Certain fossils, called index fossils, help geologists match rock layers. To be useful as an index fossil, a fossil must be widely distributed and represent a type of organism that existed for a brief time period. Index fossils are useful because they tell the relative ages of the rock layers in which they occur.
The<em> cell membrane</em> controls the movement of substances in and out of cells and organelles. In this way, it is selectively permeable to ions and organic molecules.
True
I think, could be wrong
Answer: An essay is a common type of academic writing that you'll likely be asked to do in multiple classes. Before you start writing your essay, make sure you understand the details of the assignment so that you know how to approach the essay and what your focus should be. Once you've chosen a topic, do some research and narrow down the main argument(s) you'd like to make. From there, you'll need to write an outline and flesh out your essay, which should consist of an introduction, body, and conclusion. After your essay is drafted, spend some time revising it to ensure your writing is as strong as possible.
