Biochem. Readiness Test

Question 1

In a chemical reaction involving 2 moles of substance A and 3 moles of substance B, the balanced chemical equation is:

2A+3B→products

If 4 moles of substance A and 5 moles of substance B are initially present, which of the following statements about the limiting reagent is true?

a) Substance A is the limiting reagent.*
b) Substance B is the limiting reagent.
c) Both substances A and B are limiting reagents.
d) There is not enough information to determine the limiting reagent.

Question 2

What is the molar concentration of a solution prepared by dissolving 5 grams of compound X (molar mass = 100 g/mol) in 500 mL of water?

a) 0.1 M*
b) 0.5 M
c) 1.0 M
d) 2.0 M

Question 3

To prepare a diluted solution, 20 mL of a stock solution with a concentration of 0.4 M is mixed with 80 mL of water. What is the final concentration of the diluted solution?

a) 0.1 M
b) 0.16 M
c) 0.32 M
d) 0.08 M*

Question 4

Identify the carbon that is the least electronegative in the following chemicals:

a) methane*
b) methanol
c) carbon monoxide
d) carbon dioxide

Answer 4

.. All carbon atoms in methane are equivalent, and they have similar electronegativity.

Question 5

What is the oxidation state of the carbon attached to the phosphate group?

Look up Glucose 6-phosphate

a) -1
b) 0*
c) +1
d) -2

Question 6

Which of the following factors determines the polarity of a chemical bond?

a) Atomic mass of the elements involved.
b) Number of valence electrons in the elements involved.
c) Difference in electronegativity between the elements involved.*
d) Total number of electrons in the molecule.

Question 7

Gum is typically made of terpene, which has a chemical formula shown below. If you accidentally “gummed” up your hair, which liquid would you use to free up your hair with least amount of damage?

a) Water
b) Peanut butter oil*
c) Vodka
d) Milk

Question 7

Which of the following compounds exhibits the highest degree of bond polarity?

a) Carbon dioxide (CO2)
b) Methane (CH4)
c) Water (H2O)*
d) Ethane (C2H6)

Answer 7

c) Water (H2O)

Question 8

For the scenario described in previous question, which one of the following chemical phenomena is responsible?

a) The hydrophobic effect*
b) Le Chatelier’s Principle
c) A change in Gibbs free energy
d) Buffer capacity

Question 9

Which of the following statements accurately compares strong and weak acids?

a) Strong acids have a higher pH than weak acids.
b) Strong acids are less reactive than weak acids.
c) Strength is dependent on their dissociation in water.*
d) Weak acids have a higher conductivity than strong acids.

Question 9

In thin-layer chromatography (TLC), which one of the following factors primarily determines the separation of components?

a) The size of the stationary phase particles.
b) The polarity of the mobile phase.*
c) The temperature of the chromatography chamber.
d) The thickness of the TLC plate.

Question 10

Which of the following statements accurately defines Ka?

a) Ka represents the concentration of hydronium ions (H3O+) in a solution.
b) Ka is a measure of the rate at which an acid reacts with water.
c) Ka is the equilibrium constant describing the amount of acid dissociation in water.*
d) Ka indicates the strength of an acid based on its ability to conduct electricity.

Question 11

Which of the following statements best describes Ka in terms of acid strength?

a) A higher value of Ka indicates a stronger acid.*
b) A higher value of Ka indicates a weaker acid.
c) Ka measures the rate of acid dissociation, not its strength.
d) None of the above, Ka is the concentration of H3O+ in solution.

Question 12

Which of the following equations correctly represents the relationship between Ka and pKa?

a) Ka = 10^(pKa)
b) Ka = -log(pKa)
c) pKa = 10^(-Ka)
d) pKa = -log(Ka)*

Question 13

Which of the following statements correctly describes a buffer and its function?

a) A buffer is a solution that can resist changes in pH when small amounts of acid or base are added.*
b) A buffer capacity refers to a weak acid’s ability to neutralize strong acids or bases.
c) A buffer is a substance that can only maintain a pH of 7.
d) A buffer capacity refers to the amount of acid or base that can be absorbed before reaching saturation.

