Biology Chapter 2
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jillnicolle on October 16, 2011
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70 terms
Terms | Definitions |
|---|---|
 basic unit of matter | atom |
| center of an atom and is made up of protons and neutrons | nucleus |
| Is a proton positive, negative, or neutral? | positive |
| Is a neutron positive, negative, or neutral? | neutral |
| Is an electron positive, negative, or neutral? | negative |
| Why are atoms neutral despite having charged particles? | atoms have equal numbers of electrons and protons and subatomic particles have opposite charges |
| pure substance that consists entirely of one type of atom | chemical element |
| an element's atomic number represents... | the number of protons in the atom |
| atoms of the same element that differ in the number of neutrons they contain | isotopes |
| How are isotopes identified? | By their mass numbers |
| Why do all isotopes of an element have the same chemical properties? | They have the same number of electrons |
| substance formed by the chemical combination of two or more elements in definite proportions | (chemical) compound |
| holds atoms in compounds together | chemical bonds |
| the bond that is formed when electrons are shared between atoms | covalent bond |
| the bond that is formed when one or more electrons are transferred from one atom to another | ionic bond |
| positively and negatively charged atoms | ion |
| Does an atom that loses electrons have a negative charge? | no |
| structure that results when atoms are joined together by covalent bonds | molecule |
| Can atoms share six electrons and form a triple bond? | yes |
| In a water molecule, how many covalent bonds do each hydrogen atom form? | one |
| True or false: When atoms show two electrons, it is called a double bond | false |
| the slight attractions that develop between oppositely charged regions of nearby molecules | Van der Waal's forces |
| Is a water molecule neutral? | yes |
| Why is a water molecule polar? (Think of H2O) | there is an uneven distribution of electrons between the oxygen and hydrogen atoms |
| Is a hydrogen bond stronger than an ionic bond? | no |
| True or false: The attraction between the hydrogen atom on one water molecule and the oxygen atom on another water molecule is an example of a hydrogen bond. | true |
| strongest bonds that form between molecules | hydrogen bonds |
| Is a hydrogen bond stronger than a covalent bond? | no |
| attraction between molecules of the same substance | cohesion |
| attraction between molecules of different substances | adhesion |
| Why is water extremely cohesive? | hydrogen bonding |
| rise of water in a narrow tube against the force of gravity | capillary action |
| How does capillary action affect plants? | it draws water out of the roots of a plant and up into its stems and leaves |
| material composed of two or more elements or compounds that are physically mixed together but not chemically combined | mixture |
| mixture of two or more substances in which the molecules of the substances are evenly mixed | solution |
| What is the greatest solvent in the world? | water |
| mixture of water and non-dissolved materials | suspension |
| substance that is dissolved | solute |
| substance in which the solute dissolves | solvent |
| two water molecules can react to form... | ions |
| Why is water neutral despite the production of hydrogen ions and hydroxide ions? | the number of positive hydrogen ions produced is equal to the negative hydroxide ions produced |
| indicates the concentration of hydrogen ions in solution | pH scale |
| True or False: Acidic solutions have pH values below 7 | true |
| On a pH scale, what is neutral? | 7 |
| Do acidic solutions contain higher concentrations of H+ ions than pure water? | yes |
| any compound that forms H+ ions in solution | acid |
| compound that produces OH- ions in solution | base |
| weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH | buffers |
| How many valence electrons does each carbon atom have? | 4 |
| What gives carbon the ability to form chains that are almost unlimited in length? | a carbon atom can bond with other carbon atoms |
| many of the molecules in living cells are so large that they are known as... | macromolecules |
| process by which macromolecules are formed | polymerization |
| When monomers join together, what do they form? | a polymer |
| What are the four groups of organic compounds found in living things? | carbohydrates lipids nucleic acids proteins |
| What atoms make up carbohydrates? | carbon, hydrogen, and oxygen |
| True or false: Living things use carbohydrates as their main source of energy | true |
| simple sugar molecules | monosaccharides |
| What are two examples of a monosaccharide? | galactose and fructose |
| large molecules formed from monosaccharides | polysaccharides |
| How do plants and animals store excess sugar? | in a polysaccharide called glycogen |
| What kinds of atoms are lipids mostly made up of? | carbon and hydrogen |
| Each carbon atom in a lipid's fatty acid chains is joined to another carbon atom by a single bond | saturated lipid |
| At least one carbon-carbon double bond in a fatty acid | unsaturated lipid |
| A lipid's fatty acids contain more than one double bond | polyunsaturated lipid |
| Nucleic acids contain what kinds of atoms? | hydrogen, oxygen, nitrogen, carbon, and phosphorus |
| What kinds of acids do proteins contain? | amino acids |
| What are two examples of a disaccharide? | lactose and maltose |
| What is one function of a lipid? | they can be used to store energy |
| What is one function of a nucleic acid? | they store and transmit hereditary, or genetic, information (think deoxyriboNUCLEIC ACID- DNA) |
| What is one function of a protein? | they can form bones and muscles |
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