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Biol Final 2015
Terms in this set (53)
In comparison to eukaryotes, prokaryotes _____.
Prokaryotes are classified as belonging to two different domains. What are the domains?
Bacteria and Archaea
Which branch of biology is concerned with the naming and classifying of organisms?
In order for a hypothesis to be able to be used in science, which of the following must be true?
It is testable and falsifiable.
Protists and bacteria are grouped into different domains because
protists have a membrane-bounded nucleus, which bacterial cells lack
A substance that cannot be broken down into other substances by ordinary chemical procedures is a(n) _____.
Given what you know about the human body, what do you think accounts for the high percentage of oxygen (65.0%)?
The human body is made up mainly of water, and there is one oxygen atom in every water molecule.
Match each property to the appropriate subatomic particle.
The proton Symbol p, neutron, and electron are the three main subatomic particles that make up all the elements.
Sort the subatomic particles according to their masses
The proton and neutron both have masses of about 1 amu, whereas the electron mass is only about 5.5×10−4amu.
The innermost electron shell of an atom can hold up to _____ electrons.
2, This is the maximum number of electrons that can occupy the innermost electron shell.
Which of these relationships is true of an uncharged atom?
The number of protons is equal to the number of electrons.
In this situation the number of positive charges is equal to the number of negative charges.
What determines the types of chemical reactions that an atom participates in?
the number of electrons in the outermost electron shell
An atom is least likely to participate in a reaction when its outermost shell is stable.
Changing the number of _____ would change an atom into an atom of a different element.
protons in an atom
Atoms of each element have a unique number of protons within their nuclei. Changing the number of protons in an atom occurs only in nuclear reactions, not chemical reactions.
The atoms of different phosphorus isotopes _____. have different numbers of neutrons
have different numbers of neutrons.
The phosphorus atom is defined by its proton number. Changes in neutron number alter the mass of the atom, but not its chemical behavior or reactivity.
The type of bonding and the numbers of covalent bonds an atom can form with other atoms is determined by _____.
the number of unpaired electrons in the valence shell.
The fullness of the valence shell determines the pattern of covalent bonding or ionization. The reactivity of an atom is a function of the presence of unpaired electrons in one or more orbitals of their valence shells.
Carbon-12 is the most common isotope of carbon and has a mass number of 12. However, the average atomic mass of carbon found on a periodic table is slightly more than 12 daltons. Why?
Some carbon atoms in nature have more neutrons
Magnesium has an atomic number of 12. What is the most stable charge for a magnesium ion?
a +2 charge
How many neutrons are present in the nucleus of a phosphorus-32 (32P) atom (see the figure above)?
Based on electron configuration, which of the elements in the figure above would exhibit a chemical behavior most like that of oxygen?
Can the atomic mass of an element vary?
Yes. Adding or losing neutrons will change the atomic mass without forming a different element.
What type of bond is joining the two hydrogen atoms?
A covalent bond is one in which electron pairs are shared.
A(n) _____ refers to two or more atoms held together by covalent bonds
A molecule is defined as two or more atoms held together by covalent bonds.
This atom can form up to _____ single covalent bond(s).
4, There are four electrons in the outermost electron shell.
A(n) _____ bond joins these two oxygen atoms
double covalent, The oxygen atoms are sharing two pairs of electrons.
The brackets are indicating a(n) _____ bond.
hydrogen, A hydrogen atom with a net positive charge is attracted to an oxygen atom with a net negative charge
What name is given to the bond between water molecules?
Atoms with the same number of protons but with different electrical charges _____.
are different ions
Ions are charged atoms.
In salt, what is the nature of the bond between sodium and chlorine?
Sodium and chlorine ions are attracted to each other
a positively charged sodium ion and a negatively charged chlorine ion
Sodium loses an electron and thus becomes positively charged; chlorine gains an electron and thus becomes negatively charged.
An ionic bond involves _____.
an attraction between ions of opposite charge
This is the definition of an ionic bond
Which answer correctly ranks the atoms in terms of decreasing electronegativity (the highest electronegativity first)?
O, N, C, H
Congratulations! Remember this, and you'll be able to predict polarity when molecules have O or N linked to C or H.
Which atom in the pictured molecule will have the strongest partial positive charge?
The C that's in C=O.
Good for you! This C atom is bound to the two most electronegative atoms in the molecule (O), both of which are pulling electrons from C.
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 nonpolar
Yes! When two atoms of the same kind form a covalent bond, they share electrons equally because their electronegativity is the same.
Use your knowledge of electronegativity to pick out the most polar bond in the list below O-H O-N O-C C-H
Yes! O and H are at opposite ends of the electronegativity scale, so the polarity is very large
If you want a molecule that is highly polar, look for one that contains: C-S C-H O-N S-H H-N
N and H differ in electronegativity more than any other bonded pair of atoms in the list, making the N-H bond most polar.
A carbon atom and a hydrogen atom form what type of bond in a molecule?
nonpolar covalent bond.
Atoms with similar electronegativities form nonpolar covalent bonds.
Hydrogen bonding is most often seen _____.
when hydrogen is covalently bonded to an electronegative atom.
Highly electronegative atoms attract shared electrons more strongly than hydrogen does, resulting in a slight positive charge on the hydrogen atom. The slightly positive hydrogen atom is then attracted to another electronegative atom, forming a hydrogen bond.
What is the maximum number of covalent bonds that an oxygen atom with atomic number 8 can make with hydrogen?
Bonds between two atoms that are equally electronegative are _____.
nonpolar covalent bonds
What is the difference between covalent bonds and ionic bonds?
Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between charged atoms.
Which bond or interaction would be difficult to disrupt when compounds are put into water?
covalent bonds between carbon atoms
Van der Waals interactions may result when _____.
electrons are not symmetrically distributed in a molecule.
What is the maximum number of hydrogen atoms that can be covalently bonded in a molecule containing two carbon atoms
Nitrogen (N) normally forms three covalent bonds with a valence of 5. However, ammonium has four covalent bonds, each to a different hydrogen (H) atom (H has a valence of 1). What do you predict to be the charge on ammonium?
The reactivity of an atom arises from
the existence of unpaired electrons in the valence shell.
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.
Calcium ions are typically concentrated in the endoplasmic reticulum.
Ligand binding causes
receptor tyrosine kinase proteins to phosphorylate and form dimers.
The stage of cell signaling in which the signal is converted to a form that can bring about a response in the cell is called
cells shrink and form lobes, which are eventually shed as membrane fragments.
In a phosphorylation cascade, protein kinases phosphorylate proteins, and protein phosphatases dephosphorylate them
Phosphorylation affects cellular functioning by
Phosphorylation affects cellular functioning by activating or inactivating proteins.
The regular sequence of growth & division that cells undergo.
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