The annular and spirally thickened conducting elements generally develop in the protoxylem when the root or stem is:
1. maturing
2. elongating
3. widening
4. differentiating
1. shoot apical meristem
2. position of axillary buds
3. size of leaf lamina at the node below each internode
4. intercalary meristem
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. all tissues except epidermis and vascular bundles
2. epidermis and cortex
3. all tissues internal to endodermis
4. all tissues external to endodermis
Gymnosperms are also called softwood spermatophytes because they lack:
1. Cambium
2. Phloem fibres
3. Thick-walled tracheids
4. Xylem fibres
Tracheids differ from the tracheary elements in:
1. Having casparian strips
2. Being imperforate
3. Lacking nucleus
4. Being lignified
Read the different components from I to IV in the list given below and tell the correct order of the components with reference to their arrangement from the outer side to the inner side in a woody dicot stem.
I. | Secondary Cortex |
II. | Wood |
III. | Secondary phloem |
IV. | Phellem |
The correct order is:
1. | III, IV, II, I | 2. | I, II, IV, III |
3. | IV, I, III, II | 4. | IV, III, I, II |