Download Active Reading 3.1: Matter and Substances

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Holt Biology: Chemistry of Life
Active Reading 3.1: Matter and Substances
Read the passage below. Notice that the sentences are numbered. Then answer the
questions that follow.
1 Covalent bonds are chemical bonds that form when two or more atoms share
electrons to form a molecule. 2 A molecule is a group of atoms held together by
covalent bonds. 3 Like the rivets and welds that connect steel girders in a skyscraper,
covalent bonds join the atoms in molecules of living things. 4 Because the number of
protons is equal to the number of electrons in a molecule, the molecule has no net
electrical charge. 5 Some examples of molecules include carbon dioxide (CO2), water
(H2O), and oxygen (O2).
1. What term is defined in Sentence 1?
2. How are covalent bonds and atoms related?
3. Why does molecule appear in boldface type in Sentence 2?
4. An analogy is a comparison. What analogy is made in Sentence 3?
5. All of the following are examples of molecules except (circle the correct answer)
a. carbon dioxide.
b. iron.
c. water. d. oxygen gas.
SKILL: RECOGNIZING SIMILARITIES AND DIFFERENCES
1. A Venn diagram is a type of graphic organizer used to identify similarities and
differences between two concepts. Read each statement, draw a Venn diagram, and
write your answer in the appropriate place on the diagram.
a. In the left oval, list the key traits of acids.
b. In the right oval, list the key traits of bases.
c. In the area formed by the overlapping ovals, list traits shared by both acids and bases.
2. Which of the following pH values indicates a slightly acidic solution?
a. 3
b. 6.5
c. 9
d. 11
Active Reading 3.3: The Chemistry of Cells
Read the passage below. Notice that the sentences are numbered. Then answerthe
questions that follow.
Carbohydrates are organic compounds made of carbon, hydrogen, and oxygen atoms
in the proportion of 1:2:1. 2 Carbohydrates are a key source of energy, and they are
found in most foods—especially fruits, vegetables, and grains. 3 The building blocks of
carbohydrates are single sugars called monosaccharides, such as glucose (C6H12O6)
and fructose. 4 Glucose is a major source of energy in cells. 5 Disaccharides are double
sugars formed when two monosaccharides are joined. 6 For example, sucrose, or
common table sugar, consists of glucose and fructose. 7 Polysaccharides are chains of
three or more monosaccharides. 8 A polysaccharide is an example of a macromolecule,
a large molecule made up of many smaller molecules.
1
1. What elements form an organic compound classified as a carbohydrate?
2. What does the 2 represent in the proportion given in Sentence 1?
3. What three food groups are good sources of carbohydrates?
4. The prefix mono- means “one.” What word in Sentence 3 contains this prefix?
What is the meaning of this word?
5. What chemical formula is given in Sentence 3? How many atoms are in a molecule of
this compound?
6. The prefix di- means “two.” What term in Sentence 5 contains this prefix? What is the
meaning of this term?
7. In Sentence 6, which two monosaccharides join to form table sugar?
8. The prefix poly- means “more than one.” What term in Sentence 7 contains this
prefix? What is the meaning of this term?
9. An example of a macromolecule is a(n)
a. oxygen atom.
b. monosaccharide.
c. glucose molecule.
d. polysaccharide.