The chemical level of organization textbook questions
steroid
(also, sterol) lipid compound composed of four hydrocarbon rings bonded to a variety of other atoms and molecules
Explain why CH is one of the most common molecules found in nature. Are the bonds between the atoms ionic or covalent?
A carbon atom has four electrons in its valence shell. According to the octet rule, it will readily participate in chemical reactions that result in its valence shell having eight electrons. Hydrogen, with one electron, will complete its valence shell with two. Electron sharing between an atom of carbon and four atoms of hydrogen meets the requirements of all atoms. The bonds are covalent because the electrons are shared: although hydrogen often participates in ionic bonds, carbon does not because it is highly unlikely to donate or accept four electrons.
AB+CD→AD+BE Is this a legitimate example of an exchange reaction? Why or why not?
A. It is not. An exchange reaction might be AB+CD→AC+BD or AB+CD→AD+BC. In all chemical reactions, including exchange reactions, the components of the reactants are identical to the components of the products. A component present among the reactants cannot disappear, nor can a component not present in the reactants suddenly appear in the products.
Oxygen, whose atomic number is eight, has three stable isotopes: O, O, and O. Explain what this means in terms of the number of protons and neutrons.
A. Oxygen has eight protons. In its most abundant stable form, it has eight neutrons, too, for a mass number of 16. In contrast, O has nine neutrons, and O has 10 neutrons.
Once dietary fats are digested and absorbed, why can they not be released directly into the bloodstream?
All lipids are hydrophobic and unable to dissolve in the watery environment of blood. They are packaged into lipoproteins, whose outer protein envelope enables them to transport fats in the bloodstream.
reactions release energy.
Catabolic, exergonic, and decomposition
Which of the following is a molecule, but not a compound?
H2 (H20 ,2H,H+)
Could two atoms of oxygen engage in ionic bonding? Why or why not? A. Identical atoms have identical electronegativity and cannot form ion
Identical atoms have identical electronegativity and cannot form ionic bonds. Oxygen, for example, has six electrons in its valence shell. Neither donating nor accepting the valence shell electrons of the other will result in the oxygen atoms completing their valence shells. Two atoms of the same element always form covalent bonds.
The pH of lemon juice is 2, and the pH of orange juice is 4. Which of these is more acidic, and by how much? What does this mean?
Lemon juice is one hundred times more acidic than orange juice. This means that lemon juice has a one hundred-fold greater concentration of hydrogen ions.
During a party, Eli loses a bet and is forced to drink a bottle of lemon juice. Not long thereafter, he begins complaining of having difficulty breathing, and his friends take him to the local emergency room. There, he is given an intravenous solution of bicarbonate. Why?
Lemon juice, like any acid, releases hydrogen ions in solution. As excessive H enters the digestive tract and is absorbed into blood, Eli's blood pH falls below 7.35. Recall that bicarbonate is a buffer, a weak base that accepts hydrogen ions. By administering bicarbonate intravenously, the emergency department physician helps raise Eli's blood pH back toward neutral.
Magnesium is an important element in the human body, especially in bones. Magnesium's atomic number is 12. Is it stable or reactive? Why? If it were to react with another atom, would it be more likely to accept or to donate one or more electrons?
Magnesium's 12 electrons are distributed as follows: two in the first shell, eight in the second shell, and two in its valence shell. According to the octet rule, magnesium is unstable (reactive) because its valence shell has just two electrons. It is therefore likely to participate in chemical reactions in which it donates two electrons.
If the disaccharide maltose is formed from two glucose monosaccharides, which are hexose sugars, how many atoms of carbon, hydrogen, and oxygen does maltose contain and why?
Maltose contains 12 atoms of carbon, but only 22 atoms of hydrogen and 11 atoms of oxygen, because a molecule of water is removed during its formation via dehydration synthesis.
When you do a load of laundry, why do you not just drop a bar of soap into the washing machine? In other words, why is laundry detergent sold as a liquid or powder
Recall that the greater the surface area of the reactants, the more quickly and easily they will interact. It takes energy to separate particles of a substance. Powder and liquid laundry detergents, with relatively more surface area per unit, can quickly dissolve into their reactive components when added to the water.
The most abundant elements in the foods and beverages you consume are oxygen, carbon, hydrogen, and nitrogen. Why might having these elements in consumables be useful?
