BIO 1121 Human Anatomy & Physiology I chapter 2

Anabolic or synthesis reactions absorb or require

energy and are thus endergonic reactions.

When we consume food and process it in our cells, we extract energy from it. A type of chemical reaction in which the amount of energy released is greater than the activation energy needed to start the reaction is called a(n) __________.

exergonic reaction

Which of the following statements about the pH scale is FALSE?

A pH of 0 means there are no free hydrogen ions in the solution.

The chemical properties of every element are determined by

the number and arrangement of electrons in the outer energy level The number of protons in the nucleus helps determine an atom's chemical identity, not its chemical properties. The number of protons and neutrons in the nucleus helps determine an atom's chemical identity, not its chemical properties. The atomic weight of an atom helps determine its chemical identity, not its chemical properties.

Which of the following is not a lipid?

deoxyribonucleic acid Deoxyribonucleic acid, also known as DNA, is a nucleic acid, not a lipid. DNA is the main biological molecule used for information transfer and processing in cells. It is found in all nucleated cells in the body, and forms the common genetic library of information found in cells. Triglycerides are also known as fats, which are lipids. Steroids are ring-structured lipids. Eicosanoids are lipids.

Dissolved ions that can conduct an electrical current in a solution are called

electrolytes Dissolved ions that can conduct an electrical current in a solution are called electrolytes. Because of its own polarity or charged regions, water molecules pull apart ionic chemicals and separate them into ions in a solution. Because of their charges, these ions mix with water very easily and are hydrophilic. Also, since they conduct electric currents they are called electrolytes. Water is solvent, whereas the ions in solution are the solutes.

pH measures the concentration of __________ in a solution

free hydrogen ions pH is a measure of the concentration of free hydrogen ions in solution. The adjective "free" means they are not bonded to any other atom. Hydrogen ions are very reactive and because of this, a hydrogen ion concentration in excess of that required for homeostasis can disrupt normal functioning of other molecules in the body. The concentration of hydrogen ions must be homeostatically regulated so the body can function properly. The term molarity is used to define the concentration solutes other than hydrogen ions in solutions.

A solution that has a pH of 2 would best be described as

strongly acidic

The symbol H2O means that each molecule of water is composed of

two hydrogen atoms and one oxygen atom Two hydrogen atoms and two oxygen atoms would be designated as H2O2. Four hydrogen atoms and one oxygen atom would be designated as H4O. Four hydrogen atoms and two oxygen atoms would be designated as H4O2.

What is the term for a chemical that dissociates into anions and cations that are neither hydroxide nor hydrogen ions?

Salt A salt is an ionic compound containing any cation except a hydrogen ion, and any anion except a hydroxide ion. When put in water, a salt dissolves or dissociates into anions and cations. However, if one of the cations released into solution was a hydrogen ion, this chemical would be an acid. If one of the anions released into solution was a hydroxide ion, this chemical would be a base.

Which of the following is the most specific term for the type of chemical reaction that breaks a molecule into smaller fragments by breaking its chemical bonds?

-Decomposition reaction Exchange reactions involve both breaking and creating new chemical bonds. Synthesis reactions involve creating new bonds. Anabolic reactions are the same as synthesis reactions. Decomposition reactions involve the breaking of chemical bonds between atoms. This process always results in the production of smaller compounds from a larger compound. These reactions are also termed catabolic and are critical during the digestion of food. The breaking of these bonds enables our bodies to rearrange the macromolecules in food so that they can be incorporated into our tissues. The breakdown of larger molecules into smaller ones enables our bodies to rearrange the macromolecules in food so that they can be incorporated into our tissues.

Organic catalysts made by a living cell to increase the rates of reactions are called

-enzymes Enzymes are organic catalysts produced by all cells, and increase the rate at which biological reactions occur. The main job of these organic catalysts is to lower activation energy, a process that is needed for any given chemical reaction to take place in a cell. Enzymes are usually composed of proteins and are very specific to each chemical reaction. Buffers keep pH levels stable. Nucleic acids store and process information. Metabolites are any group of intermediate products in a pathway.

A + B > AB is an example of a(n) __________ reaction.

-synthesis The reaction A + B > AB is a typical synthesis reaction. These types of reactions always result in larger molecules being produced from smaller molecules. Because these reactions require the creation of additional chemical bonds, they typically require an input of energy in the form of ATP. Decomposition reactions involve creating smaller molecules, not bigger molecules. Exergonic reactions release heat when bonds are broken. Reversible reactions can go in both directions, and are indicated using a double-headed arrow between reactants and products.

If oxygen has an atomic weight of 16, what is the molecular weight of an oxygen molecule?

