explain how to how it is possible to have thousands of different proteins when there are only 20 different animal acid

Are the raw materials for respiration the opposite of the end products for photosynthesis?

How many trees are in one piece of paper?

Two atoms are different isotopes of the same element. Therefore, these two atoms have differing numbers of___. A. Protons B. Neutrons C. Charges D. Electrons

The species richness of a community refers to the A) number of food chains. B) number of different species. C) energy content of all species. D) relative numbers of individuals in each species. E) total number of all organisms.

What are the sources of fresh water in California

After a hypothesis has been repeatedly tested and becomes widely accepted, it is considered a

The root of the tooth is held by the periodontal ligament a. True b. Falsee

At the center of the Andromeda galaxy is a source of x rays that scientist believe is a black hole with how many more times than the sun

True or false? The more similar two organisms are, the more distant their common ancestor is.

The blood-brain barrier a. is fully developed in humans when they are born. b. prevents many drugs from entering the brain. c. is designed to allow all drug compounds into the brain. d. cannot be penetrated, even with trauma to the brain.