BIOL 1406 Chapter 10
Identify the chloroplast
A
___________ splits water into 1/2 O2, H+, and e-
A
In the thylakoid membranes, the pigment molecules in a light-harvesting complex ______________
Absorb and transfer light energy to the reaction-center chlorophyll
Refer to the figure. If the carbon atom of each of the incoming CO2 molecules is labeled with a radioactive isotope of carbon, which organic molecules will be radioactively labeled after one cycle?
B, C, D, and E
Which of the following graphs has the best-fit regression lines correctly drawn?
C
Which of the following molecules is the primary product of photosystem I?
NADPH
Where does the Calvin cycle take place?
Stroma of the chloroplast
The ultimate source of energy to support most life on Earth is ____________
Sunlight
You obtain the pigments called carotenoids in your diet when you eat carrots. Why do carotenoids appear yellow and orange?
They absorb blue/green light and reflect yellow and red wavelengths of light
Identify the stroma
E
Where does the Calvin cycle occur?
E
Which of these phosphorylates ADP to make ATP?
E
Which of the following sequences correctly represents the flow of electrons during photosynthesis?
H2O → NADPH → Calvin cycle
What is the relationship between the wavelength of light and the quantity of energy per photon?
They are inversely related
What is the biological significance of the light-independent reactions of photosynthesis?
They convert carbon dioxide to sugar
Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants?
They protect against oxidative damage from excessive light energy
Plants are photoautotrophs. What does this mean?
They use light energy to drive the synthesis of organic molecules from inorganic material
Why are there several structurally different pigments in the reaction centers of photosystems?
This arrangement enables the plant to absorb light energy of a variety of wavelengths
In the electromagnetic spectrum, the type of radiation that we call visible light occurs between ________________
Ultraviolet radiation and infrared radiation
Assuming that the y-axis tick marks will be separated by 10 (0, 10, 20, and so on), what is the largest value that should appear on the y-axis?
100
Assuming that the x-axis tick marks will be separated by 200 (0, 200, 400, and so on), what is the largest value that should appear on the x-axis?
1200
In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules?
3
What wavelength of light in the figure is most effective in driving photosynthesis?
420 mm
Approximately what wavelength of light is best absorbed by chlorophyll a, the pigment that participates directly in the light reactions?
435 nm
Which wavelength of light is best absorbed by chlorophyll b?
455 nm
How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose?
6
Which of these equations best summarizes photosynthesis?
6 CO2 + 6 H2O → C6H12O6 + 6 O2
Chlorophyll can be found in ______________
A and C
What are the products of linear electron flow?
ATP and NADPH
Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
ATP and NADPH
Chloroplast membrane vesicles are equilibrated in a simple solution of pH 5. The solution is then adjusted to pH 8. Which of the following conclusions can be drawn from these experimental conditions?
ATP will not be produced because there is no ADP and inorganic phosphate in the solution
What event accompanies energy absorption by chlorophyll (or other pigment molecules of the antenna complex)?
An electron is excited
What is the relationship between increasing concentration of CO2 and the dry mass of corn?
As CO2 increases, the dry weight of corn decreases
What is the relationship between increasing concentration of CO2 and the dry mass of velvetleaf?
As CO2 increases, the dry weight of velvetleaf increases
Considering that velvetleaf is a weed invasive to cornfields, how would you predict increased CO2 concentration to affect interactions between the two species?
As atmospheric CO2 rises, velvetleaf weeds may grow larger and better compete with corn, reducing grain yields
Which of the following statements is a correct distinction between autotrophs and heterotrophs?
Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic
What variable's response to the independent variable was measured by the researchers, and what are the units for this variable?
Average dry mass of one plant, in grams
Which of the following graphs correctly presents the data from the experiment?
