Question

The organization of the shoot apex into tunica and corpus is determined largely on the basis of-
A. Rate of shoot tip growth
B. Rate of cell division
C. Planes of cell division
D. Regions of meristematic activity

Answer 1

Hint:The terminal meristem of the shoot is known as the shoot apical meristem. It is the continuing embryonic region of the plant and produces new cells and tissues which leads to the formation of new organs. The shoot apical meristem is the self-determining and autonomous part of the plant.

Complete solution:
Schmidt postulated tunica- corpus theory which is based on the studies of shoot apices of angiosperms or flowering plants. In contradiction of the apical cell theory, the tunica-corpus theory is only applicable to the shoot apex and not to the root. The three types of meristematic tissues are apical (present at the tips), intercalary (present in the middle), and lateral (present at the sides).
Schmidt differentiated two tissue zones in the shoot apex and named them tunica and corpus.
Plasmodesmata exist between the tunica and corpus cells. It is considered that plasmodesmata control the gene expression which leads to the formation of the three tissues, namely, protoderm, ground meristem, and provascular tissue.

So, the right answer is option B.

Additional Information:
Corpus is the tissue zone of shoot apex present on the inner side. It comprises cells which are numerous cell layers deep. The tunica overarches the corpus. Meristematic tissues that compose this zone are generally larger than tunica. The initial cells of the corpus are present below the tunica.

Note:Chimaera refers to a plant or a plant organ which have tissues of wide-ranging genetic origin which lies adjacent to one another. In some plants, the meristematic region has at least two populations of cells that differ in chromosome numbers. The chimera of the plant can be recognized only at the cytological level and is termed as cyto chimera.