Question

practice
a class of biology students performed a series of experiments to determine optimum rates of fermentation
a particular strain of yeast. the following graphs were produced from the data they collected. analyze thei
results to answer the following questions. darken the circle that corresponds to your answer choice.

1. for this strain of yeast, how does yeast concentration affect the rate of fermentation?

ⓐ as yeast concentration increases, the rate of fermentation decreases.
ⓑ as yeast concentration increases, the rate of fermentation increases.
ⓒ the rate of fermentation is greatest at an optimum yeast concentration around 30 grams per liter.
ⓓ the concentration of yeast has little effect on the rate of fermentation.

1. for this strain of yeast, what are the optimum conditions for maximizing the rate of fermentation?

ⓐ a temperature less than 10°c and a ph less than 2
ⓑ a temperature greater than 50°c and a ph greater than 8
ⓒ a temperature around 30°c and a ph around 4.5
ⓓ a temperature around 40°c and any ph level

1. in their experiments, students used glucose as the sugar being fermented. a group of students wanted to

experiment further to see if different types of sugar would affect the rate of fermentation. they graphed their
results below.

which type of sugar showed the greatest rate of fermentation?
ⓐ lactose ⓑ fructose ⓒ glucose ⓓ sucrose

Explanation:

Question 1

Step1: Analyze the yeast concentration graph

The first graph has yeast concentration (x - axis) and rate of fermentation (y - axis). The curve is increasing, meaning as yeast concentration (grams per liter) increases, the rate of fermentation (ml of \(CO_2\) per hr) increases.

Step2: Evaluate the options

• Option A: Says rate decreases with increasing yeast concentration, which is opposite to the graph. Eliminate.
• Option B: Says rate increases with increasing yeast concentration, matches the graph.
• Option C: The graph is a curve that is increasing, not showing a peak at 30 grams per liter. Eliminate.
• Option D: The graph shows a clear trend, so yeast concentration has an effect. Eliminate.

Step1: Analyze the temperature graph

The second graph (temperature vs rate of fermentation) has a peak around \(30^{\circ}C\), meaning the optimum temperature is around \(30^{\circ}C\).

Step2: Analyze the pH graph

The third graph (pH vs rate of fermentation) has a peak around pH 4.5, meaning the optimum pH is around 4.5.

Step3: Evaluate the options

• Option A: Temperature less than \(10^{\circ}C\) and pH less than 2: From the graphs, at low temperature and low pH, the rate is low. Eliminate.
• Option B: Temperature greater than \(50^{\circ}C\) and pH greater than 8: At high temperature (above \(50^{\circ}C\)) and high pH (above 8), the rate is low. Eliminate.
• Option C: Temperature around \(30^{\circ}C\) and pH around 4.5: Matches the peaks of the temperature and pH graphs.
• Option D: Temperature around \(40^{\circ}C\) and any pH level: The temperature graph shows a decrease after \(30^{\circ}C\), and pH matters (so "any pH level" is wrong). Eliminate.

Step1: Analyze the sugar fermentation graph

The graph for different sugars (sucrose, glucose, fructose, lactose) vs time (x - axis) and volume of \(CO_2\) (y - axis). The steeper the slope, the higher the rate of fermentation (since rate is change in volume over time).

Step2: Evaluate the options

• Option A: Lactose has a very flat line, low rate. Eliminate.
• Option B: Fructose has a less steep slope than sucrose. Eliminate.
• Option C: Glucose has a less steep slope than sucrose. Eliminate.
• Option D: Sucrose has the steepest slope, meaning the greatest rate of fermentation.

Answer:

B. As yeast concentration increases, the rate of fermentation increases.

Question 2