32 Since an oxygen molecule is made up of two oxygen atoms bound together, the weight of an oxygen molecule is 32. This is the result of adding together the atomic weights of each oxygen atom in the molecule. Remember: 8 is only half the weight of a single oxygen atom. Remember: 16 is the weight of only a single oxygen atom. Remember: 2 is only a fraction of the weight of a single oxygen atom.

From the following choices, select the one that shows an example of a decomposition reaction.

AB --> A + B The reaction AB --> A + B is an example of a decomposition reaction. These are catabolic reactions in which a large molecule is broken down into smaller subunits. This is a vital part of many cellular processes including nutrient absorption and energy metabolism. Energy is liberated from ATP by way of a decomposition reaction, which breaks apart a high-energy phosphate bond. The reaction AB + CD --> AD + CB is an exchange reaction. The reaction A + B --> AB is a synthesis reaction. The reaction C + D --> CD is also a synthesis reaction.

Which of the following molecules is a compound containing bonds between phosphate groups?

ATP ATP is a compound containing bonds between phosphate groups. Although energy is contained in all chemical bonds, the bonds of ATP are specially suited for storing and transferring larger amounts of energy. ATP is the main vehicle for energy transfer within the cell. DNA stores information, not energy. Glycerides are building blocks of lipids, but they do not transfer energy. Glucose is a sugar that can be broken down to form ATP.

Which of the following statements is correct?

An anion is a negatively charged atom or group of atoms. Atoms are normally neutral since they have the same number of protons and electrons. The number of neutrons is not always the same as protons. When atoms form ionic bonds they do so by giving away electrons or accepting electrons from another atom. This makes the number of protons and electrons different and gives the atom an excess charge. Since anions have an excess of electrons, they have a negative charge. Ions are not neutral since the term is used to designate an atom, or group of atoms, that have either a positive or negative charge.

What are isotopes of an element?

Atoms whose nuclei contain the same number of protons, but different numbers of neutrons Isotopes are atoms whose nuclei contain the same number of protons but different numbers of neutrons. These atoms all have the same atomic number, which is determined by the number of protons in their nucleus. Although isotopes are all variants of one particular element, isotopes vary in their atomic mass. The heavier nuclei in larger isotopes generally make the isotope more unstable. Isotopes are not atoms whose nuclei contain different numbers of protons and electrons. Isotopes are not atoms with an equal number of protons, neutrons, and electrons. Atoms whose nuclei contain different numbers of protons are distinct elements.

Which statement about buffers is FALSE?

Buffers are composed of a strong acid and a strong base. Buffers are composed of a strong acid and a strong base is false. Buffers are composed of a weak acid and its salt, which act as a weak base. Buffers are the first line of defense against large pH changes, and they help to maintain homeostasis. If the buffer is exposed to an acid, it uses its base to neutralize the acid and accepts hydrogen ions from solution. If the buffer is exposed to a base, it uses its acid to neutralize it and donates hydrogen ions to the solution.

What type of chemical bond is formed when two atoms share electrons?

Covalent bond involve two atoms sharing electrons, which forms a stable bond. This type of bond is one of the strongest chemical bonds. The covalent bond also forms the main bonding of macromolecules that form the tissues of the body, such as proteins, carbohydrates, and fats. Ionic bonds are formed between anions and cations. Isotope bonds are not a category of bonds. Hydrogen bonds are formed by the weak electrostatic attractions between charged areas of compounds.

Comparing the structure and functions of DNA and RNA, which of the following statements is most accurate?

DNA is copied into RNA and that copy is used to build specific proteins. DNA is copied into RNA and that copy is used to build specific proteins is most accurate. DNA in our cells determines our inherited characteristics. DNA does this by encoding the information needed to build proteins. By controlling the manufacturing of enzymes, DNA regulates not only protein synthesis, but all aspects of cellular metabolism. Several forms of RNA cooperate to build specific proteins by using information provided by DNA. RNA usually exists as a single-stranded molecule. Uracil is found in RNA, not DNA. DNA uses the pentose sugar, deoxyribose.

Which type of bond has the most important effects on the properties of water and the shapes of complex molecules?

Hydrogen bond Ionic bonds are not stable in an aqueous solution. Covalent bonds are too strong to participate in more transient biochemical interactions requiring hydrogen bonds. Polar covalent bonds are too strong to regulate the unzipping of DNA.

What happens to an enzyme that is subjected to extremely high temperatures?

