AP Biology Review Question with complete solution 2023

AP Biology Review Question with complete solution 2023Elements 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. AD 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. AD 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.