Back of the book questions bio 200, Mastering Biology Chapter 2 Homework, mastering biology chapter 2 Module
6. We can represent atoms by listing the number of protons, neutrons, and electrons-for example, 2p+, 2n0, 2e- for helium. Which of the following represents the $O isotope of Oxygen? A. 6p+, 8n0,6e- B. 8p+, 10n0, 8e- C. 9p+,9n0, 9e- D. 10p+, 8e0,9e-
B. 8p+, 10n0, 8e-
What is the mass number of an ion with 109 electrons, 159 neutrons, and a +1 charge?
269
An atom's atomic number is 7. Its valence is most likely ...
3
If a strand of DNA has the nitrogen base sequence 5'-ATTTGC-3', what will be the sequence of the matching strand?
3'-TAAACG-5'
Which of the following events occurs during transcription?
A molecule of RNA is formed based on the sequence of nucleotides in DNA.
What does the term electron orbital describe?
An electron orbital describes a three-dimensional space where an electron can be found 90% of the time.
Which statement about the following reaction is true? 4 Fe + 3 O2 → 2 Fe2O3
Four atoms of Fe react with 3 molecules of O2 to form 2 molecules of Fe2O3
Which statement is true of the relation between life and chemical equilibrium?
Living cells avoid chemical equilibrium by taking in energy and materials. The only way to avoid equilibrium is to exchange materials and energy with the environment.
Which answer correctly ranks the atoms in terms of decreasing electronegativity (the highest electronegativity first)?
O, N, C, H
Use your knowledge of electronegativity to pick out the most polar bond in the list below.
O-H because they are on opposite ends of the electronegativity scale
1. Compared with P, the radioactive isotope 2P has A. a different atomic number. B. one more proton. C. one more electron. D. one more neutron.
One more neutron
The initiator tRNA attaches at the ribosome's _____ site.
P
What model most accurately represent the current view of the structure of an atom? Probability or planetary model?
Probability model.
Which of the following subatomic particles always has a positive charge?
Proton
What name is given to the process in which pre-mRNA is edited into mRNA?
RNA processing
Can rotations occurs around single bonds?
Yes
Which of these does NOT contain a structural protein?
ovalbumin (This is a storage protein)
what type of bond joins the monomers in a protein's primary structure?
peptide
tertiary structure is NOT directly dependent on
peptide bonds
A nucleotide is composed of a(n) _____.
phosphate group, a nitrogen-containing base, and a five-carbon sugar
The unequal sharing of electrons within a water molecule makes the water molecule _____.
polar
Chemical energy is a form of _____ energy. kinetic potential motion entropic heat
potential
Enzymes are _____
protein
Changing the number of _____ would change an atom into an atom of a different element.
protons in an atom
The site of translation is
ribosomes in the cell cytoplasm.
What type of bond joins the carbon atom to each of the hydrogen atoms?
single (nonpolar) covalent
The atoms of different phosphorus isotopes _____.
have different numbers of neutrons
Fluorine's atomic number is 9 and its atomic mass is 19. How many neutrons does fluorine have?
10
In molecules, C, H, O, and N atoms usually make __, __, __, and __ bonds respectively.
4, 1, 2, 3
The direction of synthesis of an RNA transcript is _____.
5' —> 3'
What is the atomic number of an atom that has 6 protons, 6 neutrons, and 6 electrons?
6
If a DNA double helix is 100 nucleotide pairs long and contains 25 adenine bases, how many guanine bases does it contain?
75, 100 nucleotide pairs are a total of 200 nucleotides. Because of base pairing, if there are 25 adenine there must also be 25 thymine. This leaves 200-50 = 150 nucleotides to be divided evenly between guanine and cytosine.
4. Which statement is true of all atoms that are anions? A. The atom has more electrons than protons. B. The atom has more protons than electrons. C. The atom has fewer protons than does a neutral atom of the same element. D. The atom has more neutrons than protons.
