BSCI 105 Lecture 2: BSCI105 Chapter 2- The Chemical Context of Life
27 Jan 2016
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Bsci105 chapter 2: the chemical context of life 1/26/16 7:00. 2. 1: matter consist of chemical elements on pure form & in combinations called compounds organisms are composed of matter anything that takes up space & has mass. Elements: a substance that can"t be broken down to other substances by chemical reactions (92 elements) Compound: substance consisting of 2 or more different elements combined in a fixed ratio. Essential elements: 20-25% of the 92 elements are needed for organism to live a healthy life and reproduce, but there are some variations; humans need 25 elements and plants 17. 4 elements (oxygen, carbon, hydrogen, and nitrogen) make up 96% of living matters and calcium, phosphorus, potassium, sulfur and a few other account for the rest of the 4% . Trace elements: are required by an organism in only minute quantities and are all needed by all forms of life. (fe (iron) and iodine (i) are the most important. )
