Ch. 2 Flashcards
What is the smallest particle of an element that still retains its distinctive chemical properties?
Atom
Which type of subatomic particle is NOT in the nucleus of an atom?
A. Electrons
B. Protons
C. Neutrons
Electrons
The atomic number of an element is determined by the number of what type of particle in the atom’s nucleus?
Protons
In an atom, the number of positively charged protons is the same as the number of:
negatively charged electrons.
Which subatomic particles have essentially the same mass?
A. Protons and neutrons
B. Protons and electrons
C. Electrons and neutrons
Protons and Neutrons
Isotopes of the same element have different numbers of what type of subatomic particle?
Neutrons
The atomic weight of an atom is its mass relative to which of the following atoms?
A. Hydrogen
B. Helium
C. Carbon
Hydrogen
How much does a mole of carbon atoms (having an atomic weight of 12) weigh?
12 grams
In living organisms, four elements make up 96.5% of an organisms weight. What are these four elements?
Carbon, hydrogen, nitrogen, and oxygen
Which subatomic particles undergo rearrangements when atoms combine with others to form molecules?
A. Protons
B. Neutrons
C. Electrons
Electrons
T or F: The atoms found in living tissues all have complete outer electron shells and are therefore quite stable on their own.
False
What type of bond is formed when two atoms share electrons?
A covalent bond
What type of bond is formed when one atom donates electrons to another atom?
An ionic bond
14.What dictates the number of bonds an atom can make?
A. The number of protons in its nucleus
B. The state of its outermost electron shell
C. The state of its innermost electron shell
The state of its outermost electron shell
An oxygen atom, with 6 electrons (of a possible 8) in its outer electron shell, has the capacity to form a maximum of how many covalent bonds?
2
Which type of covalent bond allows for rotation about the bond axis?
A. Single bond
B. Double bond
C. Triple bond
Single bond
Which term describes a covalent bond in which electrons are shared unequally?
A. Nonpolar
B. Polar
C. Ionic
Polar
Which of the following covalent bonds is nonpolar?
A. The bond between oxygen and hydrogen, –O–H
B. The bond between nitrogen and hydrogen, –N–H
C. The bond between carbon and hydrogen, –C–H
The bond between carbon and hydrogen, –C–H
Which type of bond is the strongest?
A. Ionic
B. Hydrogen
C. Covalent
Covalent Bond
Which of the following atoms is most likely to participate in an ionic bond?
A. Carbon, with an outer electron shell filled with 4 of a possible 8 electrons
B. Phosphorus, with an outer electron shell filled with 5 of a possible 8 electrons
C. Chlorine, with an outer electron shell filled with 7 of a possible 8 electrons
Chlorine, with an outer electron shell filled with 7 of a possible 8 electrons
What are substances held together solely by ionic bonds generally called?
Salts
T or F: Electrostatic attractions are stronger than covalent bonds.
False
In water, hydrogen bonds form between:
a hydrogen atom and an oxygen atom.
Consider an O–H covalent bond in H2O. Which atom more strongly attracts electrons and acquires a partial negative charge?
Oxygen
Hydrophilic molecules:
mix well with water
Which statement is true?
A. Substances that release protons when they dissolve in water are termed acids and result in a pH higher than 7.
B. Substances that release protons when they dissolve in water are termed bases and result in a pH higher than 7.
C. Substances that release protons when they dissolve in water are termed acids and result in a pH lower than 7.
Substances that release protons when they dissolve in water are termed acids and result in a pH lower than 7.
Which of the following substances is a weak acid? A. Glucose B. HCl C. Acetic acid D. Adenine
Acetic Acid
Which is NOT true of a base?
A. A base is the opposite of an acid.
B. A base has a pH lower than 7.
C. A base is any molecule capable of accepting a proton.
A base has a pH lower than 7.
Which substance is considered organic?
A. H2O (water)
B. CH4 (methane)
C. NaCl (table salt)
CH4 (Methane)
Carbon, which has four electrons in its outer shell (capacity 8 electrons), can form a maximum of how many covalent bonds with other atoms?
4
T or F: Most of the organic matter in a living organism consists of macromolecules, with a much smaller contribution from the small molecules that serve as potential subunits for macromolecules.
True
What is the term for the simplest sugars?
Monosaccharide
Which carbohydrates contain hundreds or thousands of sugar subunits?
A. Monosaccharides
B. Polysaccharides
C. Oligosaccharides
Polysaccharides
A covalent bond between two sugar molecules forms at an –OH group on one sugar and an –OH group on another. When the two groups join in a condensation reaction, what molecule is released?
H2O
The reverse of a condensation reaction is called:
a hydrolysis reaction
hich term best describes a fatty acid?
A. Hydrophilic
B. Hydrophobic
C. Amphipathic
Amphipathic
Which term describes a hydrocarbon tail of a fatty acid that has no double bonds between its carbon atoms?
