Practice Questions
Biomolecules
Name the type of linkage that connects monosaccharide units to form polysaccharides.
Propose a simple dietary plan for an individual diagnosed with both scurvy and night blindness. Justify your choice of food items.
Name the vitamin responsible for the coagulation of blood and list one of its dietary sources.
Compare fibrous proteins and globular proteins based on their structure, solubility in water, and one specific example of each.
Justify the use of DNA fingerprinting over traditional fingerprints for criminal identification in forensic science.
Justify why enzymes are considered more efficient catalysts than inorganic catalysts for biological reactions.
Define enzymes and state their general chemical nature.
Contrast the storage of Vitamin C and Vitamin A in the body and apply this to explain why their dietary requirements differ.
Identify the functional group that characterizes an aldose and a ketose.
Describe how vitamins are classified. List two vitamins from each class.
Define polysaccharides and give one example.
List the three main chemical components of a nucleotide.
Analyze the amphoteric behavior of amino acids by demonstrating how glycine () reacts in both acidic and basic solutions.
Compare the glycosidic linkages found in starch (amylose) and cellulose and analyze how this structural difference affects their digestibility by humans.
Contrast DNA and RNA on five distinct points: the pentose sugar, nitrogenous bases, overall structure, primary location in a eukaryotic cell, and main biological function.
Apply your understanding of protein denaturation to analyze why a prolonged high fever can be a serious medical condition.
A tripeptide is formed from one molecule of Alanine (Ala), one of Glycine (Gly), and one of Valine (Val). Demonstrate how many different primary structures are possible for this tripeptide and write the structure for one of them, for example, Gly-Ala-Val, showing the peptide bonds.
Design a short, single-stranded DNA segment of 6 bases containing all four nitrogenous bases. Formulate the structure of its complementary strand, indicating the hydrogen bonds between base pairs. Justify why the two strands are described as complementary but not identical.
Evaluate the statement: 'Denaturation of a protein permanently destroys its primary structure.' Justify your conclusion.
A polypeptide has the primary sequence: Gly-Ala-Cys-Phe-Cys. Propose two types of bonds, other than peptide bonds, that could stabilize its tertiary structure and justify their formation.
Explain the term 'invert sugar' in the context of the hydrolysis of sucrose.
Define the denaturation of proteins.
Analyze why sucrose is a non-reducing sugar while maltose is a reducing sugar, even though both are disaccharides composed of hexose units.
Compare and contrast the primary, secondary, tertiary, and quaternary structures of proteins. Examine the types of bonds or forces that stabilize each level of structure.
Compare the structures of amylopectin and glycogen. Analyze why glycogen is considered a more efficient energy storage molecule in animals.
Analyze the statement: 'The two strands in a DNA double helix are not identical but are complementary.' Explain this concept using the specific base pairing rules.
Critique the original definition of carbohydrates as 'hydrates of carbon' with the general formula . Support your critique with at least two specific counterexamples.
Formulate a two-step reaction scheme to convert starch into saccharic acid. Justify the reagents and conditions required for each step.
Justify why lactose is classified as a reducing sugar while sucrose is not, based on their respective glycosidic linkages.
Critique the classification of insulin (51 amino acids) as a protein rather than a polypeptide.
Critique the necessity of taking daily supplements of water-soluble vitamins (like C and B-complex) compared to fat-soluble vitamins (like A and D).
Explain the difference between essential and non-essential amino acids. Provide one example for each category.
Explain the principle of complementarity in the structure of a DNA double helix.
Explain the chemical basis for classifying a carbohydrate as a reducing sugar. Name one example of a reducing sugar and one non-reducing sugar.
Describe how a peptide linkage is formed between two amino acids.
Summarize the key structural and functional differences between DNA and RNA.
Evaluate the key structural differences between DNA and RNA and propose how these differences relate to their respective biological functions of long-term information storage versus short-term information transfer.
Propose a series of chemical tests to distinguish between glucose, sucrose, and starch in three unlabeled test tubes. Justify the expected observations for each test.
Demonstrate the formation of a dinucleotide from two deoxyadenosine monophosphate units, clearly showing the phosphodiester linkage between the and carbon atoms of the deoxyribose sugars.
Examine the chemical evidence that supports the open-chain structure of D-glucose. Specifically, analyze the conclusions drawn from its reactions with (i) prolonged heating with HI, (ii) Bromine water, and (iii) Acetic anhydride.
Analyze the experimental observations that could not be explained by the open-chain structure of glucose, which led to the proposal of its cyclic hemiacetal structure.
Design a hypothetical tripeptide containing one acidic, one basic, and one neutral amino acid. Propose its structure, name it, and evaluate its behavior in both highly acidic (pH < 2) and highly basic (pH > 10) solutions by drawing the dominant ionic forms.
An enzyme 'X' specifically catalyzes the hydrolysis of maltose into glucose. Propose a name for this enzyme. Design an experiment to evaluate the effect of a significant pH change (e.g., from pH 7 to pH 2) on the activity of enzyme 'X'. Predict and justify the outcome.
Describe the primary and secondary structures of proteins. Name the type of bonding responsible for stabilizing the secondary structure.
An unknown carbohydrate gives a positive test with Tollens' reagent and upon complete acid hydrolysis yields only D-glucose. When this carbohydrate is treated with an enzyme known to cleave -1,4 glycosidic bonds, no reaction occurs. Analyze these findings to propose a likely identity for this carbohydrate.