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Bio Lab Exam 2
Labs 5, 6, 7, 8
| Question | Answer |
|---|---|
| Electrons are removed from _______ to produce _______ during photosynthesis | water, oxygen |
| Process of water losing an electron during photosynthesis | oxidation |
| At what wavelength(s) does chlorophyll absorb the most light? | 420-450 (blue) and 650-680 (red); absorbs the most at blue |
| what two chlorophylls were separated from carotenoids and used in Lab 5? | Chlorophyll A and B |
| What type of leaves were used for Lab 5? | spinach leaves |
| How were the pigments extracted from the leaves in Lab 5? | by bringing 95% ethanol to a boil and heating the spinach leaves in the solution |
| what solutions were used in lab 5? | petroleum ether, ethanol, and 92% methanol |
| What was the first experimental group in Lab 5? | Carotene mixed with ethanol |
| What were the two other experimental groups in Lab 5? | Chlorophyll B mixed with methanol and Chlorophyll A mixed with Petroleum ether |
| What was the wavelength of the highest absorbance for Carotene | 440 nm |
| What was the wavelength of the highest absorbance for Chlorophyll A? | 440 nm |
| What was the wavelength of the highest absorbance for Chlorophyll B? | 460 nm |
| Which pigment was diluted in Lab 5 and why? | Chlorophyll A; to compare wavelengths and height of peaks of concentrated vs. diluted solutions with pigments. |
| Does changing the concentration of the pigment substantially alter the position (wavelength) of the peaks? | No, the pigment is not changing, therefore, the wavelength of maximum absorbance will not change. Each pigment has its own unique wavelength of maximum absorbance |
| Does changing the concentration of the pigment substantially alter the height (absorbance) of the peaks? | Yes, the more pigment that is present, the higher the peaks. These peaks will occur at the same wavelength, however, regardless of the concentration |
| What appears to be the relationship between the concentration of pigment and the height of the peaks? | direct relationship |
| What major property of chlorophyll a, chlorophyll b and carotenoids did we take advantage of in order to separate them from one another? | solubility |
| What was the independent variable of Lab 5? | The type of pigment used (and the concentration) |
| What was the dependent variable of Lab 5? | The wavelength of maximum absorbance (and the height of the peaks) |
| What was the purpose of Lab 6? | To measure the rate at which water is oxidized during photosynthesis when the amount of chloroplasts is varied |
| What is the result of water being oxidized? | Oxygen gas is released |
| Where are electrons taken from water during photosynthesis | photosystem 2 |
| What was the independent variable of Lab 6? | The amount of chloroplasts added to the reaction mixture |
| What was the dependent variable of Lab 6? | The rate of water oxidation (shown by DPIP losing it's blue color as a result of being reduced (gaining electrons) and becoming more transparent) |
| Why was a buffer used for the isolation and function assessment of chloroplasts in lab 6? | To eliminate pH as a variable in the experiment. |
| Why was bisulfite added to the "blank" tubes in the experiments with chloroplast function in lab 6? | The bisulfite reduced the DPIP, so the blank had everything in it that the experimental tube had, except the blue color |
| When the amount of chloroplasts was varied, what do the results show about chloroplast function? | The more chloroplasts that were added, the lower the absorption. This is because the more DPIP was reduced, the more it lost its color. Transparent solutions have lower absorbance rates. |
| Where do the electrons that reduce the DPIP come from? Where do these electrons normally end up when the full process of photosynthesis is occurring? How important is this for the overall process of photosynthesis? | The electrons come from water. They usually end up in photosystem 2. The electrons from water replenish the ones that leave photosystem 2 to head to photosystem 1 and later the Calvin cycle. |
| What wavelength(s) do you think would have been most effective for driving the reduction of DPIP in the reaction? What wavelengths would have been least effective for driving the reduction of DPIP? Why? | Purple/blue and red would have generated the most effective results. Green would have had the least effective results. |
| If DPIP spontaneously loses its blue color, what should have happened in the “No light, no heat” control? | absorbance would be low (high oxidation of water) |
| If heat is necessary for the DPIP to change color, what should have happened in the “No light, heat” control? | absorbance would be low (high oxidation of water) |
| If light and heat are required for DPIP to lose its color, how should the change in absorbance be different between the “Light and heat” control and the “Light, no heat” condition? Does light alone appear to be needed to drive the DPIP reduction? | Absorbance would be low for "light and heat" and high for "light and no heat". Light is the only factor that influences DPIP to become reduced and have a low absorption (high oxidation of water) |
| What are the electrons that are stolen from water in photosynthesis eventually used for? | to reduce CO2 to produce glucose and to also create ATP |
| Does Oxygen play a direct role in photosynthesis? | No, it is a byproduct of photosynthesis |
| What was the purpose of Lab 7? | To determine the effect of light quantity on the rate of oxygen production by an alga called Chlorella |
| What is the name of the specimen used in Lab 7 that was measured? | Chlorella- it is an aquatic photosynthetic unicellular organism |
| What was the independent variable of Lab 7? | The light quantity projected onto the Chlorella sample measured as PFR (photon fluence rate) |
| What was the dependent variable of Lab 7? | The rate at which Chlorella produced oxygen; measured using an oxygen sensor |
| What is the relationship between oxygen production and PFR (amount of light casted on the Chlorella sample) | direct; the more light, the more oxygen produced. As PFR increased, so did oxygen production rate |
| If the "no light control" rate was negative, what was happening to oxygen in the dark Chlorella tube? For what do plants use oxygen? | The oxygen was being used by Chlorella for cellular respiration and since there was no light present, the oxygen was not being replenished. This is because photosynthesis was not occurring when no light was casted on the Chlorella sample. |
