B. Lactate to blood
C. Bicarbonate to blood
D. Sulfate to blood

Main ammonium form in blood/urine is:
A. NH3
B. NH4+
C. NO3-
D. NH2-

Urinary excretion that helps remove acid:
A. CO3--
B. HPO4--
C. H2PO4-
D. H2CO3

Urinary phosphate form depends on:
A. Urine pH and blood pH
B. Plasma glucose and ketones
C. Hemoglobin and albumin
D. CO2 diffusion gradient

Dehydration occurs when intake is less than:
A. Renal plus extrarenal loss
B. Only renal water loss
C. Only sweat loss
D. Only respiratory loss

Dehydration causes:
A. Increased Total body water, decreased ECF
B. Decreased Total body water, ECF, ICF
C. Increased Total body water, increased ICF
D. Decreased Total body water, increased ECF

Dehydration can occur during:
A. Only fasting
B. Only high-salt intake
C. Fasting and normal intake
D. Only prolonged exercise