It seems to me the correct answer would be nucleous
If you were to cross a large redwood tree, like for an example a sequoia, from the middle of the trunk you would first cross the annual rings, indicators of the trunk growth over the years, then after that you would cross the phloem, the ''piping'' of the tree responsible for the transport of water throughout the tree and in the end you would cross the tree's bark, the protective layer on surface of the trunk.
Provided that there's no diagram, most molecules have particular areas on the molecules, called the "active area" that act as a lock to a particular substrate's molecular structure, providing the key.
An enzyme's active area is only able to be "unlocked" by a certain substrate's "key".
Answer: The environment changed suddenly from a shallow ocean setting to a river system.
Explanation: Changes seen in rock layers represent changes in Earth's local history. The rock layer stack overall shows a shallow ocean setting. But the youngest layer at the top was deposited by a river. This shows the geologist that the local environment changed suddenly from an ocean setting to a river system.
