BIOL 107 Lab Final Exam Questions
and Answers
What are the main disadvantages of using biomass in biofuel production? - Answer-
The use of biomass requires pre-treatment to break down cellulose, which causes the
process to become very costly and time-consuming.
Explain the acronym EATS in terms of photosynthesis. - Answer- E - energy from light is
absorbed by chlorophyll
A - activation of electrons in photosystem
T - transfer of electrons in the electron transport chain
S - sugar is produced by the Calvin cycle
Compare plasmid and genomic DNA in the context of Labs 8 and 9. - Answer- Plasmid
DNA is circular and free-floating in the cytoplasm (in bacterial cells), which genomic
DNA is anchored to the plasma membrane. Plasmid DNA are also smaller and
supercoiled.
How are MWMs (molecular weight markers) used to determine the molecular weights of
DNA fragments? - Answer- Distance traveled by DNA molecules of known weight
(MWM/DNA ladders) are compared to distance migrated by DNA fragments of unknown
weights to determine molecular weights.
What is the role of SYBR Safe in electrophoresis? - Answer- SYBR Safe is a fluorescent
dye that binds to the DNA and causes larger pieces to bind more and fluoresce brighter.
In the photosynthesis experiment in Lab 7, what does a negative value for the change in
absorbance indicate? Why is this? - Answer- The initial reading at t=0 was subtracted
from the final and a decrease in colour indicates a positive photosynthetic reaction.
What is a negative control? - Answer- A group in which the independent variable is
absent
When should you reject your null hypothesis? - Answer- When the p-value obtained is
less than 0.05 (This means that the results of the experiment are statistically
significant.)
What was the control in Lab 4 (the experiment that studied the effects of smoke
treatment on Tetrahymena cells)? What kind of control was it? - Answer- The control in
this experiment was water in place of smoke treatment and it was a negative control.
, Why was ONPG used to test enzyme activity? - Answer- ONPG is a substrate that is
similar to lactose and easier to measure.
Why did lower (more acidic) pHs not bind to ONPG and result in lower lactase activity? -
Answer- Enzymes are made up of proteins, which fold and bond to create a 3D
structure, forming an active site where enzymes can bind. Different pHs affect protein
folding and these lower pHs caused the proteins not to fold correctly and therefore the
ONPG could not bind properly to the active site.
Why was sugar cane used as a control in Lab 6 (the biofuels experiment)? - Answer-
Sugar cane contains large amounts of glucose, which makes it effective for the
production of CO2 through fermentation. Since it is known that sugar cane will result in
high rates of fermentation, it makes for a good control in this experiment to compare to
other groups that are not yet known to be effective or not.
Why are second-generation biofuels being researched as alternatives to plant materials
like sugar cane and corn? - Answer- Many ethical and environmental concerns surround
the use of food crops as sources of biofuels, such as the driving up of food prices due to
increased demand and deforestation due to sugar cane crops being planted in cleared
parts of the rainforest.
Why does cellulase treatment increase the rate of fermentation? What other step had to
be completed in Lab 6 before cellulase treatment? - Answer- Cellulase breaks down
cellulose, which in the experiment in Lab 6, the yeast was unable to do on its own
because it does not have enzymes that can break down cellulose. Microfibrils are what
make up cellulose and have very complex structures that make it difficult for cellulase to
reach the cellulose it down into glucose, so pre-treatment using heat or mechanical
methods must be completed first to break up the cell wall.
What is the difference between an absorption spectrum and an action spectrum in
regards to the photosynthesis experiment in Lab 7? - Answer- An absorption spectrum
determines which wavelengths of light are absorbed by chloroplast pigments and an
action spectrum demonstrates which colours of light result in the highest rates of
photosynthesis.
Why was DCPIP used in Lab 7 to measure the rate of photosynthesis? - Answer-
DCPIP is an indicator dye that changes colour when reduced (gain of electrons). It goes
from being blue when in its oxidized form to colourless in its reduced form. The less
colour loss in DCPIP, the higher rate of photosynthesis.
Which colours/groups resulted in the highest and lowest absorbances (and rates of
photosynthesis) in Lab 7 and why? - Answer- Red showed the highest absorbance,
followed by blue. Green showed a low absorbance, similar to the dark control because
spinach chloroplasts reflect green light, therefore absorbing it the least out of all the
colours.
and Answers
What are the main disadvantages of using biomass in biofuel production? - Answer-
The use of biomass requires pre-treatment to break down cellulose, which causes the
process to become very costly and time-consuming.
