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GATE 2019 BT Q.28: solution and answer

GATE 2019 · BTQ.28 · 2 marks · MCQ

Match the organelles in Group I with their functions in Group II.

Group I:
P. Lysosome
Q. Smooth ER
R. Golgi apparatus
S. Nucleolus

Group II:
1. Digestion of foreign substances
2. Protein targeting
3. Lipid synthesis
4. Protein synthesis
5. rRNA synthesis

  1. (A)

    P-1, Q-3, R-2, S-5

  2. (B)

    P-1, Q-4, R-5, S-3

  3. (C)

    P-2, Q-5, R-3, S-4

  4. (D)

    P-1, Q-3, R-4, S-5

See the question in the paper
GATE 2019 BT question 28Tap to open full size

Answer and solution

ANSWER

The correct match is P-1, Q-3, R-2, S-5, which is option (A).

Official answer: ASource: Official answer key, GATE 2019 BT (IIT Madras)

  1. Lysosome (P) contains hydrolytic enzymes that digest foreign/phagocytosed material and worn-out cell components → matches function 1 (Digestion of foreign substances).

  2. Smooth ER (Q) lacks bound ribosomes and is the principal site of lipid and steroid synthesis; protein synthesis (via bound ribosomes) is a rough ER function, not smooth ER → matches function 3 (Lipid synthesis), ruling out function 4.

  3. Golgi apparatus (R) receives proteins made on the rough ER, chemically modifies them (e.g., glycosylation), and sorts/packages them into vesicles for delivery to their correct destinations — this is protein targeting, not protein synthesis → matches function 2 (Protein targeting), which rules out option (D)'s R-4 pairing.

  4. Nucleolus (S) is the site of rRNA synthesis/processing and ribosomal subunit assembly → matches function 5 (rRNA synthesis).

  5. Combining all four matches: P-1, Q-3, R-2, S-5, which is option (A).

  6. Checking the distractors confirms (A) is uniquely correct: (B) swaps Golgi and Smooth ER's roles with rRNA/lipid synthesis (both wrong); (C) mismatches every pair; (D) is correct for P, Q, and S but incorrectly assigns protein synthesis (4) instead of protein targeting (2) to the Golgi apparatus.

KEY IDEA

Each organelle has a defining, distinguishing biochemical role: lysosomes digest material via hydrolytic enzymes, smooth ER synthesizes lipids (rough ER, not smooth, is associated with protein synthesis via bound ribosomes), the Golgi apparatus modifies, sorts, and targets proteins to their destinations (it does not synthesize proteins itself), and the nucleolus is the site of rRNA synthesis and ribosome subunit assembly.

WATCH OUT FOR

Confusing Golgi apparatus's role (protein targeting/sorting/packaging) with protein synthesis (which occurs on ribosomes, often on rough ER) — this trap is embedded in option (D), which correctly matches P, Q, and S but wrongly assigns R-4 (protein synthesis) to the Golgi instead of R-2 (protein targeting).

From the GATE 2019 BT paper. Every question of this paper · Download the full paper · All 15 Cell biology questions, with notes

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