Chapter 2: Chemical Basis of Life Flashcards
What are the elements that most living matter is composed of?
oxygen, carbon, hydrogen, nitrogen, calcium, phosphorus
Trace elements are common additives to
food and water
How can radioactive isotopes harm us and how are they helpful?
Damages molecules, especially DNA
valuable in basic research and medicine
- process of photosynthesis
- Alzheimer’s research
How are covalent bonds formed?
through the sharing of electrons
What is the difference between polar and nonpolar bonds?
polar bonds- unequal sharing of electrons; one side of molecule is more electronegative
nonpolar bonds- equal sharing of electrons
What are ionic bonds?
attractions between ions of opposite charges
How do chemical reactions change the composition of matter?
composition is changed as bonds are broken and formed to create reactants and products
What is cohesion?
tendency of like molecules to stick together
What is surface tension?
measure of the difficulty to break the surface of a liquid
How is water the solvent of life?
polar solutes dissolve when water molecules surround them; form aqueous solutions
What is an acid?
a compound that releases H+ ions in solution
What is a base?
a compound that accepts H+ ions in solution
A cells pH is maintained at 7, how does this occur?
by buffers, which minimize changes in pH
Radioactive isotopes of an atom often have an increased
a) # of neutrons in the nucleus
b) # of protons in the nucleus
c) # of electrons in the nucleus
d) valence
a) # of neutrons in the nucleus
Can large proteins dissolve in water?
Yes as long as the protein has enough polar or ionic residues on their surface
A solution at pH 6 contains ______ H+ than the same amount of a solution at pH 8.
a) 20 times more
b) 100 times more
c) 2 times less
d) 100 time less
b) 100 times more
Most of the unique properties of water result from the fact that water molecules
a) are the most abundant molecules on Earth’s surface
b) are held together by covalent bonds
c) are constantly in motion
d) are polar and form hydrogen bonds
d) are polar and form hydrogen bonds
In chemical terms you would say that Coke-a-cola is an aqueous solution where water is the _____, sugar is a ______, and carbon dioxide makes the solution _____.
a) solvent…solute…basic
b) solute…solvent…basic
c) solvent…solute…acidic
d) solute…solvent…acidic
c) solvent…solute…acidic
The atomic number of chlorine is 17. Chlorine combines with hydrogen forming the compound hydrogen chloride. Based on the number of valence electrons in the chlorine atom, predict the molecular formula of the compound.
a) H2Cl
b) HCl2
c) HCl
d) HCl4
c) HCl
Why can two hydrogen atoms not satisfy the carbon’s valence in methane (CH4)?
carbon atom has a full valence shell, requiring each of its four unpaired electrons to pair with the electrons of a hydrogen atom
Carbon 12: atomic number, mass number, valence
Which of these numbers is most related to the chemical behavior of the atom?
atomic number: 6
mass number: 12.01
valence: 4
the electrons in the valence shell
What makes a compound an acid or a base?
Give a strong example of each
Acid- higher concentration of H ions than OH
Base- compound that reduces H ion concentration
Strong Acid: HCl
Strong Base: NaOH
Do proteins classify as compounds
Yes, proteins are compounds containing C, H, O, N, S,
Farmers spray water on crops to protect from freezing temperatures, how do water’s emergent properties contribute to this?
When water is cooled, hydrogen bonds are formed which releases a significant amount of heat. The heat protects the plant’s cells
three characteristics of cohesive behavior…
- strong bonding attraction
- helps transport H2O against gravity in plants
- forms surface tension
adhesion is the
attraction between different substances (polar w/ nonpolar molecules and surfaces)
What is heat of vaporization?
the heat a liquid must absorb in 1g to be converted into a gas
increase vaporization…
retains heat
what efficiently maintains homeostasis?
dissolved molecules suspended into H2O
what state of matter makes for “slow” molecule reaction?
a solid
water’s complexity for supporting life
- cohesive behavior
- ability to moderate temp.
- expansion upon freezing
- versatility as a solvent
What happens when ionic compounds are dissolved by water?
ions are surrounded by hydrogen shells
what is pH?
measure of hydrogen ions in solution
what is an acid?
any substance that dissociates with water to increase H ions
A stronger acid indicates…
a lower pH
What is a base?
a substance that combines w/ H dissolved ions
a stronger base indicates…
a higher pH
what are buffers?
a substance resisting changes in pH
