12. One of the main functions associated with simple squamous epithelium is diffusion, active transport, secretion, absorption, providing structural support, and the enzymes needed to make proteins from amino acid building blocks. Organelles involved in these functions include the endoplasmic reticulum, Golgi apparatus, ribosomes, and mitochondria. 14. The tubular transport system that moves molecules throughout the cell includes the endoplasmic reticulum, ribosomes, and peroxisomes. 15. Choose the organelle that consists of microtubules and functions both in distributing chromosomes during cell division and in forming portions of cilia and flagella.