1. Some substances passes through small holes in the surface cell membrane. This is called diffusion and does not require cell to expend energy.In this way the passive transport occur if the cell doo not expend any energy. 2.In active transport,the particles move across the cell membrane from slower concentration to higher concentration . Active transport is the energy requiring process of pumping molecules and ions across membranes uphill against a gradient.This process uses the energy of ATP. 3. Endocytosis and Exocytosis are important mechanisms for bringing substances into and out of a cell.The vesicles fuse with the plasma membrane ,causing the contents of the vesicles to spill outside the cell.
That would be the mitochondria. They produce the energy needed for activities that occur in the cell, thus its being called the "powerhouse of the cell"
Jsu’s hey isuejeuwywh isiah suyeyw usuyw usuyw isiah sisyphean sustenances sishbw siwiwu
Plants and animals need nitrogen to make amino acids, proteins and DNA, but the nitrogen in the atmosphere is not in a form that they can use.