2.2 Bio Content

Question 1

What percentage of the human body is made up of water?

Answer 1

60–70%

Question 2

Why is water critical to life?

Answer 2

It is a polar molecule that can form hydrogen bonds.

Question 3

What makes water polar?

Answer 3

Oxygen has a partial negative charge; hydrogens have partial positive charges.

Question 4

What type of bond forms between water molecules?

Answer 4

Hydrogen bonds.

Question 5

What are the four major properties of water?

Answer 5

Cohesion/Adhesion, Temperature Moderation, Expansion on Freezing, and Solvent Versatility.

Question 6

What is cohesion?

Answer 6

Attraction between like molecules (water to water).

Question 7

What is adhesion?

Answer 7

Attraction between unlike molecules (water to glass).

Question 8

What causes surface tension in water?

Answer 8

Cohesion due to hydrogen bonding between surface molecules.

Question 9

What is capillary action?

Answer 9

The tendency of water to rise in narrow tubes due to adhesion and cohesion.

Question 10

Why is water a good temperature moderator?

Answer 10

It absorbs and releases large amounts of heat with minimal temperature change.

Question 11

What is specific heat?

Answer 11

The energy needed to raise the temperature of 1 gram of a substance by 1°C.

Question 12

What is heat of vaporization?

Answer 12

The energy required to change 1 gram of liquid into gas.

Question 13

Why does sweating cool the body?

Answer 13

Evaporative cooling removes heat from the surface.

Question 14

Why is ice less dense than liquid water?

Answer 14

It forms an open crystal lattice with hydrogen bonds.

Question 15

What is the biological importance of ice floating?

Answer 15

It insulates bodies of water, protecting aquatic life.

Question 16

What makes water an efficient solvent?

Answer 16

Its polarity and ability to form hydrogen bonds with polar molecules.

Question 17

What are hydrophilic substances?

Answer 17

Polar or charged molecules that dissolve in water.

Question 18

What are hydrophobic substances?

Answer 18

Nonpolar molecules that do not dissolve in water.

Question 19

What happens when water dissociates?

Answer 19

It forms H⁺ and OH⁻ ions.

Question 20

What is an acid?

Answer 20

A substance that donates protons (increases H⁺ concentration).

Question 21

What is a base?

Answer 21

A substance that accepts protons (decreases H⁺ concentration).

Question 22

What is the pH of pure water?

Answer 22

7 (neutral)

Question 23

What pH values represent acids and bases?

Answer 23

Acids < 7; Bases > 7

Question 24

What do buffers do?

Answer 24

Maintain homeostasis by resisting changes in pH.

Question 25

Why is carbon important for life?

Answer 25

It can form four covalent bonds and many complex structures.

Question 26

What are organic compounds?

Answer 26

Molecules containing carbon bonded to other elements.

Question 27

Why is carbon versatile?

Answer 27

It is tetravalent and can bond in chains, rings, and double bonds.

Question 28

What are isomers?

Answer 28

Molecules with the same formula but different structures.

Question 29

What are the 3 types of isomers?

Answer 29

Structural, Geometric, and Enantiomers.

Question 30

What are structural isomers?

Answer 30

Differ in covalent arrangement of atoms.

Question 31

What are geometric isomers?

Answer 31

Differ in spatial arrangement around double bonds (cis/trans).

Question 32

What are enantiomers?

Answer 32

Mirror-image molecules (left- and right-handed).

Question 33

What are functional groups?

Answer 33

Atom groups that attach to carbon skeletons and affect molecular function.

Question 34

Hydroxyl (-OH)

Answer 34

Alcohol; polar; forms hydrogen bonds.

Question 35

Carboxyl (-COOH)

Answer 35

Carboxylic acid; acts as acid.

Question 36

Carbonyl (C=O)

Answer 36

Aldehydes & Ketones; creates reactive sites.

Question 37

Amino (-NH₂)

Answer 37

Amine; acts as a base.

Question 38

Phosphate (-PO₄²⁻)

Answer 38

Organic phosphate; adds negative charge; energy transfer (ATP).

Question 39

Sulfhydryl (-SH)

Answer 39

Thiol; forms disulfide bonds.