Anatomy of Flowering Plants Test - 51

The multilayered structure formed by extrastelar secondary growth in dicot stem is called Periderm. it is formed in the place of cortex. it is formed by the activity of a ring of meristamatic tissue formed by the dedifferentiation of parenchyma present in the cortex. It is called cork cambium or phellogen. It undergoes periclinal divisions, produces cells towards the outer side and innerside. The cells towards the outerside form into cork or phellem and the cells towards the innerside form into secondary cortex or phelloderm. Cork, cork cambium and secondary cortex together called Periderm.

So, the correct option is 'Phellem, Phellogen, and phelloderm.

a) Conjuctive present – applicable, because it is present between xylem and phloem.

b) Presence of protein compound in Casparian strips – not applicable, because, a lingo-suberised substance is present on the radial and tangential walls of the endodermis.

c) Polyarch xylem bundles – not applicable, because , in the stele of dicot root two to four xylem strands are present. So the stele is diarch to tetrarch.

d) Presence of pericycle – applicable – because, pericycle is outer most layer of the stele, and it is parenchymatous, take part in the production of lateral roots and vascular cambium.

The large sized, slightly raised sports or aerating pores present in the cork tissue are called Lenticels. These are found in old dicotyledonous stems. They many be oval, rounded or oblong in shape. They have outer raised margins and internally, loosely arranged colourless parenchyma cells are present, called as complementary cells, These are meant for gaseous exchange.

So, the correct answer is 'Lenticels'.

In dicotyledonous stems, during intra stellar secondary growth, intrafascicular cambium(primary meristem) and interfascicular cambium(secondary meristem) joins together and form into a ring of cambium is called vascular cambium. It is partly primary meristem and partly secondary meristem. Its activity is continuous and uninterrupted. It produces secondary vascular tissues(secondary xylem and secondary phloem) and ray parenchyma. 

Secondary vascular tissues, ray parenchyma, periderm are secondary tissues.

• The radial vascular bundle is a simple arrangement of the xylem and phloem which are separated by non-conductive tissues.
• These type of vascular bundles are present in dicot and monocot roots.
• When xylem and phloem are present in patches and occupy different radii it is called a radial vascular bundle.
• In this type of vascular bundle the xylem and phloem alternate each other (separated by non-conductive tissues).
• So, the correct answer is 'Alternate radii'.

The quiescent centre is the main part of the root-promeristems containing the initials of the epidermis. It also contains cortex and stele.

These cells can be divided as these are inactive and are present at the pole of the cortex and stele.

The cells with QC will have small dictyosomes, nuclei, with little cytoplasm.

These cells also have little endoplasmic reticulum, mitochondria and contain low concentrations of RNA, DNA, and protein then the other cells of the root apex.

So, the correct answer is option A.