Solved cryptogram
Iron at the heart of hemoglobin is what lets your blood carry oxygen around your body.
Biology Facts, sourced to Royal Society of Chemistry.
What it means
Each hemoglobin molecule holds four iron atoms, and each of those can grab one oxygen molecule in the lungs and release it in the tissues. The binding is reversible, which is the whole trick. Carbon monoxide is dangerous because it binds to the same site far more tightly and does not let go, so the blood is still full of iron and can no longer carry anything.
The claim comes from Royal Society of Chemistry, and the page it comes from was read on 2026-08-27 to confirm it still says this.
This is not the kind of claim that goes out of date, which is why it was set as a puzzle rather than a fact with a shelf life.
Solve it yourself
This fact is a cryptogram here: 70 letters over 20 different ones, graded hard.
- SourceRoyal Society of Chemistry
- CollectionBiology Facts
- Difficultyhard
- Length70 letters, 20 of them different
Nearby in the collection
The facts either side of this one.
- Royal Society of Chemistrymedium, 71 letters
- Royal Society of Chemistrymedium, 78 letters
- U.S. Geological Surveyhard, 66 letters
- National Eye Institutemedium, 73 letters
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