Question

Animals with radial symmetry have embryos (blastula) with:

A. two germ layers, the ectoderm and the endoderm.
B. no germ layers as they free-form.
C. three germ layers, the ectoderm, the mesoderm and the endoderm.
D. one germ layer.
E. None of these.

Answer 1

Animals with radial symmetry have embryos with two germ layers, the ectoderm and the endoderm, which means they are diploblasts.

Step-by-step explanation:

Animals with radial symmetry have embryos, known as blastulas, with two embryonic germ layers: an inner layer called the endoderm and an outer layer called the ectoderm. These animals are referred to as diploblasts, and they feature a nonliving layer between the endoderm and ectoderm. This nonliving layer is not a coherent third layer of tissue. Therefore, animals with radial symmetry typically do not develop a middle germ layer like the mesoderm that is found in more complex animals, often with bilateral symmetry, known as triploblasts. Considering the options provided, the correct answer to the schoolwork question is: A. two germ layers, the ectoderm and the endoderm.