Only certain battery voltages exist, because this voltage depends intrinsically on the battery's chemical composition.
learn.sparkfun.com/tutorials/battery-technologies/all (CC BY-SA) has a very good summary list, reordered from lowest to highest voltage:
Battery ShapeChemistryNominal VoltageRechargeable?
AA, AAA, C, D (Rechargeable)NiMH or NiCd1.2VYes
AA, AAA, C, and DAlkaline or Zinc-carbon1.5VNo
Coin CellLithium3VNo
Silver Flat PackLithium Polymer (LiPo)3.7VYes
9VAlkaline or Zinc-carbon9VNo
Car BatterySix-cell lead acid12.6VYes
Power, Sex, Suicide by Nick Lane (2006) part 5 "Murder or suicide" mentions that the key events that leads to apoptosis is when certain proteins normally present in the inner mitochondrial membrane spill out, and that this often happens when free radicals are produced in excess: the cell is really not doing well in those cases. This point suggests that the initial mitochondrial endosymbiosis happened due to a parasite that lived inside another cell. It mentions that even today we see parasites kill the host cell when they feel that the cell does not have many nutrients. This frees the parasites to then infect other cells.
All pages below are from the second edition from 2018. It seems that there weren't any changes in the text, the updated preface mentions
As it happens, nearly 15 years have passed since the 1st edition of Power, Sex, Suicide was published, and I am resisting the temptation to make any lame revisions. Some say that even Darwin lessened the power of his arguments in the Origin of Species through his multiple revisions, in which he dealt with criticisms and sometimes shifted his views in the wrong direction. I prefer my original to speak for itself, even if it turns out to be wrong.
This is partly addressed in the preface of the second edition from 2018.
Central thesis:
Smaller points:
Nitpicks:
  • the book calls ATP synthase "ATPase" in several points, which is confusing because -ase means "something that breaks", and in 2020 parlance, there are ATPases which actually break ATP: en.wikipedia.org/wiki/ATPase. The book itself acknowledges that on page 135:
    The ATPase is freely reversible. Under some circumstances it can go into reverse, whereupon it splits ATP, and uses the energy released to pump protons up the drive shaft, back across the membrane against the pressure of the reservoir. In fact the very name ATPase (rather than ATP synthase) signifies this action, which was discovered first. This bizarre trait hides a deep secret of life, and we’ll return to it in a moment.
Some criticisms:
  • some of the later chapters are a bit more boring, like the stuff about warm-blooded animals. Perhaps is it that Ciro Santilli is more interested in the molecular aspects than macro
  • the author talks about some very recent research at the time. While this does highlight his expertise, some of the points mentioned might still be in a state of flow. This is acknowledged by the author himself on the 2018 updated preface however.
Adenosine triphosphate by Ciro Santilli 37 Updated 2025-07-16
The fact that ATP is the universal energy storage mollecule of all life on Earth is such an incredible unifying principle of biology!
It is the direct output of all the major forms of "energy generation" in cells: ATP synthesis mechanism.
It is just as fundamental as the genetic code for example.
No wonder dozens of Nobel Prizes were related to its discovery, given its complexity.
ATP is the direct output of all the major forms of "energy generation" in cells:

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 5. . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact