Q. No.Grass leaves curl inwards during very dry weather. Select the most appropriate reason from the following :
1. Tyloses in vessels
2. Closure of stomata
3. Flaccidity of bulliform cells
4. Shrinkage of air spaces in spongy mesophyll
Phloem in gymnosperms lacks:
1. Both sieve tubes and companion cells
2. Albuminous cells and sieve cells
3. Sieve tubes only
4. Companion cells only
Which of the statements given below is not true about the formation of Annual Rings in trees?
| 1. | Annual rings are not prominent in trees of temperate regions. |
| 2. | Annual rings are a combination of spring wood and autumn wood produced in a year. |
| 3. | Differential activity of cambium causes light and dark bands of tissue - early and late wood respectively. |
| 4. | Activity of cambium depends upon variation in climate. |
1. bast fibers
2. sieve tubes
3. companion cells
4. sieve cells
1. Ventral meristem
2. secondary meristem
3. Primary meristem
4. All of these
1. Cucurbita
2. Salvia
3. Calotropis
4. None of these
1. Epidermal extensions
2. Hypodermis
3. Endodermis
4. Epidermal appendages
1. Stomata
2. Hydathode
3. Guard cell
4. None of these
In the sieve elements, which one of the following is the most likely function of P-proteins?
1. Depletion of callose on sieve plates
2. Providing energy for active translocation
3. Autolytic enzymes
4. Sealing off mechanism on wounding
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