True/False
Indicate whether the statement is true or false. Write + for true and 0 for false.
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1. |
Atoms have a positive charge.
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2. |
An element is made up of more than one kind of atom.
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3. |
Hydrogen and oxygen atoms have an equal number of electrons.
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4. |
A molecule is an atom that has gained or lost an electron.
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5. |
An atom that gains or loses one or more electrons is called an ion.
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6. |
An atom with more electrons than protons has a positive charge.
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7. |
Ionic bonds form between two negatively charged particles.
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8. |
A covalent bond forms between two atoms that share electrons to form a molecule.
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9. |
Adhesion is an attraction between different substances.
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10. |
The ability of water to retain heat helps cells maintain homeostasis.
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11. |
Nonpolar molecules dissolve well in water.
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12. |
Water molecules attract nonpolar molecules such as oil.
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13. |
Organic compounds contain carbon atoms that are covalently bonded to other elements—typically hydrogen, oxygen, and other carbon atoms.
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14. |
A nucleotide has four parts.
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15. |
RNA is made up of a double strand of nucleotides.
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16. |
DNA stores hereditary information that can be used to make proteins.
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17. |
When cells break down food, the energy from the food is temporarily stored as ATP.
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18. |
The amount of energy needed to cause a chemical reaction to start is called activation energy.
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19. |
Without enzymes, chemical reactions necessary for life would not occur at a rate sufficient to sustain life.
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20. |
Enzymes speed up a chemical reaction by increasing the activation energy of the reaction.
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21. |
When an enzyme binds with its substrate, the activation energy needed for the chemical reaction to occur is increased.
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22. |
Chemical reactions that occur in cells are called biochemical reactions.
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Multiple Choice
Identify the choice that best completes the statement or answers the question.
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23. |
Atoms are composed of
a.
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protons. |
c.
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electrons. |
b.
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neutrons. |
d.
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All of the above |
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24. |
The electrons of an atom
a.
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are found in the nucleus along with the protons. |
b.
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occupy the space surrounding the nucleus. |
c.
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have a positive charge. |
d.
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are attached to the positive charge of neutrons. |
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25. |
The smallest particle of matter that can retain the chemical properties of carbon is a(n)
a.
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carbon molecule. |
c.
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carbon atom. |
b.
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carbon macromolecule. |
d.
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element. |
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26. |
A substance that is composed of only one type of atom is called a(n)
a.
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nucleus. |
c.
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element. |
b.
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cell. |
d.
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molecule. |
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27. |
All matter is composed of
a.
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cells. |
c.
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atoms. |
b.
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molecules. |
d.
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carbon. |
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28. |
A molecule that has a partial positive charge on one side and a partial negative charge on the other side is called a
a.
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nonpolar molecule. |
c.
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charged molecule. |
b.
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polar molecule. |
d.
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bipolar molecule. |
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29. |
A chemical formula shows the
a.
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kinds of bonds found in the molecule. |
b.
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kinds of bonds found in the compound. |
c.
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kinds of elements found in the compound. |
d.
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arrangement of the elements found in the compound. |
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30. |
Ionic bonds form between molecules that have
a.
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opposite charges. |
c.
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no charges. |
b.
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the same charge. |
d.
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neutral charges. |
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31. |
The bond formed when two atoms share a pair of electrons is called a(n)
a.
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hydrogen bond. |
c.
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covalent bond. |
b.
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ionic bond. |
d.
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water bond. |
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32. |
Sharing of electrons in the outer energy levels of two atoms
a.
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results in ion formation. |
b.
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occurs in covalent bonds. |
c.
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only occurs if both are atoms of the same element. |
d.
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is found only among carbon atoms. |
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33. |
Water is important to life because it
a.
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surrounds all cells. |
b.
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is found inside cells. |
c.
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influences the shape of the cell membrane. |
d.
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All of the above |
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34. |
Nonpolar molecules have
a.
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no negative or positive poles. |
c.
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only a negative pole. |
b.
