Tag: internal structure of dicot leaf
Questions Related to internal structure of dicot leaf
Match the columns.
| A) | Syntheticauxin | i) | Zeatin |
|---|---|---|---|
| B) | Natural cytokinin from coconut milk | ii) | IBA |
| C) | naturalauxin | iii) | Kinetin |
| D) | purine from herring sperm DNA | iv) | NAA |
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$A-iv,B-i,C-ii,D-iii$
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$A-ii,B-i,C-iv,D-iii$
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$A-iv,B-iii,C-ii,D-i$
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$A-ii,B-iii,C-iv,D-i$
One of the following is absent in the phloem of mostly monocots.
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Sieve tubes
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Phloem parenchyma
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Companion cells
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Phloem fibres
Mark out the incorrect statements.
A) Bulliform cells are found on adaxial epidermis of grasses.
B) All vascular bundles have different size in leaf showing parallel venation.
C) Endodermis, pericycle, vascular bundle and pith constitute the stele.
D) Bastfibresare absent in primary phloem.
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B only
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D only
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A & B only
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B & C only
Generally, the patterns of the leaf veins, or vascular bundles are pinnate and the veins are free; that is, they all diverge and never coalesce, either along their sides or at the ends. So, the incorrect statement is all vascular bundles have different size in leaf showing parallel venation.
Dorsiventral leaf is identified by the presence of
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Stomata on both the epidermis
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Stomata mainly present on the lower epidermis
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No stomata on the epidermis
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Sunken stomata on the upper epidermis
In dorsiventral leaf, epidermis is in two layers, one on each surface of the leaf. Both the layers are composed of compactly arranged, barrel-shaped cells. Intercellular spaces are absent. A cuticle surrounds both the layers. Multicellular hairs called as trichomes are present on both the layers. Stomata occur only in the lower epidermis. This condition is described as hypostomatic.
Bulliform or motor cells occur in
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Upper epidermis of dicot leaves
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Upper epidermis of monocot leaves
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Lower epidermis of monocot leaves
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Lower epidermis of dicot leaves
Bulliform cells or motor cells are large, bubble shaped epidermal cells that occur in groups on the upper surface of the leaves of many grasses. Loss of turgor pressure in these cells causes leaves to roll up during water stress. During drought, the loss of moisture through vacuoles induces bulliform cells to cause the leaves of many grass species to close as the two edges of the grass blade fold up toward each other. Once, adequate water is available, these cells enlarge and the leaves open again. Bulliform cells are absent in dicot leaves.
Thus, the correct answer is option B.
In isobilateral leaves
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Lower surface is brighter green
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Upper surface is lighter green
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Both the surfaces are equally green
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Upper surface is dark green while the lower surface is lighter green
Leaves, in which both sides appear in equally green color are called isobilateral leaves. It is due to the presence of spongy parenchyma.
So, the correct option is ‘both the surface are equally green’.
Many grass leaves are capable of folding and unfolding due to
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Parallel veins
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Isobilateral nature
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Thin lamina
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Bulliform cells
Many grass leaves, folds during drought conditions and unfolds during moisturized conditions. It is due to the presence of large, thin-walled cells present on the adaxial side of the upper epidermis, called Bulliform cells.
So, the correct option is ‘Bulliform cells’.
Ligule occurs on the leaf of
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Barley
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Oat
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Rice
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All of the above
The ligule is a part of the leaf that is found at the junction of the leaf blade and sheath of the leaf. It may take several forms. But commonly, it is a translucent membrane or a fringe of hairs. It is seen in plants belonging to the family Poaceae. Hence, ligule occurs on the leaf of Barley, Oat and Rice.
Leaves of many grasses are capable of folding and unfolding because they
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Are very thin
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Are isobilateral
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Have specialised bulliform cells
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Have parallel vascular bundles
Grasses have monocot leaves. Leaves of grasses have specialized bulliform cells on the upper epidermis. These bulliform cells are capable of folding and unfolding of leaves to help in the process of transpiration.
Monocot leaves possess
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Intercalarly meristem
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Lateral meristem
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Apical meristem
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Mass meristem
- The shoots can be categorized as long shoots and short shoots (on the basis of the distance between two nodes).
- Internode is the length of the stem between two nodes.
- The variable length of internodes in culm of sugarcane is mainly due to the presence of intercalary meristem (residual apical meristem).
- An intercalary meristem is the meristems present at the base of the internodes of stem or leaf.
- It helps in the elongation and growth of the plants at the nodes and internodes (stems and leaves).
- In monocots such as in grasses it enables longitudinal growth of the leaves and in hollow stem or culm of bamboo and sugarcane, it helps in increasing the length of the stems.
- So, the correct answer is 'Intercalary meristem'.