Unlike other methods such as diffusion or osmosis, active transport requires extra energy provided by the organism from such as cellular respiration. In addition, they also require a carrier protein, which can change its shape to bring the substance through the cell membrane.
Some examples requiring active transport may include root hair cells absorbing mineral ions, or our small intestine absorbing digested nutrients into our body.
the effect of external physical factor on cell division is clearly seen on in density dependent inhibition( a phenomenon in which crowded cell stop dividing)
