Question

According to apical cell theory, there is a single apical cell with three cutting faces in the shoot apex. This theory is applicable only for some higher algae, bryophytes and pteridophytes and not applicable to gymnosperms and angiosperms. This theory was given by:
A. C.Nageli
B. Hanstein
C. Schmidt
D. Clowes

Answer 1

Hint: Apical cell theory was given by von Nageli in 1858. This theory says that a single apical cell constitutes the growth point in most of the cryptogams( a plant that has no true flowers or seeds). This single cell is called ‘APICAL CELL’. The activity of this single apical cell leads to the development of a complete plant body.
The apical cell is tetrahedral in shape and has three or four cutting faces among which a single face is directed upward and the rest points downwards.
A single apical cell composing an apical meristem is present in vascular cryptogams.
In higher plants the apical cell theory was replaced by the concept that the different parts of the plant body have independent origin.

Complete answer:
A. C.Nageli is the correct option as he was the one who proposed this theory.
B. Hainstein gave histogen theory which explained about the shoot apex.So this option is not correct.
C. This is not the right option as Schmidt gave the theory for isothermal calculations.
D. Clowes introduced the word ‘Cytogenerative centre'. So, this option is not correct according to the question.

Note:
Cell apical theory is applicable only for some higher algae, bryophytes and pteridophytes but is not applicable to gymnosperms and angiosperms. Apical cell theory was Suppressed by histogen theory which was given by Hainstein. According to this theory, the tissue of a plant body originates from a mass of meristem where the three histogens( dermatogen, periblem and plerome) can be distinguished.