It becomes denatured. An enzyme that is subjected to extremely high temperatures becomes denatured. "Denatured" is a term used to indicate that a protein has become unfolded. Folding is a property associated with proteins and their potential to carry out their specific function. This property is not seen in carbohydrates or lipids. Extremely high temperatures do not enable enzymes to catalyze several reactions at once. Extremely high temperatures do not enable enzymes to catalyze reactions at a faster rate. Extremely high temperatures do not enable enzymes to catalyze only one reaction at a time.

What is the primary function of monosaccharides such as glucose?

It becomes denatured. An enzyme that is subjected to extremely high temperatures becomes denatured. "Denatured" is a term used to indicate that a protein has become unfolded. Folding is a property associated with proteins and their potential to carry out their specific function. This property is not seen in carbohydrates or lipids. Extremely high temperatures do not enable enzymes to catalyze several reactions at once. Extremely high temperatures do not enable enzymes to catalyze reactions at a faster rate. Extremely high temperatures do not enable enzymes to catalyze only one reaction at a time.

Why is water particularly effective as a solvent?

Its polarity creates positive and negative regions that interact with many types of molecules. The polarity of water creates positive and negative regions that interact with many types of molecules. This polarity results from the polar covalent bonds between oxygen and hydrogen in the water molecule. This causes more negative charges to accumulate around the oxygen and more positive charges to accumulate around the hydrogens. Cations and anions are produced by hydration but are not responsible for water's effectiveness as a solvent. Hydrophobic molecules have nonpolar, not polar, covalent bonds. High heat capacity does not impact dissolution the way the polarity of the water molecule itself does.

Why are lipid deposits important as energy reserves?

Lipids provide twice as much energy as carbohydrates. Lipids provide twice as much energy as carbohydrates. For this reason, lipids are described as energy-dense. Due to this higher energy density, lipids function as an ideal energy-storage medium in the body. With lipids as stored energy, the human body can keep a large amount of energy in reserve, very efficiently. Lipids are not readily broken down to release energy. Lipids are not a quick energy source. Lipids appear as fat deposits on the body, but their appearance is not why they are important.

Which statement is most accurate?

Most inorganic compounds are ionically bonded. Inorganic compounds are generally held together by ionic bonds. There are always exceptions to a rule. Water, oxygen, and carbon dioxide are inorganic even though they contain covalent bonds. Although most organic molecules have carbon atoms as their "backbone," carbon dioxide is an exception to that rule. Inorganic molecules are also generally small and contain only a few atoms bonded together.

If the second energy level of an atom has one electron, how many more electrons does it need in order for that energy level to be filled to its maximum capacity?

Seven The second electron shell of the atom in this question needs seven more electrons in order to be filled completely. The octet rule states that in an atom with two or more shells, the first shell is filled with two electrons and subsequent shells are filled with eight electrons each. When an outer electron shell is filled, the reactivity of the atom is reduced. On the other hand, empty spaces in a shell make the atom more chemically reactive. Two electrons would leave five empty spaces in this atom's outer shell. Five electrons would leave two empty spaces in this atom's outer shell. One electron would leave six empty spaces in this atom's outer shell

Water is the primary solvent in our body fluids. Which statement about water and its solvent properties as solvent is correct?

The oxygen end of the water molecule is partially negatively charged and the hydrogen end is partially positively charged. The oxygen end of the water molecule is partially negatively charged and the hydrogen end is partially positively charged is a correct statement. Because water is formed by polar covalent bonds, there is an unequal sharing of electrons. The shared electrons spend more time in the electron shells of oxygen than in the shells of hydrogen. This results in the oxygen end being partially negatively charged and the hydrogen end being partially positively charged. Water is a polar molecule but it is not an ion. Any chemical that dissolves in water is also either completely or partially polar or ionically bonded and thus hydrophilic. Because of this, hydration spheres will form around these molecules and cause them to dissolve. Oils and fats are nonpolar and will not dissolve in water. Molecules that do not dissolve in water are hydrophobic.

Which of the following statements about inorganic molecules is false?

They contain carbon and hydrogen atoms as their primary structural elements. Inorganic molecules do NOT contain carbon and hydrogen as their primary structural elements. Because of this, many inorganic molecules also tend to be less complex than organic molecules. Since organic molecules can form long chains of carbon atoms, they are capable of forming molecules composed of hundreds or even thousands of carbon atoms. Inorganic compounds can include oxygen. Inorganic compounds can include acids and bases. Water is an inorganic molecule.

Which of the following statements about enzymes is false?

They raise the activation energy required to start a chemical reaction. Enzymes are protein catalysts that accelerate chemical reactions. Instead, these biological catalysts always lower activation energy, which enables a chemical reaction to move forward. Activation energy is a type of chemical hurdle that must be overcome for a chemical reaction to take place.

