Question

Diploblastic and triploblastic are terms that describe
A. The number of invaginations during embryonic development
B. The number of heads during embryonic development
C. The number of germinal layers during embryonic development
D. The number of cell types during development

Answer 1

Hint: During embryonic development the body’s inner cavity and the cells form certain patterns which help in describing the organism as diploblastic or triploblastic in nature based on this organization.

Complete Answer:
Let us analyze the options to find out the correct answer.
Option A: Invagination occurs during the gastrulation stage of embryonic development. It is the production of a tube on the surface of an embryo when an extended finger is pressed radially against a partially inflated balloon. There are two main forms of invagination: axial and orthogonal. Therefore, this is the incorrect option.

Option B: The number of heads during embryonic development is not related to the diploblastic and triploblastic origin of an organism. Therefore, this is the incorrect option.

Option C: Germ layers are formed during the embryonic development in which the cells divide into three layers called endoderm, ectoderm and mesoderm. Endoderm forms the innermost germ layer, ectoderm the outermost and mesoderms is the middle layer that exists between the endoderm and ectoderm. Based on the presence of layers, organisms are classified as diploblastic and triploblastic. Diploblastic have only two layers called endoderm and ectoderm while triploblastic organisms consist of endoderm, endoderm and mesoderm. Therefore, this is the correct option.

Option D: The number of cell types during development is different and gives rise to layers upon further development. It is not associated with the triploblastic or diploblastic origin of any organisms.Therefore, this is the incorrect option.

Thus, the correct option is C) The number of germinal layers during embryonic development.

Note: Examples of diploblastic organisms include poriferan while platyhelminthes are triploblastic organisms having three germinal layers.