Q33 / 200 · MHT CET - Medical 2026 (22 April Shift 2) · Biology
Tobacco plants produce flowers in the following conditions EXCEPT:
- ALong uninterrupted dark period.
- Correct answerBLong uninterrupted light period.
- CShort light period with uninterrupted long dark period.
- DA long dark period is interrupted by a flash of red light and immediately followed by a far-red light.
Solution
Tobacco is a short-day plant (SDP), which requires a continuous, uninterrupted dark period exceeding a critical duration to initiate flowering.
A long uninterrupted dark period or a short light period followed by a long uninterrupted dark period will induce flowering in tobacco.
If a long dark period is interrupted by a flash of red light, flowering is inhibited. However, if the red light is immediately followed by far-red light, the inhibitory effect is reversed, and the plant will flower.
A long uninterrupted light period implies a short dark period, which is less than the critical dark period required. Under this condition, a short-day plant like tobacco will not produce flowers.
Answer: Long uninterrupted light period.
A long uninterrupted dark period or a short light period followed by a long uninterrupted dark period will induce flowering in tobacco.
If a long dark period is interrupted by a flash of red light, flowering is inhibited. However, if the red light is immediately followed by far-red light, the inhibitory effect is reversed, and the plant will flower.
A long uninterrupted light period implies a short dark period, which is less than the critical dark period required. Under this condition, a short-day plant like tobacco will not produce flowers.
Answer: Long uninterrupted light period.
Hence, the correct answer is option: 'B'.