Biology Chapter 2 Study Questions

Sugar dissolves when stirred into water. The sugar is the ______, the water is the ______, and the sweetened water is the ______. A) solute... solvent... solution B) solvent... solute... solution C) solution... solvent... solute D) solution... solute... solvent

A)

What name is given to the bond between water molecules? A) hydrogen B) single (nonpolar) covalent C) ionic D) polar covalent E) hydrophobic

A)

Why is water considered a polar molecule? A) The oxygen end of the molecule has a slight negative charge, and the hydrogen end has a slight positive charge. B) Both hydrogens are at one end of the molecule, and oxygen is at the other end. C) The oxygen atom attracts the hydrogen atoms. D) The oxygen is found between the two hydrogens.

A)

The simplest unit of matter that still retains the properties of an element is a(n) _____. A) atom B) compound C) cell D) electron

A) An atom is the simplest unit of an element that still retains the properties of that element.

What is the arrow pointing to? There are ions and molecules forming water solution. The structure of 2 different bound atoms, the larger of which is negatively charged and highlighted with an arrow. A) hydroxide ion B) hydrogen ion C) hydronium ion D) proton E) water

A) The arrow is indicating a hydroxide ion (OH-).

An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many protons does boron have? A) 5 B) 0 C) 16 D) 6 E) 11

A) The atomic number is equal to the number of protons.

In the reaction glucose + fructose → sucrose + water, _____ is a reactant and _____ is a product. A) glucose ... water B) sucrose ... fructose C) sucrose ... water D) glucose ... fructose

A) The direction in which the arrow is pointing indicates that glucose and fructose are reactants and sucrose and water are products.

How does the pH of the solution on the right compare with that of the solution on the left? There are 2 pictures of ions and molecules forming water solution. In the right picture, the negatively charged ions of 2 different bound atoms are prevailing. In the left picture, positively charged single atoms are prevailing. A) The solution on the right is basic relative to the solution on the left. B) Both of these solutions are equally acidic. C) Both of these solutions are equally basic. D) The solution on the right is acidic relative to the solution on the left. E) The solution on the right is neutral relative to the solution on the left.

A) The solution on the right has a lower concentration of hydrogen ions relative to hydroxide ions than does the solution on the left.

What is the atomic number of an atom that has 6 protons, 6 neutrons, and 6 electrons? A) 6 B) 18 C) -1 D) 0 E) 12

A) This is an atom of carbon, an element with 6 protons. Atomic number is the number of protons in an atom.

Relative to a pH of 6, a pH of 4 has a ______. A) 200 times higher H+ concentration B) 100 times higher H+ concentration C) 20 times higher H+ concentration D) 100 times lower H+ concentration

B)

What type of bond is joining the two hydrogen atoms? There are 2 hydrogen atoms with a pair of electrons shared between these 2 atoms. A) ionic B) covalent C) hydrophilic D) hydrogen E) hydrophobic

B) A covalent bond is one in which electron pairs are shared.

Four elements combine to make about 96% of the mass of the human body. Which of the following elements is one of the four? A) phosphorus B) carbon C) iron D) calcium

B) Carbon atoms serve as the backbone for all biological molecules. The four elements that make up over 96% of the mass of a human body are hydrogen, oxygen, nitrogen, and carbon.

Carbon-12 and carbon-13 are different in the number of their _____. A) electrons B) neutrons C) protons D) protons and electrons

B) Carbon-12 and carbon-13 are isotopes. Isotopes differ only in the number of their neutrons.

The tendency of molecules of the same kind to stick together is called _________. A) adhesion B) cohesion C) buffering D) evaporative cooling

B) In general, cohesion refers to the tendency of molecules of the same kind to stick together. For example, water molecules stick together as a result of hydrogen bonding.

In a neutral solution the concentration of _____. A) hydrogen ions is less than the concentration of hydroxide ions B) hydrogen ions is equal to the concentration of hydroxide ions C) water molecules is less than the concentration of hydroxide ions D) hydrogen ions is greater than the concentration of hydroxide ions E) water molecules is less than the concentration of hydrogen ions

B) This is the definition of a neutral solution.

Substances that contain two or more elements in a fixed ratio are called _____. A) isotopes B) compounds C) cells D) matter

B) When elements combine in fixed ratios and are joined together by chemical bonds, they form compounds. On Earth, compounds are much more common than elements.

