It's a classic argument from ignorance.
In this case it's photosynthesis in flowering plants. He posted this figure from the Kegg database ....
Then he says,
In photosynthesis , 26 protein complexes and enzymes are required to go through the light and light independent reactions, a chemical process that transforms sunlight into chemical energy, to get glucose as end product , a metabolic intermediate for cell respiration. A good part of the protein complexes are uniquely used in photosynthesis. The pathway must go all the way through, and all steps are required, otherwise glucose is not produced. Also, in the oxygen evolving complex, which splits water into electrons, protons, and CO2, if the light-induced electron transfer reactions do not go all the five steps through, no oxygen, no protons and electrons are produced, no advanced life would be possible on earth. So, photosynthesis is a interdependent system, that could not have evolved, since all parts had to be in place right from the beginning. It contains many interdependent systems composed of parts that would be useless without the presence of all the other necessary parts. In these systems, nothing works until all the necessary components are present and working. So how could someone rationally say, the individual parts, proteins and enzymes, co-factors and assembly proteins not present in the final assemblage, all happened by a series of natural events that we can call ad hoc mistake "formed in one particular moment without ability to consider any application." , to then somehow interlink in a meaningful way, to form electron transport chains, proton gradients to " feed " ATP synthase nano motors to produce ATP , and so on ? Such independent structures would have not aided survival. Consider the light harvesting complex, and the electron transport chain, that did not exist at exactly the same moment--would they ever "get together" since they would neither have any correlation to each other nor help survival separately? Repair of PSII via turnover of the damaged protein subunits is a complex process involving highly regulated reversible phosphorylation of several PSII core subunits. If this mechanism would not work starting right from the beginning, various radicals and active oxygen species with harmful effects on photosystem II (PSII) would make it cease to function. So it seems that photosynthesis falsifies the theory of evolution, where all small steps need to provide a survival advantage.I responded on Facebook, pointing out that the cytochrome bc complex and ATP synthase pre-date photosynthesis [Facebook: Photosynthesis]. I also pointed out that there are many living species that use only simpler versions of photsystem I or only photosystem II to carry out photosynthesis [e.g. A Simple Version of Photosynthesis]. Those nasty little facts don't seem to fit with his claim that, "In these systems, nothing works until all the necessary components are present and working."
I probably should have known better. Otangelo Grasso's standard response to such criticism is to avoid dealing directly with his false statements and shift the goalposts on to some other topic. He then posts all kinds of links to websites that seem to back up his claims even if they have nothing to do with the criticisms. You can see him at work on the Facebook thread.
It's pretty frustrating. I probably shouldn't respond to kooks, especially those who think they are experts in biochemistry.