Exaptation
Explanation:
In this example, the lateral extensions that developed were meant for thermoregulation.
But these became sufficiently large to support gliding through the air and later on were used for flight.
Thus the structure assumed a function for which it was not meant and its original function shifted to a completely different dimension giving rise to modern insect wings. So we can say that this is an example of Exaptation.
There are all sorts of ways to reconstruct the history of life on Earth. Pinning down when specific events occurred is often tricky, though. For this, biologists depend mainly on dating the rocks in which fossils are found, and by looking at the “molecular clocks” in the DNA of living organisms.
There are problems with each of these methods. The fossil record is like a movie with most of the frames cut out. Because it is so incomplete, it can be difficult to establish exactly when particular evolutionary changes happened.
Modern genetics allows scientists to measure how different species are from each other at a molecular level, and thus to estimate how much time has passed since a single lineage split into different species. Confounding factors rack up for species that are very distantly related, making the earlier dates more uncertain.
These difficulties mean that the dates in the timeline should be taken as approximate. As a general rule, they become more uncertain the further back along the geological timescale we look. Dates that are very uncertain are marked with a question mark.
Answer:
Chlorophyll "a"
Explanation:
The reaction centers of the photosystem have chlorophyll "a" molecules. The chlorophyll "a" that functions as a reaction center for the photosystem II has absorption maxima at 680 nm and therefore, it is called P680. The reaction center of photosystem I also have chlorophyll "a" molecules that have the absorption peak at 700 nm. The chlorophyll "a" molecules serving as reaction centers transfer the photoexcited electrons to a primary acceptor during the light-dependent phase of photosynthesis.
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