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 |
Closed vascular bundles lack:
1. Ground tissue
2. Conjuctive tissue
3. Cambium
4. Pith
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
Mechanical support to the growing parts of the plant such as young stem and petiole of leaf is provided by a living tissue called
| 1. | Collenchyma | 2. | Aerenchyma |
| 3. | Chlorenchyma | 4. | Sclerenchyma |
| 1. | subsidiary cells | 2. | bulliform cells |
| 3. | lenticels | 4. | complementary cells |
| 1. | Dumb-bell shaped | 2. | Kidney shaped |
| 3. | Rectangular | 4. | Barrel-shaped |
Cortex is the region found between:
1. epidermis and stele
2. pericycle and endodermis
3. endodermis and pith
4. endodermis and vascular bundle
Read the following statements with respect to pericycle and choose the suitable option
| (a) | It is the outermost portion of stele, that may be paranchymatous or sclerenchymatous. |
| (b) | It is absent in monocot stems. |
| (c) | It is always single layered. |
| 1. | Only (a) is correct |
| 2. | Only (b) is incorrect |
| 3. | Only (c) is incorrect |
| 4. | Both (a) & (b) are incorrect |
Read the following statements about dicot stem and
choose the correct option.
| (a) | Vascular bundles are arranged in a ring. |
| (b) | Vascular bundles are conjoint, collateral and open type. |
| (c) | Endarch type of arrangement of secondary xylem. |
| 1. | Only (b) is correct |
| 2. | Only (c) is incorrect |
| 3. | Both (a) and (b) are incorrect |
| 4. | All three statements are correct |