Question

Notochord, skeletal system and dermis are derived from
A. Mesoderm
B. Endoderm
C. Ectoderm
D. All of the above

Answer 1

Germ layers are found in animal embryos in the gastrulation stage. The germ layer gives rise to various tissues or organs of a fully formed/developed individual. There are three main germ layers namely the ectoderm, mesoderm, and endoderm.

Complete answer:
The embryos of poriferans and coelenterates have two germ layers namely the ectoderm (outer germ layer) and endoderm (inner germ layer). These animals are called diploblastic. Ectoderm gives rise to the epidermis which is the outer layer of the body wall. The endoderm gives rise to the gastrodermis, the tissue that lines the gut cavity. The animals which possess all these 3 layers including ectoderm, mesoderm germ layer (in between), and endoderm, are commonly called triploblastic animals.
Mesoderm has three different components which include the paraxial mesoderm, intermediate mesoderm, and lateral plate mesoderm. Among this, the paraxial mesoderm gives rise to the bones, cartilages and the subcutaneous tissues of the skin. However, the intermediate mesoderm gives rise to kidney, gonads, their associated ducts, and adrenal glands. The lateral plate of mesoderm forms the heart, blood vessels, and blood cells. The notochord is present beneath the nerve cord and is mesodermal in origin. It may persist in some chordates while in some others it is replaced during the embryonic period by the vertebral column that forms around the nerve cord.
Therefore, the mesoderm gives rise to notochord, skeletal system and dermis of an individual.

Hence, the correct answer is (A).

Note:
All chordates are bilaterally symmetrical, coelomates, triploblastic with organ system level of organization. Some of the other derivatives of mesoderm include connective tissues, skin, muscles, dentine of teeth, dura mater, adrenal cortex, kidney, endothelium of blood vessels and pharyngeal arches muscles.