AP Biology Exam Review

• Elements


  Elements are substances that cannot be broken down into simpler substances by chemical means.

  
• Oxygen


  Oxygen is an element with symbol O and atomic number 8. It is a highly reactive nonmetal and oxidizing agent. In living organisms, oxygen is used in respiration and in a number of organic molecules.

  
• Carbon


  Carbon is an non mental element with symbol O and atomic number 6. It is the second most abundant element in living organisms and is present in all organic compounds.

  
• Hydrogen


  Hydrogen is an element with symbol H and atomic number 1. Hydrogen combines with non-metallic elements to form water and other organic compounds.

  
• Nitrogen


  Nitrogen is an element with the symbol N and atomic number 7. In biology, nitrogen is important as it is found in a number of organic compounds and is used in fertilizers and antibiotics.

  
• Trace elements


  Trace elements are elements required by an organism in very small quantities. Trace elements include iron, iodine, and copper.

  
• Atom


  An atom is the smallest unit of an element that retains its characteristic properties; they are the building blocks of the physical world.

  
• Protons


  Protons are positively charged subatomic particles that are found in an atom's nucleus.

  
• Neutrons


  Neutrons are uncharged subatomic particles found in an atom's nucleus.

  
• Electrons


  Electrons are negatively charged subatomic particles that spin around the nucleus.

  
• Nucleus


  The nucleus is the positively charged core in an atom made up of neutrons and protons.

  
• Isotopes


  Atoms that have the same number of protons but differ in the number of neutrons in the nucleus are called isotopes.

  
• Compound


  A chemical compound is formed when two or more different types of atoms are combined in a fixed ration.

  
• Chemical reaction


  A chemical reaction describes a chemical change in which reactants react to form products chemically different from the reactants.

  
• Chemical bond


  The atoms of a compound are held together by chemical bonds, which may be ionic bonds, covalent bonds, or hydrogen bonds.

  
• Ionic bond


  An ionic bond is formed between two atoms when one or more electrons are transferred from one atom to the other. In this case, one atom becomes negatively charged and one atom becomes positively charged.

  
• Ions


  An ion is a charged form of an atom.

  
• Covalent bond


  A covalent bond is formed when electrons are shared between atoms and can be polar or non-polar.

  
• Non-polar covalent


  A non-polar covalent bond is a covalent bond in which the electrons are shared equally between the atoms.

  
• Polar covalent


  A polar covalent bond is a covalent bond in which the electrons are shared unequally - one atom attracts electrons more than the other.

  
• Polar


  A molecule is polar if it has partially positive and partially negative charged ends, such as water.

  
• Hydrogen bonds


  Hydrogen bonds are intermolecular attractions that form when a hydrogen bond that is covalently bonded to one electronegative atom that it also attracted to another electronegative atom. Hydrogen bonds are individually weak but are strong when present in large numbers.

  
• Cohesion


  Cohesion refers to the tendency of water molecules to stick together and allows water to have a high surface tension.

  
• Adhesion


  Adhesion refers to the tendency of water molecules to stick to other substances, which accounts for the phenomenon of capillary action.

  
• Capillary action


  Capillary action is the ability of water, or other liquids, to travel against gravity in a thin vessel and accounts for the ability of water to rise up the roots, trunks, and branches of trees.

  
• Heat capacity


  Heat capacity refers to the ability of a substance to store heat and is the quantity of heat required to change the temperature of a substance by 1 degree. Water has a high heat capacity, allowing it to keep a fairly stable temperature in our bodies and in the environment.

  
• Surface tension


  Surface tension is a property of water, due to the cohesiveness of its molecules, that allows things (sometimes organisms) to float and stride on its surface without sinking.

  
• Acidic


  A solution is acidic if it contains excess hydrogen ions. It will have a pH less than 7.

  
• Basic


  A solution is basic if it releases hydroxide ions when added to water. These solutions are said to be alkaline and are usually slippery.

  
• Neutral


  A solution is neutral, neither basic nor acidic, if it has a pH of 7.

  
• pH scale


  The pH scale is a logarithmic scale to measure acidity, with 1 being most acidic, 14 being most basic, and 7 being neutral.

  
• Organic compounds


  Organic compounds are compounds that contain carbon and include carbohydrates, lipids, proteins, and nucleic acids.

  
• Inorganic compounds


  Inorganic compounds are compounds that do not contain carbon atoms (except for some simple carbon compounds such as carbon oxides)

  
• Carbohydrates


  Carbohydrates are organic compounds that contain carbon, hydrogen, and oxygen, usually in a ratio of 1:2:1.

  
• Monosaccharides


  Monosaccharides are the simplest sugars which serve as an energy source for cells. The two most common monosaccharides are glucose and fructose.

  
• Disaccharides


  Disaccharides are formed by two sugar molecules combining together through dehydration synthesis. An example of a disaccharide is maltose, make by linking two glucose molecules.

  
• Polysaccharides


  Polysaccharides are made up of many repeated unites of monosaccharides, and is therefore a type of polymer. The most common polysaccharides are starch, cellulose, and glycogen. Polysaccharides are often storage forms of sugar.

  
• Glucose


  Glucose is the most abundant monosaccharide and is a six-carbon sugar with the chemical formula C-6, H-12, O-6. Glucose comes in two forms: alpha glucose and beta glucose, which differ simply by a reversal of the H and OH of the first carbon.

  
• Fructose


  Fructose is a monosaccharide that is a common sugar in fruits. It is a six-carbon sugar with the chemical formula C-6, H-12, O-6.

  
• Glycosidic bond


  A glycosidic bond is a covalent bond in which a carbohydrate binds to another group, which could also be a carbohydrate. A glycosidic bond is found between the two glucose molecules in maltose.