Ch 2. Chemistry comes alive

Electrons bear a positive charge equal in strength to the negative charge of the proton. t of f?

false

Colloids (emulsions) are heterogeneous mixtures.

true (Colloids, also called emulsions, are heterogeneous mixtures, which means that their composition is dissimilar in different areas of the mixture.)

The major function of RNA is to carry out the genetic instructions for protein synthesis.

true (RNA carries out the genetic instructions for protein synthesis.)

Enzymes are unchanged in a reaction; they can be reused, and are NOT needed in large quantities.

true (Three basic steps appear to be involved in enzyme action: 1. The enzyme's active site binds to the substrate(s) on which it acts, temporarily forming an enzyme-substrate complex. 2. The enzyme-substrate complex undergoes internal rearrangements that form the product(s). 3. The enzyme releases the product(s) of the reaction. Because enzymes are unchanged by their catalytic role and can act again and again, cells need only small amounts of each enzyme.)

In biochemistry, and thus in the body, the universal solvent is __________.

water

Which of the following is the primary energy-transferring molecule in cells?

ATP

Which of the following is NOT a way to distinguish an acid from a base?

An acidic substance will have a sticky feel. (Acids have a sour taste, can react with (dissolve) many metals, and "burn" a hole in your rug. Bases have a bitter taste and feel slippery.)

Which of the following is true of atoms?

Atoms of any given element will differ from those of all other elements and provide its unique physical and chemical properties. (Each element is composed of particles or building blocks, called atoms. Every element's atoms differ from those of all other elements and give the element its unique physical and chemical properties.)

Which of the following is FALSE regarding DNA?

DNA carries out the orders for protein synthesis issued by RNA.

Which of the following is true of an isotope?

Isotopes have the same number of protons but differ in the number of neutrons they contain.

Which of the following is a property of matter?

Matter can exist in solid, liquid, or gaseous state.

Which of the following best defines potential energy?

Potential energy is stored energy that has the capacity to do work but is not presently doing so.

Which of the following does NOT represent an accurate hierarchy in the natural combination of matter?

When two or more similar kinds of atoms bind, they form an isotope. (Most atoms do not exist in the free state but are chemically combined with other atoms. Such a combination of two or more atoms held together by chemical bonds is called a molecule. Two or more identical atoms bonded together form molecules of that element. When two or more different kinds of atoms combine, they form molecules of a compound. Compounds are chemically pure, and all of their molecules are identical. Mixtures are substances composed of two or more components.)

protein building blocks/monomers

amino acids

If the pH or temperature of the environment that contains a protein is altered dramatically, then the protein may __________.

become denatured

Polar molecules are electrically balanced as a result of the equal sharing of electrons between the atoms of the molecules.

false (Nonpolar molecules are electrically balanced as a result of the equal sharing of electrons between the atoms of the molecules. Polar molecules are created as a result of unequal electron pair sharing. Water is one of the most important polar molecules in a living system.)

triglycerides building blocks/monomers

glycerol and fatty acids

Something with a pH of 5 would __________.

have more H+ ions than OH- ions (Acids have a pH below 7, while bases have a pH above 7. A neutral solution has a pH of 7. The lower the pH, the more acidic the substance. A substance's pH is related to the balance of H+ (hydrogen) ions and OH- (hydroxide) ions. A substance with more H+ ions than OH- ions will have a pH below 7, and thus will be acidic. A substance that has an equal concentration of H+ and OH- is neutral (pH of 7). When the concentration of H+ is less than the concentration of OH-, the substance will have a pH above 7 and be considered basic.)

carbohydrates building blocks/monomers

monosaccharides

DNA building blocks

nucleotides

Which of the following is NOT one of the four basic elements that compose approximately 96% of a human's body weight?

potassium

buffers _____

stabilize pH

Which of the following types of chemical reactions always involves atoms or molecules combining to form a larger, more complex molecule?

synthesis

In an ionic bond, __________.

there is a transfer of one or more electrons from one atom to the other (An ionic bond is a chemical bond between atoms formed by the transfer of one or more electrons from one atom to the other.)

All organic molecules contain carbon.

true

The atomic number of any atom is equal to the number of protons in its nucleus.

true