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1 | |
Which of the following is defined as a tiny particle that cannot be subdivided into smaller substances without losing its properties? |
| | A) | Matter |
| | B) | Atom |
| | C) | Proton |
| | D) | Neutron |
| | E) | Electron |
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2 | |
Scientists use isotopes of various elements to determine the age of specific samples. What is different about isotopes that allow them to be used in this manner? |
| | A) | The number of neutrons. |
| | B) | The number of electrons. |
| | C) | The number of protons. |
| | D) | The proportion of isotopes concentrated in fossils relative to the rest of the organic matter on earth. |
| | E) | They are Martian microbes. |
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3 | |
Which of the following defines a molecule? |
| | A) | The donation of or sharing of electrons |
| | B) | A combination of two or more different elements |
| | C) | The volume in space where electrons are likely to be found |
| | D) | A chemical substance that results from the combination of two or more atoms |
| | E) | A subatomic particle that is positively charged |
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4 | |
What type of bond results when electrons are donated from one atom to another? |
| | A) | Covalent |
| | B) | Polar |
| | C) | Ionic |
| | D) | Hydrogen |
| | E) | Glycosidic |
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5 | |
What characteristic of the water molecule allows it to play an extensive role in many biological reactions? |
| | A) | It is a neutral molecule. |
| | B) | It is a cation. |
| | C) | Its chemical formula is H2O. |
| | D) | It is a polar molecule. |
| | E) | It forms ionic bonds with other water molecules. |
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6 | |
A positively charged ion is known as a what? |
| | A) | Anion |
| | B) | Neutron |
| | C) | Cation |
| | D) | Oxidizing agent |
| | E) | Polar molecule |
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7 | |
Which of the following statements regarding hydrogen bonds is incorrect? |
| | A) | They commonly form between a hydrogen in one molecule and an oxygen or nitrogen in another molecule. |
| | B) | They occur between water molecules. |
| | C) | They are a type of attractive force between nearby molecules or atoms. |
| | D) | They are partly responsible for the structure and stability of proteins and nucleic acids. |
| | E) | They are strong bonds. |
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8 | |
What accounts for most of the energy exchange in cells? |
| | A) | Hydrogen bonds |
| | B) | Movement of electrons from molecule to molecule |
| | C) | Electrolytes |
| | D) | Chemical formulas of the reactants |
| | E) | The pH of the cell |
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9 | |
What is the most common solvent in natural systems? |
| | A) | Water |
| | B) | Ethanol |
| | C) | Methanol |
| | D) | Lactic acid |
| | E) | Acetic acid |
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10 | |
Under what conditions do most cells, including those of humans, function best? |
| | A) | pH 1 |
| | B) | pH 4 |
| | C) | pH 7 |
| | D) | pH 10 |
| | E) | pH 14 |
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11 | |
What element is the fundamental element of life? |
| | A) | Nitrogen |
| | B) | Hydrogen |
| | C) | Sodium |
| | D) | Oxygen |
| | E) | Carbon |
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12 | |
Which of the following is not one of the four main families of organic compounds? |
| | A) | Carbohydrates |
| | B) | Lipids |
| | C) | Nucleic acids |
| | D) | Monosaccharides |
| | E) | Proteins |
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13 | |
Disaccharides and polysaccharides contain monosaccharides joined together by what type of bonds? |
| | A) | Covalent |
| | B) | Hydrogen |
| | C) | Ionic |
| | D) | Peptide |
| | E) | Glycosidic |
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14 | |
Polysaccharides are present in all but which cell structure components? |
| | A) | Lipopolysaccharide |
| | B) | Glycocalyx |
| | C) | Phospholipids |
| | D) | Peptidoglycan |
| | E) | Cellulose |
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15 | |
Which of the main groups of compounds classified as lipids are significant in the formation of biological membranes? |
| | A) | Triglycerides |
| | B) | Phospholipids |
| | C) | Fatty acids |
| | D) | Steroids |
| | E) | Waxes |
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16 | |
According to the fluid mosaic model proposed by Singer and Nicholson, which of the following is untrue regarding membrane structure? |
| | A) | A membrane is a continuous bilayer. |
| | B) | Membranes are static and do not change. |
| | C) | Various globular proteins are embedded within the bilayer. |
| | D) | The bilayer is formed by lipids that are oriented with the polar lipid heads toward the outside and the nonpolar tails toward the center of the membrane. |
| | E) | The bilayer membrane is selectively permeable. |
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17 | |
What is the most common organic molecule in a cell? |
| | A) | Proteins |
| | B) | Lipids |
| | C) | Polysaccharides |
| | D) | Carbon dioxide |
| | E) | Nucleic acids |
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18 | |
Among the groups which make a typical amino acid, which one imparts the unique characteristics to a molecule and to the proteins that contain it? |
| | A) | Carbon. |
| | B) | Amino group. |
| | C) | Carboxyl group. |
| | D) | Variable R group. |
| | E) | A hydrogen atom. |
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19 | |
Amino acids are joined together by what type of bond? |
| | A) | Covalent |
| | B) | Hydrogen |
| | C) | Ionic |
| | D) | Peptide |
| | E) | Glycosidic |
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20 | |
What level of protein structure arises when various functional groups exposed on the outer surface of the protein molecule interact by forming hydrogen bonds? |
| | A) | Primary |
| | B) | Secondary |
| | C) | Tertiary |
| | D) | -helix |
| | E) | Quaternary |
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21 | |
Which of the following agents does not cause protein denaturation? |
| | A) | Neutral pH |
| | B) | Heat |
| | C) | Alcohol |
| | D) | Certain chemical disinfectants |
| | E) | Acidic pH |
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22 | |
Which of the following is not a component of all nucleotides? |
| | A) | Nitrogen base |
| | B) | Pentose sugar |
| | C) | Deoxyribose |
| | D) | Phosphate |
| | E) | Purine or pyrimidine |
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23 | |
What base always binds with adenine in DNA? |
| | A) | Uracil |
| | B) | Cytosine |
| | C) | Guanine |
| | D) | Adenine |
| | E) | Thymine |
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24 | |
The structure of RNA differs slightly from that of DNA. Which of the following describes this difference? |
| | A) | DNA contains deoxyribose, while RNA contains ribose. |
| | B) | DNA contains a phosphate group, while RNA contains a sulfur group. |
| | C) | DNA contains a 5-carbon sugar, while RNA contains a 6-carbon sugar. |
| | D) | DNA does not contain nitrogen bases, while RNA does. |
| | E) | DNA is composed of four possible nitrogen bases, while RNA is composed of five possible nitrogen bases. |
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25 | |
What is not a fundamental characteristic of all cells? |
| | A) | They tend to be spherical, polygonal, cubical, or cylindrical in shape. |
| | B) | Their internal cell contents are encased in a cell or cytoplasmic membrane. |
| | C) | They are unicellular or multicellular. |
| | D) | They are complex in function. |
| | E) | They have chromosomes composed of RNA. |
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