The correct answer is - No.
The Cambrian explosion is a term used for the big and rapid diversification of the animal species, but it is not the period in which the animal life started. The animal life started in the period between 620 and 550 million years ago, in what is known as the Vendian Period. In the Vendian Period, the first complex animal organisms appeared, started to develop and evolve, though it is not a period where there was a high diversification of the species. The later Cambrian Period provided better living conditions, and that resulted in a so called ''explosion of life'', which resulted in much more new species developing and evolving.
Cellulose. Our bodies as humans lack enzymes to break the cellulose down.
The answer is K-selected.
The population size of K-selected species is fairly constant in time, unlike the population size of r-selected species. r-selected species are usually bellow carrying capacity and the population size is density independent. On the contrary, K-selected species are usually near or at carrying capacity and the population size is density dependent.
There are four main types of tissue: muscle, epithelial, connective and nervous. Each is made of specialized cells that are grouped together according to structure and function. Muscle is found throughout the body and even includes organs such as the heart. Our outer layer of skin is epithelial tissue.
