The evidence suggested that differential predation was the most likely cause of the variations in life histories of guppy populations. You can read and understand this question. Most cells have very little mass. Cells vary in size. Tissues are organized into organs.
All cells are microscopic in size.
All cells have cytoplasm. All cells contain genetic information. All cells can divide to produce other cells. All cells have a plasma membrane. Biologists have identified several hundred thousand different species.