Celestial phenomena have intrigued humans for centurys.

a. centurians

b. centureys

c. centuries

d. correct as is

Which organelle makes the protein that are needed by the cell

What properties of bone prevented matt from breaks and damage to internal organs?

Suppose that a glutamine residue in the active site of an enzyme was mutated to alanine. As expected, the alanine mutant was inactive, suggesting that the glutamine residue was critical to the catalytic mechanism.

Most organs are composed of what?

Explain why fewer plant are at the bottom of deep lakes.

Which phrase describes the way air particles vibrate with respect to the way a sound wave travels? A. Opposite to B. Parallel to C. Equal to D. Perpendicular to

Global climate change will have no impact to life on the Earth.

What makes sexually reproduced offspring genetically different from their parents?

When a person pushes a large load up an inclined plane, where does the person get the energy to do this task? A. The chemical energy in from his food is transformed into mechanical energy. B.

What is the source of the oxygen released into the air as a product of photosynthesis?