AP Biology Test 11/23
How many PGAL molecules will it take to make one molecule of glucose?
2 (*my explanation* since each PGAL molecule contains 3 carbon atoms)
How many turns of the Calvin cycle will it take to make one molecule of glucose?
2 turns
Calculate the total number of ATP and NADPH molecules used in the production of one molecule of glucose
2 turns ( 9 ATP + 6 NADPH) = 18 ATP and 12 NADPH
What is photosynthesis?
A process by which organisms convert light energy into chemical energy
When ATP loses a phosphate group _____ is released for cells and a molecule of ________ forms?
energy, ADP
What helps weaken these high-energy bonds so energy can be released and then later help reform them?
enzymes
How many high-energy bonds does ATP contain?
1
How many total carbon atoms remain in the Calvin cycle at this point?
15 (5 PGAL)
Calculate the total number of carbon atoms represented in all of the RuBP molecules used in one turn of the Calvin cycle.
15 (5 carbon atoms x 3 RuBP)
Calculate the total number of carbon atoms represented in all of the PGA molecules used in one turn of the Calvin cycle.
18 (3 carbon atoms x 6 PGA)
Write a chemical reaction that summarizes all of the chemical reactions in the light-dependent reactions of photosynthesis starting with two water molecules.
2H2O + 2NADP+ + 3ADP +3Pi --> O2 + 2NADPH + 3ATP
How many CO2 molecules are used in one turn of the Calvin cycle?
3
How many RuBP molecules are used in one turn of the Calvin Cycle?
3
How many carbon atoms are in each PGA molecule?
3
How many total carbon atoms leave the Calvin cycle before the regeneration phase?
3
Identify the types and numbers of molecules that provide the free energy necessary for the regeneration of these molecules.
3 ATP
What molecule(s) are "regenerated" in this phase of the cycle?
3 molecules of RuPB
How many PGAL molecules continue on to the regeneration phase of the Calvin Cycle?
5
How many carbon atoms are in each RuBP molecule?
5
How many PGA molecules are made in one turn of the Calvin Cycle?
6
How many water molecules are produced in the reduction phase of the Calvin cycle?
6
Identify the types and numbers of molecules that provide the free energy necessary for the reduction of the PGA molecules.
6ATP and 6 NADPH
What is the summary equation for photosyntheis?
6CO2 + 6H2O ---> C6H12O6 + 6O2
Calculate the total number of oxygen, NADPH, and ATP molecules that are produced when 12 water molecules complete the light dependent reactions.
6O2 + 12NADPH + 18ATP
What occurs in the Calvin cycle (light independent reaction)?
A cycle with 3 main steps to generate glucose. Carbon fixation, reduction, regeneration
What does the electron transport chain do?
A sequence of electron carrier molecules (membrane proteins) they shuttle electrons during redox reactions to make ATP
Name the embedded protein complex found in the thylakoid membrane that converts ADP to ATP using free energy from a flow of hydrogen ions.
ATP synthase
Why is ATP made in the light reaction? where is it used?
ATP synthase performs phosphorylation to make ATP which will provide the chemical energy to fuel the Calvin cycle.
How does chemiosmosis generate ATP in the light reactions?
As a H+ gradient develops in the inner thylakoid space (lumen), H+ pass through ATP synthase which phosphorylates ADP into ATP.
What is the energy source for the light independent reactions?
ATP, NADPH
What does ATP stand for?
Adenosine triphosphate (ATP)
Which color of light is most effective for photosynthesis?
Blue + Red
Compare chemiosmosis in cellular respiration vs. photosynthesis
Both have ETC where energy is released as electrons are passed from one carrier protein to the next causing a build up H+ to allow ATP synthase to catalyze ADP into ATP.
How does the leaf anatomy of a plant relate to photosynthesis?
Broad leaves which contain the pigment chlorophyll (light absorbing molecules) and stomates - allow for gas exchange
Describe the adaptions of C4 and CAM plants that enable them to survive in hot, arid climates.
C4 plants - Structural adaptation, Bundle sheath cells + Mesophyll cells CAM plants- Temporal adaptation, closes stomates during day / open at night
Consider the term "carbon fixation." Think individually for a moment what this term might mean, then share ideas among the group. Record the group's consensus definition for carbon fixation here.
