Anatomy of Flowering Plants Test - 49

A.Collateral vascular bundle – xylem and phloem present on the same radius.These are found in stems and leaves.

B.Radial vascular bundle – xylem and phloem are present on different radii. These are found in roots.

C.Bicollateral vascular bundle – two phloems are  present on either side of the xylem and all are present on the same radius. These are found in the stems of Cucurbitaceae and Solanacae members.

D.Concentric vascular bundles – vascular tissues surrounds with one another. These are found in ferns.

In the protoxylem of monocot vascular bundles, some of the protoxylem cells disintegrate and form into a lysigenous cavity called Protoxylem lacunae. It stores water, so it is also called water cavity.

A. Medulla – central part of the stele.

B. Stele – central part of the root and dicot stem, includes pericycle, vascular bundles, medulla, medullary rays or conjuctive tissue.

C. Cortex – middle part of the dicot stem and root, includes hypodermis, general cortex and endodermis.

D. Exodermis – outer part of mature monocot root.

A. Phelloderm – also called secondary cortex.

B. Phellem – also called cork.

C. Periderm – cork, cork cambium and secondary cortex together called periderm.

D. Phellogen – also called cork cambium.

A.Collateral vascular bundle – xylem and phloem present on the same radius.

B. Radial vascular bundle – xylem and phloem are present on different radii.

C. Bicollateral vascular bundle – two phloems are present on either side of the xylem and all are present on the same radius.

D. Concentric vascular bundles – vascular tissues surrounds with one another.

A.Polyarch – stele with many xylem strands, is found in monocot roots.

B.Monoarch – stele with one xylem strand, is found in Trapa.

C.Endarch – protoxylem is present towards the centre, and metaxylem is present towards the periphery, is found in dicot and monocot stems.

D.Exarch – protoxylem is towards the periphery, metaxylem is towards the centre, is found in dicot and monocot roots.

In dicot stem, endodermal cells are rich in starch grains. So it is also called endodermoid layer or starch sheath or starch layer.

A.Radial vascular bundles – present in roots.

B.Concentric vascular bundles – present in ferns.

C.Collateral vascular bundles – present in the stems and leaves.

D.Bicollateral vascular bundles – present in the stems of Cucurbitaceae and Solanaceae.

The layer with thick walled present around the vascular bundles is called Bundle sheath. It is sclerenchymatous in monocot stem vascular bundles, parenchymatous in dicot leaf and monocot leaf. It is absent in vascular bundles of dicot stem

So, the correct answer is ‘Dicot stem’

Secondary growth does not take place in monocotyledons, because of the absence of cambium between xylem and phloem in vascular bundles. These vascular bundles are called closed vascular bundles.