JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Pharmacy I REMEDIAL BIOLOGY Previous Question Paper (June-2022 - R17)

The kingdom Monera consists of unicellular, prokaryotic organisms, primarily bacteria. Their salient features include:

• Cellular Organization: They are unicellular and lack a well-defined nucleus and membrane-bound organelles like mitochondria or chloroplasts.
• Genetic Material: The DNA is naked, circular, and localized in a region called the nucleoid. They often contain extra-chromosomal DNA known as plasmids.
• Cell Wall: Most possess a rigid cell wall composed of peptidoglycan (murein), which provides structural support.
• Ribosomes: They contain 70S type ribosomes for protein synthesis.
• Mode of Nutrition: They exhibit diverse nutritional modes, including autotrophic (photosynthetic or chemosynthetic) and heterotrophic (saprophytic or parasitic).
• Reproduction: Reproduction is primarily asexual, occurring through binary fission or budding. Genetic recombination may occur via conjugation, transformation, or transduction.
• Locomotion: Many species are motile, utilizing flagella for movement.

The internal anatomy of a typical dicot root, when viewed in a transverse section, reveals distinct tissue layers from the periphery to the center:

• Epiblema (Rhizodermis): The outermost single layer of thin-walled cells. Some cells extend to form unicellular root hairs for water and mineral absorption.
• Cortex: A broad region consisting of several layers of thin-walled parenchyma cells with intercellular spaces, which store food and conduct water.
• Endodermis: The innermost layer of the cortex, characterized by barrel-shaped cells. Their radial and tangential walls contain waxy thickenings called Casparian strips, which regulate water movement into the vascular cylinder.
• Stele: The central core comprising all tissues inside the endodermis. It includes:
  • Pericycle: A layer of parenchymatous cells where lateral roots originate.
  • Vascular Bundles: Arranged in a radial pattern where xylem and phloem alternate on different radii. Xylem is exarch (protoxylem towards the periphery).
  • Pith: Small or absent in dicot roots, but usually large and well-developed in monocot roots, consisting of parenchyma cells.