Week 3 — Quiz (auto-graded) · Biological Macromolecules

Course: Introduction to Biology — General Biology I (BIOL 101) · Silver Oak University (fictional sample) · Prof. Castellano
Objective tested: Objective 2 — the four macromolecule classes; monomers & polymers; dehydration synthesis & hydrolysis; carbohydrate, lipid, protein, and nucleic-acid structure; the four levels of protein structure; structure determines function.
Points: 10 (1 each) · Assignment group: Quizzes (10% of grade) · Due: end of Module 3.

This is the human-readable quiz with its vetted answer key and feedback. The import-ready Classic QTI is in F-quiz-week-03-qti.xml (generated by the shared validated script — parses with 10 items, every single-answer item exactly one correct). The reusable item-bank entries and the Canvas placement block are at the bottom of this file.

Blueprint

No trick questions; distractors target the Week 3 misconceptions named in the lecture outline (lipids "are polymers," DNA/RNA building blocks, dehydration vs. hydrolysis, protein-structure order).

Questions, key, and feedback

Q1 (MC). Which of the following is NOT one of the four classes of biological macromolecules?
- A. Carbohydrates
- B. Lipids
- C. Minerals ✅
- D. Nucleic acids
Feedback: The four macromolecule classes are carbohydrates, lipids, proteins, and nucleic acids. Minerals (like iron or calcium) are essential nutrients but are not one of the macromolecule families.

Q2 (MC). A cell joins two glucose monomers into a disaccharide, releasing one water molecule in the process. This bond-forming, water-removing reaction is called —
- A. hydrolysis
- B. dehydration synthesis (condensation) ✅
- C. denaturation
- D. diffusion
Feedback: Dehydration synthesis builds polymers by removing a water molecule as each new bond forms. "Build by removing water." (Hydrolysis is the reverse — it breaks bonds by adding water.)

Q3 (Multiple answer — select all that apply). Which of the following macromolecules are polymers built from repeating monomers?
- A. A carbohydrate such as starch (monomer: monosaccharide) ✅
- B. A triglyceride (fat)
- C. A protein (monomer: amino acid) ✅
- D. A nucleic acid such as DNA (monomer: nucleotide) ✅
- E. A steroid such as cholesterol
Feedback: Carbohydrates, proteins, and nucleic acids are polymers of repeating monomers (monosaccharides, amino acids, nucleotides). Lipids are NOT polymers — both a triglyceride (B) and a steroid (E) are lipids, assembled from parts rather than built from one repeating monomer.

Q4 (MC). When you digest a starchy food, your body breaks the polysaccharide back into individual sugars by adding a water molecule across each bond. This polymer-breaking reaction is —
- A. hydrolysis ✅
- B. dehydration synthesis
- C. photosynthesis
- D. protein folding
Feedback: Hydrolysis breaks polymers by adding water across each bond — literally "water (hydro) splitting (lysis)." Digestion is hydrolysis: it breaks food polymers into monomers small enough to absorb. (Dehydration synthesis is the opposite — it builds.)

Q5 (MC). Starch and cellulose are both polymers of the same monomer, glucose, yet starch is digestible stored energy and cellulose is indigestible structural fiber. The best explanation is that —
- A. starch contains glucose but cellulose does not
- B. the glucose units are linked differently, giving the two molecules different structures and therefore different functions ✅
- C. cellulose is actually a protein, not a carbohydrate
- D. starch is a lipid and so stores more energy
Feedback: Both molecules really are glucose, so the difference isn't the building block — it's the linkage between the glucose units. Different structure → different function: that's the week's central theme. (Our enzymes can break starch's bonds for energy but not cellulose's, so cellulose passes through as fiber.)

Q6 (Matching). Match each macromolecule class to its building block (monomer or basic unit).
| Class | Correct building block |
|---|---|
| Carbohydrate | Monosaccharide (e.g., glucose) |
| Protein | Amino acid |
| Nucleic acid | Nucleotide |
| Lipid (fat) | Glycerol + fatty acids (not a single repeating monomer) |
Feedback: Three classes have a single repeating monomer — carbohydrates (monosaccharides), proteins (amino acids), and nucleic acids (nucleotides). A lipid is the exception: a fat is a glycerol backbone with fatty acids attached, not a chain of one repeating unit.

