biochem practice

T/F The ability of water to retain heat helps cells maintain a constant internal temperature.

T

T/F The amount of energy needed to cause a chemical reaction to start is called activation energy.

T

T/F The role of carbohydrates in cells is to supply energy.

T

T/F When cells break down food, the energy from the food is temporarily stored as ATP.

T

T/F Because water is a polar molecule, it tends to cause ionic compounds mixed in water to dissociate into ions.

T

Without enzymes, chemical reactions necessary for life would not occur quickly or easily enough to sustain life.

T

Ionic bonds form between particles that have a. opposite charges. c. no charges. b. the same charge. d. neutral charges.

opposite charges

Covalent bonds form when a. two molecules of water share electrons. b. a molecule of water becomes an ion. c. two hydrogen atoms share electrons with one oxygen atom. d. two hydronium ions are attracted to each other.

two hydrogen atoms share electrons with one oxygen atom

Hydronium ions, H+, react with hydroxide ions, OH-, to form a. water. c. a base. b. an acid. d. a buffer.

water

In a condensation reaction, two molecules become linked together and a molecule of ____________________ is produced.

water

Which is not a unique property of water? a. Frozen water floats. b. Water retains a large amount of heat. c. Water molecules stick to each other. d. Water cools rapidly.

water cools rapidly

T/F Organic compounds are substances produced and found in living things.

T

Which of the following characteristics of water is not a result of hydrogen bonding? a. adhesive strength b. capillarity c. cohesive strength d. All of the above are a result of hydrogen bonding.

All of the above

T/F An atom with more electrons than protons has a positive charge.

F, an atom with fewer electrons has a positive charge.

When an enzyme binds with its substrate, the activation energy needed for the chemical reaction to occur is increased.

F, decreased

T/F Molecules are atoms that have gained or lost one or more electrons.

F, ions are atoms that have gained or lost one or more electrons

T/F Atoms have a positive charge.

F, neutral

T/F RNA is made up of a double strand of nucleotides.

F, single strand

T/F Water molecules attract nonpolar molecules such as oil.

F, they repel

Which organic molecule below is most closely related to nucleic acids? a. amino acids c. nucleotides b. CH2 chains d. sugars

Nucleotides

The electrons of an atom a. are found in the nucleus along with the protons. b. occupy the space surrounding the nucleus. c. have a positive charge. d. are attached to the positive charge of neutrons.

Occupy the space surrounding the nucleus

Amino acids are monomers of a. disaccharides. c. nucleotides. b. proteins. d. steroids.

Proteins

T/F Capillarity is apparent when you put a straw in water and the water level inside the straw rises higher than the level in the surrounding container.

T

T/F A covalent bond forms between two atoms that share electrons to form a molecule.

T

T/F Electrons have very little mass.

T

T/F Functional groups are side groups of carbon compounds that confer specific properties to these compounds.

T

Which of the following is not true of alcohols? a. They contain a hydroxyl group (-OH). b. They are polar molecules. c. They can affect processes in living things, either positively or negatively. d. They are the only kind of functional group in organic molecules that contain oxygen.

They are the only kind of functional group in organic molecules that contain oxygen.

The smallest particle of matter that can retain the chemical properties of carbon is a carbon a. molecule. c. atom. b. macromolecule. d. element.

atom

All matter is composed of a. cells. c. atoms. b. molecules. d. carbon.

atoms

The building blocks of most biomolecules contain the element a. carbon. c. calcium. b. nitrogen. d. sodium.

carbon

Which organic molecule below is most closely related to lipids? a. amino acids c. nucleotides b. CH2 chains d. sugars

ch2 chains

Atoms are not composed of a. protons. c. electrons. b. neutrons. d. chemical bonds

chemical bonds

The formation of polymers from monomers occurs as a result of ____________________ reactions, and the breakdown of polymers into monomers occurs as a result of ____________________ reactions.

condensation;hydrolysis

The bond formed when two atoms share a pair of electrons is called a(n) a. hydrogen bond. c. covalent bond. b. ionic bond. d. water bond.

covalent bond

Water is a polar molecule because a. it contains two hydrogen atoms for each oxygen atom. b. it has a charge. c. different parts of the molecule have slightly different charges. d. it does not have a charge.

different parts of the molecule have slightly different charges

In the molecule that has the chemical formula C2H4, the carbon atoms are bonded together with a ____________________ bond.

double

A substance that is composed of only one type of atom is called a(n) a. compound. c. element. b. cell. d. molecule.

element

Because oxygen atoms tend to attract positively charged atoms, organic compounds that contain oxygen atoms tend to form ____________________ bonds.

hydrogen

Breaking of ____________________ bonds is the first thing that happens when water is heated, which means that it takes a great deal of thermal energy to raise the temperature of water.

hydrogen

Attractions between water molecules are called a. covalent bonds. c. polar bonds. b. ionic bonds. d. hydrogen bonds.

hydrogen bonds

Which of the following is not a large biomolecule? a. carbohydrate c. lipid b. ice d. nucleic acid

ice

Carbon is different from most other elements in that a. it has four electrons in its outermost energy level. b. it readily bonds with other carbon atoms. c. it can form single, double, or triple bonds with other atoms. d. it shares two electrons with another atom when it forms a covalent bond.

it readily bonds with other carbon atoms

Acidic solutions have a pH that is a. less than 7. c. a negative number. b. between 7 and 14. d. more than 7.

less than 7

Sharing of electrons in the outer energy levels of two atoms a. results in ion formation. b. makes both atoms stable. c. only occurs if both are atoms of the same element. d. is found only among carbon atoms.

makes both atoms stable

Nonpolar molecules have a. no negative or positive ends. c. only a negative end. b. both negative and positive ends. d. only a positive end.

no negative or positive ends

Lipids are ____________________ molecules because they have no negative and positive poles.

nonpolar

A molecule that has a partial positive charge on one side and a partial negative charge on the other side is called a(n) a. nonpolar molecule. c. charged molecule. b. polar molecule. d. ion.

polar

A phospholipid is a molecule with a(n) ____________________ head.

polar

Water is very effective at dissolving other polar substances because of its ____________________.

polarity

Plants store glucose in the form of a. starch. c. cellulose. b. glycogen. d. chitin.

starch

Which of the following molecules are classified as carbohydrates? a. amino acids c. nucleotides b. fats d. sugars

sugars

When placed in the same container, oil and water do not mix because a. they are both polar. c. they are both nonpolar. b. water is polar and oil is nonpolar. d. water is nonpolar and oil is polar.

water is polar and oil is nonpolar