Chapter 2 The Chemical Basis of Life

Question 1

Chemicals are the stuff that make up our A. and those of other organisms. They also make up the B. The ordering of C. into molecules represents the D. So it is important to understand the basic concepts of chemistry to understand life. All activities of the body are based on E. F. is all the elements that make up living matter & the way atoms of those elements interact.

Answer 1

A. Bodies B. Physical Environment C. Atoms D. Lowest Level of Biological Organization E. Chemical Reactions F. Chemistry

Question 2

A. are at the base level of biological hierarchy. They are arranged into Higher and higher levels of B. Living organisms are composed of C. which is anything that occupies space and has mass (D.). Matter is in the form of E.

Answer 2

A. Chemicals B. Structural Organization C. Matter D. Weight E. Chemical elements.

Question 3

A. a substance that cannot be broken down to other substances by ordinary means. There are B. elements in nature only a few exist in pure state. C. a substance consisting of two or more different elements combined in a fixed ratio. Life requires D. essential elements.

Answer 3

A. Element B. 92 C. Compound D. 25

Question 4

A. B. C. and D. make up 96 % of the human body. Others make up E. and the rest are F.

Answer 4

A. Oxygen B. Carbon C. Hydrogen D. Nitrogen E. 4% F. Trace Elements

Question 5

Trace elements are common additives to A. and B. Some trace elements are required to prevent C. Without D., your body cannot transport oxygen. An E. prevents production of thyroid hormones, resulting in goiter

Answer 5

A. Food B. Water C. Disease D. Iron E. Iodine

Question 6

Several chemicals are added to food for a variety of reasons. A. B. and C.

Answer 6

A. Help preserve it B. Make it more nutritious C. Make it look better.

Question 7

Atoms consist of A. B. and C. An atom is the smallest unit of matter that still retains the D. Consists of 3 important subatomic particles. E. F. and G.

Answer 7

A. Protons B. Neutrons C Electrons D. Properties of a element E. Proton F. Neutron G. Electron

Question 8

A proton has a A. An Electron has a B. A neutron has a C.

Answer 8

A. Single Positive Electrical charge B. Single Negative Electrical charge C. Electrically Neutral

Question 9

Elements differ in their number of A. B. and C. D.has 2 protons 2 neutrons and 2 electrons. E. has six protons six neutrons and six electrons.

Answer 9

A Protons B. Neutrons C. Electrons D. Helium E.

Question 10

Neutrons and Protons are packed in the atoms A. The B. charge of electrons and the positive charge of C. Keep the electrons near the Nucleus. The number of Protons is the atoms D. Carbon with 6 protons has an atomic number of E. The mass number is the sum of the F. in the nucleus.

Answer 10

A. Nucleus B. Negative C. Positive D. Atomic Number E. 6 F. Protons and Neutrons

Question 11

Although all atoms of a element have the same atomic number, some differ in mass number. These are called A. Which have the same numbers of protons and electrons but different numbers of neutrons. One isotope of carbon has B. neutrons instead of 6. Carbon 14 is an unstable C. isotope that gives of energy.

Answer 11

A. Isotope B. 8 C. Radioactive

Question 12

Living cells cannot distinguish between isotopes of the same element so radioactive compounds may be used in A. When cells use the radioactive isotopes they act as B. Radioactivity can be detected by sophisticated imaging instruments. With instruments the fate of radioactive tracers can be monitored in living organisms.

Answer 12

A. Metabolic processes B. Tracers

Question 13

Radioactive tracers are frequently used in A. And for B. In addition to benefit there are also dangers withsing radioactive substances. A control exposure can cause damage to some C. In a living cell, especially DNA because chemical bonds are broken by the emitted energy which causes D. To form.

Answer 13

A. Biological research B. Medical diagnosis and treatment C. Molecules D. Abnormal bonds

Question 14

Only electrons are involved in chemical activity. Electrons occur in energy levels called A. A atom we have one two or three electron shells. The number of electrons in the outermost shell determines the B. Of the atom. The first shell is full with C. electrons, whereas the second and third will hold up to D. electrons.

Answer 14

A. Electron shells B. Chemical Properties C. 2 D.8

Question 15

atoms Want to fill their outer electron shells To accomplish this, The atom can A. This results in attractions between atoms called B. A atom with an unfilled valence (Outer shell )Tends to interact with other atoms. Atoms with a filled valence shell are C.

Answer 15

A.Share, donate, or receive B. Chemical bonds C. Inert

Question 16

A A. bond results when atoms share outer shell electrons. A B. is formed when atoms are held together with a covalent bond. Atoms in a covalently bonded molecule continually compete for shared C. Covalent bonds are the D. type of bond.The attraction (pull) for shared electrons is called E. More Electronegative atoms pull harder. In molecules of only one element, the pull towards each other is F. Because each atom has the same electronegative. The bonds formed are called G. Water has atoms with different electronegativites.

