Number and variety of living organism; includes genetic, species, and ecological types

Ageologist determines that a sample of a mineral cant be scratched by a steel nail but can be scratched by a masonry drill bit based on this information the sample mineral has to be softer than

Which statement is true about the cell theory? a) it is well-supported by evidence. b) it is unchangeable and permanent.

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