BIO 151 ch 10
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.
What is the main purpose of light-dependent reactions of photosynthesis? A)to use ATP to make glucose B)to produce NADPH and ATP C)to generate oxygen by "splitting" H2O D)to produce NADPH for use in respiration
To produce NADPH and ATP
Which of the following is a difference between chlorophyll a and chlorophyll b? A) Chlorophyll a contains magnesium in its ring structure, whereas chlorophyll b contains iron. B) Chlorophyll a absorbs yellow light, and chlorophyll b absorbs green. C) Chlorophyll a and b absorb light energy at slightly different wavelengths. D) Chlorophyll a is a pigment, and chlorophyll b is the enzyme that transfers excited electrons from chlorophyll a to electron carriers of the thylakoid membrane.
c
The process of photosynthesis probably originated ________.
in prokaryotes
Plants photosynthesize ________.
only in the light but respire in light and dark
In mechanism, photophosphorylation is most similar to A)carbon fixation B)substrate-level phosphorylation in glycolysis C)the Calvin cycle D)oxidative phosphorylation in cellular respiration E)reduction of NADP+
oxidative phosphorylation in cellular respiration
In plants, reduction of NADP+ occurs during ________.
photosynthesis
When oxygen is released as a result of photosynthesis, it is a direct by-product of ________.
splitting water molecules
In mitochondria, chemiosmosis moves protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis moves protons from the ________.
stroma to the thylakoid space
Reactions that require CO2 take place in ________.
the Calvin cycle alone
As electrons are passed through the system of electron carriers associated with photosystem II, they lose energy. What happens to this energy? A) It is used to establish and maintain a proton gradient. B) It excites electrons of the reaction center of photosystem I. C) It is lost as heat. D) It is used to phosphorylate NAD+ to NADPH, the molecule that accepts electrons from photosystem I.
A
How are the light-dependent and light-independent reactions of photosynthesis related? A) The products of light-dependent reactions are used in light-independent reactions. B) The products of light-independent reactions are used in light-dependent reactions. C) The products of light-independent reactions must be present for light-dependent reactions to take place. D) They are not related.
A
The proteins of the electron transport chain active in the light-dependent reactions ________. A) are membrane proteins present in the thylakoid B) are free proteins present in the thylakoid lumen C) absorb the same wavelengths of light as their associated chlorophylls D) are considered to be part of the reaction center of photosystem I
A
What is the primary function of the Calvin cycle? A) synthesizing simple sugars from carbon dioxide B) splitting water and releasing oxygen C) using ATP to release carbon dioxide D) using NADPH to release carbon dioxide E) transporting RuBP out of the chloroplast
A
Which of the following are directly associated with photosystem I? A ) receiving electrons from the thylakoid membrane electron transport chain B) extraction of hydrogen electrons from the splitting of water C) passing electrons to the cytochrome complex D) harvesting of light energy by ATP E) generation of molecular oxygen
A
Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle? A) ATP and NADPH B) CO2 and glucose C) ADP, i, and NADP+ D) electrons and H+ E) H2O and O2
A
What event accompanies energy absorption by chlorophyll (or other pigment molecules of the antenna complex)?
An electron is excited.
Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma (what happens across this membrane and what is that used for by cells). This damage will most directly affect the ________. A) flow of electrons from photosystem II to photosystem I B) synthesis of ATP C) absorption of light energy by chlorophyll D) splitting of water E) reduction of NADP+
B
In autumn, the leaves of deciduous trees change colors. This is because chlorophyll is degraded and ________. A) sugars are sent to most of the cells of the leaves B) carotenoids and other pigments are still present in the leaves C) the degraded chlorophyll changes into many other colors D) water supply to the leaves has been reduced
B
P680+ is said to be the strongest biological oxidizing agent. Given its function, why is this necessary? A) It obtains carbon from a sugar molecule, so it must have a stronger attraction for electrons than either oxygen or hydrogen. B) It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has. C) It is the receptor for the most excited electron in either photosystem of photosynthesis. D) It transfers its electrons to reduce NADP+ to NADPH. E) It is the molecule that transfers electrons to plastoquinone (Pq) of the electron transfer system.
