Question:
When tissue culture medium contains both auxin and kinetin in the ratio of 10:1, the pith cells of tobacco grow and form callus. Further,
Statement I: If the ratio of auxin to cytokinin is less in the medium, a number of roots are initiated from callus
Statement II: If the ratio is more (less cytokinin than auxin), a number of shoot buds are initiated.
In light of the above statements, choose the most appropriate answer from the options given below:
When tissue culture medium contains both auxin and kinetin in the ratio of 10:1, the pith cells of tobacco grow and form callus. Further,
Statement I: If the ratio of auxin to cytokinin is less in the medium, a number of roots are initiated from callus
Statement II: If the ratio is more (less cytokinin than auxin), a number of shoot buds are initiated.
In light of the above statements, choose the most appropriate answer from the options given below:
Statement I: If the ratio of auxin to cytokinin is less in the medium, a number of roots are initiated from callus
Statement II: If the ratio is more (less cytokinin than auxin), a number of shoot buds are initiated.
In light of the above statements, choose the most appropriate answer from the options given below:
Show Hint
Mnemonic: Auxin = Anchorage (Roots). Cytokinin = Canopy (Shoots). High A/C ratio = Roots; Low A/C ratio = Shoots.
Updated On: Aug 21, 2026
- Both Statement I and Statement II are correct
- Both Statement I and Statement II are incorrect
- Statement I is correct but Statement II is incorrect
- Statement I is incorrect but Statement II is correct
Show Solution
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The Correct Option is B
Solution and Explanation
Step 1: Understanding the Concept:
The interaction between Auxins and Cytokinins is the fundamental principle of hormonal control of plant morphogenesis (organogenesis). This was classically demonstrated by Skoog and Miller (1957) using tobacco pith tissue. The Auxin/Cytokinin ratio determines whether a tissue will remain as an undifferentiated callus or develop roots or shoots.
Step 2: Detailed Explanation:
According to the Skoog-Miller hypothesis:
1. Equal/Intermediate Ratio: Leads to the formation of an undifferentiated callus.
2. High Auxin to Cytokinin Ratio: (i.e., more auxin than cytokinin). This condition favors Rooting (Rhizogenesis).
3. Low Auxin to Cytokinin Ratio: (i.e., more cytokinin than auxin). This condition favors Shooting (Caulogenesis).
Evaluation of Statements:
- Statement I: "Ratio of auxin to cytokinin is less" (High CK). The statement says roots are initiated. This is incorrect; high CK favors shoots.
- Statement II: "Ratio is more" (High Auxin). The statement says shoot buds are initiated. This is incorrect; high Auxin favors roots.
Since both statements swap the physiological outcomes of the hormonal ratios, they are both incorrect.
Step 3: Final Answer:
Both Statement I and Statement II are incorrect.
The interaction between Auxins and Cytokinins is the fundamental principle of hormonal control of plant morphogenesis (organogenesis). This was classically demonstrated by Skoog and Miller (1957) using tobacco pith tissue. The Auxin/Cytokinin ratio determines whether a tissue will remain as an undifferentiated callus or develop roots or shoots.
Step 2: Detailed Explanation:
According to the Skoog-Miller hypothesis:
1. Equal/Intermediate Ratio: Leads to the formation of an undifferentiated callus.
2. High Auxin to Cytokinin Ratio: (i.e., more auxin than cytokinin). This condition favors Rooting (Rhizogenesis).
3. Low Auxin to Cytokinin Ratio: (i.e., more cytokinin than auxin). This condition favors Shooting (Caulogenesis).
Evaluation of Statements:
- Statement I: "Ratio of auxin to cytokinin is less" (High CK). The statement says roots are initiated. This is incorrect; high CK favors shoots.
- Statement II: "Ratio is more" (High Auxin). The statement says shoot buds are initiated. This is incorrect; high Auxin favors roots.
Since both statements swap the physiological outcomes of the hormonal ratios, they are both incorrect.
Step 3: Final Answer:
Both Statement I and Statement II are incorrect.
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