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both negative and positive poles. |
d.
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only a positive pole. |
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35. |
When placed in the same container, oil and water do not mix because
a.
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they are both polar. |
c.
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they are both nonpolar. |
b.
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water is polar and oil is nonpolar. |
d.
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water is nonpolar and oil is polar. |
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36. |
Due to the polarity of water, compounds that dissolve best in water contain
a.
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nonpolar bonds. |
c.
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polar bonds. |
b.
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ionic bonds. |
d.
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Both (b) and (c) |
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37. |
Water is a polar molecule because
a.
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it contains two hydrogen atoms for each oxygen atom. |
b.
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it has a charge. |
c.
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different parts of the molecule have slightly different charges. |
d.
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it does not have a charge. |
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38. |
Acidic solutions have a pH that is
a.
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less than 7. |
c.
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a negative number. |
b.
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between 7 and 14. |
d.
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more than 7. |
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39. |
Hydrogen ions, H+, react with hydroxide ions, OH-, to form
a.
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water. |
c.
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a base. |
b.
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an acid. |
d.
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None of the above |
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40. |
Which of the following is not an organic macromolecule?
a.
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carbohydrate |
c.
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lipid |
b.
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ice |
d.
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nucleic acid |
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41. |
All organic compounds contain the element
a.
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carbon. |
c.
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calcium. |
b.
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nitrogen. |
d.
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sodium. |
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42. |
Which of the following organic molecules are classified as carbohydrates?
a.
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amino acids |
c.
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nucleotides |
b.
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fatty acids |
d.
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sugars |
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43. |
Polysaccharides are
a.
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carbohydrates. |
c.
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proteins. |
b.
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lipids. |
d.
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unsaturated fats. |
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44. |
Lipids are
a.
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polar molecules. |
c.
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water soluble. |
b.
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similar to water molecules. |
d.
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nonpolar molecules. |
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45. |
Which of the following organic molecules are most closely related to proteins?
a.
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amino acids |
c.
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nucleotides |
b.
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fatty acids |
d.
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sugars |
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46. |
Long chains of amino acids are found in
a.
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carbohydrates. |
c.
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proteins. |
b.
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lipids. |
d.
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sugars. |
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47. |
All of the following are examples of lipids except
a.
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saturated fats. |
c.
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cholesterol. |
b.
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starch. |
d.
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earwax. |
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48. |
Lipids are soluble in
a.
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water. |
c.
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oil. |
b.
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salt water. |
d.
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All of the above |
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49. |
Which organic molecules below are most closely related to lipids?
a.
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amino acids |
c.
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nucleotides |
b.
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fatty acids |
d.
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sugars |
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50. |
Which of the following organic molecules are most closely related to nucleic acids?
a.
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amino acids |
c.
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nucleotides |
b.
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fatty acids |
d.
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sugars |
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51. |
Which of the following is a carbohydrate?
a.
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DNA |
c.
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wax |
b.
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insulin |
d.
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sucrose |
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52. |
Carbohydrates and lipids have many carbon-hydrogen bonds; therefore, they both
a.
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store energy in these bonds. |
c.
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dissolve only in vinegar. |
b.
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are easily dissolved in water. |
d.
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exist only in cells of plants. |
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53. |
Refer to the illustration above. Molecules like Molecule B are found in
a.
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carbohydrates. |
c.
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nucleic acids. |
b.
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lipids. |
d.
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proteins. |
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54. |
Liquid fats called oils contain
a.
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mostly unsaturated fatty acids. |
c.
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many glucose molecules. |
b.
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mostly saturated fatty acids. |
d.
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amino acids. |
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55. |
Animals store glucose in the form of
a.
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cellulose. |
c.
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wax. |
b.
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glycogen. |
d.
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lipids. |
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56. |
The shape of a protein is primarily determined by
a.
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the type and sequence of its amino acids. |
b.
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its size. |
c.
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its cell location. |
d.