Which type of lipid provides the energy reserve that is stored in our bodies?

Triglycerides or neutral fats Triglycerides or neutral fats provide the energy reserve that is stored in our bodies. Three fatty acids are joined to glycerol to form triglycerides. Fatty acids are long carbon chains with hydrogen atoms attached. All the bonds holding the carbons and hydrogens together store a lot of energy. These fats are deposited in specialized sites of the body and provide a significant energy reserve. Phospholipids make up most of the plasma membrane of cells, but are not used for energy. Steroids are hormones. They are not for a store of energy. Eicosanoids have important functions in the body, but they are not used for their energy content. \

Which property of water allows us to maintain a stable body temperature?

Water has a high heat capacity. Because water has a high heat capacity, it resists temperature changes and allows us to maintain a stable body temperature within homeostatic limits. A large portion of body weight is water. This helps to resist temperature changes when the body is exposed to varying temperatures in our environment. For this reason, humans can maintain a normal range of body temperature and function properly in various environments without great difficulty. Although water is a good solvent, a good lubricant, and can participate in chemical reactions, these are not the properties of water that allow it to maintain stable body temperature.

Which of the following statement about water's ability to help us maintain homeostasis is FALSE?

When heated, liquid water is easily converted into water vapor. The following is a FALSE statement: When heated, liquid water is easily converted into water vapor. Recall that water molecules are formed by polar covalent bonding. This unequal sharing of electrons causes water molecules to develop charged regions, which leads to hydrogen bonding between water molecules. Thus, to separate water molecules and convert water to vapor, it takes a lot of heat energy so water remains liquid over a wide range of temperature. It has thermal inertia and resists temperature changes. When it is converted to a gas (evaporation), water takes a lot of heat away from the body. The properties of water help us to maintain temperature homeostasis.

In chemical notation, the symbol 2H means

`two atoms of hydrogen In chemical notation, the symbol 2H means two atoms of hydrogen. If these two hydrogen atoms react with oxygen gas, water is produced. Two molecules of hydrogen would be designated as 2H2. One molecule of hydrogen would be designated as H2. Two atoms of helium would be designated as 2He.

A pure chemical substance made up of atoms of two or more types of elements in a fixed proportion is specifically called

a compound Compounds are formed when two or more different elements bind together in a fixed proportion via any type of chemical bonds. These collections of atoms can be simple, with only two atoms bound, or can be very complex, with hundreds or thousands of atoms bound together. Molecules are composed of two or more atoms bound together by shared electrons. Isotopes are atoms of the same element composed of different numbers of neutrons. Chemical bonds bind the atoms of a compound together.

A pure chemical substance made up of atoms of two or more types of elements in a fixed proportion is specifically called

a compound Molecules are composed of two or more atoms bound together by shared electrons. Isotopes are atoms of the same element composed of different numbers of neutrons. Chemical bonds bind the atoms of a compound together. Compounds are formed when two or more different elements bind together in a fixed proportion via any type of chemical bonds. These collections of atoms can be simple, with only two atoms bound, or can be very complex, with hundreds or thousands of atoms bound together.

The unequal sharing of electrons in a molecule of water is an example of

a polar covalent bond The water molecule is an example of a molecule containing polar covalent bonds. This type of bond involves the unequal sharing of electrons within a molecule, which creates a difference in charge distribution. In water, this is the result of oxygen's stronger attraction for the shared electrons, so the electrons spend more time around the oxygen atom and less time around the hydrogen atoms.An ionic bond is formed between cations and anions. A double covalent bond is not found in water. A hydrogen bond is found between molecules of water, not within them.

The subatomic particle that is found in the nucleus of an atom and has a positive charge is

a proton Neutrons are subatomic particles located in the nucleus and have no electrical charge. Electrons are subatomic particles that form a shell around the nucleus. Isotopes are variants of an element, so they are not subatomic. Protons are the positively charged subatomic particles that are located in the nucleus of an atom. The number of protons determines the atomic number. The number of protons plus the number of neutrons determine the mass of an atom.

Which of the solutions below is the most acidic?

a solution with a pH of 2 A solution with a pH of 2 is close to a pH of 0, which is the most acidic end of the pH scale. As you go toward the other end of the pH scale, a substance becomes more basic. Remember that the pH scale is a measure of the hydrogen ion concentration of a solution. A solution with a pH of 5 is close to being neutral. A solution with a pH of 8 is a base. A solution with a pH of 12 is a strong base.

