Practice 1: Which of the following are the major structures of the nervous system. Check all that apply.
A. Brain
B. Heart
C. Lungs
D. Stomach
E. Spinal cord
F. Nerves

Cells destroy body cells infected by a virus or bacteria.

What type of plant is good for a bioassay and where can i buy it? i only have a month.

What's wrong with this ecological pyramid? (multiple choice)1. secondary consumers should be at the bottom of the pyramid2. the sun has an arrow leading to decomposers 3. primary consumers should come after the sun4. energy retained should increase from the bottom to the top5. the sun should be at the bottom of the pyramid