What is the meaning of the word "compelling" as it is used in the following sentence?

What would happend if organ systems failed to work together

Biologists recognize five levels of cell organization. the lowest and simplest is the cellular level. organisms here are either unicellular organisms, like protozoa, or colonial organisms. colonial organisms are composed of single-celled individuals that stay together to sustain the life of the whole colony. next on the scale of complexity is the level occupied by tissue. a tissue is a group of similar cells which perform a similar activity. tissues that are organized around a common function together make up an organ, the third level of complexity. the fourth level of organization is the system, formed by a group of organs which together perform a specific bodily process. the fifth and highest level is the organism level, in which body systems work together in a structure capable of independent life. main idea:

The purpose of an informative essay is to express personal feelings about a topic. describe events from a certain point of view. instruct the reader about a topic. express and defend an opinion.