| What are the three main patterns of population increase studied in Lab 8? | Linear, unrestricted exponential, and logistic |
| Linear growth | Growth rate is constant and independent of population size (y=mx+b with m as rate of increase, x as time, and b as initial population size) |
| What does a linear growth graph look like? | A straight line with a positive slope (rate of increase is constant) |
| Unrestricted Exponential growth | Growth rate is proportional to population size (A=Pe^rt with r as rate of increase, t as time, and P as initial population size) |
| What does an unrestricted exponential growth graph look like? | The right side of a parabola (rate of increase and slope are not constant; as the population grows, so does the growth rate) |
| What does a logistic growth graph look like | lag phase (number of births is greater than deaths, but growth is slow due to small population size), log phase (birth rate still exceeds death rate and the population experiences rapid growth), and the stationary phase (birth and death rates are equal) |
| What is the stationary phase in logistic growth also known as | carrying capacity (K) |
| Carrying capacity | number of individuals in a population that an environment can support indefinitely |
| Logistic growth | Growth rate is influenced by the difference between carrying capacity and population size (log) |
| How does the intrinsic rate of increase (r) affect the rate of growth? | The smaller the intrinsic rate of increase (r), the slower the rate of growth to reach its carrying capacity |
| Is carrying capacity impacted by the value of "r" | No, "r" just states how fast a population will reach carrying capacity. It does not change carrying capacity |
| How does the initial population size affect the time required to reach carrying capacity? | As the initial population size gets larger, the population reaches carrying capacity faster |
| Why is it important to first determine the carrying capacity for each population when their niches do not overlap? | So that it may be used a comparison when their niches do overlap. The carrying capacity for one population decreases with the more overlap that occurs. |
| What is the relationship of initial population size and carrying capacity | The carrying capacity is constant and will not change as a result of differing initial population sizes. |
| Predation graph | Two lines that oscillate in response to each other (large one is prey, and bottom smaller one is predators) |
| Competition graph | The success of one species results in the downfall of the other species. As species 1 gets larger, species 2 gets smaller. This is due to overlapping of niches and species 1 having the competitive advantage/being more efficient. |
| The reduction of DPIP by chloroplasts was coupled to which reaction? | The oxidation of water |
| Which of the following exercises that you performed in lab best shows that chloroplasts play a crucial role in the color change of DPIP | Comparing the absorbance changes in separate tubes in which increasing amounts of chloroplasts were added. |
| Which of the following do chloroplasts and sodium bisulfite hold in common? | Sodium bisulfite and chloroplasts may cause DPIP that is initially blue in solution to become colorless |
| Which of the following are capable of reducing DPIP? | Sodium bisulfite and illuminated chloroplasts |
| Where were the peaks located on the absorption spectrum of chlorophyll b? | 460 nm and 640 nm (blue and red) |
| What is done to determine the absorption spectrum of a substance? | Measure its absorbance over a range of different wavelengths of light |
| In the oxygen production lab, how was PFR varied? | The PFR was varied by adjusting the distance between the light source and the tube containing Chlorella. |
| In the oxygen production lab, what compensation was made for the heat generated by the lamps? | A tank of water was placed in the light path to absorb heat. |
| Without regard to the mode of population growth, what best characterizes the rate of population growth? | The slope of the population size versus time graph at any point in time |
| In which of the following types of population growth is the rate of growth independent of population size? | Linear |
| What characterizes exponential growth? | The slope of the population size versus time graph is proportional to population size. |
| fundamental niche | a theoretical niche that does NOT take competition or limiting resources into account |
| realized niche | actual niche of a population; takes competition and limiting resources into account (real world) |
| which is larger, fundamental niche, or realized niche | fundamental niche |
| photosyntheis produces | glucose, ATP, electrons, and protons |
| NADP+ is _____ in photosynthesis to produce ______ | reduced; NADPH |
| chlorophyll absorbs what during photosynthesis | photon energy |
| what is carbon fixation | when plants absorb CO2 from the atmosphere and convert it to organic compounds |
| primary purpose of cellular respiration in plants is | to break down glucose for cellular processes |
| what is the electron acceptor in cellular respiration in plants | oxygen |
| what is the electron acceptor in photosynthesis | Carbon dioxide |
| what is the electron donor for both cellular respiration and photosynthesis in plants | water |
| what do photosystems do? | absorb photons |
| where does the Calvin cycle occur | in the stroma |
| where does photosynthesis occur | in the thylakoid membrane |
| primary role of chlorophyll A in photosynthesis | initiate the process of energy transfer in photosynthesis |
| what is the porphyrin ring | it is found in chlorophyll and has a central magnesium ion |
| primary role of the antenna complex in a plants photosystem | to capture photons of light and transfer them to the reaction center (electrons flow from the antenna complex to the reaction center) |
| main function of ATP synthase in cellular respiration and photosynthesis | synthesize ATP from ADP and a phosphate group by utilizing a proton gradient |
| primary purpose of the Calvin cycle in photosynthesis | fix carbon dioxide from the atmosphere into organic molecules (primarily glucose) |
| what is the electron acceptor in the Calvin cycle | RuBP |
| Carbon dioxide is _______ during the Calvin cycle | reduced |
| what is Photon Fluence Rate (PFR) | a measure of light quantity |
| what does photosystem 2 do? | removes electrons from water, absorbs light energy, and oxidizes water |
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