<u>Evolution:</u> In simple terms is the advancement of the less developed form of life into a more complex form of life, as these organisms go through a series of changes through time,t. As the evolution is resulted from the different changes and improvements been made inside the living organism's body or we can say its over all structure.
<u>For example:</u>
The coccyx bone or the tail bone is said to be evolved inside the human beings, when the went through a different pathway rather then living like the rest of the primates. So, its now a fused form of bone structure formed after the fusion of three bones present on the lower region of the spinal cord.
There are number of specie of mammals which has adopted there body to live in the severe conditions, like the climate in the Antarctica. Most of the organisms living there posses an extra covering over there body and makes them able to survive in such cold climates.
Along, with that there are many microscopic organisms which has arranged there chemical balance in such way that there body is able to coordinate properly inside the harsh conditions and perform a more proper functioning,as they have arrange there cell organelle
There also some fish specie which has evolved them selves in order to become more versatile in collecting the right amount of nutrients and oxygen from the water molecules.
During contraction of skeletal muscle fibers, the thin filaments slide inward toward the A band's center as a result of cycles of crossbridge binding and bending.