Answer:columnar describes cell shape.
Simple describe the number of layers
Explanation: epithelial tissues are one of the four major tissues of the body.the others being nervous, muscular, connective tissues.
Epithelial tissues are made up of thin cells that cover the external and internal surface of the body.
The cells may form one layer or more and they occur in several shapes.if they form one layer ,it is called simple.if they form several layers,it is called stratified.
Some are called pseudo-stratified because the cells occur with varying lengths and give the impression of stratified but they are actually made up of one layer.
Simple columnar epithelium is a single layer of tall, closely packed cells. They possess cellular extensions ,such as microvilli in the small intestine, or the cilia in the female reproductive tract.
In active transport, materials move from an area of high concentration to an area of lower concentration (goes down the concentration gradient) and it requires or uses energy in the form of ATP (adenosine triphosphate)
Answer:
"Survival of the fittest" is a phrase that originated from Darwinian evolutionary theory as a way of describing the mechanism of natural selection. The biological concept of fitness is defined as reproductive success.
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