学霸笔记

Lect 1  Introduction to Biochemistry 1. Briefly explain about basic chemistry. Atom: the smallest particle of an element and it retains characteristics of element. Each atom has an equal no of proton and electron(electrically balanced). Each atom has ability to work(chemical energy from electron). Nucleus: center of an atom, contain protons and neutrons. Proton: Positively charged. Neutron: Neutral. Electron: move in regions outside the nucleus. Negatively charged. Element: substances that cannot be broken down into simpler substances. It consists only one atom. Ex: H, O, C. Each element has a set of properties that distinguish it from the others. Ex: O2 is odourless/colourless at room temperature. Molecule: smallest unit of compound. It has properties of compound. Ex: ratio H:O=1:2, formula is H2O. Ion: electrically charged (+/-) molecule Compound: substances made from elements. Chemical formula shows kind and proportions of atom. Ex: salt NaCl. 2. Briefly explain about organic an...

Practice 1 - Main Idea Read the text below and choose the best answer for the following questions.              Global warming, the result of man’s industrial activities, cannot be stopped or slowed down in a short period of time. Greenhouse gases, such as methane and carbon dioxide, are in the atmosphere in much greater concentrations today than ever before. These gases, which have built up over hundreds of years, are triggering certain reactions in the atmosphere.             One such reaction is the warming of the earth. Most scientists agree that the concentration of greenhouse gases will continue to rise for the next few decades. They further predict that temperatures will rise steadily, resulting in hotter, drier world. The resulting climate change from global warming will have real and serious consequences. For example, sea levels will rise by 18 to 59 centimetres.             There is ...