Question 14

Which of the following pairs represents a buffer system?

a) Sodium chloride (NaCl) and hydrochloric acid (HCl)
b) Potassium hydroxide (KOH) and sulfuric acid (H2SO4)
c) Carbonic acid (H2CO3) and bicarbonate ion (HCO3-)*
d) Nitric acid (HNO3) and ammonia (NH3)

Answer 14

..carbonic acid (H2CO3) is a weak acid, and bicarbonate ion (HCO3-) is its conjugate base.

Question 15

What is the pH of a solution with a hydrogen ion concentration ([H+]) of 1 x 10^-5 M?

a) 2
b) 5*
c) 7
d) 9

Question 16

A solution contains a weak acid ([HA] = 0.05 M) and its conjugate base ([A-] = 0.01 M), pKa = 3.8. Determine the pH of this solution:

a) 3.1*
b) 3.8
c) 4.2
d) 4.8

Question 17

Which of the following statements accurately describes chemical equilibrium?

a) It occurs when reactants are completely consumed, and products are formed.
b) It is a dynamic state where the rates of the forward and reverse reactions are equal.*
c) It is achieved when there are more products than reactants.
d) Chemical equilibrium only occurs in irreversible reactions.

Question 18

Which one of the following conditions represents a case of steady state?

a) A person who is running and sweating.*
b) a cup of pure liquid water.
c) a beakerful of diluted acetic acid.
d) a reaction with free Gibbs energy equal to zero.

Question 19

Which of the following expressions correctly represents the reaction quotient (Q) for the chemical equation: 2A + 3B ⇌ C?

a) Q = [A]2[B]3
[C]
b) Q = [C]
[A]2[B]3*
c) Q = [C]2
[A]3[B]
d) Q = [A]2[B]3[C]

Question 20

For the following reaction: A + B ⇌ C + D, given the equilibrium concentrations of A = 0.1 M, B = 0.2 M, C = 0.3 M, and D= 0.4 M, determine the value of the equilibrium constant (Keq):

a) 0.5
b) 2
c) 5
d) 6*

Question 21

Which of the following statements correctly describes the Gibbs free energy (ΔG) of a spontaneous chemical reaction?

a) ΔG is positive in an exothermic reaction.
b) ΔG is negative in an endergonic reaction.
c) ΔG is 0.
d) ΔG can be positive or negative depending on the reaction conditions.*

Question 22

Apply Le Chatelier’s Principle to predict the effect of perturbing an equilibrium
In a biochemical reaction involving the conversion of glucose-6-phosphate (G6P) to fructose-6-phosphate (F6P), which of the following changes would favor the forward reaction?

a) Decreasing the concentration of G6P.
b) Decreasing the concentration of F6P.*
c) Decreasing the pH of the solution.
d) Adding an enzyme inhibitor to the reaction.

Question 23

Which of the following statements is CORRECT regarding changes in enthalpy (ΔH) and entropy (ΔS) in a chemical reaction?
Question 27 options:

a) ΔH relates to the randomness or disorder of the system, while ΔS measures the heat exchanged during the reaction.
b) ΔH describes the heat energy of the reactants and products, while ΔS describes the degree of randomness or disorder of the system.
c) ΔH quantifies the heat released or absorbed during a reaction, while ΔS quantifies the change in the number of moles of reactants and products.
d) ΔH quantifies the concentration of reactants and products in a reaction, while ΔS represents the change in temperature of the system

Question 24

For the biochemical reaction: glucose-6-phosphate (G6P) ⇌ fructose-6-phosphate (F6P), if the standard Gibbs free energy change (ΔG°) is -3.4 kJ/mol, what is the equilibrium constant (Keq) for the reaction at 298 K?

a) 1.37
b) 3.94*
c) 35.1
d) 100.0

Question 25

In the reverse reaction where pyruvate is converted to lactate, which molecule is oxidized?

a) Pyruvate
b) Lactate
c) NAD+
d) NADH*

Question 26

Which functional group is NOT present in the following oligopeptide?

