Let us say something about Energy that I know while I was in high school Physics class. Energy is usually defined as the ability to do work. In general; we would say that energy is fundamental entity whose availability and flow are required for all phenomena, natural or artificial. Energy neither be created nor destroyed; rather it is changed from one form to another. That means mechanical energy, such as the kinetic energy of motion can be converted to heat energy.
Let’s come to the type of energy source used by cell?
Cells seek their energy in the form of food molecules or sunlight. The Sun is the ultimate source of energy for almost all cells, because photosynthetic prokaryotes, algae, and plant cells uses solar energy to make the complex organic food molecules that other cells rely on for the energy required sustaining growth, metabolism, and reproduction. Complex organic food molecules such as sugars, fats, and proteins are rich sources of energy for cells.
Prokaryotic or Eukaryotic Cells do not use the energy from oxidation reactions as soon as it is released. Instead, they convert it into small, energy-rich molecules such as ATP and nicotinamide adenine dinucleotide (NADH), which can be used throughout the cell to power metabolism and construct new cellular components.
Passive Transport is one form of energy transfer in a cell that does not require the use of energy, molecules move randomly in a cell and molecules spread out in a cell from an area of high concentration to low concentration. There are also three type of Passive transporting in a cell: - Diffusion, Facilitative Diffusion and Osmosis. Active Transport is that cell requires uses of energy; molecules move actively where they are needed and movement of molecules from an area of low concentration to high concentration. There are also three types of active transport: - Protein Pumps, endocytosis and exocytosis.
In case of Passive transport there in no specific energy used to transport molecules in a cell. The process uses concentration gradient (Example, the movement of two different gas elements in one medium). But in case of Active Transport there are specific energy used to transport molecules in a cell which is ATP and Protein carrier (Example, the movement of sodium Potassium pump by using ADP in a cell membrane).
Work Cited:
. http://www.nature.com/scitable/topicpage/cell-energy-and-cell-functions-14024533
. Biology Today and Tomorrow 4th Edition STARR EVERS STARR