Which picture represents North America in the winter? A B C Or D

Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods.

Which is a function of vascular tissue? a. to perform photosynthesis b. to transport water and nutrients c. to absorb minerals and sugar d. to interact with soil fungi

People with one sickle cell allele are not likely to get malaria. what is this an example of?