A DNA molecule consists of two polynucleotide strands hydrogen bonded to each other. The hydrogen bonding is very specific. Which of the following nitrogenous bases will form complementary base pairs in DNA?

adenine and thymine Adenine and thymine form complementary base pairs in DNA. Five nitrogenous bases occur in nucleic acids: adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U). Adenine and guanine are double-ringed molecules called purines. The other three bases are single-ringed molecules called pyrimidines. Both RNA and DNA contain adenine, guanine, and cytosine. Uracil occurs only in RNA, and thymine occurs only on DNA. Purines and pyrimidines will hydrogen bond. The shapes of the nitrogenous bases allow adenine to bond only to thymine, and cytosine to bond only to guanine.

Proteins differ from carbohydrates because proteins

always contain nitrogen Proteins differ from carbohydrates because proteins always contain nitrogen. In contrast to carbohydrates and lipids, proteins are not primarily used for fuel by cells to produce ATP. Rather, proteins compose most of the enzymes in the body as well as structural material in the cells. Proteins do contain carbon, hydrogen, and oxygen. Proteins are not quick sources of energy. Proteins are organic compounds.

Proteins are composed of subunits called

amino acids Amino acids are the structural subunits that comprise proteins. Like carbohydrates and lipids, amino acids are composed of carbon, hydrogen, and oxygen atoms bound together by covalent bonds. In addition to these elements, amino acids also contain nitrogen atoms. Amino Acids Nucleotides are subunits that make up nucleic acids. Fatty acids are subunits of triglycerides. Monosaccharides are subunits of carbohydrates.

Which of the following is a type of molecule that releases hydrogen ions into a solution and lowers the pH of that solution?

an acid An acid is a type of molecule that releases hydrogen ions into solution. By definition, because of this property, an acid will also lower pH, and the pH number will get smaller. This property of pH is critical in biological systems and in our cells because all cells and tissues function optimally only within a certain range of pH. A base absorbs hydrogen ions. A salt results from the reaction of an acid and a base. A buffer resists changes in pH.

A solute that dissociates to release hydrogen ions into solution and thus causes a decrease in pH is __________.

an acid An acid will dissociate in water and releases hydrogen ions. As the pH decreases this increase in hydrogen ion concentration is registered on the pH scale as a decrease in number. As the number decreases toward zero, the solution gets more acidic. Salts dissociate to form cations and anions other than hydrogen and hydroxide ions. Bases dissociate to form hydroxide ions. Pure water does not liberate excess hydrogen ions and cause a solution to become more acidic.

A type of reaction in which simple molecules are bonded together to make a larger, more complicated molecule is called a(n) __________ reaction.

anabolic Reactions constantly happen in the body in which metabolic processes build new and more complicated molecules. These types of reactions are anabolic or synthesis reactions. Catabolic, decomposition, or hydrolysis reactions are reactions in which complex molecules are broken down into simpler molecules.

The smallest stable units of matter are called

atoms Atoms are the smallest stable units of matter. These units form the foundation of all successive levels of matter by forming chemical bonds with each other. The levels of complexity are largely determined by the number of these atoms binding to each other. Molecules are collections of two or more atoms bound to each other. Protons are positively charged subatomic particles located in the nucleus of an atom. Electrons are negatively charged subatomic particles that form shells in an atom.

The smallest stable units of matter are called

atoms Molecules are collections of two or more atoms bound to each other. Protons are positively charged subatomic particles located in the nucleus of an atom. Electrons are negatively charged subatomic particles that form shells in an atom.

A chemical that can release free hydroxide ions or accept free hydrogen ions in a solution is a(n)

base A chemical that can release free hydroxide ions or accept free hydrogen ions in a solution is a base. If you had acid indigestion, there would be too many free hydrogen ions in your stomach. You would want a treatment that removes free hydrogen ions from the solution in your stomach. "Tums," or any antacid, would do that because it is a base. Bases are hydroxide ion donors or hydrogen ion acceptors. By accepting hydrogen ions, the base neutralizes the acid. An acid is a compound that releases free hydrogen ions into solution. Salts are ionic compounds that do not contain hydrogen ions or hydroxide ions.

To maintain homeostasis in the human body, the normal pH range of the blood must remain

between 7.35-7.45 \\\ To maintain homeostasis in the human body, the normal pH range of the blood must remain between 7.35-7.45. Biological systems and tissues are characterized by this range of the pH scale because enzymes, which are mostly proteins, require this range. If the pH goes out of this range, enzymes will not function, which would jeopardize all cell metabolic functions. The end result could be tissue or cell death. The pH range 6.80-7.20 is acidic and is too low for the human body to function properly. A pH of 7.0 is neutral and and is more acidic than the pH of human blood. The pH range 6.80-7.80 is too wide to allow the human blood to remain in its homeostatic range of 7.35 to 7.45.

