Answer:
Blastocyst,Blastoderm
Explanation:
The blastula is made up of a hollow spherical layer of cells, referred to as the blastoderm which surrounds a yolk or fluid-filled space called the blastocele or blastocoel. In most mammals, including humans, the structure formed next is the blastocyst, a mass of inner cells that are distinct from the blastula
The pair of characteristics that one must use to classify a fish is the presence of jaw and skeleton type. Agnatha fishes are also called jawless fishes and they lack bony skeletons. Cartilaginous fishes are composed of cartilage skeletons. Bony fishes have bony skeleton structures.
Vertebrates developed about 550 million years ago. The oldest vertebrate fossils are those of FISH with no jaws. These e<span>arly jawless fish did not have paired fins and their bodies were covered with heavy, bony scaled, but their skeletons were made of cartilage. For the next 50 million years, they were the only vertebrates.</span>
Answer:
Horns and columns.
Explanation:
The spinal cord is the important component of the central nervous system. The spinal cord consists of the nerves of the body and control the reflex actions of the body.
Spinal cord consist of white matter and grey matter. The motor and sensory axons are present on white matter. The white matter covers the grey matter and arranged into the different columns. The grey lies inside the white matter and consists of neuronal cell bodies. The grey matter is completely organised in the horns.
Thus, the answer is horns and columns.
The scales or outer layer of an artichoke are called bracts
