activities of living organisms (animals, burrows, plant roots), pressure from overlying load/materials and atmospheric conditions.
Folds, wrinkles, etc!
by folding the membrane of an organelle, surface area is optimized while volume remains the same. that is why mitochondria looks folded on the inside when you see pictures of it. the higher the surface area to volume ratio, the more efficient the organelle.
The answer is : randomization was not used in sample selection. The major difference between experimental and quasi-experimental designs is lack of randomization in sampling selection.
