Human Biology Chapter 2

Question 1

An atom has an equal number of ____ and _____and is electrically ______

Answer 1

electrons; protons; neutral

Question 2

What has a negative charge?

Answer 2

electron

Question 3

The atomic number of an element is its number of _____

Answer 3

protons

Question 4

The atomic mass of an element is its number of ____

Answer 4

protons and neutrons

Question 5

Isotopes of an element differ from each other by their number of

Answer 5

neutrons

Question 6

An atom has an atomic number of 11 and an atomic mass of 23. How many neutrons in its nucleus?

Answer 6

12 neutrons

Question 7

In an atom the number electrons = the number of ____

Answer 7

protons

Question 8

A chlorine atom with an atomic mass of 35 and am atomic number of 17 possesses ____ protons and ____ neutrons

Answer 8

17; 18

Question 9

Chlorine has 7 electrons in its outermost energy level. To become stable must it lose or gain electrons? How many?

Answer 9

Gain 1

Question 10

Which atom has the greatest atomic mass:

• carbon
• hydrogen
• oxygen
• nitrogen

Answer 10

oxygen

Question 11

An ion is an atom that has ____

Answer 11

gained or lost electrons

Question 12

An atom that has lost one electron is a positive or negative ion?

Answer 12

positive ion

Question 13

a bond formed as a result of sharing of electrons is called a ____ bond

Answer 13

covalent

Question 14

Nitrogen has 5 electrons in its outermost energy shell. How many electrons can it share with outer atoms to become stable?

Answer 14

3

Question 15

Weak bonds that form between polar covalent molecules, such as water, are called ____ bonds

Answer 15

hydrogen

Question 16

a pH of 7.4 possesses more ____ than ____

Answer 16

OH- than H+

Question 17

A pH f 2 is _____ as a pH of 5

Answer 17

1000 times as acidic

Question 18

A chemical that prevents large changes in pH is best called a

Answer 18

buffer

Question 19

Which of the following is an inorganic molecule:

• protein
• lipid
• water
• carbohydrate

Answer 19

water

Question 20

Anything that has mass and occupies space is called

Answer 20

matter

Question 21

The purest substance that contains only one type of atom is called a(n)

Answer 21

element

Question 22

What are found in the nucleus of an atom and has a positive charge?

Answer 22

proton

Question 23

____ from isotopes helps to stabilize their nuclei

Answer 23

radiation

Question 24

atoms contain 3 subatomic particles:

Answer 24

protons; neutrons; electrons

Question 25

the atomic number is equal to the number of

Answer 25

protons

Question 26

atoms of an element that differ by their number of neutrons are called

Answer 26

isotopes

Question 27

an atom that gains or loses an electron or electrons is called a(n)

Answer 27

ion

Question 28

unequal sharing of electrons

Answer 28

polar covalent bond

Question 29

a bond that forms between the charged ends of two water molecules

Answer 29

hydrogen bond

Question 30

the branch of chemistry that deals with carbon compounds is called

Answer 30

organic chemistry

Question 31

new species can arise through a process called

Answer 31

evolution

Question 32

in the scientific method a ____ is a tentative explanation of a phenomeon

Answer 32

hypothesis

Question 33

what is the purest form of matter that cannot be separated into different substances by chemical means?

Answer 33

element

Question 34

what is a negatively charged particle that is found in the nucleus of an atom?

Answer 34

neutron

Question 35

what is a positively charged particle that is found in the nucleus of an atom?

Answer 35

proton

Question 36

Humans are unique among animals because of their

Answer 36

complex culture

Question 37

in an experiment, the control group

Answer 37

does not receive experimental treatment

Question 38

evolution is something that occurs in ____

Answer 38

populations

Question 39

ions can have a ____ or a _____ charge

Answer 39

positive or negative

Question 40

a molecule that helps to regulate pH is called

Answer 40

buffer

Question 41

pH measures ____

Answer 41

the level of acidity