Lecture 4Plant Tissues

and Bodiversity

Plant organs:A plant has two organ systems: 1) the shoot system, 2) the root system. The shoot system is above ground and includes the organs such as leaves, buds,stems, flowers and Fruits.The root system includes the parts of the plant below ground, such as the roots and tubers.

Plant Tissues:Plant cells are formed at meristems, and then develop into Permanent tissues that are of 3 types:

Meristematic Tissues This tissue is composed of relatively small cells with thin walls and large nuclei and small vacuoles.

Its main function is division and growth .  The production of new cells is confined to certain areas of the plant known as Apical Meristems that are present in the tops of the roots and stems.

Apical meristem in stem Apical meristem in root

Dermal tissues:Epidermis

It is the outer layer of cells in leaves, stems and roots.

It consists of one layer of striated circular cells and covered externally by cuticle and associated with pores .

Ground tissues:

Parenchyma Cells:Located below the epidermal tissue Function: Protection and Storage.

Collenchyma:They have thick wall Function: Support and protection

Sclerenchyma :They have thick secondary wall Function: Support only

Vascular Tissues:

Xylem tissue It is responsible for transporting water and salts from

root to leaves .

Phloem tissue -It is responsible for transporting food from leaves to the rest of the plant.

Xylem Tissues Phloem Tissues

What is biodiversity ?

Biodiversity (or biological diversity) is used to refer to the variability among living organisms .

It means the differences in plant and animal

species, and its associated genetic diversity and assembly of organisms .

It includes:

genetic diversity species diversity

ecosystem diversity

Principles of the division and classification ofviruses -bacteria - algae - plant

1-Classification of Viruses:A - DNA virusesB- RNA viruses

Nucleic acid type

Capsid symmetry Examples Virus Family

ds-DNA ComplexSmallpox

virusPoxviridae

ds-DNA IcosahedralHepatitis B

virusHepadnaviridae

ds-DNA Icosahedralpapilloma

virusPapovaviridae

Nucleic acid type

Capsid symmetry Examples Virus Family

ss(+) Icosahedral Yellow fever virus Flaviviridae

ss(-)RNA HelicalMeasles virus, Mumps virus

Paramyxoviridae

ss(+) Icosahedral Rhino virus Picornaviridae

B- RNA Viruses

2 -Classification of Bacteriakingdom Monera (Prokaryotes) A – Gram negative bacteria

B – Gram positive bacteria

Family Genus Characteristic Cell Shape

NeisseriaceaeNeisseria , Veilonella Aerobic Cocci

EnterobacteriaceaeShigella,

SalmonellaFacultative anaerobic Bacilli

A – Gram Negative bacteria

Family Genus Characteristics Cell Shape

MicrococcaceaestaphylococcusMicrococcus

Spherical shape in clusters Cocci

BacillaeceaeBacillus

Clostridium

Rod-shapedAerobic Sporing

Anaerobic SporingBacilli

B- Gram- Positive bacteria

Shapes of bacterial cells

3-Classification of algae

Storage products

Pigments Chlorophyll Taxonomic group

Fats , oils, volutin

β-carotenephycoxanthinxanthophyll

a,c Bacillariophyta

Starch, oilsβ-caroteneLycopene

Luteina,b

Chlorophycophyta(green algae)

Fats , oilsβ-carotene

xanthophylla,c

Xanthophycophyta)yellow green algae(

Starch, oilsβ-carotene

phycocyanina,c

Cyanophycophyta(blue green algae)

Laminarin Mannitol

β-carotenephycoxanthin

a,cPhaecophycophyta

)brown algae(

Floridean starch

oils

β-carotenephycoerythrinphycocyanin

a,bRhodophycophyta

(red algae)

Shapes of Algae