B
____________ releases energy that is used to pump hydrogen ions from the stroma into the thylakoid compartment
B
A flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights, which are set to cycle between 12 hours of light and 12 hours of dark. The dissolved oxygen concentrations in both flasks are monitored. Predict what the relative dissolved oxygen concentrations will be in the flask with algae compared to the control flask. The dissolved oxygen in the flask with algae will _____________
Be higher in the light, but lower in the dark
A gardener is concerned that her greenhouse is getting too hot from too much light and seeks to shade her plants with colored translucent plastic sheets, the color of which allows passage of only that wavelength. What color should she use to reduce overall light energy but still maximize plant growth?
Blue
Suppose a plant has a unique photosynthetic pigment and the leaves of this plant appear to be reddish yellow. What wavelengths of visible light are absorbed by this pigment?
Blue and violet
Energized electrons from _____________ enter an electron transport chain and are then used to reduce NADP+
C
In autumn, the leaves of deciduous trees change colors. This is because chlorophyll is degraded and _____________
Carotenoids and other pigments are still present in the leaves
The photosynthetic membranes are found in the ____________ in plant cells
Chloroplasts
What variable did the researchers intentionally vary in the experiment, and what are the units for this variable? (This is the independent variable)
Concentration of CO2 in the air, in parts per million
What is the estimated dry mass of corn and velvetleaf plants at an atmospheric CO2 concentration of 800 ppm?
Corn: 84 g; velvetleaf: 50 g
What is the estimated dry mass of corn and velvetleaf plants at an atmospheric CO2 concentration of 390 ppm (current levels)?
Corn: 91 g; velvetleaf: 38 g
As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find that 30,000 molecules of ATP were consumed, but only 20,000 molecules of NADPH were consumed. Where did the extra ATP molecules come from?
Cyclic electron flow
Identify a thylakoid
D
T/F: The chemiosmotic hypothesis states that the synthesis of ATP generates a proton gradient that leads to electron flow through an electron transport chain
False
T/F: The region of ATP synthase that catalyzes the production of ATP from ADP and inorganic phosphate spans the chloroplast membrane
False
P680+ is said to be the strongest biological oxidizing agent. Given its function, why is this necessary?
It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has
The overall function of the Calvin cycle is _____________
Making sugar
After 3-PGA is phosphorylated, it is reduced by _______________
NADPH
What compound provides the reducing power for Calvin cycle reactions?
NADPH
Which of the following products of the light reactions of photosynthesis is consumed during the Calvin cycle?
NADPH
Can you tell from these absorption spectra whether red light is effective in driving photosynthesis?
One cannot tell from this graph, but because chlorophyll a does absorb red light, we can predict that it would be effective in driving photosynthesis
Plants photosynthesize ____________
Only in the light but respire in light and dark
The figure shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?
Other pigments absorb light in addition to chlorophyll a
In its mechanism, photophosphorylation is most similar to _____________
Oxidative phosphorylation in cellular respiration
Photosynthesis is a redox reaction. This means that H2O is ____________ during the light reactions and CO2 is _____________ during the Calvin cycle
Oxidized ... Reduced
Which of the following is a product of the light reactions of photosynthesis?
Oxygen, ATP, and NADPH
If pigments from a particular species of plant are extracted and subjected to paper chromatography, which of the following is most likely?
Paper chromatography would separate the pigments from a particular plant into several bands
Which term describes ATP production resulting from the capture of light energy by chlorophyll?
Photophosphorylation
Which process produces oxygen?
Photosynthesis
In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during ______________
Photosynthesis and respiration
Which of the following statements best describes the relationship between photosynthesis and respiration?
Photosynthesis stores energy in complex organic molecules; respiration releases energy from complex organic molecules
According to the chemiosmotic hypothesis, what provides the energy that directly drives ATP synthesis?
Proton gradient
Which of the following particles can pass through the ATP synthase channel?
Protons
Which of the following are directly associated with photosystem I?
Receiving electrons from the thylakoid membrane electron transport chain
_____________ has a longer wavelength than ____________
Red ... Green
In the process of carbon fixation, RuBP attaches a CO2 to produce a six-carbon molecule, which is then split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces glyceraldehyde 3-phosphate (G3P), what more needs to happen to complete the Calvin cycle?
