Biology Chapter 2 Review

Transcription

1 Biology Chapter 2 Review Vocabulary: Define the following words on a separate piece of paper. Element Compound Ion Ionic Bond Covalent Bond Molecule Hydrogen Bon Cohesion Adhesion Solution Solute Solvent Acid Base ph Monomer Polymer Peptide Bond Chemical Reaction Reactant Product Bond Energy Equilibrium Activation Energy Exothermic Endothermic Catalyst Enzyme Substrate Active Site Short Answer: Answer the following questions in complete sentences on a separate piece of paper. 1. Potassium ions (K + ) have a positive charge. What happens to a potassium atom s electrons when it becomes an ion? In order for Potassium to become a positive ion it must lose electrons. 2. How is hydrogen bonding among water molecules related to the structure of the water molecules? Because water molecules are polar, it allows hydrogen bonds to form between the positively charged Hydrogen atoms of one molecule with the negatively charged Oxygen atom of another molecule. 3. Explain the difference between solvents and solutes. A solvent is the substance present in the greatest amount. The solute is the substance in the lesser amount that is being dissolved in the solvent. 4. Describe the relationship between hydrogen ions (H + ) and ph. How is ph related to a solution s acidity? ph measures the concentration of H + ions. The higher the ion concentration the power the ph. 5. Carbon forms a very large number of of compounds. What characteristic of carbon atoms allows the formation of all of these compounds? Explain. Carbon only has 4 valence electrons. This allows it to form covalent bonds easily, and it can have up to 4 covalent bonds at any one time. 6. Identify and explain examples of monomers and polymers in carbohydrates, proteins, and nucleic acids.

2 Carbohydrate monomers are glucose or fructose. An example of a polymer would be starch or glycogen. Protein monomers are amino acids. A protein would be a polymer of those amino acid monomers. Nucleic acids monomer would be a DNA molecule (with a phosphate group, sugar, and base) or an RNA molecule. Nucleic acid polymer would be the whole DNA molecule or RNA molecule, where nucleic acids are linked together through the phosphate and bases. 7. Explain the relationship between a protein s structure and its ability to function. In order for a protein to function its structure must be correct. If the structure is wrong, it will not be able to serve its function. 8. Explain the difference between exothermic and endothermic reactions. An endothermic reaction absorbs more energy in the form of activation energy than it releases. An exothermic reaction releases more energy than it absorbs in activation energy. 9. What is the role of enzymes in organisms? Enzyme help to allow chemical reactions to take place in a given place and in a time frame that helps the organism. It also allows for specificity in an organisms reactions. 10. How are phospholipids similar to lipids such as triglycerides? How are they different? Phospholipids are similar to triglycerides in that they both contain fatty acids. Phospholipids are different from triglycerides in that the fatty acids are attached to a phosphate group that makes the molecule have a polar head and a nonpolar tail. Triglycerides are three fatty acids attached to a glycerol molecule. 11. Suppose that you have a cold. What characteristics must cold medicine have that allow it to be transported throughout your body? Explain. The cold medicine would have to be polar to allow it to be absorbed by your blood to travel through your body. 12. Describe the structure and function of starch and cellulose. How are the molecules similar? How are they different? Starch has the same molecule in the same orientation (glucose). Cellulose also utilizes glucose, but every other molecule is upside down. 13. Suppose you had a friend who wanted to entirely avoid eating fats. What functions of lipids could you describe to convince that person of the importance of fats to his or her health? Lipids are important in your cell membranes. They are used for both the phospholipid bilayer and for the cholesterol within the bilayer. Therefore, without some fats, you re cells would not function properly. 14. List and briefly explain the three properties of water that make it an important molecules in our bodies. 1. Water has a high specific heat, which allows it to absorb the heat produced by chemical reactions in our cells. 2. Cohesion: Water sticks to other surfaces, allowing it to move through places like the roots of plants. 3. Adhesion: water sticks together, allowing it to move as a unit 15. How do the structures of saturated fatty acids and unsaturated fatty acids determine what state we find them in (solid, liquid, gas)?

3 Saturated fatty acids have carbons that are completely saturated with hydrogens. They are generally straight. Unsaturated fatty acids have some double or triple bonds where the carbon is not saturated with hydrogens. This causes the molecule to bend. Therefore, saturated fatty acids can become solids because they are straight and are easily packed close together. Unsaturated fatty acids are hard to pack together and therefore end up being found more in liquid form. 16. List and briefly describe the four layers of protein structure. Primary: The individual amino acids Secondary: The alpha helices and beta sheets formed by the amino acids Tertiary: The relationship between alpha helices and beta sheets to each other Quaternary: The 3 D shape of the protein 17. DNA and RNA are both examples of nucleotides. How are they different? How are they the same? DNA has deoxyribose sugar, with the bases A, T, C, G. RNA uses ribose sugar with bases A, U, C, G. Multiple Choice: 1. Which four elements make up 96% of the human body? a. Calcium, Phosphorus, Potassium, and Sodium b. Carbon, Oxygen, Sodium, and Calcium c. Carbon, Oxygen, Nitrogen, and Hydrogen d. Phosphorus, Potassium, Sodium, and Hydrogen 2. Which of the following bonds between atoms is strongest? a. Ionic Bond b. Covalent Bond c. Hydrogen Bond d. Peptide Bond 3. What term describes the sugar in a glass of lemonade? a. Solvent b. Solution c. Solute d. Protein 4. What is the ph of a neutral solution? a. 3 b. 11 c. 1 d. 7

4 5. In what kind of molecule are the instructions for building proteins stored? a. Carbohydrate b. Nucleic Acid c. Protein d. Lipid 6. What are the reactants and the products in the following reaction? 2H 2 >2H 2 O + a. Reactant: H 2 ; products: H 2 O and b. Reactants: H 2 O and ; product: H 2 c. Reactants: H 2 and ; product H 2 O d. Reactants: H 2 O and H 2 ; products H 2 O and 7. What happens when a chemical reaction reaches equilibrium? a. Reactants are made at a faster rate than products are. b. Products are made at a faster rate than reactants are. c. Products are no longer made d. Both reactants and products are made at equal rates. 8. What happens to a catalyst during a chemical reaction? a. It is destroyed. b. It combines with the product. c. More catalyst molecules are made. d. It is not changed. 9. How does a catalyst affect the activation energy of a chemical reaction? a. It raises the activation energy of the reaction. b. It lowers the activation energy of the reaction. c. It has no effect on the activation energy of the reaction. d. First it lowers the activation energy to start the reaction, then it raises the activation energy to keep the reaction under control. 10. What conditions are likely to affect the shape of an enzyme? a. Concentration of substrate b. temperature c. ph d. both temperature and ph

5 Diagrams: 1. Label the charges (positive or negative) on the water molecule below. Positive Negative 2. In the the diagram below, what do the lines between the individual atoms stand for? Each individual line stands for a covalent bond between 2 electrons. 3. Label the diagrams below as a saturated fatty acid or an unsaturated fatty acid. Saturated Unsaturated 4. Label the parts of the phospholipid bilayer below, identifying which part is hydrophilic and which part is hydrophobic.

6 Hydrophilic (water loving) polar heads Hydrophobic fatty acid tails Hydrophobic fatty acid tails Hydrophilic (water loving) polar heads 5. Draw the structure of an amino acid below. Label the four parts that make up the backbone of each amino acid.