Level 1 — RecognitionTranscription, Translation & Gene Expression

Transcription, Translation & Gene Expression

⏱ 20 minutes30 marksprintable — key stays hidden on paper

Level 1: Recognition (MCQ + Matching + True/False)

Time limit: 20 minutes Total marks: 30

Section A — Multiple Choice (1 mark each) — 10 marks

Choose the single best answer.

1. The central dogma of molecular biology describes the flow of genetic information as:

(a) Protein → RNA → DNA
(b) DNA → RNA → Protein
(c) RNA → DNA → Protein
(d) DNA → Protein → RNA

2. Which type of RNA carries amino acids to the ribosome?

(a) mRNA
(b) rRNA
(c) tRNA
(d) snRNA

3. The enzyme responsible for synthesising RNA from a DNA template is:

(a) DNA polymerase
(b) RNA polymerase
(c) Ligase
(d) Helicase

4. During RNA processing in eukaryotes, the segments removed from the pre-mRNA are called:

(a) Exons
(b) Codons
(c) Introns
(d) Anticodons

5. The 5′ cap and poly-A tail are added to eukaryotic mRNA in order to:

(a) Code for extra amino acids
(b) Protect the mRNA and aid stability/export
(c) Signal transcription termination on DNA
(d) Bind directly to tRNA

6. A region of DNA to which RNA polymerase binds to begin transcription is the:

(a) Terminator
(b) Operator
(c) Promoter
(d) Ribosome binding site

7. The genetic code is described as "degenerate" because:

(a) Some codons code for no amino acid
(b) Most amino acids are specified by more than one codon
(c) Codons overlap with each other
(d) The code differs completely between species

8. In the ribosome, the site where the growing polypeptide chain is held is the:

(a) A site
(b) P site
(c) E site
(d) T site

9. Translation always begins at the start codon, which is:

(a) UAA
(b) UAG
(c) AUG
(d) UGA

10. Alternative splicing allows a single gene to:

(a) Produce identical proteins each time
(b) Produce multiple different protein products
(c) Copy itself during replication
(d) Add amino acids after translation

Section B — Matching (1 mark each) — 8 marks

Match each term in Column X to its correct description in Column Y. Write the letter.

Column X		Column Y
11. mRNA		A. Structural + catalytic component of the ribosome
12. tRNA		B. Carries the coding message from DNA to ribosome
13. rRNA		C. Has an anticodon and carries a specific amino acid
14. Anticodon		D. Three-base sequence on tRNA that pairs with a codon
15. A site		E. Exit site where deacylated tRNA leaves the ribosome
16. E site		F. Aminoacyl site where incoming charged tRNA binds
17. Intron		G. Non-coding sequence removed during splicing
18. Exon		H. Coding sequence retained in mature mRNA

Section C — True/False WITH Justification (2 marks each) — 12 marks

State True or False (1 mark) and give a one-line justification (1 mark).

19. RNA polymerase requires a primer to begin transcription, just like DNA polymerase.

20. The codons UUU and UUC both code for the amino acid phenylalanine, illustrating degeneracy of the genetic code.

21. Introns are the parts of the pre-mRNA that are translated into protein.

22. Post-translational modification can occur only before the polypeptide leaves the ribosome.

23. During elongation of transcription, RNA polymerase reads the DNA template strand in the 3′→5′ direction while building RNA 5′→3′.

24. A stop codon such as UAA is recognised by a tRNA carrying a special "stop" amino acid.

Answer keyMark scheme & solutions

Section A — MCQ (1 mark each)

1. (b) DNA → RNA → Protein — the classic central dogma; transcription then translation. (1)

2. (c) tRNA — transfer RNA carries specific amino acids to the ribosome via its anticodon. (1)

3. (b) RNA polymerase — synthesises RNA using a DNA template; DNA polymerase makes DNA. (1)

4. (c) Introns — non-coding intervening sequences excised during splicing; exons are retained. (1)

5. (b) Protect mRNA and aid stability/export — cap and tail prevent degradation and assist nuclear export/ribosome recognition. (1)

6. (c) Promoter — the DNA region where RNA polymerase binds to initiate transcription. (1)

7. (b) Most amino acids are specified by more than one codon — multiple codons → same amino acid. (1)

8. (b) P site — peptidyl site holds the tRNA attached to the growing chain. (1)

9. (c) AUG — start codon, codes for methionine. (1)

10. (b) Produce multiple different proteins — different exon combinations yield different mRNAs. (1)

Section B — Matching (1 mark each)

Q	Answer	Reason
11. mRNA	B	Messenger carries DNA's message to ribosome
12. tRNA	C	Has anticodon, carries amino acid
13. rRNA	A	Ribosomal, structural + catalytic
14. Anticodon	D	3-base tRNA sequence pairing with codon
15. A site	F	Aminoacyl site — incoming charged tRNA
16. E site	E	Exit site — deacylated tRNA leaves
17. Intron	G	Non-coding, removed in splicing
18. Exon	H	Coding, retained in mature mRNA

Section C — True/False + Justification (2 marks each)

19. FALSE (1) — RNA polymerase can initiate synthesis de novo; it does not require a primer (unlike DNA polymerase). (1)

20. TRUE (1) — UUU and UUC both = Phe; two codons → one amino acid is exactly what degeneracy/redundancy means. (1)

21. FALSE (1) — Introns are removed during splicing and are not translated; exons are the coding parts. (1)

22. FALSE (1) — Post-translational modification (e.g. folding, cleavage, glycosylation, phosphorylation) occurs after the polypeptide is synthesised/released. (1)

23. TRUE (1) — Polymerase reads the template strand 3′→5′ and synthesises the new RNA in the 5′→3′ direction. (1)

24. FALSE (1) — Stop codons are recognised by release factors, not by a tRNA; there is no "stop amino acid." (1)

Total: 30 marks

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  {"claim":"Section A total marks = 10 (10 MCQs x 1)","code":"result = (10*1 == 10)"},
  {"claim":"Section B total marks = 8 (8 matches x 1)","code":"result = (8*1 == 8)"},
  {"claim":"Section C total marks = 12 (6 items x 2)","code":"result = (6*2 == 12)"},
  {"claim":"Paper total marks = 30","code":"a=10*1; b=8*1; c=6*2; result = (a+b+c == 30)"},
  {"claim":"Total question count is 24","code":"result = (10 + 8 + 6 == 24)"}
]