Before there was any life on earth, which gas was absent from earth's ancient atmosphere?

A. nitrogen

B. ammonia

C. oxygen

D. methane

A person who is depression-prone tends to have increased activity in his or her:

The neuroglia that produce the myelin sheath around axons in the peripheral nervous system are called: a. Schwann cells. b. oligodendrocytes c. microglia. d. astrocytes e. satellite cells.

Which of the following is a function of the cell membrane of a cell? A. The production of energy from food molecules using cellular respiration. B. The production of genetic material through DNA transcription. C.

The general term for small photosynthetic organisms found near the surface of the coean is

Genes involved in the production of abnormal red blood cells have an abnormal sequence of

20. In certain species of summer squash, fruit color is determined by two interacting genes. A dominant allele, W, determines white color, and a recessive allele (w) allows the fruit to be colored.

When you look out the window, you can see constantly moving air. air is cycled in order to reach equilibrium. B) since these change the density of air and we know the air flows from the region of high density to the region of low density.

What effects do deforestation have on the animals?

Which best defines a diploid cell during meiosis? a cell that has double the number of chromosomes as the parent cell a cell that has half the number of chromosomes as the parent cell a cell that has double the number of chromosomes as the daughter

What is the best definitionof magnetosphere? a. a magnetosphere is a magnetic field around earth. b. a magnetosphere is the groups of atoms that are lined up inside a magnet. c.