Help is very much appreciated <3 (7th grade science)

1. N/A

2. a cell

3. organ system

4.Tissues are groups of similar cells that have a common function. While an organ is a structure that is composed of at least two or more tissue types and performs a specific set of functions for the body.

5.

nervous system - The nervous helps the whole body communicate, our body needs to communicate so we can actually do things like breathing.

respiratory system - The respiratory system gives cells the oxygen they need to survive, and cells keep humans alive. Humans cannot survive without breathing.

digestive system - The digestive system is important for breaking down foods into nutrients, those nutrients are then used to heal and nourish the human body. The digestive system also helps us pass toxic wastes that build up in our bodies, so we don't get sick.

hope this helps :)

atp is used for energy.