CO2 is removed from the atmosphere and is incorporated into an organic molecule
Where does carbon fixation occur?
Calvin Cycle
Where is glucose made?
Calvin Cycle
What is another name for the light-independent reactions?
Calvin cycle
Where do the ATP and NADPH produced during the light-dependent reactions go when the process is complete?
Calvin cycle
Where does the NADPH go that is made in this process?
Calvin cycle
The structures inside the organelle in Model 1 are called thylakoids. What compound necessary for photosynthesis is contained in the thylakoids?
Chlorophyll
What compound is best able to absorb the light energy from the Sun and convert it into chemical energy?
Chlorophyll
Which pigments are most effective for photosynthesis? Least Effective?
Chlorophyll (most effective) Accessory pigments (carotenoids) carotenes + xanthophylls (least effective)
Bacteria do not have chloroplast, yet some can still do photosynthesis. How is this possible?
Cyanobacteria, they contain light absorbing pigments
What is the source of replacement electrons for those released from photosystem I? (In light dependent reactions)
Electrons that have gone through ETC
Is photosynthesis an endergonic or exergonic reaction?
Endergonic (*my explanation* energy is taken in from the sun)
What molecule does the PGA molecule turn into during the Reduction phase of the Calvin cycle?
G3P (PGAL)
What is G3P? How is it related to glucose?
G3P is a product of the Calvin cycle (a three carbon sugar) The G3P that doesn't continue in cycle will be used by the cell to make glucose.
What is the function of accessory pigments such as carotenoids?
Help plants absorb other wavelength of light
Describe specifically how the structures of the G3P and PGA are different?
PGA (intermediate) (*my explanation* G3P has one less oxygen atom than PGA)
Where are electrons released from water molecules? (In light dependent reactions)
In photosystem II, in the inner thylakoid
Explain what happened to the carbon atoms from the carbon dioxide molecules that entered the Calvin cycle.
Incorporated into PGA which changes into G3P
Explain in detail, using complete sentences, how the two reactions (light-dependent and light-independent) depend on each other.
Light-dependent: 18 ATP and 12 NADPH (made here) are needed to fuel light-independent reactions. Light-independent: 18 ADP and 12 NADP+ (made here) are given back to light dependent reactions. (*** my answer***)
In photosynthesis, 12 water molecules are shown as reactants, but 6 water molecules are shown as products. Are any of the 12 water molecules products of the light-dependent reactions?
No
Is carbon dioxide involved in the light-dependent reaction?
No
Is the total number of carbon atoms present in the Calvin cycle changed during the reduction phase?
No (*my explanation* PGA and PGAL (G3P) have the same number of carbon atoms. 6 PGAL molecules have 18 carbon atoms, 6 PGA molecules will have 18 carbon atoms)
Explain where the hydrogen and oxygen atoms in the water molecules in the reduction phase of the Calvin cycle originated
O2 was removed from PGA, H comes from NADPH
What things are made or given off in this process?
Oxygen (into the atmosphere), ATP and NADPH (into the Calvin Cycle)
What happens to the water molecule after it is split? Oxygen- Hydrogen- Electrons-
Oxygen- released through the stomata into the atmosphere Hydrogen- builds up in the thylakoid Electrons- replace the excited electron that left photosystem II (p680)
What TYPES of molecules are there? (In the light dependent ETC diagram (not including chemiosmosis)
Phospholipids- Transmembrane proteins- photosystem II + I + cytochrome complex Electron transport carriers- pq, cytochrome complex, pe, ferredoxin
What is the splitting of water by light energy called?
Photolysis
What do photons do?
Photons deliver energy to the electrons to energize electrons from their ground state to an excited state.
Name the embedded protein complex found in the thylakoid membrane that uses excited electrons to reduce NADP+ into NADPH.
Photosystem I
Where are electrons released from chlorophyll by a photon of light coming in from the Sun? (In light-dependent reactions)
Photosystem I and II
Name the embedded protein complex found in the thylakoid membrane that provides excited electrons to the electron transport chain
Photosystem II
Which part of the spectrum drives photosynthesis?
Red +Violet
Which main enzyme is involved in the Calvin Cycle? How does it relate to photorespiration?
RuBisCO - it initiates carbon fixation in the Calvin cycle, it combines with O2 to initiate photorespiration
What occurs in the light dependent reaction?