These four elements—oxygen, carbon, hydrogen, and nitrogen—together make up more than 95 percent of the mass of the human body, and the body cannot make elements, so it is helpful to have them in consumables.
Ty is three years old and as a result of a "stomach bug" has been vomiting for about 24 hours. His blood pH is 7.48. What does this mean?
Ty's blood is slightly alkaline.
In a hurry one day, you merely rinse your lunch dishes with water. As you are drying your salad bowl, you notice that it still has an oily film. Why was the water alone not effective in cleaning the bowl?
Water is a polar molecule. It has a region of weakly positive charge and a region of weakly negative charge. These regions are attracted to ions as well as to other polar molecules. Oils are nonpolar, and are repelled by water.
Phospholipids
a lipid compound in which a phosphate group is combined with a diglyceride
phosphorylation
addition of one or more phosphate groups to an organic compound
Which of the following is a functional group that is part of a building block of proteins?
amino
activation energy
amount of energy greater than the energy contained in the reactants, which must be overcome for a reaction to proceed
electron shell
area of space a given distance from an atom's nucleus in which electrons are grouped
periodic table of the elements
arrangement of the elements in a table according to their atomic number; elements having similar properties because of their electron arrangements compose columns in the table, while elements having the same number of valence shells compose rows in the table
The smallest unit of an element that still retains the distinctive behavior of that element is an
atom
anion
atom with a negative charge
cation
atom with a positive charge
ion
atom with an overall positive or negative charge
ionic bond
attraction between an anion and a cation
amino acid
building block of proteins; characterized by an amino and carboxyl functional groups and a variable side-chain.
Denaturation
change in the structure of a molecule through physical or chemical means
covalent bond
chemical bond in which two atoms share electrons, thereby completing their valence shells
lipid
class of nonpolar organic compounds built from hydrocarbons and distinguished by the fact that they are not soluble in water
Carbohydrates
class of organic compounds built from sugars, molecules containing carbon, hydrogen, and oxygen in a 1-2-1 ratio
nucleotide
class of organic compounds composed of one or more phosphate groups, a pentose sugar, and a base
protein
class of organic compounds that are composed of many amino acids linked together by peptide bonds
polysaccharide
compound consisting of more than two carbohydrate monomers bonded by dehydration synthesis via glycosidic bonds
base
compound that accepts hydrogen ions (H ) in solution
acid
compound that releases hydrogen ions (H ) in solution
uracil
contains nitrogen , is a pyrimidine , is found in RNA
peptide bond
covalent bond formed by dehydration synthesis between two amino acids
disulfide bond
covalent bond formed within a polypeptide between sulfide groups of sulfur-containing amino acids, for example, cysteine
Which of the following statements about chemical bonds is true?
covalent bonds are stronger than ionic bonds.
AB→A+B is a general notation for a(n) ________ reaction.
decompostion
deoxyribonucleic acid (DNA)
deoxyribose-containing nucleotide that stores genetic information
hydrogen bond
dipole-dipole bond in which a hydrogen atom covalently bonded to an electronegative atom is weakly attracted to a second electronegative atom
In DNA, nucleotide bonding forms a compound with a characteristic shape known as a(n) ____
double helix
bond
electrical force linking atoms
kinetic energy
energy that matter possesses because of its motion
chemical energy
form of energy that is absorbed as chemical bonds form, stored as they are maintained, and released as they are broken
What organic compound do brain cells primarily rely on for fuel?
glucose
functional group
group of atoms linked by strong covalent bonds that tends to behave as a distinct unit in chemical reactions with other atoms
A phospholipid
has both polar and nonpolar regions
proton
heavy subatomic particle having a positive charge and found in the atom's nucleus
neutron
heavy subatomic particle having no electrical charge and found in the atom's nucleus
C6 H12O6 is the chemical formula for a
hexose monosaccharide
Solution
homogeneous liquid mixture in which a solute is dissolved into molecules within a solvent
Which of the following combinations of atoms is most likely to result in a chemical reaction?
