Chapter 2: Introduction to chemistry of life

Question 1

Atoms

Answer 1

is the smallest unit of ordinary matter that forms a chemical element.

Question 2

Element

Answer 2

contains only one type of atom, e.g., carbon, sulfur, or hydrogen.

Question 3

Compounds

Answer 3

Substances containing two or more types of atom combined

Question 4

Proton

Answer 4

a stable subatomic particle occurring in all atomic nuclei, with a positive electric charge

Question 5

Neutrons

Answer 5

a subatomic particle of about the same mass as a proton but without an electric charge

Question 6

Electron

Answer 6

a stable subatomic particle with a charge of negative electricity,

Question 7

Atomic number

Answer 7

the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.

Question 8

Atomic weight

Answer 8

total weight of an atom

Question 9

Isotopes

Answer 9

• An element with a similar chemical make-up and the same atomic number, but different atomic weights to another or others.

Question 10

Chemical compound

Answer 10

is a chemical substance composed of many identical molecules composed of atoms from more than one element held together by chemical bonds.

Question 11

Molecules

Answer 11

consist of two or more atoms that are chemically combined.

Question 12

Chemical bond

Answer 12

a lasting attraction between atoms, ions, or molecules that enables the formation of chemical compounds.

Question 13

Covalent bonds

Answer 13

a chemical bond that involves the sharing of electron pairs between atoms.

Question 14

Ionic bonds

Answer 14

is a chemical link between two atoms caused by the electrostatic force between oppositely charged ions in an ionic compound.

Question 15

Electrolytes

Answer 15

are minerals that carry an electrical charge when dissolved in water.

Question 16

pH scale

Answer 16

The pH scale measures how acidic or basic a substance is. The pH scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic.

Question 17

Acidosis

Answer 17

occurs when your kidneys and lungs can’t keep your body’s pH in balance.

Question 18

Alkalosis

Answer 18

occurs when your body has too many bases. It can occur due to decreased blood levels of carbon dioxide, which is an acid.

Question 19

Carbohydrates

Answer 19

(sugars and starches) are composed of carbon, oxygen and hydrogen.

Question 20

Glucose

Answer 20

Glucose is one of the body’s preferred sources of fuel in the form of carbohydrates. It , is a mono­saccharide (mono = one; saccharide = sugar).

Question 21

Functions of sugar

Answer 21

• providing a ready source of energy to fuel cell metabolism
• providing a form of energy storage, e.g., glycogen
• forming an integral part of the structure of DNA and RNA
• acting as receptors on the cell surface, allowing the cell to recognize other molecules and cells.

Question 22

Amino acids

Answer 22

organic compounds that combine to form proteins.

Question 23

Lipids

Answer 23

is any of various organic compounds that are insoluble in water (they are hydrophobic).
They are made up mainly of carbon, hydrogen, and oxygen atoms, and some contain additional elements, like nitrogen or phosphorus.

Question 24

Fats

Answer 24

are classified as saturated or unsaturated, depending on the chemical nature of the fatty acids present.

Question 25

Nucleotides

Answer 25

a compound consisting of a nucleoside linked to a phosphate group. Nucleotides form the basic structural unit of nucleic acids such as DNA.

Question 26

Nucleic acids

Answer 26

a complex organic substance present in living cells, especially DNA or RNA, whose molecules consist of many nucleotides linked in a long chain.

Question 27

Enzymes

Answer 27

are proteins that act as catalysts for biochemical reactions – that is, they speed the reaction up but are not themselves changed by it, and therefore can be used repeatedly.

Question 28

Diffusion

Answer 28

refers to the movement of molecules from an area of high concentration to an area of low concentration, and occurs mainly in gases, liquids, and solutions.

Question 29

Osmosis

Answer 29

refers specifically to the diffusion of water down its concentration gradient.

Question 30

Extracellular fluid (ECF)

Answer 30

denotes all body fluid outside the cells.

ECF consists mainly of blood, plasma, lymph, cerebrospinal fluid and fluid in the interstitial spaces of the body.

Question 31

Intracellular Fluid (ICF)

Answer 31

• The composition of intracellular fluid (ICF) is largely controlled by the cell itself because there are selective uptake and discharge mechanisms present in the cell membrane.

Question 32

Buffers

Answer 32

• Acids and bases are constantly produced in the body by various cellular activities. However, the pH of the body fluids is maintained within a narrow range by buffer mechanisms.