Answer 16

A. Covalent B. Molecule C. Electrons D. Strongest E. Electronegativity F. Equal G. Non polar Covalent Bonds

Question 17

Oxygen attracts the shared electrons more strongly than hydrogen so, the shared electron spends more time near A. The result is a polar covalent bond.

Answer 17

A. Oxygen

Question 18

In h2o the oxygen atom has a slight negative charge and the hydrogens have a slight positive charge. Molecules with this unequal distribution of charges are called A. The number of bonds that can be formed depends on the number of B needed to fill the valence shell.

Answer 18

A. Polar Molecules B. Electrons

Question 19

An A. is an atom or molecule with an electrical charge resulting from gain or loss of electrons. when an electron is lost a B. charge results; when one is gained, a C. charge results. Two ions with opposite charges attract each other. One atom gives up an electron and one accepts (gains) it. When the attraction holds the ions together, it is called an D.

Answer 19

A. Ion B. Positive C. Negative D, Ionic Bond

Question 20

Hydrogen as a part of a polar covalent bond will share attractions with other Electronegative atoms. water molecules are electrically attracted to oppositely charged regions on neighboring A.. Because the positively charged region is always a hydrogen atom the bond is called a B.

Answer 20

A Molecules B. Hydrogen Bond

Question 21

Structure of atoms and molecules determines how they A. A B. is the breaking and making of chemical bonds, leading to changes in the composition of matter. The starting materials before the reaction are the C. The resulting materials are the D. Matter is not created or destroyed but rather E. The formation of water from hydrogen and oxygen is an example of a F. The reactants H2 and O2 are converted to H2O the product. Organisms do not make water but they do carry out a large number of chemical reaction that rearrange G.

Answer 21

A. Behave B. Chemical Reaction C. Reactants D. Product E. Rearranged F. Chemical reaction G. matter

Question 22

Hydrogen bonding causes molecules to stick together, a property called A. Cohesion is much stronger for water than other liquids. Cohesion is related to surface tension (a measure of how difficult it is to break the surface of liquid) because of hydrogen bonding, water has a a greater ability to B. temperature change than other liquids.

Answer 22

A. Cohesion B. Resist

Question 23

Waters hydrogen bonds make liquid water A. Heat is the energy associated with movement of atoms and molecules in matter. B. measures the intensity of heat (average speed of the molecules).
Heat must be absorbed to C. hydrogen bonds before the water molecules move faster. Heat is D. when hydrogen bonds form.

Answer 23

A. Cohesive B.Temperature C. Break D. Released

Question 24

Ice is A dense than liquid water. Water can exist as a B. Water is less dense as a solid, a property due to C. When water freezes, each molecule forms a stable D. with four neighbors. a three dimensional crystal results. There is space between water molecules the ice crystal has fewer molecules than an equal volume of E. Ice is less dense than water so it floats.

Answer 24

A. Less B. Gas. liquid or solid C. Hydrogen bonding D. Hydrogen E. Water

Question 25

A A. is a liquid consisting of a uniform mixture of two or more substances. The dissolving agent is the B. The substance that is dissolved is the C. Water is a versatile solvent that is fundamental to life processes. Its versatility results from its Polarity. Table salt is an example of a D. that will go into solution in water. Sodium and chloride ions are attracted to each other because of their E.

Answer 25

A. Solution B. Solvent C. Solute D. Solute E. Charges

Question 26

The chemistry of life is sensitive to A. and B. conditions. A few water molecules can break apart into ions. Hydrogen Ions C. Hydroxide Ions D. Both are extremely E. A F. between the two is critical for chemical processes to occur in a living Organism.

Answer 26

A. Acidic B. Basic C. H+ D. OH- E. Reactive F. Balance

Question 27

Chemicals other than water can contribute H+ to a solution. they are called A. such as Hydrochloric acid (HCI) aka stomach acid. A acidic solution has a B. concentration of H+ than OH- Some chemicals accept hydrogen ions and remove them from solutions called C. For example, sodium hydroxide NaOH provides OH- that combines with H+ to produce a D. This reduces the H+ concentration.

Answer 27

A. Acids B. Higher C. Bases D. H2 O water

Question 28

A pH scale A. Is used to describe whether a solution is B. pH range is from zero “ most acidic” to 14 “ most basic” a solution that is neither acidic or basic isC. Ph = 7

Answer 28

A. Potential of hydrogen B. Acidic or basic C. Neutral

Question 29

When we burn fossil fuels “ gasoline and heating oil”, air polluting compounds and Co2 are released into the A. Sulfur and nitrous oxides react with water in the air to form B. These fall to earth as C., Which is rain, snow, or fog with a pH lower than D. The CO2 and the H2O react to form E. Additional CO2 in the atmosphere contributes to the greenhouse effect and alters ocean chemistry.

Answer 29

A. Atmosphere B. Acids C. Acid precipitation D. 5.6 E. Carbonic acid