Acidosis is defined as

blood pH below 7.35 Acidosis is defined as a blood pH below 7.35. Because the normal homeostatic range of blood pH is 7.35 to 7.45, acidosis would result from a pH below 7.35. The term acidosis does not reveal how large the deviation from homeostatic pH is, only the direction of the pH change. As the pH scale is formulated, moving toward zero makes a solution more acidic. Therefore, a pH reading below 7.35 is more acidic and out of the normal homeostatic range of blood pH. This is acidosis.

A carbohydrate molecule is made up of

carbon, hydrogen, and oxygen A carbohydrate molecule is made up of carbon, hydrogen, and oxygen atoms. Carbohydrates are one of the main macromolecules used to produce ATP inside a cell. Larger carbohydrate molecules are known as starches. When starches are broken down, their smaller subunits, the monosaccharides, are used as the fuel inside the cell. Fatty acids are components of lipids. Carbon, calcium, and sodium do not make up carbohydrates. Nitrogen is not a component of naturally occurring carbohydrates.

A molecule that is hydrophobic

could be a fat or an oil A molecule that is hydrophobic could be a fat or an oil. These molecules, because they contain nonpolar covalent bonds, do not mix with water. This is reflected in the name "hydrophobic," which means "water-fearing." A molecule that is hydrophobic could be a fat or an oil. These molecules, because they contain nonpolar covalent bonds, do not mix with water. This is reflected in the name "hydrophobic," which means "water-fearing."

Enzymes catalyze reactions by

decreasing the activation energy. Activation energy is an energy threshold that must be exceeded in order for chemical reactions to take place. Enzymes cause this threshold, which is a barrier, to be lowered so that less energy is required. Virtually all chemical reactions in a cell require energy. By using enzymes, the cell can save energy by using less of it to get work done. Increasing the activation energy would slow reactions down, not accelerate them. Breaking down proteins is not required for enzymes to catalyze reactions. Synthesizing carbohydrates is not required for enzymes to catalyze chemical reactions.

When table salt is put into a glass of water it dissolves. The term used for breaking of ionic bonds and the separation of ions is

dissociation or ionization The term used for breaking of ionic bonds and the separation of ions is dissociation or ionization. Water molecules with their own polar regions pull apart the Na+ and Cl- ions that make up table salt. This dissociation or ionization causes these ions to go into solution or dissolve. They stay separate because they are surrounded by a layer of water molecules called a hydration sphere. At this point, the ions are electrolytes. Digestion is the breakdown of substances in the digestive tract. Polarity is the property of water that allows dissociation or ionization to take place.

Carbohydrates are very important to the body because they serve as primary sources of

energy Carbohydrates are very important to the body because they serve as primary sources of energy. Carbohydrates in food are broken down into smaller subunits, the monosaccharides. The main monosaccharide used for energy, glucose, is kept within a range of values in the bloodstream so that all tissues can have access to fuel. Metabolites are any group of products in a pathway, but they are not a primary function of carbohydrates. Tissue repair and growth are important functions of proteins, not carbohydrates. Digestible forms of food include carbohydrates, but this is not the function of carbohydrates.

Organic catalysts made by a living cell to increase the rates of reactions are called

enzymes Enzymes are organic catalysts produced by all cells, and increase the rate at which biological reactions occur. The main job of these organic catalysts is to lower activation energy, a process that is needed for any given chemical reaction to take place in a cell. Enzymes are usually composed of proteins and are very specific to each chemical reaction. Buffers keep pH levels stable. Nucleic acids store and process information. Metabolites are any group of intermediate products in a pathway.

When we consume food and process it in our cells, we extract energy from it. A type of chemical reaction in which the amount of energy released is greater than the activation energy needed to start the reaction is called a(n)

exergonic reaction The type of chemical reaction in which the amount of energy released is greater than the activation energy needed to start the reaction is called an exergonic reaction. The value in eating metabolic fuels or energy-rich foods is the energy stored in those foods. When we break them down, we release this energy for our use. This type of energy-releasing reaction is an exergonic reaction. Anabolic or synthesis reactions absorb or require energy and are thus endergonic reactions.

Which type of protein generally forms extended sheets or strands and usually plays a structural role in cells?

fibrous protein Fibrous proteins form the structural foundations that give a cell form and shape. These proteins usually form large sheets or strands made of repeating units of smaller subunits known as monomers. These proteins thus form the bulk of many cells in the body, much like bricks give a house form and structure. Globular proteins make up enzymes, not structural proteins. Polypeptides are subunits of proteins. Hemoglobin functions to bind oxygen, not to form structure.

