In photosystem II, P680 transfers an electron to pheophytin upon excitation by a photon. How is this electron replaced

because the asteroid belt is between the mars and jupiter orbits, it is around 2.2 to 3.2 astronomical units (au) from the sun – which is approximately 329,115,316 to 478,713,186 km. the average distance between objects is a massive 600,000 miles.

explanation:

stress fractures occur largely in the feet and legs and are common in sports that require repetitive impact, primarily running/jumping sports such as gymnastics or track and field.

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.