Answer to Question 1
The ectoderm develops into the tissues that are on the outside or near the surface of the animal's body. These include the skin, hair, hooves, and certain endocrine glands that secrete hormones into the bloodstream. This layer also forms the central nervous systemthe brain, spinal cord, and all the nerve branches. A group of endodermis cells form a rod-like structure (notochord) that gives rise to the vertebral column. The endoderm forms the digestive system, lungs, liver, and other endocrine glands. The mesoderm layer develops into the skeletal and muscular system of the animal, including bones, muscles, tendons, cartilage, and ligaments. The heart, veins, arteries, and other parts of the circulatory system are also developed in this layer. In addition, the reproductive system is formed from the mesoderm layer.
Answer to Question 2
sand, less than 52 percent; silt, 28 to 50 percent; clay, 7 to 27 percent
The experimental approach used by Masui and Markert to identify cyclin and cyclin-dependent kinase (
Layers of the Integument
layers of the skull to memorize for intracranial questions
Men experience more trauma in their lifetimes, but women are more likely to develop PTSD.
Tissue layers in the bronchi.
The Ocean’s Layers