Answer:
Gastrulation takes place after cleavage and the formation of the blastula and the primitive streak. It is followed by organogenesis, when individual organs develop within the newly-formed germ layers. Each layer gives rise to specific tissues and organs in the developing embryo.Cells in each germ layer differentiate into tissues and embryonic organs. The ectoderm gives rise to the nervous system and the epidermis, among other tissues. The mesoderm gives rise to the muscle cells and connective tissue in the body. The endoderm gives rise to the gut and many internal organs.
Answer:
depending on conditions !
Explanation:
e.g a peat bog or somewhere like the north pole vs a humid jungle or hot desert
things to consider
air composition in the environment to feed microbes
temperature to speed up reactions
any natural catalysts
PH of your environment
The most common example that determines the similarities in anatomical features among organisms is the bone structure, commonly used in comparative anatomy. For example, the forelimbs or appendages of bats, humans, cats and whales have the same basic parts but they differ in function. Fins of whales and wings of bats have the same skeletal parts, but fin is used for swimming while wing is for flight. These structures could be termed as homologous, analogous, or homoplastic. However, recent developments have been made than just basing to the skeleton - the main reason why we have comparative genomics today.