ah cellular energetics the unit of AP Bio where you know that the answer is oxidative phosphorilation but can't actually remember what it means hey I'm Melanie King it from the absolute recap and I make AP Bio easier with podcast study guides videos and the ultimate review [Music] packet if you're looking for the unit 3 summary video it's inside the ultimate review packet it's still completely free to watch but you'll need to sign up for the free preview with this link and while you're there take a look at all of the other great resources that come with the ultimate review packet like study guides exclusive practice videos practice sheets multiple choice questions and a fulllength AP style practice exam plus everything has answer keys but I don't want to totally leave you hanging so here's a short clip from the summary video with 3.4 cellular energy all living things require a constant input of energy or else well you stop stop living first let's debunk some myths and make our chemistry and physics colleagues happy myth number one energy is released when bonds are broken truth breaking bonds requires energy but the emphasis needs to be on the remaining energy of the products are they at a lower energy state or higher than the reactants it's important to note that the difference in energy from reactants to products Remains the Same in a catalyzed versus uncatalyzed reaction myth number two energy is lost as heat truth the laws of thermody Dynamic state that energy cannot be created or destroyed and the entropy of a system is always increasing energy isn't lost it's just transferred and while yes it is difficult for biological systems to reuse and transfer heat energy into another form it all comes out in the wash some metabolic reactions are energy storing While others are energy relasing but all require activation energy to get started exergonic reactions like ATB hydrolysis and cellular respiration have energy exiting the system with reactants at a higher energy level than the products in contrast endergonic reactions like ATP formation and photosynthesis require additional energy Beyond activation and have reactants at a lower energy level than the products so energy is stored in these products but where does the input energy come from well for ATP perhaps it's chemiosmosis through ATP synthes and for photosynthesis that would be light so if you like my YouTube videos and podcasts you're going to love the ultimate review pocket it has all of the content you need to understand and the skills you need to practice get an A in your class and crush your exams not convinced to sign up yet that's okay you can still listen to the absolute recap biology Edition podcast and watch all of my free videos here on YouTube thanks for watching and I'll see you next recap