B
Which of the following sequences correctly represents the flow of electrons during photosynthesis? A) NADPH → O2 → CO2 B) H2O → NADPH → Calvin cycle C) H2O → Calvin cycle → photosystem II D) NADPH → electron transport chain → O2 E) NADPH → chlorophyll → Calvin cycle
B
Chlorophylls absorb most light in which colors of the visible range? A)green and red B)violet and red C)green and blue D)blue and red
Blue and Red
The light-independent reactions of plants function to make organic molecules using carbon dioxide as a carbon source. What is the electron source that helps reduce carbon dioxide to sugars and other organic molecules? A. NADH B. ATP C. NADPH D. electrons from oxygen
C. NADPH
Photorespiration ________. A) generates oxygen and consumes ATP, carbon dioxide, and sugars B) generates ATP and sugars and consumes oxygen and carbon dioxide C) consumes carbon dioxide and generates ATP, sugars, and oxygen D) generates carbon dioxide and consumes ATP and oxygen
D
What wavelength of light in the figure is most effective in driving photosynthesis? A) 625 mm B) 730 mm C) 475 mm D) 420 mm E) 575 mm
D
Which of the following statements best describes the relationship between photosynthesis and respiration? A) Photosynthesis is catabolic; respiration is anabolic. B) Photosynthesis occurs only in plants; respiration occurs only in animals. C) ATP molecules are produced in photosynthesis but not in aerobic respiration. D) Photosynthesis stores energy in complex organic molecules; respiration releases energy from complex organic molecules E) Respiration runs the biochemical pathways of photosynthesis in reverse.
D
Which process is most directly driven by light energy? A) carbon fixation in the stroma B) creation of a pH gradient by pumping protons across the thylakoid membrane C) reduction of NADP+ molecules D) removal of electrons from chlorophyll molecules E) ATP synthesis
D
Why are there several structurally different pigments in the reaction centers of photosystems? A) They enable the reaction center to excite electrons to a higher energy level. B) They enable the plant to absorb more photons from light energy, all of which are at the same wavelength. C) Excited electrons must pass through several pigments before they can be transferred to electron acceptors of the electron transport chain. D) This arrangement enables the plant to absorb light energy of a variety of wavelengths.
D
Where do the enzymatic reactions of the Calvin cycle take place? A) matrix of the mitochondria B) thylakoid space C) thylakoid membranes D) cytosol around the chloroplast E) stroma of the chloroplast
E
Which of the events listed below occurs in the light reactions of photosynthesis? A) ATP is phosphorylated to yield ADP. B) NADP is produced. C) Carbon dioxide is incorporated into PGA. D) NADPH is reduced to NADP+. E) Light is absorbed and funneled to reaction-center chlorophyll a.
E
As electrons are passed through the system of electron carriers associated with photosystem II, they lose energy. What happens to this energy?
It is used to establish and maintain a proton gradient.
If photosynthesizing green algae are provided with CO2 containing heavy oxygen (18O), subsequent analysis will show that 18O is absent from which of the following molecules produced by the algae? A)O2 B)ribulose bisphosphate (RuBP) C)glyceraldehyde 3-phosphate (G3P) D)3-phosphoglycerate E)glucose
O2
Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?
The light reactions provide ATP and NADPH to the Calvin cycle, and the Calvin cycle returns ADP, i, and NADP+ to the light reactions.
How are the light-dependent and light-independent reactions of photosynthesis related?
The products of light-dependent reactions are used in light-independent reactions.
The pH of the inner thylakoid space has been measured, as have the pH of the stroma and of the cytosol of a particular plant cell. Which, if any, the relationship would you expect to find? a)The pH within the thylakoid is less than that of the stroma. b)The pH of the thylakoid space is higher than anywhere else in the cell. c)There is no consistent relationship. d)The pH of the stroma is lower than that of the other two measurements. e)The pH of the stroma is higher than that of the thylakoid space but lower than that of the cytosol.
a)The pH within the thylakoid is less than that of the stroma.
The accumulation of free oxygen in Earth's atmosphere began with the origin of ________.
cyanobacteria using photosystem II
In a plant cell, where are the ATP synthase complexes located? a)thylakoid membrane only b)plasma membrane only c)inner mitochondrial membrane only d)thylakoid membrane and inner mitochondrial membrane e)thylakoid membrane and plasma membrane
d) thylakoid membrane and inner mitochondrial membrane
The chemiosmotic process in chloroplasts involves the ________.
establishment of a proton gradient across the thylakoid membrane
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 ________. A)test for the liberation of O2 in the light B)determine if they have thylakoids in the chloroplasts C)do experiments to generate an action spectrum D)test for production of either sucrose or starch E)test for CO2 fixation in the dark
to test for liberation of O2 in the light.
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