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Biomolecules question

2023 · 25 Jan · Shift 1 · Q4
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Biomolecules question

2023 · 25 Jan · Shift 1 · Q4

JEE MainChemistryBiomoleculesMCQ+4 / −1
Match items of Row I with those of Row II. Row I : JEE Main 2023 (Online) 25th January Morning Shift Chemistry - Biomolecules Question 56 English Row II : (i) α\alphaα-D\mathrm{D}D-(−)(-)(−)-Fructofuranose\mathrm{Fructofuranose}Fructofuranose(ii) β\betaβ-D-(−)(-)(−)-Fructofuranose (iii) α\alphaα-D-(−)(-)(−) Glucopyranose (iv) β\betaβ-D-(−)(-)(−)-Glucopyranose Correct match is
  1. A
    A →\to→ iii, B →\to→ iv, C →\to→ i, D →\to→ ii
  2. B
    A →\to→ iv, B →\to→ iii, C →\to→ i, D →\to→ ii
  3. C
    A →\to→ i, B →\to→ ii, C →\to→ iii, D →\to→ iv
  4. D
    A →\to→ iii, B →\to→ iv, C →\to→ ii, D →\to→ i
View written solutionFree

Correct answer: A

To solve this matching question, we identify the Haworth projection features of each sugar form.

1. Key rule for α\alphaα and β\betaβ forms

For D-sugars in Haworth form:

  • The terminal CH2OH\mathrm{CH_2OH}CH2​OH group is generally up.
  • α\alphaα-anomer: anomeric OH\mathrm{OH}OH is down.
  • β\betaβ-anomer: anomeric OH\mathrm{OH}OH is up.

2. Identify anomeric carbon

  • In glucose (an aldose), the anomeric carbon is C-1.
  • In fructose (a ketose), the anomeric carbon is C-2.

3. Distinguish pyranose and furanose

  • Glucopyranose has a six-membered ring.
  • Fructofuranose has a five-membered ring.

So:

  • Structures with 5-membered ring correspond to fructofuranose.
  • Structures with 6-membered ring correspond to glucopyranose.

4. Match the four entries

Given Row I:

  1. α\alphaα-D-(−)(-)(−)-Fructofuranose
  2. β\betaβ-D-(−)(-)(−)-Fructofuranose
  3. α\alphaα-D-(−)(-)(−)-Glucopyranose
  4. β\betaβ-D-(−)(-)(−)-Glucopyranose

Now using the standard Haworth criteria:

  • A must be α\alphaα-D-glucopyranose ⇒\Rightarrow⇒ iii
  • B must be β\betaβ-D-glucopyranose ⇒\Rightarrow⇒ iv
  • C must be α\alphaα-D-fructofuranose ⇒\Rightarrow⇒ i
  • D must be β\betaβ-D-fructofuranose ⇒\Rightarrow⇒ ii

Thus the correct matching is: A→iii,B→iv,C→i,D→iiA \to iii,\quad B \to iv,\quad C \to i,\quad D \to iiA→iii,B→iv,C→i,D→ii

5. Compare with options

This corresponds to Option A.

6. Verification with stored answer

Stored correct answer = A

Our derived answer = A

Hence, they agree.

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