Exploring Life - Exploring Life (Chapter 1) Life exists...

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Exploring Life (Chapter 1) Life exists from the microscopic scale to the global. Living systems are much more than the sum of their parts. Organisms include a great diversity of species. Evolution accounts for life’s unity and diversity. Biologists use discovery science and hypothesis-based science to explore life. The Chemical Context of Life (Chapter 2) Matter consists of chemical elements in pure form and in combinations called compounds. An element’s properties depend on its structure. o Protons and neutrons are in the nucleus. o Electrons exist at different energy levels in electron shells; the outermost is the valence shell. Atoms with incomplete valence shells can form chemical bonds with other such atoms by sharing, gaining, or losing electrons. o In a covalent bond, 2 atoms share a pair of electrons. (Double or triple bonds can also form).
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o Electron transfer forms ions. An ionic bond is the attraction between oppositely charged ions. o Weak bonds include hydrogen bonds and van der Waals interactions. Chemical reactions make and break chemical bonds as reactants are converted to products. Water (Chapter 3) Water molecules are polar. Hydrogen bonding between water molecules gives water unique properties that allow life to exist on Earth. o Cohesion and adhesion allow capillary action, which functions during water transport in plants. o Waters high specific heat and high heat of vaporization moderate temperatures on Earth. o Ice floats because hydrogen bonds lock water in a crystalline lattice that reduces its density. o Water is a versatile solvent. o Hydrophilic substances have an affinity for water, while hydrophobic substances repel water. Dissociation of water molecules affects the pH. o Acidic solutions have a pH < 7.
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o Basic solutions have a pH > 7. o Buffers minimize changes in pH. Carbon and Molecular Diversity (Chapter 4) Organic chemistry is the study of carbon compounds. Carbon atoms can form diverse molecules by forming bonds with up to 4 other atoms.
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Exploring Life - Exploring Life (Chapter 1) Life exists...

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