An uncharged atom of gold has an atomic number of 79 and an atomic mass of 197. This atom has ______ protons, ______ neutrons, and ______ electrons. A) 118... 276... 118 B) 79... 34... 79 C) 79... 118... 79 D) 118... 79... 118

C)

Nitrogen has an atomic number of 7; therefore, it has ______ electrons in its outermost electron shell. A) 2 B) 18 C) 5 D) 10

C)

A substance that resists changes in pH is referred to as a(n) _____. A) base B) solution C) buffer D) acid

C) Buffers resist changes in pH by either accepting or donating hydrogen ions.

What is the term for atoms that are electrically charged as a result of gaining or losing electrons? A) molecule B) compound C) ion D) isotope

C) Ions are atoms that are electrically charged as a result of gaining or losing electrons.

All atoms of an element have the same number of ______. A) electrons B) neutrons C) protons plus neutrons D) protons

D)

Sweating cools your body by ______. A) hydrogen bonding B) radiation C) cohesion D) evaporative cooling

D)

Which of the following elements, essential to life, is a trace element? A) carbon B) phosphorus C) calcium D) iodine

D)

The brackets are indicating a(n) _____ bond. There are 2 water molecules. The oxygen atom of one molecule has delta minus charge. One of the hydrogen atoms of another water molecule has delta plus charge. The brackets between these 2 atoms unite charge labels and dots between them, representing that these 2 atoms have an interaction. A) polar covalent B) ionic C) single (nonpolar) covalent D) hydrogen E) hydrophobic

D) A hydrogen atom with a net positive charge is attracted to an oxygen atom with a net negative charge.

Fluorine's atomic number is 9 and its atomic mass is 19. How many neutrons does fluorine have? A) 9 B) 19 C) 81 D) 10 E) 28

D) Atomic mass is equal to the number of protons plus the number of neutrons (19-9 = 10).

Which of these refers to atoms with the same atomic number but different atomic masses? A) These atoms are different elements. B) These atoms have different numbers of electrons. C) These atoms are isomers. D) These atoms are isotopes. E) These atoms have different numbers of protons.

D) Atoms with the same atomic number and different atomic masses are referred to as isotopes.

In salt, what is the nature of the bond between sodium and chlorine? A) hydrophobic B) polar covalent C) nonpolar covalent D) ionic E) hydrogen

D) Sodium and chlorine ions are attracted to each other.

What is the arrow pointing to? There are ions and molecules forming water solution. A single atom which is positively charged is highlighted with an arrow. A) hydronium ion B) hydroxide ion C) water molecule D) hydrogen ion E) electron

D) The arrow is indicating a single proton, a hydrogen ion (H+).

An ionic bond involves _____. A) no atoms other than sodium and chlorine B) the unequal sharing of an electron pair C) water avoidance D) an attraction between ions of opposite charge E) the sharing of a single pair of electrons

D) This is the definition of an ionic bond.

A(n) _____ refers to two or more atoms held together by covalent bonds. A) shell B) isotope C) community D) ion E) molecule

E) A molecule is defined as two or more atoms held together by covalent bonds.

Atoms with the same number of protons but with different electrical charges _____. A) have different atomic masses B) have different atomic numbers C) are different isotopes D) have different numbers of neutrons E) are different ions

E) Ions are charged atoms.

A(n) _____ bond joins these two oxygen atoms. There are 2 oxygen atoms with 2 shared electron pairs. Also, each of the atoms has a pair of electrons in the inner electron shell. In the outer electron shell, each atom has 2 pairs of electrons in addition to those 2 which are shared. A) quadruple covalent B) ionic C) hydrogen D) single covalent E) double covalent

E) The oxygen atoms are sharing two pairs of electrons.

This atom can form up to _____ single covalent bond(s). There is an atom with 2 electron shells. The inner electron shell contains a pair of electrons. The outer electron shell contains 4 electrons. A) 0 B) 3 C) 1 D) 2 E) 4

E) There are four electrons in the outermost electron shell.

The ________ of water molecules to each other helps transport water from the roots to the leaves in plants.

cohesion

When water warms or cools, ______ either break or form. Thus, water absorbs or releases a great deal of ______, helping to moderate temperatures.

hydrogen bonds, heat

Because ______ is less dense than liquid water, it floats and protects lakes and oceans from freezing solid.

ice

The ________ of water molecules and the hydrogen bonds between water molecules explain most of water's life-supporting properties.

polarity

Water is a versatile ______. Blood and other biological fluids are aqueous solutions with a diversity of dissolved _______.

solvent, solutes