This is the practice workbook for BCH 216 (Biochemistry II), the second-semester Molecular Biology paper for ABUAD 200 Level Pharmacy. Its job is simple: give you real questions to test yourself on, each with a worked answer that explains the reasoning, not just the final word.
If you want the topic-by-topic teaching notes first, read our companion BCH 216 Molecular Biology Study Guide, then come back here to check whether the concepts actually stuck. Work each question on your own before reading the answer. The 25 worked questions below are a representative sample spread across all nine topics of the course; the complete question bank with its full answer key is in the interactive reader at the foot of the page.
- Cover the answer, attempt the question in one or two full sentences, then compare.
- If you miss one, send yourself back to that topic in the study guide before moving on.
- Revisit the questions you got wrong a day or two later, not just once.
- These are original revision items, not past papers and not a prediction of any exam.
1. Nucleic Acid Chemistry
The fundamentals: what a nucleotide is made of, the sugar that separates DNA from RNA, and what happens when strands melt and re-pair.
Q. Which pentose sugars distinguish RNA from DNA?
Answer: RNA contains D-ribose; DNA contains 2-deoxy-D-ribose. Ribose carries an ,OH group on its 2' carbon; deoxyribose does not, which is what makes DNA the more chemically stable, long-term store of information.
Q. Which scientist established that the ratio of purines to pyrimidines in DNA is always 1:1?
Answer: Erwin Chargaff (Chargaff's rule). His finding that A pairs with T and G with C in a 1:1 ratio was a direct clue to the double-helix base-pairing model.
Q. When heat-denatured DNA strands are cooled and re-pair, what is the process called?
Answer: Annealing (re-association / re-naturation). Strands with higher GC content re-pair faster because each G,C pair has three hydrogen bonds rather than two.
Q. RNA molecules with catalytic activity are known as ___.
Answer: Ribozymes. Their existence shows RNA can act as both information carrier and catalyst, which supports the idea of an early RNA world.
2. Central Dogma & Protein Synthesis
Reading direction and the codon table are near-certain marks. Know which strand is the template and the exact start and stop codons.
Q. Which DNA strand is read as the pattern for building mRNA?
Answer: The template (antisense) strand. It is read 3' to 5' so that the mRNA is built 5' to 3'; the other strand is the coding (sense) strand and matches the mRNA sequence.
Q. Name the standard start codon and the three stop codons.
Answer: Start codon: AUG (codes for methionine). Stop codons: UGA, UAA, and UAG. AUG both starts translation and codes for methionine; the three stop codons carry no amino acid and instead signal release of the finished chain.
3. DNA Replication
Replication questions reward precise wording about semi-conservative copying and knowing which enzyme does which job.
Q. Replication is termed semiconservative. Explain what each daughter molecule contains.
Answer: Each daughter DNA keeps one original (parental) strand and one newly synthesized strand. This was shown by the Meselson,Stahl experiment; the parent strand acts as the template for the new one.
Q. Which enzyme adds new nucleotides to the growing DNA strand?
Answer: DNA polymerase. It works only 5' to 3', needs a primer to start, and proofreads as it goes to keep the error rate low.
Q. Contrast leading- and lagging-strand synthesis in one word each.
Answer: Leading strand: continuous; lagging strand: discontinuous. The lagging strand is copied as short Okazaki fragments because synthesis can only run 5' to 3' while the fork opens the other way.
4. Heme Degradation
Follow the pathway as a sequence and know the products of ring cleavage, the pigments that end up in stool and urine, and the clinical sign when bilirubin builds up.
Q. List the products released when heme oxygenase cleaves the heme ring.
Answer: Biliverdin, carbon monoxide (CO), and ferrous iron, Fe(II). Note that this pathway is the body's main natural source of carbon monoxide.
Q. Name the gut-derived pigments produced from bilirubin in stool and urine.
Answer: Stercobilin (faeces) and urobilin (urine). Both come from bilirubin after gut bacteria act on it; stercobilin gives faeces their brown colour.
Q. Accumulation of bilirubin in tissues produces which clinical sign?
Answer: Jaundice. Yellowing of the skin and the whites of the eyes; distinguishing unconjugated from conjugated bilirubin points to whether the cause is pre-hepatic, hepatic or post-hepatic.
5. Xenobiotic Metabolism
The cytochrome P450 naming detail, the make-up of glutathione and the paracetamol antidote are classic earners here.
Q. Cytochrome P450 is named for the wavelength of its CO-bound absorption peak. State both.
Answer: It absorbs maximally at 450 nm when bound to carbon monoxide (CO). The 450 nm peak when bound to CO is where the 'P450' name comes from.
