Tag: internal structure of stem(dicot and monocot)
Questions Related to internal structure of stem(dicot and monocot)
Cortex and pith remain indistinguishable in
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Monocot stem
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Monocot root
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Periderm
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Dicot stem
Cortex and pith remain indistinguishable in a monocot stem. The epidermis is a layer of cells that cover the plant body, including the stems, leaves, flowers and fruits, that protects the plant from the outside world. In old stems the epidermal layer, cortex and primary phloem become separated from the inner tissues by thicker formations of cork. But in the monocots the cortex and pith are indistinguishable.
Therefore, the correct answer is option A.
Identify the incorrect statement with respect to monocot stem.
(a) Hypodermis is made up of sclerenchyma
(b) Ground tissue is differentiated
(c) Vascular bundles which are situated towards the centre are larger in size and less in number
(d) Each vascular bundle is conjoint, collateral and closed and xylem is endarch.
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a, b and c
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b, c and d
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only b
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b and c
Monocot stem are characterized by
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Conjoint collateral and open vascular bundle
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Conjoint collateral and closed vascular bundle
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Radial
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None of the above
Anatomy of the monocot stem shows that while the vascular bundles are oval in shape, numerous and scattered, it is by nature, conjoint, collateral, closed and endarch without any lysigenous activity.
What is present around a vascular bundle of a monocot stem?
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Pericycle
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Endodermis
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Pericycle & endodermis both
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Bundle sheath
Lysigenous cavity and Y-shaped xylem occurs in
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Dicot stem
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Monocot root
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Monocot stem
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Dicot root
Lysigenous intercellular spaces is type of intercellular space arises through dissolution of entire cells, which are therefore called as lysigenous cavity. These cavities of intercellular spaces store up water, gases and essential oils in them. The examples are commonly found in water plants and many monocotyledonous stems. The secretory cavities in Eucalyptus, Citrus and Gossypium are good examples. In monocot stem the vascular bundle encloses both xylem and phloem. Xylem is found towards the inner surface and phloem towards the outer surface. Cambium is absent. Hence, the vascular bundles are described as conjoint, collateral and closed. In the xylem, there are two metaxylem and two protoxylem vessels arranged in the shape of Y.
Which type of vascular bundles are found in monocot stem?
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Collateral, open, endarch
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Radial, open, diarch
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Radial, open, mesarch
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Collateral, closed, endarch
Monocot stem vascular bundles are found irregularly scattered in the ground tissue. Towards the periphery, the bundles are smaller in size while towards the centre, they are larger in size. The smaller bundles are younger, while the larger ones are older. Hence, the arrangement is described as centrifugal.
Hard bast (bundle cap) occurs in
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Sunflower stem
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Wheat stem
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Sunflower root
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Both of (A) and (C)
Hard bast is the patch of sclerenchyma present on outside of each vascular bundle, thereby forming a bundle cap over each bundle. They serve to provide additional mechanical support to the stem and are present in Sunflower stem. Wheat stem represent a monocot stem in which each vascular bundle is surrounded by thick walled bundle sheath, they do not have hard bust. Root is marked by presence of primary xylem and phloem in different radii, separated from each other.
Therefore, the correct answer is option A.
Which type of vascular bundles are found in monocot stem?
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Collateral, open, endarch
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Radial, open, diarch
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Radial, open, mesarch
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Collateral, closed, endarch
Monocot stem vascular bundles are found irregularly scattered in the ground tissue. Towards the periphery, the bundles are smaller in size while towards the centre, they are larger in size. The smaller bundles are younger, while the larger ones are older. Hence, the arrangement is described as centrifugal or endarch.
In monocot stems, secondary growth cannot occur, because vascular bundles are
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Scattered
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Open
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Closed
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Radial
Secondary growth refers to the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips of stems and roots, causing them to elongate and gives rise to primary tissue.
What is the characteristics of a vascular bundle of monocot stem?
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Open and surrounded by a sclerenchymatous bundle sheath
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Closed and not surrounded by bundle sheath
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Closed and surrounded by bundle sheath
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Open and not surrounded by a bundle sheath
In a monocot stem the vascular bundles are not arranged in a circle but are usually scattered throughout the ground tissue. There is no clearly defined pith as there is in many dicotyledonous species.