Anatomy of Flowering Plants Test - 78

Cedar was very important to the Egyptians. They used it for making boat. These boats were built of relatively short blocks of timber. It was very easy to reach the cities and towns by boat through Nile. It was cheap and quick. The necessary water power was provided by the current and the wind. People traveled through Nile with stone for projects or grain for the kings stores and merchants carried wares for sale. It was believed to be first used about 4000 B.C. and became Egypt's major exports. 
Thus, the correct answer is option B.

2-6 xylem and phloem i.e., vascular bundles are present in the dicotyledonous root. Monocot roots have more than 8 vascular bundles. 

Removal of ring bark of a tree from the trunk is called as ring barking. This leads to death of the plant. During ring barking, the vascular cambium, secondary phloem and periderm are removed. Due to this, tree is unable to synthesize more phloem. Thus, transport of organic food molecules produced by leaves is interrupted to the roots. Therefore, roots cannot function and eventually dies and in turn tree dies. 
Thus, the correct answer is option B.

Grafting is a technique whereby tissues from one plant are placed or inserted into another in such a way that the vascular tissues of both the plants may join together. The plant which is selected for its roots is called as the stock and the one selected for its stems and leaves and flowers is called as the scion. For successful grafts, the events that should take place is the production of the callus tissue between the cells of the stock and scion. 

Secondary growth is the type of growth which results from the cell division in cambia or lateral meristem and that causes the stem and roots to thicken.
Dracaena shows secondary thickening in their stem. 
Cucurbita shows secondary growth in stem and roots. 
Bambusa lack secondary growth. 
Thus, the correct answer is option C.

During secondary growth in dicot roots, phellogen or cork cambium produce periderm. The cork cambium produces cork or phellem towards the periphery. Secondary cortex (secondary phloem) is produced by the cambium and while periderm is developed by phellogen. Thus, the cork cambium produces phelloderm on inside and phellem or cork on outside. 
Thus, the correct answer is option A.

• The outermost layer of monocot root is rhizodermis/epidermis (B) which has compactly arranged tubular cells and unicellular root hair (A) as their extension. 
• Just beneath the epidermis are multiple layers of parenchymatous cells with ample intercellular space, it is the cortex (C). 
• The innermost layer of the cortex forms endodermis (D) which has compactly arranged barrel-shaped cells with casparian strips at their anticlinal wall. The uniseriate layer of thin-walled parenchymatous cells, present below endodermis, which are sclerified in old roots makes pericycle. 
• The vascular bundles are present as alternating strands of xylem and phloem, the discrete xylem strands (F) alternated with phloem strands (G). The central parenchymatous or sclerenchymatous cells form pith (E). 

A growth layer in secondary xylem seen in a cross section of a woody stem or branch. A tree ring is simply a layer of wood produced during one tree's growing season. Each tree ring marks a line between the dark late wood that grew at the end of the previous year and the relatively pale early wood that grew at the start of this year.
One annual ring is composed of a ring of early wood and a ring of late wood. The growth occurs in the cambium (the thin, continuous sheath of cells between bark and wood). In spring, the cambium begins dividing. This creates new tissue and increases the diameter of the tree at two places - 1. Outside the cambium. The outer cells become part of the phloem. The phloem carries food produced in the leaves to the branches, trunk, and roots. Some of the phloem dies each year and becomes part of the outer bark.
2. Inside the cambium. The inner cells become part of the xylem. These cells contribute most of a tree's growth in diameter. The xylem carries water and nutrients from the roots to the leaves. These cells show the most annual variation. When a tree grows quickly, the xylem cells are large with thin walls. This early wood or springwood is the lighter-colored part of a tree ring. In late summer, growth slows; the walls of the xylem cells are thicker. This late wood or summerwood is the darker-colored part of a tree ring. So, annual rings and growth rings are formed due to the fluctuations in the activity of cambium and not because of xylem and phloem. 
Therefore, the correct answer is option D.

C. Phellogen

Monocot stem vascular bundles are found irregularly scattered in the ground tissue.