<span>1. O negative
2. O positive
3. A negative
4. A positive
5. B negative
6. B positive
7. AB negative
<span>8. AB positive</span></span>
Cell Membrane because it transport nutrients into the cells and also transport toxic substances out of the cell .
The nitrogen cycle. Animal and plant waste decomposes and adds nitrogen to the soil, which bacteria convert into a form that plants use to grow. Animals eat the plants, which completes the cycle.