Chapter 6: Anatomy of Flowering Plants

Solution coming soon.

i. Structural: In deciduous trees, an abscission zone, also known as a separation zone, is formed at the base of the petiole. It is composed of a top layer and bottom layer. The cells in the top layer have weak cell walls, and the bottom layer expands in winter and breaks the cell walls of the top layer, this results in the shedding of leaves.

ii. The loss of chlorophyll may also result in the abscission process.

iii. Hormonal: Abscisic acid hormone stimulates abscission.

Pinus does not shed its leaves during a particular season and is always evergreen. Hence, Pinus is considered as an evergreen tree belonging to gymnosperms. The leaves in gymnosperms can withstand in extreme temperatures, humidity and wind.

When any plane passing through the central axis of the plant cell divides the cell into two identical halves called radial symmetry

a. Plasmodesmata – A microscopic channel between two cells through the cell wall are called Plasmodesmata.

b. Middle lamella – It is a layer in the cell wall and is made of calcium pectate (mainly) and magnesium pectate.

c. Secondary wall – this is a non-extensible layer. It is made of hemicelluloses. It provides rigidity to the cell.

a. Exarch is a condition where the protoxylem is present towards the periphery and the metaxylem is present towards the centre. Endarch is where the protoxylem is present towards the centre and metaxylem is present towards the periphery

b. A stele is the central part of the root or stems whereas a vascular bundle is a part of stele.

c. Earlier formed xylem is called protoxylem and later formed xylem is called metaxylem

d. Interfascicular cambium is present in between the primary xylem and primary phloem, whereas intrafascicular cambium is present in between the two vascular bundles making the cambium continuous and forming a complete ring of cambium

e. Open vascular bundles are capable of secondary growth, whereas the closed vascular bundles are not capable of secondary growth

f. Stem hair is multicellular, and they are epidermal outgrowths known as trichomes, whereas root hair is unicellular, and they are unicellular elongations of epidermal cells.

Chapter 6, Anatomy of Flowering Plants, deals with different parts of a plant. The subject of Botany involves the close study of the science behind the parts of a plant. Plants are made of different groups of cells called tissues, which perform specific functions. The three categories of tissues are as follows:

• Secretory tissues
• Meristematic tissues
• Permanent tissues