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GATE 2024 BT Q.47: solution and answer

GATE 2024 · BTQ.47 · 2 marks · MSQ

Which of the following is/are considered as biotic elicitor(s) in plant cell culture?

  1. (A)

    Cellulase

  2. (B)

    Chitin

  3. (C)

    Chitosan

  4. (D)

    Mercuric chloride

See the question in the paper
GATE 2024 BT question 47Tap to open full size

Answer and solution

ANSWER

The biotic elicitors are (A) cellulase, (B) chitin and (C) chitosan.

Official answer: A, B, CSource: Official answer key, GATE 2024 BT (IISc Bengaluru)

  1. An elicitor is a compound that triggers a defence response in cultured plant cells and so raises secondary metabolite production. Biotic elicitors are of biological origin (fungal or bacterial cell wall components, enzymes, yeast extract, plant cell wall fragments). Abiotic elicitors are physical or chemical agents such as heavy metal salts.

  2. (A) Cellulase is an enzyme of fungal origin that breaks down plant cell wall cellulose. It is used as a biotic elicitor, and the wall fragments it releases also act as oligosaccharide elicitors. Correct.

  3. (B) Chitin is a fungal cell wall polymer. Chitin and its oligomers are classic biotic elicitors that plant receptors recognise. Correct.

  4. (C) Chitosan is deacetylated chitin, of fungal and crustacean origin. It is a widely used biotic elicitor in cell cultures. Correct.

  5. (D) Mercuric chloride is an inorganic heavy metal salt, which is an abiotic elicitor. Wrong.

  6. So the biotic elicitors are cellulase, chitin and chitosan: A, B and C.

KEY IDEA

Sort elicitors by origin. Anything from a living organism (fungal wall polymers such as chitin and chitosan, enzymes such as cellulase, pectinase, yeast extract) is biotic. Heavy metal salts and physical stresses are abiotic.

WATCH OUT FOR

Treating an enzyme such as cellulase as not an elicitor, or lumping chitosan with chemicals because it is a processed derivative. Chitosan and cellulase are of biological origin, so they are biotic. Only the heavy metal salt, mercuric chloride, is abiotic.

From the GATE 2024 BT paper. Every question of this paper · Download the full paper · All 8 Plant tissue culture questions, with notes

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