A concentration gradient because diffusion is from a higher concentration to lower concentration.
They let things in and out
Answer:
tissues --> organs --> organ system --> whole organisms
Explanation:
The simplest is tissues, while the most complex is whole organisms.
1) Tissue is an aggregation of cells
2) Organ is composed of tissues that perform similar functions.
3) Organ system refers to a group of organs that work together and coordinated to perform one or more functions. An example is the nervous system.
4) whole organism is a discrete and complete living thing, such as animal. It comprises of tissues, organs, organ systems all working together as a coordinated unit.
Answer:
The researchers are studying mockingbirds as part of an effort to better understand how species adapt to urbanization.