Wednesday, 26 February, 2020

NEET EXAM BIOLOGY NOTES-ULOTHRIX-NEET EXAM NOTES IN PDF

neet-exam-biology-notes-ulothrix

NEET EXAM BIOLOGY NOTES-ULOTHRIX-NEET EXAM NOTES IN PDF



ULOTHRIX (POND WOOL)

 

SYSTEMATIC POSITION : (NEET EXAM BIOLOGY NOTES)

Kingdom : Plantae

Sub kingdom ; Thallophyta

Division : Chlorophyta

Class : Chlorophyceae

Order : Ulotrichales

Family : Ulotrichaceae

Genus : Ulothrix

 

HABIT AND HABITAT



  • Ulothrix mainly found in fresh water.
  • The majority of species of Ulothrix occurs in cold slow moving streams.
  • Marine species, eg., Ulothrix flacca. (intertidal zone of sea and saline marshes)
  • Lithophyte species. – Ulothrix implexa – Fresh water species. – Ulothrix zonata.
  • Ulothrix zonata is the main species of Ulothrix which is found in India. 

 

THALLUS STRUCTURE (NEET EXAM BIOLOGY NOTES)




  • The thallus of Ulothrix is multicellular, filamentous, unbranched and bright green in colour.
  • All the cells of the filament are similar but basal cell and apical cell are different. All cells present between basal cell and apical cell are called intercalary cells. 
  • Shape of the cells are cylindrical but they looks rectangular in external appearance. 
  • The upper most or apical cell is somewhat dome shaped and basal cell is elongated and narrow at the base. 
  • The filament attached to the substratum with its specialized cell which is called Holdfast or Rhizoidal cell or Hapteron. 
  • At the base of holdfast develops fine processes or fingers like structure are called Haptera. 
  • The holdfast cell of the thallus is living and non green, Chloroplast absent in hold fast. 
  • The cell wall of the filament is double layered. 
  • The outer layer is Protopectin. (Precursor of pectin and insoluble in water). The inner layer is cellulose. 
  • A large vacuole is present in the centre of the cell. Surrounding the vacuole, the cytoplasm present as a thin layer and to form a primordial utricle. 
  • Chloroplast contains two or three pyrenoids. (Protein particles which are surrounded by starch.) 
  • These pyrenoids are concerned with storage of starch. 

 

REPRODUCTION 

 



Ulothrix reproduce by three methods : 

(1) Vegetative reproduction. 

(2) Asexual reproduction. 

(3) Sexual reproduction. 

 

VEGETATIVE REPRODUCTION 

It takes place generally in favourable conditions.

Fragmentation :The filaments break up into two or more pecies. They are called fragments

Each fragment divides to form a new Ulothrix filament.

Fragmentation occurs due to –

  • Incidental reasons. 
  • Death of intervening cells or middle lamella. 
  • Strong waves of water
  • Change of pH or temperature 

 

 

ASEXUAL REPRODUCTION 

It takes place in favourable unfavourable conditions.

In favourable conditions : By Zoospores.

Zoospores formation occurs generally near the apex and progresses towards the base of filament. (Basipetal order) 

Zoospores are of two types – 

(1) Micro zoospores. 

(2) Macro zoospores.

click here ulothrix complites notes with practice paper
NEET EXAM BIOLOGY NOTES

 



 

 

 

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