BIOL 1201 Chapter : BIO Chapter 2
Document Summary
Biologists specialize in the study of life. Organisms and their environments are natural systems to which the concepts of chemistry and physics apply. This chapter focuses on the chemical components that make up all matter. 2. 1: matter consists of chemical elements in pure form and in combinations called compounds. Organisms are composed of matter: matter- anything that takes up space and has mass. Elements- substance that cannot be broken down to other substances by chemical reactions. Chemists recognize 92 elements occurring in nature. Compound- substance consisting of two or more different elements combined in a fixed ratio: nacl. A compound has characteristics different from those of its elements. 20-25% of the 92 natural elements are essential elements that an organism needs to live a healthy life and reproduce. Essential elements- similar among organisms, but there is some variation: humans need 25 elements, plants need 17. Oxygen, carbon, hydrogen, and nitrogen make-up 96% of living matter.