Regeneration of RuBP
Which of the following reactions ensures that the Calvin cycle can make a continuous supply of glucose?
Regeneration of RuBP
Which of the following does NOT occur during the Calvin cycle?
Release of oxygen
What process is most directly driven by light energy?
Removal of electrons from chlorophyll molecules
Carbon fixation involves the addition of carbon dioxide to _____________
RuBP
When light strikes chlorophyll molecules, they lose electrons, which are ultimately replaced by ______________
Splitting water
When oxygen is released as a result of photosynthesis, it is a direct by-product of ______________
Splitting water molecule
Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will most directly affect the ______________
Synthesis of ATP
What is the primary function of the Calvin cycle?
Synthesize simple sugars from carbon dioxide
Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be to _______________
Test for liberation of O2 in the light
An action spectrum plots the rate of photosynthesis at various wavelengths of visible light, and it shows that blue light with a wavelength of about 490 nm is effective in driving photosynthesis. Based on this information and the absorption spectra shown at left, what role may chlorophyll b and carotenoids play in photosynthesis?
These pigments are able to absorb more wavelengths of light (and thus more energy) than chlorophyll a alone can absorb. As part of light-harvesting complexes in photosystems, they broaden the range of light that can be used in the light reactions
In a plant cell, where are the ATP synthase complexes located?
Thylakoid membrane and inner mitochondrial membrane
T/F: The light-dependent reactions of photosynthesis use water and produce oxygen
True
Early investigators thought the oxygen produced by photosynthetic plants came from carbon dioxide. In fact, it comes from ___________
Water
The electrons of photosystem II are excited and transferred to electron carriers. From which molecule or structure do the photosystem II replacement electrons come?
Water
The light reactions of photosynthesis use ___________ and produce ______________
Water ... NADPH
Theodor W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light. An outcome of Engelmann's experiment was to help determine the relationship between ________________
Wavelengths of light and the rate of photosynthesis
Do these results support the conclusion from other experiments that C3 plants have a better growth response than C4 plants under increased CO2 concentration? Why or why not?
Yes, because C3 velvetleaf had a positive growth response to increased CO2, but C4 corn had a negative growth response to it
Halobacterium has a photosynthetic membrane that appears purple. Its photosynthetic action spectrum is the inverse of the action spectrum for green plants. (That is, the Halobacterium action spectrum has a peak where the green plant action spectrum has a trough.) What wavelengths of light do the Halobacterium photosynthetic pigments absorb?
Green and yellow
A spaceship is designed to support animal life for a multiyear voyage to the outer planets of the solar system. Plants will be grown to provide oxygen and to recycle carbon dioxide. Since the spaceship will be too far from the sun for photosynthesis, an artificial light source will be needed. What wavelengths of light should be used to maximize plant growth with a minimum of energy expenditure?
Green light
The process of photosynthesis probably originated _____________
In prokaryotes
In autotrophic bacteria, where is chlorophyll located?
In the infolded plasma membrane
If atmospheric CO2 concentration increases from 390 ppm to 800 ppm, what is the estimated percentage change in dry mass for corn? For velvetleaf?
The dry mass of corn would decrease by about 8%, and the dry mass of velvetleaf would increase by about 32%
If only chlorophyll a were involved in the light reactions, would blue light (wavelength about 490 nm) be effective in driving photosynthesis?
The graph indicates that chlorophyll a absorbs very little blue light, so we can predict that blue light would not be effective
In a plant, the reactions that produce molecular oxygen (O2) take place in ___________
The light reactions alone
Which set of reactions uses H2O and produces O2?
The light-dependent reactions
Which of the following statements best describes the relationship between the light-dependent and light-independent reactions of photosynthesis?
The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions
What is the importance of the light-independent reactions in terms of carbon flow in the biosphere?
The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars
