2. Plant and Leaf

Table of Contents Introduction Oxygen, carbohydrates Plant and leaf Photoautotropism Photsynthesis and Technology Historical perspective Photosynthesis Equation Light in Photosynthesis Structures of the leaf The Menora

Science

Living creatures can be divided into two categories, based on how they utilize resources in order to survive. Heterotrophs are organisms that need to eat or digest other organisms in order to survive, while autotrophs are organisms that can survive by use of inorganic (inanimate) matter alone. Photosynthesis is the most important process enabling organisms to be autotrophic. Autotrophs that utilize the process of photosynthesis are more specifically referred to as photoautotrophs. (There are a small number of organisms that utilize chemical processes other than photosynthesis in order to survive; they are generally classified as chemoautotrophs.) Quantitatively, photosynthesis produces approximately 160 billion tons of carbohydrates each year-there is no chemical process on earth that is more productive.

Kabbalah

Human respiration acts in an opposite way to that of photosynthesis in plants: while plants in the light absorb carbon dioxide and emit oxygen, humans absorb oxygen and emit carbon dioxide. Similarly, plants, when in the light, manufacture carbohydrates while humans, incapable of manufacturing them themselves, only digest them. When out of the light, e.g. during nighttime, plants are like humans and digest the food that they produced through photosynthesis during the day. Humans in our world are defined as heterotrophs.

Nevertheless the Torah speaks of a future person, the Messiah (, Mashiah), who will function, like plants, as an autotroph-more specifically, as a photoautotroph. The first hint of this is the fact that Mashiah is referred to both by the prophets and by our sages as a 'plant' (, tzemah) .

Our sages have described the 'Coming World' (, olam haba) as a place where "the righteous sit, their crowns on their heads, enjoying [var., nourishing themselves from] the radiance of the Shehinah [G-d's indwelling presence]." The expression "their crowns on their heads" alludes to the sefirah of Crown which, as stated earlier, corresponds to the human respiratory system. Hence, by nourishing themselves with Divine light ('the radiance of the Shehinah' ) and air alone, the Righteous Ones (, tzadikim)-those individuals who conduct themselves in a righteous manner-in the Coming World will possess qualities similar to today's photoautotrophic organisms-plants. The light in this case is 'the radiance of the Shehinah,' or, in other words, the future Divine revelation which will permeate all of creation and be beheld by all flesh, and it will be this revealed Divine 'light' that will be used as a source of physical nourishment.

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