What was the purpose of adding iodine after the application of the principal stain?

Which of the following statements is most likely correct about a rock belonging to the jurassic age and a rock belonging to the cambrian age? options: 1) they have identical fossils of organisms that have evolved over time. 2) both have animal fossils preserved in them due to weathering and erosion. 3) they contain different fossils because life on earth has changed through time. 4) the fossils in them were formed on the surface of earth due to exposure to sunlight.

Omg substrates with the same size and shape as the active site will bind to the enzyme. why is the key labeled the “bad” substrate?

Why is a mushroom considered a heterotroph