Look up Oligopeptide find one with green on left and blue on right

a) Carboxyl
b) Amide
c) Amine
d) Ester*

Question 27

Which of the following statements accurately describes Beer’s Law, regarding absorbance and a solute in solution?

a) The absorbance of light is directly proportional to the concentration of the solute.*
b) The absorbance of light is inversely proportional to the concentration of the solute.
c) The absorbance of light is unrelated to the concentration of the solute.
d) The absorbance of light depends on the color of the solute, not its concentration.

Question 28

According to Beer’s Law, if a solution has an absorbance of 0.5 and a molar absorptivity (ε) of 100 M^-1cm^-1, what is the concentration of the solute in the solution given the path length (l) of 1 cm?

a) 0.05 M
b) 0.5 M
c) 5 M
d) 5 mM*

Question 29

How does the presence of a catalyst affect the activation energy of a chemical reaction?

a) It decreases the activation energy, making the reaction proceed faster.*
b) It increases the activation energy, slowing down the reaction.
c) It has no effect on the activation energy of a reaction.
d) The effect depends on the specific reaction conditions.

Question 30

How does the presence of a catalyst affect the position of equilibrium in a chemical reaction?

a) A catalyst shifts the equilibrium towards the reactants.
b) A catalyst shifts the equilibrium towards the products.
c) A catalyst has no effect on the position of equilibrium.*
d) The effect depends on the specific reaction conditions.

Question 31

Which of the following accurately describes the process of polysaccharide formation from monosaccharides?

a) It involves the covalent bonding of monosaccharides through peptide bonds.
b) Condensation reactions join monosaccharides via glycosidic bonds.*
c) The addition of phosphate groups to monosaccharides forms phosphodiester bonds.
d) It is driven by the hydrolysis of monosaccharides, forming of ester bonds.

Question 32

Which of the following functions is NOT typically associated with carbohydrates in biological systems?

a) Energy storage and utilization.
b) Structural support and protection.
c) Cell recognition and signaling.
d) Enzymatic catalysis.*

Question 33

Which of the following statements best describes the relationship between amino acids and proteins?

a) Amino acids are the functional units of proteins, responsible for carrying out specific biological activities.
b) Proteins are formed from the condensation of nucleotides, while amino acids serve as building blocks for nucleic acids.
c) Amino acids and proteins are unrelated molecules with distinct biological functions and structures.
d) Amino acids are the monomeric subunits that combine to form proteins through peptide bond formation.*

Question 34

Which of the following statements accurately describes the relationship between proteins and enzymes?

a) Enzymes are a type of protein that catalyze biochemical reactions in living organisms.*
b) Proteins are a type of enzyme that facilitate the synthesis of other proteins.
c) Enzymes are a subset of proteins that are involved in structural functions within cells.
d) Proteins and enzymes are distinct molecules with separate roles in cellular processes.

Question 35

Which biomolecule does NOT have a polymeric structure?

a) Carbohydrate
b) Nucleic acid
c) Protein
d) Lipid*

Question 36

Which of the following functions is NOT commonly associated with lipids in biological systems?

a) Cell membrane formation and integrity.
b) Energy storage and insulation.
c) Signaling and communication between cells.
d) Enzymatic catalysis of metabolic pathways.*

Question 37

Which of the following statements accurately describes the structure and main function of mitochondria?

a) Mitochondria are double-membraned organelles involved in protein synthesis.
b) Mitochondria have a single membrane and are responsible for storing genetic material.
c) Mitochondria contain extensive folds called cristae, where ATP production occurs.*
d) Mitochondria are involved in the detoxification of harmful substances in the cell.

