Answer:
The Cell.
Explanation:
Living organisms are composed of single or multiple cells. The cell is termed the building block of life. Single cell organisms are called unicellular while multiple cell organisms are called multicellular. A single cell organism is capable of performing all the basic functions of life like reproduction, respiration etc
It’s corresponding molecule that or bonds to. I think it is a substrate.
The ostrich doesn't strictly live in one biome, while it is true that they live in a warmer, dryer climate most of the time. But they are also known to live in colder regions as well, they live a nomadic lifestyle, as long as they can find food and water they can live happily.
Hope this helps!