Anatomy and Physiology Ch. 2 (Exam 1)

steroid

(also, sterol) lipid compound composed of four hydrocarbon rings bonded to a variety of other atoms and molecules

Explain why CH4 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.

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.

Could two atoms of oxygen engage in ionic bonding? Why or why not?

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.

AB + CD → AD + BE Is this a legitimate example of an exchange reaction? Why or why not?

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.

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.

Oxygen, whose atomic number is eight, has three stable isotopes: 16O, 17O, and 18O. Explain what this means in terms of the number of protons and neutrons.

Oxygen has eight protons. In its most abundant stable form, it has eight neutrons, too, for a mass number of 16. In contrast, 17O has nine neutrons, and 18O has 10 neutrons.

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.

Visit this website to view the periodic table. In the periodic table of the elements, elements in a single column have the same number of electrons that can participate in a chemical reaction. These electrons are known as "valence electrons." For example, the elements in the first column all have a single valence electron—an electron that can be "donated" in a chemical reaction with another atom. What is the meaning of a mass number shown in parentheses? http://www.ptable.com/

The mass number is the total number of protons and neutrons in the nucleus of an atom.

Watch this video to observe the formation of a disaccharide. What happens when water encounters a glycosidic bond? https://www.youtube.com/watch?v=b7TdWLNhMtM

The water hydrolyses, or breaks, the glycosidic bond, forming two monosaccharides.

When an atom donates an electron to another atom, it becomes a. an ion b. an anion c. nonpolar d. all of the above

a. an ion

Which of the following statements about chemical bonds is true? a. Covalent bonds are stronger than ionic bonds. b. Hydrogen bonds occur between two atoms of hydrogen. c. Bonding readily occurs between nonpolar and polar molecules. d. A molecule of water is unlikely to bond with an ion.

a. covalent bonds are stronger then ionic bonds

What organic compound do brain cells primarily rely on for fuel? a. glucose b. glycogen c. galactose d. glycerol

a. glucose

A phospholipid ________. a. has both polar and nonpolar regions b. is made up of a triglyceride bonded to a phosphate group c. is a building block of ATP d. can donate both cations and anions in solution

a. has both polar and nonpolar regions

Which of the following combinations of atoms is most likely to result in a chemical reaction? a. hydrogen and hydrogen b. hydrogen and helium c. helium and helium d. neon and helium

a. hydrogen and hydrogen

The energy stored in a foot of snow on a steep roof is ________. a. potential energy b. kinetic energy c. radiant energy d. activation energy

a. potential energy

phosphorylation

addition of one or more phosphate groups to an organic compound

activation energy

amount of energy greater than the energy contained in the reactants, which must be overcome for a reaction to proceed

anion

atom with a negative charge

cation

atom with a positive charge

The smallest unit of an element that still retains the distinctive behavior of that element is an ________. a. electron b. atom c. elemental particle d. isotope

b. atom

A pentose sugar is a part of the monomer used to build which type of macromolecule? a. polysaccharides b. nucleic acids c. phosphorylated glucose d. glycogen

b. nucleic acids

CH4 is methane. This compound is ________. a. inorganic b. organic c. reactive d. a crystal

b. organic

A substance formed of crystals of equal numbers of cations and anions held together by ionic bonds is called a(n) ________. a. noble gas b. salt c. electrolyte d. dipole

b. salt

The ability of an enzyme's active sites to bind only substrates of compatible shape and charge is known as ________. a. selectivity b. specificity c. subjectivity d. specialty

b. specificity

The bonding of calcium, phosphorus, and other elements produces mineral crystals that are found in bone. This is an example of a(n) ________ reaction. a. catabolic b. synthesis c. decomposition d. exchange

b. synthesis

Nitrogen has an atomic number of seven. How many electron shells does it likely have? a. one b. two c. three d. four

b. two

amino acid

building block of proteins; characterized by an amino and carboxyl functional groups and a variable sidechain

