PLANT KINGDOM

POINTS TO REMEMBER :


CLASSIFICATION :

Artificial System of Classification :

  • Used superficial morphological characters.
  • Based on a few characteristics like habit, colors, number and shape of leaf.
  • Mainly based on vegetative characters.
  • Such system developed by Linnaeus.

Natural System of Classification :

  • Based on natural affinities among organisms
  • Included external as well as internal features like anatomy, embryology and phytochemistry.
  • Developed by George Bentham and J. D. Hooker

Phylogenetic System of Classification :

  • Based on evolutionary relationships between the various organisms.
  • Organism belongs to same taxa have a common ancestors.
  • Developed by Hutchinson.

Numerical Taxonomy :        

  • Carried out using computers
  • Based on all observable characteristics
  • Data processed after assigning number and codes to all the characters.

Cytotaxonomy :       

  • Based on cytological information.
  • Gives importance to chromosome number, structure and behaviour.

Chemotaxonomy :

  • Based on chemical constituents of the plants.

ALGAE :

  • Chlorophyll bearing, simple, thalloid, autotrophic and mostly aquatic organisms. Moist stone, soils and wood are the other habitat.
  • The size ranges from microscopic unicellular forms like Chlamydomonas, to colonial forms like Volvox and to filamentous forms like Ulothrix and Spirogyra. A few marine forms such as kelps, form massive plant bodies.
  • Reproduce vegetatively by fragmentation.
  • Reproduce asexually mostly by producing motile spore called zoospores.
  • Reproduce sexually by producing gametes.
  • Isogamous: both gametes are same size and motile
  • Anisogamous: both gametes are dissimilar in size but motile.
  • Oogamous: male gamete is smaller but motile, female gamete is large and non- motile.

Importance of Algae :

  • At least half of the total carbon dioxide fixation on earth carried out by them.
  • Increase oxygen level in the environment.
  • Many species like Laminaria, Sargassum etc. are used as food.
  • Agar obtained from Gelidium and Gracilaria is used in ice-creams and jellies and also used to culture bacteria.
  • Algin obtained from brown algae and carrageen from red algae used commercially.
  • Chlorella and Spirullina are unicellular algae, rich in protein and used as food supplement even by space travelers.

CBSE Biology (Chapter Wise) Class XI ( By Mr. Hare Krushna Giri ) 
Email Id : [email protected]