Question

Intermediate between diploblastic and triploblastic body structure is found in
A. Porifers
B. Coelenterates
C. Ctenophores
D. Platyhelminthes

Answer 1

Body structure is a complex anatomical part of a living being including the construction and arrangement of various parts located in the body. The body structure is a physical structure which includes the bones, flesh and organs of a person or any animal.

Complete Answer:
Based on the body structure organisms are divided into two types-
1. Diploblastic organisms
2. Triploblastic organisms

1. Diploblastic organisms:
Diploblastic organisms are the organisms which develop from blastula and have two germ layers. That are –
a. Ectoderm – The ectoderm always develops into the outer skin layer, nervous system and nephridia.
b. Endoderm – Endoderm always develop into the tissues that are associated with gutt and associated glands.
Diploblastic animals are radially symmetrical. These animals do not have body cavities or coelom. Diploblastic animals include jellyfishes, corals, sea anemones, etc.

2. Triploblastic organisms:
Triploblastic organisms are the organisms that develop from the germ layers gastrula in which 3 germ layers are present. That are –
a. Ectoderm – Ectoderm gives rise to the epidermis, hairs, eye lenses, brain, spinal cord, etc.
b. Mesoderm – Mesoderm gives rise to muscles, bone, connective tissues, circulatory system, etc.
c. Endoderm – Endoderm develops into the lungs, stomach., colon, liver, urinary bladder etc.
These germ layers form during the gastrulation of the blastula. These animals are bilaterally symmetrical. They have body cavities or coelom. Triploblastic organisms include mollusks, arthropods, vertebrates, etc.

A. Porifers – Diploblastic animals
B. Ctenophores – Ctenophores are the intermediate one as they consider two main layers that are endoderm and ectoderm. These two; layers sandwich a jelly-like material called a mesoglea which looks like a middle layer. So, even ctenophores have 2 layers but due to the presence of mesoglea, they are considered as intermediate one.
C. Coelenterates – Diploblastic animals
D. Platyhelminthes – Triploblastic animals
Therefore, it has been clear from the above discussion that intermediate between diploblastic and triploblastic body structure is found in Ctenophores.

Hence, option C is the correct answer for this question.

Note: The functional and structural unit of the body of an organism is a cell which grouped together to form tissues. Tissues are further grouped together to form organs and various organs constitute to form an organ system. The combination of these organ systems make a full organism.