A. The atom has more electrons than protons.
An atom has 6 electrons, 6 protons, and 6 neutrons. You can tell that this atom belongs to the element _____ because _____________________.
C; it has 6 protons.
The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____.
CUG
5. Which of the following statements correctly describes any chemical reaction that has reached equilibrium? A. The concentrations of products and reactants are equal. B. The reaction is now irreversible. C. Both forward and reverse reactions have halted. D. The rates of the forward and reverse reactions are equal.
D. The rates of the forward and reverse reactions are equal.
Which one of the following does not play a role in translation? Anticodon tRNA Ribosomes DNA Amino acids
DNA
n the diagram below, the two blue strands represent _____. https://session.masteringbiology.com/problemAsset/1367720/2/Part_ABC.jpg
DNA
Which fact is most important in explaining how molecules convert thermal energy to activation energy (EA)?
Distortion increases a molecule's potential energy. In a collision, kinetic energy becomes the potential energy of distortion, which can weaken bonds enough to permit a reaction.
What type of bond shares two pairs of electrons?
Double covalent
What determines the atom's size?
Electrons
Which of these correctly illustrates the pairing of DNA and RNA nucleotides?
GTTACG CAAUGC
If you want a molecule that is highly polar, look for one that contains:
H-N because they differ most in electronegativity
By making two covalent bonds, an O atom (with 8 protons) fills its valence shell. Why does the atom's charge stay close to zero?
Shared electrons aren't always near oxygen.
What relationships is true of an uncharged atom?
The number of protons is equal to the number of electrons.
A chemist calculates that a certain reaction would result in ΔH = -9 kJ and TΔS = +1 kJ. What can you conclude?
The reaction will occur spontaneously, because it decreases G. ΔG = ΔH - TΔS = -9 kJ - (+1 kJ) = -10 kJ. Since the free energy decreases, the reaction will run spontaneously.
What shell has a highest energy?
The valence shell
Which statement about weak bonds is correct?
Weak bonds are transient and easily reversible.
Partial charges occur when ...
a covalent bond links atoms of two kinds and atoms share electrons unequally.
During RNA processing a(n) _____ is added to the 3' end of the RNA.
a long string of adenine nucleotides
Which of these is exhibiting kinetic energy? a person sitting on a couch while watching TV an archer with a flexed bow a rock on a mountain ledge the high-energy phosphate bonds of a molecule of ATP a space station orbiting Earth
a space station orbiting Earth
Polypeptides are assembled from _____.
amino acids
Proteins are polymers of _____. a) glycerol b) amino acids c) nucleotides d) CH2O units e) hydrocarbons
amino acids
Radioactive decay is likely to occur when ...
an atom has too many neutrons. The atomic nucleus because unstable if the ration of protons to neutrons is too far from unity
An ionic bond involves _____.
an attraction between ions of opposite charge
In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP? redox digestion potentiation cellular respiration anabolism
cellular respiration
Translation occurs in the _____.
cytoplasm
Each water molecule is joined to _____ other water molecules by ____ bonds.
four ... hydrogen
The tendency of an atom to pull electrons toward itself is referred to as its _____.
electronegativity
In a double covalent bond, a carbon atom shares ...
electrons in two orbitals.
A substance that cannot be broken down into other substances by ordinary chemical procedures is a(n) _____.
element
"Conservation of energy" refers to the fact that _____. energy cannot be created or destroyed but can be converted from one form to another if you conserve energy you will not be as tired the entropy of the universe is always increasing the net amount of disorder is always increasing no chemical reaction is 100 percent efficient
energy cannot be created or destroyed but can be converted from one form to another
The RNA segments joined to one another by spliceosomes are _____.
exons
Which of these are by-products of cellular respiration? carbon dioxide and water heat, carbon dioxide, and water ATP and carbon dioxide ATP, carbon dioxide, and water glucose, carbon dioxide, and water
heat, carbon dioxide, and water
The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases.
hydrogen bonds
the secondary structure of a protein results from
hydrogen bonds
Defensive proteins are manufactured by the _____ system.
