1. 2. After an enzyme is mixed with its substrate, the amount of product formed
is determined at 10-second intervals for 1 minute. Data from this experiment
are shown below.
Time (sec)
0
10
20
30
40
50
60
Product formed (mg)
0.00
0.25
0.50
0.70
0.80
0.85
0.85
Draw a graph of these data and answer the following questions.
a. What is the initial rate of this enzymatic reaction?
b. What is the rate after 50 seconds? Why is it different from the
initial rate?
c. What would be the effect on product formation if the enzyme were
heated to a temperature of 100 oC for 10 minutes before repeating the
experiment? Why?
STANDARDS: MAX = 9 pts
GRAPH : max= 3pts
axis X = Time (ind); Y = Product (dep)
scale and label axis (1 pt)
curve plotted - drawn curve necessary (1 pt)
(1 pt)
a. initial rate: max=2 pts
setup (.25-.00)/(10-0) (1 pt)
answer 0.025 mg/sec or .25 mg/10 sec (1 pt)
b. rate after 50 sec max = 2 pts
Zero (1 pt)
Setup (.85-.85)/(60-50) (1 pt)
Why? (1 pt) (must have to get 2 pts)
Substrate gone or reaction at equilibrium
Other explanation - any are possible
Product inhibition
Product changes pH or temp optimum
Product release time varies
EXPLANATIONS:
c. Temperature variation- max = 2 pt
Change: stops reaction; no product formation; rate near or at zero
Explanation: Conformational shape change - denaturation
(inactivation - "kills" in quotes)

2. Question 1 1996
1. The unique properties (characteristics) of water make life possible on Earth. Select three properties of
water and define the property and give one example of how the property affects the functioning of living
organisms.
One point awarded for Identification of Water property with it’s correct definition (Need both to earn
point). Point for each correct Example for each property of water.6 pts.Total.
Identification
Polarity
Hydrogen bonding
Cohesion
Adhesion
High specific heat
Heat of Vaporization
Universal solvent
Unusual Phase Change
Dissociation/ionization
Definition
Unequal distribution of electrons
Weak intermolecular attraction
between H and O
Attraction of water molecules to
each other
Attraction of water molecules to
other molecules
Ability to absorb energy, allowing
water temp to change slowly
Energy rqd for Liquid to gas
Dissolves many compounds
Ice floats (less dense) 4C most
dense
H2O-> H3O + OH
H2O -> OH + H
Example
Formation of hydrogen bond
Electrostatic attraction
Transpiration, surface tension
Capillarity, transpiration
Moderates temperature on
organsims
Sweating, water cycle,
transpiration
Hydrophobic and hydrophilic
Thermal mixing, nutrient
upwelling, isulation of ponds
Buffers, metabolism, e source,
photosynthesis, hydrolysis
1. The physical structure of a protein often reflects and affects its function.
(a) Describe THREE types of chemical
bonds/interactions found in proteins. For each
type, describe its role in determining protein
structure. (6 points; 1 point for
bond/interaction description, 1 point for
description of role) Bond/interaction
Description
Covalent/
peptide
sharing electrons OR
linking amino acids together
Disulfide/
covalent
Hydrogen
disulfide, S–S bond (bridges);
sulfur-containing R group bonding
H–O or H–N interactions
van der Waals
unequal electron clouds in R group;
dipole moments
nonpolar R groups
charged R groups
Hydrophobic
Ionic
Role associated to bond/interaction
amino acid sequence OR primary
structure
(no credit for chain or polypeptide
alone)
tertiary or quaternary structure
α helix, β sheet; secondary, tertiary, or
quaternary structure
tertiary or quaternary structure
tertiary or quaternary structure
tertiary or quaternary structure