Question

The shell of a turtle or tortoise is divided into an upper and lower section. What is the lower section called?
A. Plastron
B. Scute
C. Carapace
D. Subshell

Answer 1

Shells of animals such as tortoises and turtles as a protective organ for all the vital organs, and also functions as a shield for saving itself from unfavorable conditions. The shells are made by the modification of pelvic parts, ribs and some other bones.

Complete step by step answer:
Plastron is the flat portion of the shell present on the ventral or belly region. It covers the lower section of the body, this part is comprised of nine bones, two epiplastra which are located at anterial portion of the plastron is homologous to the clavicle bones present in the other tetrapods.
Considering the other options:
Scute: It is an external plate comprised of bones or the scales which has horns laid over it. It is present on the shells of turtles. It can also be seen on the skin of other reptiles such as crocodiles and the birds’ feet.
Caraspace: The upper or the dorsal section present in the exoskeleton present predominantly in the arthropods such as prawns, and also present in turtles and tortoises. It is mainly the back portion of the shell of turtles or tortoises. Scutes can be considered a part of the caraspace.
Subshell: There is no such part in this animal.
Thus, from the above given options the most appropriate one is A that is the lower section of the shell is known as plastron.

Note:
The shells of the turtles and tortoises are very hard, the structures are able to withstand very high pressure. These structures help in escaping from the predators. The hardness of the shells are due to the presence of keratin plates which are also known as scutes.