# 🧬 NOTES - BIOLOGY nitrogen, which is a proxy for protein, CAM (crassulacean acid metabolism) Roughly >20k edible plants, but 90% of calories come from 20 of them, and 50% come from wheat/rice/maize. entire clades (evolutionary groups) compensation point light intensity or CO₂ concentration at which the rate of photosynthesis exactly equals the rate of respiration in a plant animals and plants respire burn sugars to create new tissue chemical compounds to defend daily metabolic processes for survival - put some energy in storage reserves in the form of starch and sugar - produce defense chemicals (alkaloids, toxins, etc) and mechanical defense (spines, thorns, hairs, wax) - produce reproductive tissues like pollen, nectar, flowers and fruits/seeds for plant to grow it must be above compensation point Respiration (which burns sugars for energy) increases exponentially with temperature (roughly doubling every 10°C rise). warm nights mean the plant burns more stored carbohydrates (sugars, starch) just to maintain basic metabolism What is the proposed mechanism for implementing a cut back? A global population with 8 billion people and 1950s carbon emissions implies an average living standard somewhere in the realm of the 1900s. Are you volunteering to move back to the horse and buggy? Bear in mind that the industrialized world of 1950 was only inhabited by a small portion of the global population at most a billion people. The only path forward is technological innovation to reduce or remove carbon emissions. Plant metabolism depends on temperature and light in a way they can't control. If it's too warm and/or sunny, plants "run too hot" and exhaust themselves to death. If it's too cold or shady, they can't "run enough" and die from inadequate fuel and other biochemical precursors. C3, C4, CAM There are three main types of photosynthesis: C3, C4, and CAM (Crassulacean Acid Metabolism). C3 is the most common, while C4 and CAM are adaptations that help plants conserve water and thrive in hot, dry environments. C3 and C4 photosynthesis are two different pathways that plants use to convert carbon dioxide into sugars. C3 plants, which include most plants, fix carbon dioxide into a three-carbon compound, while C4 plants, like maize and sugarcane, fix it into a four-carbon compound, allowing them to be more efficient in hot and dry environments. mushrooms respire by taking in oxygen and producing carbon dioxide, similar to humans. photosynthesis - chemical process energy (sun) -> food / glucose (sugar) chloroplasts in cell ; green pigment / chlorophyll absorbs light glucose -> cellulose / starch (for energy storage) glucose - respiration is one of the most important processes for all living thing cellular respiration stomata aerobic respiration dark respiration (no light) photorespiration (light involved) night respiration - cooler during the day plants get stressed from working all day Natural Science Biology Earth Science Geology Geochemistry Hydrology Chemistry Physics Organic chemistry focuses on compounds that contain carbon, particularly those with carbon-hydrogen bonds inorganic chemistry deals with compounds that typically do not contain carbon-hydrogen bonds, such as metals and minerals. Both fields study the properties, reactions, and structures of various chemicals, but they emphasize different types of compounds. Khan Academy https://www.khanacademy.org/science/biology/intro-to-biology https://openstax.org/details/books/biology-2e all cells derive their energy from a single type of chemical reaction, the redox reaction, where electrons are transferred from one molecule to another in the end respiration and burning are equivalent; the slight delay in the middle is what we know as life