Hello Students: DAY- 18 Evening Coffee with NEET

HELLO STUDENTS: DAY- 18 Evening

SPECIFIC FACTS FROM PLANT ANATOMY FOR NEET BIOLOGY PREPARATIONS :

Different Theories of Apical Meristems :

I) APICAL CELL THEORY=

1)proposed by HOFMEISTER(1852)

2)Supported by NAGELI(1858)

II)HISTOGEN THEORY=

1) proposed by Hanstein(1870)

2) Supported by STRASBURGER

3)The shoot apices comprises three distinct zones DERMATOGEN (for Epidermis),PERIBLEM(for Cortex)and PLEROME(for Stele including Central cylinder and pith)

4) CALYPTROGEN is responsible for the formation of ROOT CAP.

4) Haberlandt (1914), proposed new terms PROTODERM for Dermatogen, GROUND MERISTEM for Periblem and PROCAMBIUM for Plerome.

III)TUNICA-CORPUS THEORY=

1)First proposed by SCHMIDT (1924)

2)Noticed two distinct zones Tunica in periphery and Corpus in inner core.

IV) MANTLE-CORE HYPOTHESIS= 

1)was proposed by Popham and Chan(1950)

V)KORPER KAPPE THEORY=

1)First proposed by SCHUEPP(1917)for root apices

2)Korper zone forms the body(korper is characterized by inverted T divisions) and 

3)KAPPE zone forms the cap(Kappe is characterized by straight T divisions)

VI) QUIESCENT CENTRE CONCEPT=

1)was proposed by Clowes(1961)

2)this explain root meristem activity

3)this centre is located between root cap and differentiating cells of the roots

4) QUIESCENT CENTRE is apparently inactive region of cells in root PROMERISTEM

4)cell divisions are very few in Quiescent centre and there is little synthesis of new proteins ,RNAs and DNA.

5)it may function us RESERVE MERISTEM

6) it is the site of hormone synthesis.

Mr.R.Soundarapandian, MSc, MEd, MPhil, 

PG Asst Zoology 
SIR MCTM Boys Higher Secondary School, 

Purasawalkam Chennai-84.