Question

In the diagram of the cross-section of the vascular bundle of monocot stem given aside, different parts have been indicated by alphabets; choose the answer in which these alphabets have been correctly matched with the parts which they indicate.

• A. A - Bundle sheath, B - Broken phloem, C - Metaphloem, D - Metaxylem, E - Protoxylem, F - Xylem parenchyma, G - Lysigenous cavity
• B. A - Bundle cap, B - Metaphloem, C - Protophloem, D - Protoxylem, E - Metaxylem, F - Lysigenous cavity, G - Xylem parenchyma
• C. A - Bundle sheath, B - Primary phloem, C - Secondary phloem, D - Primary xylem, E - Secondary xylem, F - Xylem fibres, G - Hydathode
• D. A - Bundle cap, B - Metaxylem, C - Metaphloem, D - Protoxylem, E - Protophloem, F - Lysigenous cavity, G - Xylem parenchyma

Answer 1

The correct option is A A - Bundle sheath, B - Broken phloem, C - Metaphloem, D - Metaxylem, E - Protoxylem, F - Xylem parenchyma, G - Lysigenous cavity

Monocot stem is characterized by presence of collateral, closed scattered vascular bundles with well developed sclerenchymatous sheath outside and no pith at the center. The sheath is termed as bundle sheath.

The vascular bundles of monocot stem have xylem towards centre and phloem towards periphery. The phloem has sieve tubes and companion cells. The broken protophloem is present towards bundle sheath and metaphloem is present towards the center.

Phloem parenchyma is absent. The xylem formed first is present near the center and is termed as protoxylem, while metaxylemis present towards the periphery.

The xylem is made up of two types of cells vessels and parenchyma.

Lysigenous cavities are present on outer side of protoxylem, which are the result of crushed outer protoxylem.