The answer is 'Cambrian' explosion. This took place approximately 541 million years ago. 'Explosion' refers to the evolution of a large range of new major animal phyla. Scientists know this by the large number of diverse fossils from this period. Prior to this period, organisms were single-celled, but over the Cambrian Explosion, lasting about 80 million years, life forms diversified rapidly to resemble the life forms existing today.
Isotonic solution.
Since it has the same salt concentration as the cell the solution is neither hypotonic or hypertonic.
Answer: a. endoderm-bone
Explanation: In the context of embryonic development, bone tissue may arise from several precursor cell populations, such as the neural crest (some facial bones), lateral mesoderm (bones of the limbs, among others), and paraxial mesoderm (vertebrae and part of the skull). There is no evidence to suggest that any of the bony structures is derived from the endoderm germ layer.
There is no difference in mental abilities between genders