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None of the above |
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57. |
The two types of nucleic acids are
a.
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chlorophyll and retinal. |
c.
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lipids and sugars. |
b.
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DNA and RNA. |
d.
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glucose and glycogen. |
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58. |
DNA stores
a.
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fat. |
c.
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protein. |
b.
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carbohydrates. |
d.
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heredity information. |
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59. |
The two strands of a DNA molecule are held together by
a.
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ionic bonds. |
c.
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hydrogen bonds. |
b.
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covalent bonds. |
d.
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None of the above |
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60. |
A molecule shaped like a spiral staircase (double helix) is typical of
a.
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deoxyribonucleic acid. |
c.
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lipids. |
b.
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ribonucleic acid. |
d.
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carbohydrates. |
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61. |
ATP (adenosine triphosphate) stores energy for cells to use in the bonds between its
a.
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amino acids. |
c.
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nucleotides. |
b.
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carbon atoms. |
d.
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phosphates. |
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62. |
Refer to the illustration above. Which graph illustrates what happens during an energy-releasing reaction?
a.
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Graph A |
b.
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Graph B |
c.
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both graphs because they each show a different stage of an energy releasing reaction |
d.
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None of the above |
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63. |
Refer to the illustration above. Which graph illustrates a reaction during which energy is released?
a.
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Graph A |
b.
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Graph B |
c.
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both graphs because all chemical reactions release energy |
d.
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None of the above |
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64. |
Refer to the illustration above. Which of the following statements regarding the graph is true?
a.
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Reaction 2 occurs faster than Reaction 3 because Reaction 2 requires more energy than Reaction 3. |
b.
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The difference between the graphs shown for Reaction 2 and Reaction 3 is because of a difference in the activation energy of these reactions. |
c.
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Reactant A contains more energy at the beginning of the reaction than product C has after the reaction. |
d.
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All of the above |
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65. |
Refer to the illustration above. Reaction 3 in the graph
a.
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probably occurred in the presence of a catalyst. |
b.
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requires more activation energy than Reaction 2. |
c.
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is the same as Reaction 1, but faster. |
d.
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is slower than Reaction 2. |
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66. |
The molecule on which an enzyme acts is called a(n)
a.
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active site. |
c.
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organic molecule. |
b.
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inactive site. |
d.
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substrate. |
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67. |
An enzyme
a.
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is not used up when catalyzing a reaction. |
b.
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lowers the activation energy of a reaction. |
c.
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bonds with a substrate molecule at the enzyme’s active site. |
d.
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All of the above |
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68. |
Which of the following conditions affects the function of enzymes?
a.
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pH |
c.
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enzyme concentration |
b.
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heat |
d.
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All of the above |
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69. |
Reducing activation energy
a.
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is a violation of the laws of nature. |
b.
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requires higher temperatures than those found within cells. |
c.
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occurs only when reactants are quickly added to the reaction mixture. |
d.
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is accomplished by the action of catalysts on reactants. |
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70. |
Enzymes
a.
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are able to heat up molecules so that they can react. |
b.
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always provide carbon dioxide for chemical reactions. |
c.
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are biological catalysts. |
d.
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absorb excess heat so that reactions occur at low temperatures. |
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71. |
A cell contains
a.
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thousands of different kinds of enzymes, each promoting a different chemical reaction. |
b.
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one kind of enzyme that promotes thousands of different chemical reactions. |
c.
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approximately 100 kinds of enzymes, each promoting a different chemical reaction. |
d.
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one enzyme that promotes photosynthesis and one enzyme that promotes cellular respiration. |
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72. |
Amylase is a digestive enzyme that breaks down starch into
a.
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amino acids. |
c.
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glycogen. |
b.
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glucose. |
d.
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cellulose. |
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73. |
The digestive enzyme pepsin works with hydrochloric acid to break down proteins in the stomach. Pepsin probably works best at a pH of
a.
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11. |
c.
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3. |
b.
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7. |
d.
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Both (b) and (c). |
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