Here are three quotes by the late Isaac Asimov (1920-1992) on photosynthesis.
[Graphic: Structure of a chloroplast, Estrella Mountain Community College]
Note the language of design, that even atheists like Asimov could not avoid using when describing molecular machines:
"... chlorophyll is part of an intricate and well-organized mechanism that acts as a smoothly-working whole to carry through a photosynthetic process that includes many steps" which has to be all in place "if all you have is an ignition key and nothing else, it won't get you moving" and assembled just right "even if you sit down on the road and pile a heap of loose automobile parts all about yourself" :
"If we extract chlorophyll from plant tissues in pure form and supply it, in the test tube, with carbon dioxide, water, and sunlight, we will find that photosynthesis will not take place. Even if we throw in the carotenes and any other pure substances we find in plant cells, it will not help. Apparently, within plant tissue, chlorophyll is part of an intricate and well-organized mechanism that acts as a smoothly-working whole to carry through a photosynthetic process that includes many steps. Chlorophyll makes the key step possible and without it nothing can happen, but the key step, by itself, is not enough. (To draw an analogy from the more familiar world of the automobile-the ignition key sets in motion a whole series of events in the complicated automotive mechanism and starts you moving over the road at a rapid rate of speed. However, if all you have is an ignition key and nothing else, it won't get you moving even if you sit down on the road and pile a heap of loose automobile parts all about yourself.)" (Asimov, I., "Photosynthesis," George Allen & Unwin: London, 1970, p.53. My emphasis)
"The chloroplast-thus shown finally to be a self-contained photosynthetic unit-- contains the complete assembly-line for the purpose within itself", "all properly and intricately arranged" for a "good and sufficient reason":
"And what about an organelle to handle the photosynthetic half of the carbon cycle. ... Eventually, these chlorophyll-containing organelles were named `chloroplasts.' ... The structure of the chloroplast seems to be even more complex than that of the mitochondrion. The interior of the chloroplast is made up of many thin membranes stretching across from wall to wall. These are the `lamellae.' In most types of chloroplasts, these lamellae thicken and darken in places to make dark condensations called `grana.' The chlorophyll molecules are to be found within the grana. If the lamellae within the grana are studied under the electron microscope, they, in turn, seem to be made up of tiny units, just barely visible, that look like the neatly laid tiles of a bathroom floor. Each of these objects may be a photosynthesizing unit containing 250 to 300 chlorophyll molecules. ... The chloroplast-thus shown finally to be a self-contained photosynthetic unit--contains the complete assembly-line for the purpose within itself. It contains not only chlorophyll and carotenoids, but a full complement of enzymes, coenzymes and activators as well, all properly and intricately arranged. It even contains cytochromes, ordinarily associated with respiration, but present in the chloroplast for, as we shall see, good and sufficient reason. (In view of all this, it is no wonder that chlorophyll by itself cannot carry through photosynthesis.)" (Ibid., pp.56-57. My emphasis).
At the end of the book, Asimov's has a hand-waving `explanation' of the origin of photosynthesis (with the origin of life thrown in for good measure) which shows why, although a qualified biochemist, his forte was science fiction! Besides his preposterous claim that "blue-green algae" (i.e. cyanobacteria) "are very simple cells" (they are in fact among the most complex of all cells) Asimov forgets that there is no such thing as "a primitive form of photosynthesis" or "simple chloroplasts":
"Certain magnesium-porphyrins would form with the capacity for making use of the energy of visible light for the building up of complex compounds from simple ones-a primitive form of photosynthesis. These magnesium-porphyrins, constantly being ingested by cells, must, on at least one occasion, have remained to be incorporated into the cellular structure. Even the inefficient use of visible light in the first magnesium- porphyrin cells must have given them a tremendous advantage over ordinary cells at a time when the ultraviolet light was slowly being shut off. In the end, all our photosynthesizing cells may have originated from a single original, which may have been analogous to what we call, today, a chloroplast. Signs of that original chloroplast remain. There are two thousand species of a group of one-celled photosynthesizing organisms called `blue-green algae.' (They are not all blue-green, but the first ones studied were.) These are very simple cells, rather bacteria-like in structure, except that they contain chlorophyll and bacteria do not. Blue-green algae might almost be viewed as single, rather large, chloroplasts, and they may be the simplest descendants of the original chloroplast. ... It may be, then, that along with the simple chloroplasts and mitochondria formed in the slowly oxygenating seas, there would be certain large anaerobic cells, too. If the latter ingested the former and retained them, we would have the `modern cell' of today. And if such a scheme is valid, depending as it does on random processes, why could it not happen on planets other than the Earth? It would seem that on any planet that is sufficiently Earth-like in properties and in chemistry, life would be bound to form. According to some estimates ... there may be as many as 640,000,000 Earth-like planets in our own Galaxy alone. What precise form such life might take we cannot say, but the thought that it may exist there at all is an exciting one. The difficulties of exploration beyond the solar system are enormous, but the rewards in terms of knowledge are enormous, too. Perhaps some day-some far-distant day-men will get out there to see." (Ibid., pp.185-187. My emphasis)
the "photosynthetic process" being "an intricate and well- organized mechanism that acts as a smoothly-working whole ...that includes many steps," requiring a "complete assembly-line" that "contains not only chlorophyll and carotenoids, but a full complement of enzymes, coenzymes and activators as well, all properly and intricately arranged" into "a self-contained photosynthetic unit"!
Asimov's materialist assumption that "such a scheme is valid, depending as it does on random processes" (apart from its inherent absurdity that a "complete assembly-line," "all properly and intricately arranged," into "an intricate and well-organized mechanism that acts as a smoothly-working whole to carry through a photosynthetic process that includes many steps" could be formed by "random processes"), is self- contradicted by that he conceded that it happened only once: "on at least one occasion," and "all our photosynthesizing cells may have originated from a single original"!
PS: I have decided to quote a different verse from the Bible on creation as my `tagline' for each post.
Stephen E. Jones, BSc (Biol).
Genesis 1:1. "In the beginning God created the heavens and the earth."