Germ layer is a primary layer of cells found in the embryo. The three primary germ layers that generate most of the cells in the developing mammalian forelimb are ectoderm, mesoderm and endoderm.
Ectoderm forms the outer component of a mammalian body such as skin, hair, etc. Endoderm forms the inner layer that comprises of the linings of digestive system, lungs and thyroid. Mesoderm is the middle layer that forms the skeletal system, heart, etc.
Neural tube is generated by the inward folding of the ectoderm. This process is called neurulation. Ectoderm also forms neural crest.
Researched (copied and pasted so use in your own words)
Disturbances such as forest thinning, floods, fire and wind can all lead to secondary succession. Examples of secondary succession are the gradual replacement of old fields by forest or the vegetation recovery and change following wildfire occurrence.
Life would be very hard because then they may not be able to survive <span />
The organism (Living thing), utilizes energy, can detect changes in the environment it is in, and can rearrange and synthesize chemical compounds.
Some things to remember, Living organisms need to be able to reproduce, obtain energy, usually by eating food in order to work. They need the ability to maintain structure, a body. They need to be able to react to a change, whether it be external or internal. The organism must be able to dispose of waste. Needs the ability to grow and develop. Must be able to move. and finally death. <span />