hydrogen and hydrogen
When an atom donates an electron to another atom, it becomes
ion
macromolecule
large molecule formed by covalent bonding
Triglycerides
lipid compound composed of a glycerol molecule bonded with three fatty acid chains
prostaglandin
lipid compound derived from fatty acid chains and important in regulating several body processes
suspension
liquid mixture in which particles distributed in the liquid settle out over time
colloid
liquid mixture in which the solute particles consist of clumps of molecules large enough to scatter light
polar molecule
molecule with regions that have opposite charges resulting from uneven numbers of electrons in the nuclei of the atoms participating in the covalent bond
monosaccharide
monomer of carbohydrate; also known as a simple sugar
On the periodic table of the elements, mercury (Hg) has an atomic number of 80 and a mass number of 200.59. It has seven stable isotopes. The most abundant of these probably have
more than 80 neutrons each
PH
negative logarithm of the hydrogen ion (H ) concentration of a solution
purine
nitrogen-containing base with a double ring structure; adenine and guanine
pyrimidine
nitrogen-containing base with a single ring structure; cytosine, thiamine, and uracil
A pentose sugar is a part of the monomer used to build which type of macromolecule?
nucleic acids
adenosine triphosphate (ATP)
nucleotide containing ribose and an adenine base that is essential in energy transfer
Concentration
number of particles within a given space
atomic number
number of protons in the nucleus of an atom
isotope
one of the variations of an element in which the number of neutrons differ from each other
product
one or more substances produced by a chemical reaction
Reactant
one or more substances that enter into the reaction
CH is methane. This compound is
organic
valence shell
outermost electron shell of an atom
Together, just four elements make up more than 95 percent of the body's mass. These include
oxygen, carbon, hydrogen, and nitrogen
Diasaccharide
pair of carbohydrate monomers bonded by dehydration synthesis via a glycosidic bond
matter
physical substance; that which occupies space and has mass
A molecule of ammonia contains one atom of nitrogen and three atoms of hydrogen. These are linked with
polar covalent bonds
The energy stored in a foot of snow on a steep roof is
potential energy
enzyme
protein or RNA that catalyzes chemical reactions
The characteristic that gives an element its distinctive properties is its number of
protons
ribonucleic acid (RNA)
ribose-containing nucleotide that helps manifest the genetic code as protein
Chewing a bite of bread mixes it with saliva and facilitates its chemical breakdown. This is most likely due to the fact that
saliva contains enzymes
A substance dissociates into K and Cl in solution. The substance is a(n) ________.
salt
A substance formed of crystals of equal numbers of cations and anions held together by ionic bonds is called a(n)
salt
atom
smallest unit of an element that retains the unique properties of that element
Which of the following is most likely to be found evenly distributed in water in a homogeneous solution?
sodium ions and chloride ions
buffer
solution containing a weak acid or a weak base that opposes wide fluctuations in the pH of body fluids
The ability of an enzyme's active sites to bind only substrates of compatible shape and charge is known as
specificity
potential energy
stored energy matter possesses because of the positioning or structure of its components
electron
subatomic particle having a negative charge and nearly no mass; found orbiting the atom's nucleus
compound
substance composed of two or more different elements joined by chemical bonds
element
substance that cannot be created or broken down by ordinary chemical means
organic
substance that contains both carbon and hydrogen
Inorganic
substance that does not contain both carbon and hydrogen
catalyst
substance that increases the rate of a chemical reaction without itself being changed in the process
substrate
substrate reactant in an enzymatic reaction
mass number
sum of the number of protons and neutrons in the nucleus of an atom
Jenny mixes up a batch of pancake batter, then stirs in some chocolate chips. As she is waiting for the first few pancakes to cook, she notices the chocolate chips sinking to the bottom of the clear glass mixing bowl. The chocolate-chip batter is an example of a
suspension
The bonding of calcium, phosphorus, and other elements produces mineral crystals that are found in bone. This is an example of a(n) ________ reaction.
synthesis
Nitrogen has an atomic number of seven. How many electron shells does it likely have?
two
molecule
two or more atoms covalently bonded together
synthesis reaction
type of anabolic reaction in which two or more atoms or molecules bond, resulting in the formation of a larger molecule
decomposition reaction
type of catabolic reaction in which one or more bonds within a larger molecule are broken, resulting in the release of smaller molecules or atoms
exchange reaction
type of chemical reaction in which bonds are both formed and broken, resulting in the transfer of components
radioactive isotope
unstable, heavy isotope that gives off subatomic particles, or electromagnetic energy, as it decays; also called radioisotopes