Which of the following is a molecule, but not a compound? a. H2O b. 2H c. H2 d. H+

c. H2

Which of the following is a functional group that is part of a building block of proteins? a. phosphate b. adenine c. amino d. ribose

c. amino

C6H12O6 is the chemical formula for a ________. a. polymer of carbohydrate b. pentose monosaccharide c. hexose monosaccharide d. all of the above

c. hexose monosaccharide

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 ________. a. about 80 neutrons each b. fewer than 80 neutrons each c. more than 80 neutrons each d. more electrons than neutrons

c. more than 80 neutrons each

A molecule of ammonia contains one atom of nitrogen and three atoms of hydrogen. These are linked with ________. a. ionic bonds b. nonpolar covalent bonds c. polar covalent bonds d. hydrogen bonds

c. polar covalent bonds

A substance dissociates into K+ and Cl- in solution. The substance is a(n) ________. a. acid b. base c. salt d. buffer

c. salt

Uracil ________. a. contains nitrogen b. is a pyrimidine c. is found in RNA d. all of the above

d. all of the above

________ reactions release energy. a. Catabolic b. Exergonic c. Decomposition d. Catabolic, exergonic, and decomposition

d. catabolic, exergonic, and decomposition

In DNA, nucleotide bonding forms a compound with a characteristic shape known as a(n) ________. a. beta chain b. pleated sheet c. alpha helix d. double helix

d. double helix

Together, just four elements make up more than 95 percent of the body's mass. These include ________. a. calcium, magnesium, iron, and carbon b. oxygen, calcium, iron, and nitrogen c. sodium, chlorine, carbon, and hydrogen d. oxygen, carbon, hydrogen, and nitrogen

d. oxygen, carbon, hydrogen, and nitrogen

functional group

group of atoms linked by strong covalent bonds that tends to behave as a distinct unit in chemical reactions with other atoms

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

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

concentration

number of particles within a given space

organic compound

substance that contains both carbon and hydrogen

phospholipid

a lipid compound in which a phosphate group is combined with a diglyceride

base

compound that accepts hydrogen ions (H+) in solution

bond

electrical force linking atoms

adenosine triphosphate (ATP)

nucleotide containing ribose and an adenine base that is essential in energy transfer

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

inorganic compound

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

mass number

sum of the number of protons and neutrons in the nucleus of an atom

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

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.

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.

The characteristic that gives an element its distinctive properties is its number of ________. a. protons b. neutrons c. electrons d. atoms

a. protons

Which of the following is most likely to be found evenly distributed in water in a homogeneous solution? a. sodium ions and chloride ions b. NaCl molecules c. salt crystals d. red blood cells

a. sodium ions and chloride ions

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

ion

atom with an overall positive or negative charge

ionic bond

attraction between an anion and a cation

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? a. Ty's blood is slightly acidic. b. Ty's blood is slightly alkaline. c. Ty's blood is highly acidic. d. Ty's blood is within the normal range

b. Ty's blood is slightly alkaline.

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

carbohydrate

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

acid

compound that releases hydrogen ions (H+) in solution

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

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 ________. a. solvent b. solute c. solution d. suspension

d. suspension

Chewing a bite of bread mixes it with saliva and facilitates its chemical breakdown. This is most likely due to the fact that ________. a. the inside of the mouth maintains a very high temperature b. chewing stores potential energy c. chewing facilitates synthesis reactions d. saliva contains enzymes

d.saliva contains enzymes

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

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

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

solution

homogeneous liquid mixture in which a solute is dissolved into molecules within a solvent

macromolecule

large molecule formed by covalent bonding

triglyceride

lipid compound composed of a glycerol molecule bonded with three fatty acid chains

suspension

liquid mixture in which particles distributed in the liquid settle out over time

reactant

one or more substances that enter into the reaction

valence shell

outermost electron shell of an atom

disaccharide

pair of carbohydrate monomers bonded by dehydration synthesis via a glycosidic bond

matter

physical substance; that which occupies space and has mass

enzyme

protein or RNA that catalyzes chemical reactions

substrate

reactant in an enzymatic reaction

ribonucleic acid (RNA)

ribose-containing nucleotide that helps manifest the genetic code as protein

atom

smallest unit of an element that retains the unique properties of that element

buffer

solution containing a weak acid or a weak base that opposes wide fluctuations in the pH of body fluids

AB → A + B is a general notation for a(n) ________ reaction. a. anabolic b. endergonic c. decomposition d. exchange

c. decomposition reaction

prostaglandin

lipid compound derived from fatty acid chains and important in regulating several body processes

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

radioactive isotope

unstable, heavy isotope that gives off subatomic particles, or electromagnetic energy, as it decays; also called radioisotopes

Visit this website to learn about electrical energy and the attraction/repulsion of charges. What happens to the charged electroscope when a conductor is moved between its plastic sheets, and why? http://education.jlab.org/frost/electroscope.html

The plastic sheets jump to the nail (the conductor), because the conductor takes on electrons from the electroscope, reducing the repellant force of the two sheets.

electron shell

area of space a given distance from an atom's nucleus in which electrons are grouped