Q. Name the tripeptide glutathione's three constituent amino acids.
Answer: Gamma-glutamic acid, cysteine, and glycine. Its cysteine ,SH group is the reactive part that mops up reactive metabolites and electrophiles.
Q. Which antidote is used to treat acetaminophen (paracetamol) overdose?
Answer: N-acetylcysteine. It works by replenishing glutathione, which conjugates the toxic metabolite of paracetamol before it can damage the liver.
Q. Name the major P450 isoform responsible for metabolizing most clinical drugs.
Answer: CYP3A4. CYP3A4 metabolises more than half of clinically used drugs, which is why so many drug interactions run through it.
6. Biochemistry of Hormones
Tie receptor location to hormone solubility, and keep the endocrine versus exocrine distinction clean.
Q. To what cellular structure do water-soluble peptide hormones bind, and what does this trigger?
Answer: Receptor molecules in the cell membrane, triggering production of a second messenger. The membrane receptor triggers a second messenger such as cAMP, giving a fast but short-lived response.
Q. Glands that secrete hormones directly into the blood are termed ___; those using ducts are ___.
Answer: Endocrine glands; exocrine glands. Endocrine glands release hormones straight into the blood; exocrine glands use ducts to reach a surface or cavity.
7. Genetics & Heredity
Vocabulary marks: ploidy, chromosome numbers and the language of alleles.
Q. How many chromosome sets are in a haploid cell, and how many chromosomes in a human haploid cell?
Answer: One (1) set; 23 chromosomes in humans. A human haploid gamete has 23 chromosomes; fertilisation restores the diploid number of 46.
Q. Alternative forms of the same gene are known as ___.
Answer: Alleles. Different alleles at the same locus are what produce variation in a trait between individuals.
8. DNA Repair & Mutations
A topic the summaries barely touch, so it rewards drilling: what agents damage DNA and which disorder follows a repair defect.
Q. What is the general term for agents that cause changes in DNA base sequence?
Answer: Mutagens. All carcinogens are mutagens, but not every mutagen is a carcinogen.
Q. Which inherited disorder results from defective nucleotide excision repair?
Answer: Xeroderma pigmentosum (XP). People with XP cannot repair UV-induced dimers, so they are extremely sensitive to sunlight and prone to skin cancer.
9. Recombinant DNA Technology
Match each lab tool to its exact function, and know how DNA is pushed into a cell and why PCR uses a heat-stable polymerase.
Q. Which enzymes cut DNA at specific sequences, enabling cloning?
Answer: Restriction endonucleases (nucleases). Each enzyme cuts at its own specific recognition sequence, leaving sticky or blunt ends that let a gene and a vector be joined.
Q. Name the technique that uses an electric pulse to introduce DNA into cells.
Answer: Electroporation. A brief electric pulse makes the membrane transiently permeable so DNA can enter the cell.
Q. Which heat-stable polymerase makes PCR practical, and from what organism?
Answer: Taq polymerase, from Thermus aquaticus. Taq comes from Thermus aquaticus, a hot-spring bacterium, so it survives the repeated near-boiling denaturation steps.
How to Study BCH 216 Effectively
- Test before you re-read. Attempting a question first shows you what you actually know; re-reading notes only hides the gaps.
- Group your errors by topic. Three misses in Xenobiotic Metabolism means an afternoon on Phase I and Phase II, not another full pass of the whole syllabus.
- Say answers out loud in full sentences. Marks come from stated reasoning, not one-word recall.
- Space your practice. Redo the questions you missed a day or two later so the recall lasts until the exam.
- Pair this with the study guide: read a topic there, then answer every workbook question on it before moving to the next.
Work Through the Full Question Bank
The interactive reader below holds the complete BCH 216 practice set with its full worked answer key, grouped by the same nine topics used above. Page through it on screen or save the PDF to revise offline before your exam.
Need the concepts explained first? Our BCH 216 Molecular Biology Study Guide walks through every topic step by step with tables and worked examples.
Frequently Asked Questions
Is this BCH 216 workbook free?
Yes. Every resource on EverythingABUAD is free for ABUAD students, with no sign-up and no paywall.
How is this different from the study guide?
The study guide teaches each topic in prose with tables and examples. This workbook is for active recall: questions first, worked answers second, so you find out what you have actually learned.
Will these exact questions appear in my exam?
No. Every question was written from scratch for revision practice. None of it is taken from a real BCH 216 paper or meant to predict one.
About this resource: All questions, explanations and worked answers on this page were written, paraphrased, and adapted by the EverythingABUAD student team to support exam revision. This is an original study aid, not an official ABUAD document, and it is not a prediction of any future exam.
Written by the Everything ABUAD Team
Current students at Afe Babalola University, Ado-Ekiti. Guides are checked against the official ABUAD portal and campus notices, and confirmed with department and course reps before publishing.