After a meal, our bodies will store carbohydrates in the liver and skeletal muscle cells. These stored carbohydrates are stored in the form of

glycogen Carbohydrates stored in the liver and skeletal muscle are stored as the polysaccharide, glycogen. Glucose is an important metabolic fuel, but it is not the storage form of carbohydrates. Long branched chains of glucose are stored for later use as the polysaccharide, glycogen. While plants store carbohydrates as sucrose, humans do not. Fructose is not a storage form of carbohydrate in humans.

Which of the following is the property of water that arises because of the hydrogen bonding of water molecules to each other in the liquid state?

high heat capacity Water has a high heat capacity due to the hydrogen bonding of water molecules to each other in the liquid state. This ability of water to absorb large amounts of heat and resist changes in temperature helps us to maintain a stable body temperature. Since water makes up the largest component of our bodies, it is critical that this substance not be susceptible to temperature variation. If this were the case, our cells would not be capable of maintaining adequate temperature homeostasis. Reactivity arises because water participates as a reactant in chemical reactions in the body. Solubility is the ability of solutes to dissolve in a solvent, such as water. Lubrication is a property of water that arises because there is not a great deal of friction between water molecules..

The attraction between cations and anions is important in

ionic bonds Ionic bonds are created by the attraction between cations and anions. These bonds are generally not as strong as covalent bonds and involve one ion donating electrons to another ion. Ionic compounds generally form salts and crystalline structures. These compounds will dissolve in water and body fluids. Polar covalent bonds involve an unequal sharing of electrons between atoms. Nonpolar covalent bonds involve an equal sharing of electrons between atoms. Double covalent bonds involve two covalent bonds forming between atoms.

The attraction between cations and anions is important in

ionic bonds Polar covalent bonds involve an unequal sharing of electrons between atoms. Nonpolar covalent bonds involve an equal sharing of electrons between atoms. Double covalent bonds involve two covalent bonds forming between atoms.

Which of the following statements about water is incorrect? is composed of polar molecules is responsible for about 2/3 of the mass of the human body Correct Response has a relatively low heat capacity can be considered a 'universal solvent' contains hydrogen bonds Question 3 0 / 2 points Ionic bonds are formed when: atoms share electrons Correct Answer atoms which have either gained or lost electrons are attracted to each other Incorrect Response a pair of electrons is shared unequally by two atoms two or more atoms lose electrons at the same time Question 4 0 / 2 points The reaction A-B-C-H + HO-D-E --> A-B-C-D-E + H20 is an example of a(n): Incorrect Response decomposition reaction Correct Answer dehydration synthesis catabolism ionic interaction hydrolysis Question 5 0 / 2 points A(n) ______ is a solute which acts as a proton donor and a(n) ________ is a solute that acts as a proton acceptor. Incorrect Response base, acid salt, base Correct Answer acid, base electrolyte, acid colloid, suspension

no

The major difference between inorganic and organic compounds is that inorganic compounds are usually

not composed of carbon and hydrogen Inorganic compounds are usually NOT composed of carbon and hydrogen. Inorganic compounds are composed of any other elements bound together. The chemical bonds that glue these compounds together are usually ionic. Inorganic compounds are also generally made from a smaller collections of elements than those used in organic molecules. Organic compounds are composed of carbon, hydrogen, and oxygen. Most inorganic compounds are soluble in water, and they are smaller and less complex than organic compounds.

The major difference between inorganic and organic compounds is that inorganic compounds are usually __________.

not composed of carbon and hydrogen Inorganic compounds are usually NOT composed of carbon and hydrogen. Inorganic compounds are composed of any other elements bound together. The chemical bonds that glue these compounds together are usually ionic. Inorganic compounds are also generally made from a smaller collections of elements than those used in organic molecules. Organic compounds are composed of carbon, hydrogen, and oxygen. Most inorganic compounds are soluble in water, and they are smaller and less complex than organic compounds.

The mass number of an atom is defined as the

number of protons plus the number of neutrons in the nucleus The mass number of an atom is defined as the sum of the number of protons plus the number of neutrons in an atom. Chemical matter is defined as anything that occupies space and has mass. The smallest units of matter are atoms. Atoms are composed of subatomic particles: protons, neutrons, and electrons. All three are very small, but protons and neutrons are the two that significantly contribute to the mass of an atom. So, the total number of the protons plus the number of neutrons approximates the amount of matter contained in an atom.

Chemicals that must be in our diet in order for the body to function normally are called

nutrients Nutrients are chemicals that must be in our diet in order for the body to function normally. We must consume them in the foods that we eat because generally they can't be made by our bodies. Metabolites are chemicals involved in or byproducts of normal metabolism. A substrate would be an example of a metabolite. Solutes are simply dissolved chemicals.

