Secondary xylem and phloem in dicot stem are produced by?
1. | Apical meristems | 2. | Vascular cambium |
3. | Phellogen | 4. | Axillary meristems |
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 |
Vascular bundles in monocotyledons are considered closed because:
1. | a bundle sheath surrounds each bundle |
2. | cambium is absent |
3. | there are no vessels with perforations |
4. | xylem is surrounded all around by phloem |
Age of a tree can be estimated by:
1. biomass
2. number of annual rings
3. diameter of its heartwood
4. its height and girth
Closed vascular bundles lack:
1. Ground tissue
2. Conjuctive tissue
3. Cambium
4. Pith
Which one of the following is not a lateral meristem?
1. Intrafascicular cambium
2. Interfascicular cambium
3. Phellogen
4. Intercalary meristem
Heartwood differs from sapwood in:
1. presence of rays and fibres
2. absence of vessels and parenchyma
3. having dead and non-conducting elements
4. being susceptible to pests and pathogens
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