immune (The immune system is involved in protecting the body against invasion by foreign objects)
An Enzyme _____.
is an organic catalyst
As a result of its involvement in a reaction, an enzyme _____.
is unchanged
RNA processing converts the RNA transcript into _____.
mRNA
Which of the following does not occur during RNA processing? Segments of the RNA strand that do not actually code for the protein are removed. Segments of RNA that do code for the protein are reconnected. A modified guanine nucleotide is added to the beginning of the RNA strand as a cap. mRNA attaches to the small subunit of a ribosome. Adenine nucleotides are added to the end of the RNA strand, forming a tail.
mRNA attaches to the small subunit of a ribosome.
Which of the following is a correct statement about mRNA? mRNA includes a cap that consists of extra adenine nucleotides. Segments of mRNA that code for protein are removed before translation. mRNA binds directly to amino acids during translation. mRNA is transcribed from DNA in the cytoplasm. mRNA moves from the nucleus to the cytoplasm following RNA processing.
mRNA moves from the nucleus to the cytoplasm following RNA processing.
During RNA processing a(n) _____ is added to the 5' end of the RNA.
modified guanine nucleotide
Spliceosomes are composed of _____.
snRNPs and other proteins
Arrow A is indicating a(n) _____ protein.
structural
Why isn't this insect drowning?
surface tension
For the reaction ATP + H2O → ADP + Pi, the change in standard free energy (ΔG∘) is -30.5 kJ/mol. From this information we can conclude that ...
the forward reaction will be spontaneous under standard conditions because ΔG is less than zero.
Knowing the atomic mass of an element allows inferences about which of the following?
the number of protons plus neutrons in the element
In the diagram below, the green unit represents _____.https://session.masteringbiology.com/problemAsset/1367720/2/Part_ABC.jpg
the promoter
Two atoms always represent the same element if they have ...
the same number of protons
In eukaryotic cells the first step in protein synthesis is the _____. 1) translation of an RNA nucleotide sequence into a sequence of amino acids 2) linking of nucleotides to form a polypeptide 3) translation of a DNA nucleotide sequence into a sequence of amino acids 4) transferring of information from DNA to messenger RNA 5) removal of introns from RNA and the stitching together of exons
transferring of information from DNA to messenger RNA
What bond can form between atoms of equal electronegativity?
Van der Waals interactions can form between atoms of equal electronegativity.
What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein?
translation
https://session.masteringbiology.com/problemAsset/1367597/2/0825q.jpg What is the correct label for "A"?
energy of activation
What name is given to the reactants in an enzymatically catalyzed reaction?
substrate
In the equation ΔG = ΔH - TΔS, the change in the amount of disorder in the system is symbolized by ...
ΔS S is entropy
What name is given to the bond between water molecules?
Hydrogen
Under standard conditions the reversible reaction A + B → C + D has a ΔG∘ = -25 kJ/mol. What is ΔG when: T = 475 K, [A] = 0.5M, [B] = 0.2 M, [C] = 0.2 M, and [D] = 0.3 M?
-27 kJ/mol The nonstandard concentrations have lowered ΔG by 2 kJ.mol.
An electrically neutral molecule has the formula C3H4O2N. If the carbon atoms form the usual number of bonds, how many covalent bonds will each hydrogen atom have with other atoms in the molecule?
1
An atom has 8 protons, 8 neutrons, and 8 electrons. Another isotope of the same element might have ...
10 neutrons.
The innermost electron shell of an atom can hold up to _____ electrons.
2
Choose the correct balanced equation for the following reaction. C8H18 + O2 → CO2 + H2O
2 C8H18 + 25 O2 → 16 CO2 + 18 H2O
To fill the valence shell, an electrically neutral, unbonded atom with atomic number 8 must add ...
2 electrons.
An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many protons does boron have?
5
A positive ion with two units of charge has 10 neutrons and 8 protons. The ion also has ...
6 electrons.
The mass number of an atom is 15, and its atomic number is 7. The atom probably has...
8 neutrons in the nucleus.