Q7 (MC). Which statement about lipids is correct?
- A. Lipids are polymers built from many repeating fatty-acid monomers
- B. Lipids are polymers of amino acids
- C. Lipids are NOT polymers; a fat is a glycerol backbone with fatty acids attached ✅
- D. Lipids store and transmit genetic information
Feedback: Unlike the other three classes, lipids are not polymers. A triglyceride is glycerol + fatty acids, assembled — not a long chain of one repeating monomer. (Amino acids build proteins; genetic information is stored by nucleic acids.)

Q8 (True / False). "A protein's amino-acid sequence has little effect on its function, because the protein will fold into a working shape no matter what order the amino acids are in."
- True
- False ✅
Feedback: False. The sequence is the information. A protein's amino-acid order (its primary structure) determines how it folds, and the fold determines what it does. Changing one amino acid out of ~600 turns normal hemoglobin into sickle-cell hemoglobin — proof that the order matters enormously.

Q9 (Matching). Match each level of protein structure to its description. (Levels build up in the order primary → secondary → tertiary → quaternary.)
| Level | Correct description |
|---|---|
| Primary structure | The sequence (order) of amino acids in the chain |
| Secondary structure | Local folding into α-helices and β-pleated sheets, held by hydrogen bonds |
| Tertiary structure | The overall three-dimensional fold of the whole chain |
| Quaternary structure | Two or more folded chains assembled into one functional protein |
Feedback: Build it up in order: primary is the bare amino-acid sequence; secondary is local coils and pleats; tertiary is the whole chain's 3-D fold; quaternary is several folded chains clicking together (hemoglobin = 4 chains).

Q10 (MC). Which of the following correctly describes a difference between DNA and RNA?
- A. DNA uses the base uracil, while RNA uses thymine
- B. DNA is single-stranded, while RNA is double-stranded
- C. DNA uses the sugar deoxyribose, while RNA uses the sugar ribose ✅
- D. DNA carries no genetic information, while RNA stores the blueprint
Feedback: DNA = deoxyribose, thymine (T), double-stranded; RNA = ribose, uracil (U), usually single-stranded. Options A and B have those facts backwards (DNA has T not U, and DNA is the double-stranded one). DNA stores the genetic blueprint; RNA carries the message to build proteins.

Answer key (quick reference)

Quality gate (self-checked): each single-answer item has exactly one correct option; the multiple-answer item lists the three true polymers (A, C, D) and requires the two lipids (B, E) to be left unselected; the two matching items pair four stems to four distinct answers (class→monomer; structure level→description, in build-up order); no item asserts a fact outside the Week 3 course definitions. Week 3 is conceptual — there is no curriculum arithmetic in this quiz to mis-key (the quantitative pockets are Weeks 2, 4, 9–12, 14). Every key was vetted against the embedded definitions: lipids = not polymers; dehydration builds / hydrolysis breaks; protein levels = primary→secondary→tertiary→quaternary; DNA = deoxyribose/T/double, RNA = ribose/U/single.

Item-bank entries (for variants + the midterm/final)

All ten items are tagged course=BIOL101 · week=3 · objective=2 · topic=macromolecules and deposited in Item Bank: Week 3 — Biological Macromolecules. The final (Week 16) and the per-term variant updates draw fresh items from this bank. (Tags: q1 four-classes, q2 dehydration-synthesis, q3 which-are-polymers, q4 hydrolysis, q5 starch-vs-cellulose, q6 class-to-monomer-match, q7 lipids-not-polymers, q8 sequence-matters, q9 protein-structure-levels, q10 dna-vs-rna.)

Canvas placement block

canvas_object   = Quizzes::Quiz
title           = "Week 3 Quiz — Biological Macromolecules"
assignment_group = "Quizzes"
points_possible = 10
grading_type    = points
due_offset_days = 6        # 6 days after module start
published       = true
shuffle_answers = true
provenance      = "~ Prof. Castellano's edition · Fall 2026 · built with thecoursemaker.com"