Answer;
Mesoderm
The mesoderm is a layer of the embryo, which will become the circulatory system, bones, muscles, excretory system, and reproductive system.
Explanation;
-The germ layers develop early in embryonic life, through the process of gastrulation. An inner layer, called endoderm, and an outer layer, called ectoderm and a middle layer called mesoderm.
-The embryonic endoderm develops into the interior linings of two tubes in the body, the digestive and respiratory tube. the lining of the follicles of the thyroid gland and the epithelial component of the thymus.
-Ectoderm develops into parts of the skin, the brain and the nervous system. Mesoderm gives rise to bones, muscles, the heart and circulatory system, and internal sex organs.
I would say C because our body is continuously changing through puberty. We need more sleep, more food consumption, we need to have fantastic hygiene, etc...
Answer:
B. the hormone must enter the cell
Answer:
B, A fossil found in rocks from one time period
Explanation:
Fossils are used to determine the ages of rock layers. Index fossils are the most useful for this. Index fossils are of organisms that lived over a wide area. They lived for a fairly short period of time. An index fossil allows a scientist to determine the age of the rock it is in. Hope that this helps you :)