Before there was life on earth, which gas was absent from the ancient atmosphere?

A. ammonia

B. methane

C. nitrogen

D. Oxygen

Which type of soil holds the most water

Which statement best describes one way that both plants and animals fight pathogens? A. Both have an antigen-antibody response. B. Both have a protective outer layer. C. Both produce lymphocytes. D. Both have a lymphatic system.

Which of the following pairs does not fit the pattern shown by the other pairs? A. amino acids, protein B. fatty acids, DNA C. glucose, starch D. ribonucleotide, RNA

What type of digestion is used to break down small food particles by enzyme action?

How the moisture in a maritime polar (mp) air mass that formed over the north pacific ocean would modify as it moved inland over the western coast of north america.?

Simpler communications and decreased miscommunications are associated with

What is the signal for a vesicle storing peptide hormone to move to the plasma membrane and release contents of vesicle? a. Activation of an integrin receptor b. Activation of a g-protein c. Activation of an enzyme linked receptor d.

Which factor causes the greatest increase in an area's flash flood risk?

A body weight that is 10 to 15 percent below the desired weight is

How should we properly understand human nature?