A. Saturated
B. Unsaturated
C. Polyunsaturated
Saturated
Lipids include all except which of the following? A. Fatty acids B. Oils C. Steroids D. Amino acids
Amino Acids
Phospholipids aggregate to form cell membranes because:
they are amphipathic
Amino acids are subunits of which of the following macromolecules?
A. Polysaccharides
B. Nucleic Acids
C. Proteins
Proteins
Which chemical group is NOT found on all amino acids?
A. A carboxylic acid group
B. An amino group
C. A hydroxyl group
a hydroxyl group
What is the covalent linkage called between two adjacent amino acids in a protein?
peptide bond
What extra chemical group is found in a nucleotide but not a nucleoside?
A. Base
B. Sugar
C. Phosphate
Phosphate
What reaction involving ATP releases a large amount of energy?
A. The release of the terminal phosphate group
B. The release of the sugar group
C. The release of the base
The release of the terminal phosphate group
What type of bond links nucleotides in a nucleic acid chain?
Phosphodiester
What type of bond links two polynucleotide chains to each other in a double helix of DNA?
Hydrogen Bonds
What is NOT true of RNA?
A. It contains a different sugar than DNA.
B. It contains a different base than DNA.
C. It cannot base pair with other nucleic acids.
D. It is usually single stranded.
It cannot base pair with other nucleic acids.
Which statement is correct about base pairing in DNA?
A. A pairs with C; T pairs with G
B. A pairs with G; T pairs with C
C. A pairs with T; G pairs with C
A pairs with T; G pairs with C
How do protein, nucleic acid, and polysaccharide molecules polymerize (grow)?
By condensation reactions
T or F: The shapes of most biological macromolecules are held in place largely by strong covalent bonds that form between different parts of the molecule.
False
Which type of bond makes it possible for a macromolecule to interact with great specificity with just one out of the many thousands of different molecules present inside a cell? A. Covalent bonds B. Noncovalent bonds C. Hydrogen bonds D. Ionic bonds
Noncovalent Bonds
Describe the key features of the following chemical interactions: ionic bonds, covalent bonds, hydrogen bonds, van der Waals attractions, electrostatic attractions. Which are the strongest?
Ionic bonds are formed when electrons are donated by one atom to another. Covalent bonds occur when two atoms share a pair of electrons. Hydrogen bonds are noncovalent interactions between a positively charged hydrogen atom and a negatively charged atom, usually oxygen or nitrogen. Hydrogen bonds can form between two molecules or between different parts of a single large molecule. Van der Waals attractions are noncovalent interactions due to fluctuating electrical charges between two atoms that are very close together. Electrostatic attractions are noncovalent interactions that draw together oppositely charged atoms.
Covalent bonds are the strongest, and ionic bonds are stronger than hydrogen bonds, which are the strongest of the noncovalent interactions. Although noncovalent interactions–such as ionic bonds, hydrogen bonds, van der Waals attractions, and electrostatic changes–are individually weak, when present in large numbers, they can promote strong and specific binding.
What is the difference between a monosaccharide, a disaccharide, an oligosaccharide, and a polysaccharide? How do these sugars function in the cell?
A monosaccharide is the simplest sugar and has the general formula (CH2O)n. A disaccharide consists of two monosaccharides linked by a covalent bond. An oligosaccharide is a chain of monosaccharides, usually between 3 and 10 subunits long. A polysaccharide is sugar that contains hundreds or thousands of subunits. Simple sugars, such as the monosaccharide glucose, are used as a source of energy in the cell. Simple polysaccharides, such glycogen in animals and starch in plants, are used as long-term stores of glucose. More complex sugars, such as cellulose in plants and chitin in insects, can be used as mechanical supports.
The molecular weight of ethanol (CH3CH2OH) is 46 and its density is 0.789 g/cm3.
A. How many 12-oz (355-mL) bottles of 5% beer could a 70-kg person drink and remain under the legal limit? A 70-kg person contains about 40 liters of water. Ignore the metabolism of ethanol, and assume that the water content of the person remains constant. B. Ethanol is metabolized at a constant rate of about 120 mg per hour per kg body weight, regardless of its concentration. If a 70-kg person were at twice the legal limit (160 mg/100 mL), how long would it take for their blood alcohol level to fall below the legal limit?
A. At the legal limit (17.4 mM), ethanol in 5% beer (0.86 M) has been diluted 49.4-fold (860 mM/17.4 mM). This dilution represents 809 mL in 40 L of body water (40 L/49.4). At 355 mL per beer, this equals 2.3 beers (809 mL/355 mL).
B. It would take nearly 4 hours. At twice the legal limit the person would contain 64 g of ethanol [(0.16 g/0.1 L) x (40 L)]. The person would metabolize 8.4 g/hr [(0.12 g/hr kg) x (70 kg)]. Thus, to metabolize 32 g of ethanol (the amount in excess of the legal limit) would require 3.8 hours [(32 g) x (hr/8.4 g)].