Explain the acronym EATS in terms of photosynthesis. - Answer- E - energy from light is
absorbed by chlorophyll
A - activation of electrons in photosystem
T - transfer of electrons in the electron transport chain
S - sugar is produced by the Calvin cycle
Compare plasmid and genomic DNA in the context of Labs 8 and 9. - Answer- Plasmid
DNA is circular and free-floating in the cytoplasm (in bacterial cells), which genomic
DNA is anchored to the plasma membrane. Plasmid DNA are also smaller and
supercoiled.
How are MWMs (molecular weight markers) used to determine the molecular weights of
DNA fragments? - Answer- Distance traveled by DNA molecules of known weight
(MWM/DNA ladders) are compared to distance migrated by DNA fragments of unknown
weights to determine molecular weights.
What is the role of SYBR Safe in electrophoresis? - Answer- SYBR Safe is a fluorescent
dye that binds to the DNA and causes larger pieces to bind more and fluoresce brighter.
In the photosynthesis experiment in Lab 7, what does a negative value for the change in
absorbance indicate? Why is this? - Answer- The initial reading at t=0 was subtracted
from the final and a decrease in colour indicates a positive photosynthetic reaction.
What is a negative control? - Answer- A group in which the independent variable is
absent
When should you reject your null hypothesis? - Answer- When the p-value obtained is
less than 0.05 (This means that the results of the experiment are statistically
significant.)
What was the control in Lab 4 (the experiment that studied the effects of smoke
treatment on Tetrahymena cells)? What kind of control was it? - Answer- The control in
this experiment was water in place of smoke treatment and it was a negative control.
, Why was ONPG used to test enzyme activity? - Answer- ONPG is a substrate that is
similar to lactose and easier to measure.
Why did lower (more acidic) pHs not bind to ONPG and result in lower lactase activity? -
Answer- Enzymes are made up of proteins, which fold and bond to create a 3D
structure, forming an active site where enzymes can bind. Different pHs affect protein
folding and these lower pHs caused the proteins not to fold correctly and therefore the
ONPG could not bind properly to the active site.
Why was sugar cane used as a control in Lab 6 (the biofuels experiment)? - Answer-
Sugar cane contains large amounts of glucose, which makes it effective for the
production of CO2 through fermentation. Since it is known that sugar cane will result in
high rates of fermentation, it makes for a good control in this experiment to compare to
other groups that are not yet known to be effective or not.
Why are second-generation biofuels being researched as alternatives to plant materials
like sugar cane and corn? - Answer- Many ethical and environmental concerns surround
the use of food crops as sources of biofuels, such as the driving up of food prices due to
increased demand and deforestation due to sugar cane crops being planted in cleared
parts of the rainforest.
Why does cellulase treatment increase the rate of fermentation? What other step had to
be completed in Lab 6 before cellulase treatment? - Answer- Cellulase breaks down
cellulose, which in the experiment in Lab 6, the yeast was unable to do on its own
because it does not have enzymes that can break down cellulose. Microfibrils are what
make up cellulose and have very complex structures that make it difficult for cellulase to
reach the cellulose it down into glucose, so pre-treatment using heat or mechanical
methods must be completed first to break up the cell wall.
What is the difference between an absorption spectrum and an action spectrum in
regards to the photosynthesis experiment in Lab 7? - Answer- An absorption spectrum
determines which wavelengths of light are absorbed by chloroplast pigments and an
action spectrum demonstrates which colours of light result in the highest rates of
photosynthesis.
Why was DCPIP used in Lab 7 to measure the rate of photosynthesis? - Answer-
DCPIP is an indicator dye that changes colour when reduced (gain of electrons). It goes
from being blue when in its oxidized form to colourless in its reduced form. The less
colour loss in DCPIP, the higher rate of photosynthesis.
Which colours/groups resulted in the highest and lowest absorbances (and rates of
photosynthesis) in Lab 7 and why? - Answer- Red showed the highest absorbance,
followed by blue. Green showed a low absorbance, similar to the dark control because
spinach chloroplasts reflect green light, therefore absorbing it the least out of all the
colours.
