How do scientists determine when an era ends and an era begins

Which process accomplishes the movement of gases illustrated by the arrows in the diagram

In small populations gene frequencies can change drastically by chance alone this is called

Is a snail an vertebrate or an invertebrate

Which cell would be most efficient at absorbing nutrients? A cell with a 8:1 surface area to volume ratio or a cell with a 5:1 surface area to volume ratio? Why?

What other systems/organs work with the circulatory system? Skeletal System Digestive System Nervous System Excretory System

What is the primary function of the juxtaglomerular complex?

Which is an example of how stem cells are currently being used

Describe the type of evidence that scientists used for classifying organisms before they were able to sequence dna

Which of the following is true for DNA but not RNA? Release of PPi from the monomer provides the energy for polymerization. It has 4 different bases. It has secondary structure. None of the above; all are true for both DNA and RNA

What are two important things we use gymnosperms for?