What happens when two atoms form a chemical bond?
A chemical bond forms when two atoms transfer or share outer electrons to complete their outer shells.
2. In the term trace element, the adjective trace means that A. the element is required in very small amounts. B. the element can be used as a label to trace atoms through an organism's metabolism. C. the element is very rare on Earth. D. the element enhances health but is not
A. the element is required in very small amounts.
Two C atoms form a double bond. Each C is bound to two H atoms. Which statement is true?
All the atoms lie in a plane because the double bond limits all the atoms.
Which statement about relative potential energy of electrons is correct?
An electron in the 3 p orbital of the third electron shell has more potential energy than an electron in the 2 p orbital of the second electron shell.
7. The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound. A. HS B. HS2 C. H2S D. H4S
B. H2S
3. The reactivity of an atom arises from A. the average distance of the outermost electron shell from the nucleus. B. the existence of unpaired electrons in the valence shell. C. the sum of the potential energies of all the electron shells. D. the potential energy of the valence shell.
B. the existence of unpaired electrons in the valence shell.
Choose the appropriate balanced equation for the following chemical reaction. C6H6 + H2 → C6H12
C6H6 + 3 H2 → C6H12
Which of the following are compounds?
H2O and CH4, but not O2
In salt, what is the nature of the bond between sodium and chlorine?
Ionic
Which statement is true of the transition state?
It can break apart to yield either reactants or products and it is extremely unstable and lasts only an instant.
Which of the following is a trace element required by most living organisms?
Magnesium
Which of the following is true of activation energy?
Molecules usually get it from thermal energy.
In this molecule, what type of bond is found between the oxygen and hydrogens?
Polar Covalent
Dr. Haxton says he has found a reaction that is truly irreversible. What would a good student say?
Sorry, Doctor. All reactions are reversible.
Which statement is true of all atoms that are anions?
The atom has more electrons than protons.
What determines the types of chemical reactions that an atom participates in?
The number of electrons in the outermost electron shell
Which answer helps to explain why carbon atoms tend to make 4 covalent bonds?
The valence shell needs 8 electrons.
Which of these refers to atoms with the same atomic number but different atomic masses?
These atoms are isotopes.
True or false: Ions may form by transferring an atomic nucleus (with or without electrons) to another molecule.
True For example, a hydrogen nucleus (H+) may move between two water molecules, making an H3O+ ion and an OH- ion.
Dr. Haxton says the O-O bond is polar and the C-C bond is nonpolar. A good student would say ...
Wrong again, Ralph. Both bonds are non polar. When two atoms of the same kind form a covalent bond, they share electrons equally because their electronegativity is the same.
Atoms with the same number of protons but with different electrical charges _____.
are different ions
Potential energy is always ...
associated with position or arrangement.
Define isotope.
atoms with the same atomic number but different atomic masses
Covalent bonds hold atoms together because they ...
fill shells without giving atoms much charge and bring electrons closer to protons.
Catalysts speed reactions mainly by ...
lowering EA. Catalysts always lower EA, though they may have other effects as well. With a lower EA, a larger fraction of collisions can produce the transition state.
A(n) _____ refers to two or more atoms held together by covalent bonds.
molecule
An ionic bond is formed when _____.
one atom transfers an electron to another atom
Arrow D is indicating a _____ protein.
receptor
Compared to covalent bonds, ionic bonds ...
rely much less on electron-sharing.
The reactivity of an atom arises from _________.
the existence of unpaired electrons in the valence shell
Dr. Jones says an atom has 3 electrons in the first shell and four electrons in the second shell. Someone should tell Dr. Jones that ...
the first shell shouldn't have 3 electrons.
Chemical equilibrium is reached when _____.
the forward and reverse reactions occur at the same rate so that the concentrations of reactants and products remain the same
What name is given to the process in which a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA?
transcription
This animation illustrates the functioning of a _____ protein.
transport
Hydrogen bonding is most often seen _____.
when hydrogen is covalently bonded to an electronegative atom