Solar energy is converted into chemical energy in the form of ATP + NADPH
What is the source of replacement electrons from those released from photosystem II? (In light dependent reactions)
Splitting of water
How does CO2 get into and the O2 get out of the leaf?
Stoma
In what part of the chloroplast do the light-independent reactions occur?
Stroma
Where in the organelle are these molecules stored before they are used in photosynthesis? *carbon dioxide (CO2), water (H2O)
Stroma
How is the light independent reaction different from the light dependent reactions?
Stroma doesn't require light, requires CO2, ATP + NADPH to make C6H12O6 (light independent) Thylakoid membrane, requires light + H2O to make O2
What is the energy source for photosynthesis?
Sunlight
What is the energy source for the light dependent reactions?
Sunlight
Compare the absorption spectrum to the action spectrum
The absorption spectrum depicts different wavelengths and the color they appear The action spectrum depicts different wavelengths and the rate of photosynthesis
Where are these high energy bonds found in ATP?
The last two phosphate groups
What 3 things make up up an ATP molecule?
adenosine, ribose, 3 phosphates
What is the purpose of the Calvin cycle? Where does it occur? What are the main products?
The purpose: A cycle to generate glucose Where it occurs: stroma Main products: glucose (C6H12O6), ADP, NADP+
What is the purpose of the Light Reactions? Where does it occur? What are the main products?
The purpose: convert solar energy into chemical energy Where it occurs: thylakoid membrane Main products: O2, ATP, NADPH
What does p680 mean?
The reaction center of photosystem II is known as p680 because this pigment is best at absorbing light having a wavelength of 680 nm. It is also the most reactive.
In what part of the chloroplast do the Light-Dependent reactions occur?
Thylakoid
Where do the ADP and NADP+ go after they are used in the Calvin cycle?
Thylakoid (light dependent reactions)
In the light dependent ETC diagram (not including chemiosmosis) What phospholipid bilayer are these molecules part of?
Thylakoid membrane
Explain the role of NADP+ in photosynthesis
To become reduced (pick up electrons) and transport them to ETC
why does the water molecule split?
To replace the electron that left the reaction center of photosystem II
What is the function of ATP?
To store and transport chemical energy within cells
What happens to the PGAL molecule that does not continue on in the Calvin cycle?
Used to make Glucose or other organic molecule
The light-dependent reactions include an electron transport chain system that works in a very similar fashion to the electron transport chain in respiration. Briefly describe how this system works and what job it performs in the light-dependent reactions.
Uses energy from excited electron to move H+ against the concentration gradient
What substances are the reactants in photosynthesis?
carbon dioxide (CO2), water (H2O)
What are the 3 phases of the Calvin Cycle?
carbon fixation, reduction, regeneration
What pigment absorbs light in a chloroplast?
chlorophyll
What organelle is the site of photosynthesis?
chloroplast
What organelle would you expect to find in great abundance in a leaf cell (Mesophyll)?
chloroplasts
Which structure is a waxy layer that prevents the loss of water?
cuticle
What substances are produced during photosynthesis?
glucose (C6H12O6), oxygen (O2)
A stack of thylakoid is called a ________
granum
When the electrons are released from water molecules, what other products are formed? (In light dependent reactions)
hydrogen ions (H+) and oxygen (O2)
Where is NADPH made?
photosystem 1
Where does photolysis occur?
photosystem II
Where is ATP made?
photosystem II
Where is oxygen released?
photosystem II
What are the molecules that absorb light?
pigments
Are chloroplasts more likely to be found in animal cells or plant cells?
plant cells
What organisms do photosynthesis?
plants, algae, and some bacteria, prosists, some prokaryotes
What is the fluid in a chloroplast called?
stroma
Within the chloroplast, where does the Calvin cycle (light-independent reaction) take place?
stroma
What provides the energy used by all life on Earth?
the Sun
What is photolysis?
the splitting of molecules by light
Where is chlorophyll located within the chloroplast?
thylakoid
Within the chloroplast, where does the light dependent reaction take place?
thylakoid membrane
What are the membrane dis-sacs called?
thylakoids
Why is it necessary to have 6 CO2 entering the chloroplast?
to make glucose (*my explanation* In order to balance the reaction, 6 carbons are needed to make glucose, therefore, 6CO2 are required)