Question 38

Which of the following statements accurately describes the structure and function of biological membranes?

a) They form a rigid barrier made up of a single layer of phospholipids.
b) A bilayer of phospholipids and embedded proteins regulate the movement of molecules.*
c) They are composed of carbohydrates and nucleic acids, that provide structural support.
d) They are impermeable to all molecules, ensuring the isolation of cellular components.

Question 39

Which of the following factors determine the selective permeability of biological membranes?

a) The size and charge of molecules or ions.
b) The presence of specific transport proteins.
c) The concentration gradient of solutes across the membrane.
d) All of the above.*

Question 40

Which of the following statements is correct regarding ATP (adenosine triphosphate)?

a) ATP is a stable molecule that does not readily undergo hydrolysis to release energy.
b) ATP functions as a long-term energy storage molecule within cells.
c) ATP hydrolysis releases a phosphate group, providing energy for cellular processes.*
d) ATP synthesis occurs exclusively in the cytoplasm of eukaryotic cells.

Question 41

Which of the following sequences accurately represents the overall process of glucose catabolism with the major stages and intermediate products?

a) Glycolysis → Acetyl-CoA formation → Krebs cycle → Electron transport chain*
b) Electron transport chain → Glycolysis → Acetyl-CoA formation → Krebs cycle
c) Krebs cycle → Electron transport chain → Glycolysis → Acetyl-CoA formation
d) Acetyl-CoA formation → Krebs cycle → Glycolysis → Electron transport chain

Question 42

Which one of the following molecules is NOT made in the Krebs cycle (citric acid cycle)?

a) ATP
b) NADH
c) FADH2
d) Acetyl CoA*

Answer 42

…Acetyl CoA is a molecule that enters the Krebs cycle. It is formed during the process of glycolysis when pyruvate is converted to Acetyl CoA, and Acetyl CoA subsequently enters the Krebs cycle to participate in the production of NADH, FADH2, and ATP.

Question 43

Which ONE of the following statements accurately describes the electron transport chain (ETC) in cellular respiration?

a) It occurs in the cytoplasm and involves the transfer of electrons to generate ATP.
b) It involves the oxidation of glucose to produce carbon dioxide and water.
c) It occurs in the mitochondria and generates a proton gradient and produce ATP.*
d) It is a series of reactions that synthesizes glucose from carbon dioxide and water.

Question 44

Which ONE of the following statements accurately compares and contrasts DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)?

a) Both DNA and RNA are double-stranded molecules, but DNA contains deoxyribose sugar, while RNA contains ribose sugar.
b) DNA is involved in protein synthesis, while RNA serves as the genetic material of the cell.
c) DNA is stable and found primarily in the nucleus, while RNA is less stable and found throughout the cell.
d) Both DNA and RNA are composed of nucleotides, but DNA contains uracil as one of its bases, while RNA contains thymine.*

Question 45

Which ONE of the following accurately compares and contrasts bacteria and eukaryotes?

a) Bacteria have linear chromosomes, while eukaryotes have circular chromosomes.
b) Bacteria possess introns, whereas eukaryotes do not.
c) Bacteria primarily perform aerobic respiration, while eukaryotes rely on anaerobic metabolism.
d) Bacteria have a single compartment, whereas eukaryotes exhibit compartmentalization through membrane-bound organelles.*

Question 46

Which ONE of the following statements accurately describes the relationship between endosymbiosis and the origin of mitochondria?

a) Endosymbiosis theory proposes that mitochondria originated from the engulfment of free-living aerobic bacteria by ancestral eukaryotic cells, establishing a mutualistic relationship.*
b) Endosymbiosis is the process by which mitochondria formed a parasitic relationship with ancestral eukaryotic cells, leading to their evolution as intracellular parasites.
c) Endosymbiosis is a mechanism by which mitochondria evolved independently from eukaryotic cells, originating from a separate ancestral lineage.
d) Endosymbiosis explains the transfer of genetic material from mitochondria to the nucleus of eukaryotic cells, influencing cellular function and evolution.