The type of bond that holds amino acids together in a chain is called a(n)

peptide bond The type of bond that holds amino acids together in a chain is called a peptide bond. Proteins are long chains of amino acids joined together by dehydration synthesis reactions. These reactions creates covalent bonds between the carboxyl group of one amino acid and the amino group of another. Such a bond is called a peptide bond. Thus proteins are sometimes called polypeptides, because of all the peptide bonds holding the amino acids together. Hydrogen bonds and ionic bonds are not used to joining amino acids together in polypeptides or proteins.

Certain types of fats are modified fatty acids that coordinate and direct local cellular activities. These important regulatory chemicals are called

prostaglandins Important regulatory chemicals that coordinate and direct local cellular activities are called prostaglandins. They are short-chain fatty acids in which five of the carbons are joined in a ring. Even though they are named after the prostate gland, virtually all tissues synthesize and respond to them. Leucotrienes help regulate our response to disease. Many steroids are hormones but are made of carbon rings instead of fatty acids. Glycolipids are usually structural lipids.

Certain types of fats are modified fatty acids that coordinate and direct local cellular activities. These important regulatory chemicals are called __________.

prostaglandins Important regulatory chemicals that coordinate and direct local cellular activities are called prostaglandins. They are short-chain fatty acids in which five of the carbons are joined in a ring. Even though they are named after the prostate gland, virtually all tissues synthesize and respond to them. Leucotrienes help regulate our response to disease. Many steroids are hormones but are made of carbon rings instead of fatty acids. Glycolipids are usually structural lipids.

The presence of an appropriate enzyme affects only the

rate of the reaction Enzymes lower the activation energy which affects only the rate of a chemical reaction. Enzymes do NOT work by changing the direction of the reaction or altering the reactants or products.

The action of a buffer to maintain pH within normal limits involves

removing or replacing hydrogen ions The action of a buffer to maintain pH within normal limits involves removing or replacing hydrogen ions in solution. The concentration of hydrogen ions determines the acidity of a solution. In the human body, these ions need to be kept within normal limits since any change from these limits will change the conformation and shape of proteins. Many of the affected proteins are enzymes, which are crucial for virtually all chemical reactions in a cell. Removing or replacing sodium ions does not affect pH. Replacing bicarbonate ions is not the main activity of a buffer system. Adding weak acids is not the main activity of a buffer system.

The substances dissolved in a solution are called

solutes Solutes are substances that dissolve in a solvent. The solute plus solvent form a solution. Solute is present in smaller amounts than is a solvent in a solution. This involves a mixing of the particles of solute such that a uniform solution results. This solution usually occurs because of the ability of solvent molecules to "cage" particles of solute. This keeps the solute from falling out of solution as well as ensures a uniform distribution of the solute. Solvents, like water, are substances that dissolve a solute. Suspensions are collections of large particles in a solvent that do not dissolve, but eventually settle out of solution. Colloids are usually proteins that form gels.

Which of the following categories of lipids function as hormones?

steroids Steroids are a type of lipid that forms the structural backbone of many hormones. These hormones, also known as steroid hormones, are multiringed structures that include lipids such as cholesterol as well as sex hormones such as estrogen and testosterone. Steroid hormones such as estrogen and testosterone are produced these sex hormones are produced in the body by using cholesterol as the initial building material. Triglycerides are used for fuel, not for making hormones. Phospholipids are the major component of cell membranes, but do not function as hormones. Waxes are used to protect surfaces, not to make hormones.

Atomic number is defined as

the number of protons in the nucleus The number of protons in an atom is known as its atomic number. It is the number of protons that determines the type of atom you have. All atoms of the same element have the same number of protons in the nucleus. For example, all hydrogen (H) atoms have one proton in the nucleus and hydrogen's atomic number is 1.

The reaction involved in joining two simple sugars together to form a disaccharide requires

the removal of water to create a more complex molecule The addition of water would cause hydrolysis and breaking apart of molecules. The presence of cations and anions would not create the needed covalent bonds. The disassembling of molecules through hydrolysis would create smaller, not larger molecules.

The ideal medium for most absorption and/or transport of inorganic and organic compounds in the human body is

water Water is the ideal medium for the absorption and transport of most inorganic as well as organic compounds in the body. Of all naturally occurring liquids, water is capable of dissolving the widest variety of solutes. For this reason, water is known as the universal solvent. Oil will dissolve only a limited range of compounds. Blood is composed of water. Lymph is also composed of water.