Anatomy of Flowering Plants Test - 84

Correct Answer-B

The epidermis, primary xylem, primary phloem, pith and cortex are all produced by the apical meristem. The apical meristem after mitosis gives rise to three meristems. The secondary layer, which is made up of procambium gives rise to the primary xylem and primary phloem.

During secondary growth, intra and interfascicular cambia join together and form into a ring of cambium called vascular cambium. The cells in the vascular cambium undergo periclinal divisions and undergo elongation radially, produces secondary vascular tissues and ray parenchyma. It leads to an increase in girth of the stem.

So, the correct answer is ‘Periclinal divisions and radial elongation of cambial cells’.

Periderm is the secondary protective layer that occurs during the growth and is called the secondary growth. This is a multi-layered structure that contains cork called the phellem, the phellogen a single layer that surrounds the stem and persistent living cells called the phelloderm.

The small strip of cambium formed between the vascular bundles in dicot stem is called interfascicular cambium. It is formed by the dedifferentiation of parenchyma present in the medullary rays.

So, the correct option is ‘Between vascular bundles’.

• Casuarina is a genus of oak tree species belonging to the family Casuarinaceae.

• All the cells in the structure of roots can be traced back to few apical cells which are called initials.

• In Casuarina, only two rows of initials are observed at the root apex. 

• One of the layers gives rise to the stele and the other to the cortex and root cap.

• So, the correct answer is 'Two'.

When cell division occurs at the right angle to the length of a cell, it is called as anticlinal division. When cell division occurs parallel to the length of the cell, then it is called as periclinal division. It results in the increase of the cell numbers as well as the cell rows around that organ. This type of cell division is observed in tunica region of shoot apex.

A. Radial – xylem and phloem are present on separate radii, in the vascular bundles.

B. Conjoint – xylem and phloem are present side by side, in the vascular bundles.

C. Collateral – xylem and phloem are present on the same radius, in the vascular bundles.

D.Bicollateral   – a xylem is present in between the two phloems, and all three are on the same radius in the vascular bundles.

So, the correct option is ‘Collateral’.

In the vascular bundles of Cucurbita stems, a xylem strand and two phloem strands are present on the same radius. So the vascular bundles are called Bicollateral vascular bundles. In these bundles, two strips of cambiua are present in between the xylem and phloem.

So, the correct option is ‘ 2’.