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 |
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
Closed vascular bundles lack:
1. Ground tissue
2. Conjuctive tissue
3. Cambium
4. Pith
What is true about cork cambium?
1. It is extrastelar cambium in dicot stem.
2. In dicot stem it arises from the cells of cortex region.
3. It is also known as phellogen.
4. All the above
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
What is incorrect for companion cell?
1. It is specialized parenchymatous cell.
2. It helps in maintaining the pressure gradient in the sieve tubes.
3. It does not retain nucleus throughout the life.
4. It is absent in gymnosperms
Which of the following characters is/are related to
isobilateral leaf?
(a) Stomata are present on both surfaces.
(b) Mesophyll is differentiated into palisade and
spongy parenchyma.
(c) Sub-stomatal cavity is present below the stoma of
the abaxial epidermis.
1. Only (a)
2. Only (c)
3. Only (a) and (c)
4. (a), (b) and (c)