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CHAPTER 02
1. Figure 2.3 How many neutrons do (K) potassium-39 and potassium-40 have, respectively?
1 Figure 2.3 Potassium-39 has twenty neutrons. Potassium-40 has twenty one neutrons.
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CHAPTER 02
2. Magnesium has an atomic number of 12. Which of the following statements is true of a neutral magnesium atom?
It has 12 protons, 12 electrons, and 12 neutrons.
It has 12 protons, 12 electrons, and six neutrons.
It has six protons, six electrons, and no neutrons.
It has six protons, six electrons, and six neutrons.
It has 12 protons, 12 electrons, and 12 neutrons.
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CHAPTER 02
3. Which type of bond represents a weak chemical bond?
hydrogen bond
ionic bond
covalent bond
polar covalent bond
hydrogen bond
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CHAPTER 02
4. An isotope of sodium (Na) has a mass number of 22. How many neutrons does it have?
11
12
22
44
11
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CHAPTER 02
5. Which of the following statements is not true?
Water is polar.
Water stabilizes temperature.
Water is essential for life.
Water is the most abundant atom in Earth’s atmosphere.
Water is the most abundant atom in Earth’s atmosphere.
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CHAPTER 02
6. Using a pH meter, you find the pH of an unknown solution to be 8.0. How would you describe this solution?
weakly acidic
strongly acidic
weakly basic
strongly basic
weakly basic
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CHAPTER 02
7. The pH of lemon juice is about 2.0, whereas tomato juice's pH is about 4.0.
Approximately how much of an increase in hydrogen ion concentration is there between tomato juice and
lemon juice?
2 times
10 times
100 times
1000 times
100 times
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CHAPTER 02
8. An example of a monosaccharide is ________.
fructose
glucose
galactose
all of the above
all of the above
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CHAPTER 02
9. Cellulose and starch are examples of ________.
monosaccharides
disaccharides
lipids
polysaccharides
polysaccharides
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CHAPTER 02
10. Phospholipids are important components of __________.
the plasma membrane of cells
the ring structure of steroids
the waxy covering on leaves
the double bond in hydrocarbon chains
the plasma membrane of cells
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CHAPTER 02
11. The monomers that make up proteins are called _________.
nucleotides
disaccharides
amino acids
chaperones
amino acids
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CHAPTER 02
12. Why are hydrogen bonds and van der Waals interactions necessary for cells?
- Hydrogen bonds and van der Waals interactions form weak associations between different molecules.
- They provide the structure and shape necessary for proteins and DNA within cells so that they function properly.
- Hydrogen bonds also give water its unique properties, which are necessary for life.
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CHAPTER 02
13. Why can some insects walk on water?
- Some insects can walk on water, although they are heavier (denser) than water, because of the surface tension of water.
- Surface tension results from cohesion, or the attraction between water molecules at the surface of the body of water [the liquid-air (gas) interface].
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CHAPTER 02
14 Explain why water is an excellent solvent.
- Water molecules are polar, meaning they have separated partial positive and negative charges.
- Because of these charges, water molecules are able to surround charged particles created when a
- substance dissociates. The surrounding layer of water molecules stabilizes the ion and
- keeps differently charged ions from reassociating, so the substance stays dissolved
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CHAPTER 02
15. Explain at least three functions that lipids
serve in plants and/or animals.
- Fat serves as a valuable way for animals to store energy.
- It can also provide insulation.
- Phospholipids and steroids are important components of cell membranes.
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CHAPTER 02
16. Explain what happens if even one amino acid is substituted for another in a polypeptide chain. Provide a specific example.
- A change in gene sequence can lead to a different amino acid being added to a polypeptide chain instead of the normal one.
- This causes a change in protein structure and function.
- For example, in sickle cell anemia, the hemoglobin beta chain has a single amino acid substitution.
- Because of this change, the disc-shaped red blood cells assume a crescent shape, which can result in serious health problems.
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