when listing the levels of organization in organisms from the least complex to the most complex what level is below organs in complexity

Out of the seven main animal groups (fish, mammals, birds, insects, reptiles, amphibians, and arachnids), how many contain members with internal backbones? a. 5 b. 3 c. 7 d. 1

Abnormal softening of a gland is known as

When analyzing tree rings, what do scientists assume a thin ring indicates?