Biology Ch 3

Biology Ch 3Mouse Mischief The way in which elements bond to form compounds depends on which of the following? the size of the electronsthe shape of the nucleusthe number of neutrons in each atomthe electrons in the atoms of the elements

In what type of bond are electrons shared?ionicnuclearcovalenthydrogen

What weak bond holds together the two strands of nucleotides in a DNA molecule?ionicnuclearcovalenthydrogen

When an unknown substance is dissolved in water, hydronium ions form. What can you conclude about the substance? The substance is a gas The substance is a bas The substance is an acid The substance is a carbohydrate

Activation energy is needed only by chemical reactions that release energy

YesNoIn an atom, the number of protons is equal to the number of electrons.

YesNoA solution is a mixture of unevenly distributed substances

YesNo Polar substances dissolve well in water because water also is polar

YesNoMost of the chemical reactions in the body would not occur without enzymes

YesNoAtoms do not containprotons.electrons.ions.

The attraction between water molecules is caused by covalent bondhydrogen bondsionic and covalent bonds

An atom is called an ion when it haseither lost or gained electronslost its nucleusmore neutrons than protons

The ability of water to form drops is an example ofadhesion.cohesion. ionic bonding

One solution has a pH of 2, and another has a pH of 7. Which of the following is true? Both solutions are acidicThe solution with a pH of 2 is basic, and the solution with a pH of 7 is acidic. The solution with a pH of 2 is acidic, and the solution with a pH of 7 is neutral.

Plants store the suns energy for future use asDNAstarch.protein.

Enzymesare usually proteins.decrease the speed of chemical reactions.increase the activation energy of chemical reactions

The smallest unit of matter that cannot be broken down by chemical means is a(n)element.atom.molecule.electron.The bonds between the atoms that make up water molecules are called covalent bondhydrogen bondsionic and covalent bondcovalent and hydrogen bonds.

An atom is called an ion when it haeither lost or gained electrons.either lost or gained protons.more neutrons than protonslost its nucleus.

A solution is a mixture ofpolar and nonpolar substancesprotons and neutrons.unevenly distributed substances. evenly distributed substances.

Water is _______ , therefore _______ substances dissolve in it.polar, nonpolarpolar, polarnonpolar, nonpolarnonpolar, polar

In a chemical reaction, energy may beabsorbed.released.required.All of the above

Without energy, organisms could notmaintain homeostasis.carry out chemical reactions.make their own food.All of the above

The basic units of most biomolecules containnitrogen.oxygencarbon.amino acids

Compounds are formed whenatoms of an element lose an electron.atoms of an element gain an electronatoms of the same element join together.atoms of two different elements join together.

Enzymesare usually carbohydrates. can only catalyze a reaction oncreduce the activation energy of chemical reactionseliminate the activation energy of chemical reactions.

In an atom with the same number of electrons and protons, the electrical charge is neutral.positive.negative.impossible to determine.

Activation energy is needed by chemical reactions thatrelease energyabsorb energy.are catalyzed by enzymes. All of the above

The ability of water to form drops is an example ofa chemical change.cohesion.adhesionionic bonding

What kind of bonds do water molecules form with one another? covalenthydrogen ionicBoth (a) and (c)

Starchis made of a sugar, a base, and a phosphate groupdoes not contain carbon atoms. is made of amino acids is a carbohydrate in which energy is stored

Two solutions, A and B, are tested for pH. Solution A indicates a pH of 2. Solution B indicates a pH of 7. You conclude thatboth solutions are acidic.solution A is basic; solution B is neutral.None of the above solution A is acidic; solution B is neutral

An element is defined as a pure substance because it is made of only one kind ofcompound.molecule.atom.ion.Atoms bond with other atoms to form compounds because electrons are attracted to each otherbonding helps atoms become more stable.bonding makes an element more pure.the nuclei of atoms are attracted to each other.

When food molecules are broken down inside cells, some of the energy in the molecules is stored temporarily inproteins.RNA.DNA.ATP.

Enzymes that take part in a chemical reaction are not considered to be reactants because they do not take part in the reaction.are not changed by the reaction.have no valence electrons.are used up in the reaction