Chapter 8: Photosynthesis Questions from Notes Flashcards
What makes up ATP?
Adenine, a 5-carbon sugar called ribose, and three phosphate groups.
What is adenine?
Adenine is a nucleic acid base that is connected to ribose in ATP.
What will break the bonds of the phosphate groups to release the energy?
Water
______ has two phosphate groups instead of three, and contains some energy.
Adenosine diphosphate (ADP)
Why are phosphate groups added to AMP or ADP?
When a cell has energy available, it will store small amounts of it by recharging the compounds to a fully-charged ATP compound.
What does ATP power?
ATP powers movement, the synthesis of proteins, and responses to chemical signals at the cell surface.
Is ATP a good molecule for storing large amounts of energy over the long term.
No, ATP is not a good molecule for storing large amounts of energy over the long term.
How many seconds worth of ATP do cells produce?
2 seconds
How can cells regenerate ATP from ADP?
Cells can regenerate as needed by using the energy in foods like glucose.
How can heterotrophs obtain food?
Heterotrophs can obtain food by eating autotrophs, other heterotrophs, or decomposing other organisms.
During photosynthesis, autotrophs produce _____-_____ ________ that can be used for food.
high-energy carbohydrates
What is the chemical formula of glucose?
C6 H12 O6
What is an isomer?
An isomer has the same chemical formula, but a different atomic arrangement.
ex. glucose (C6 H12 O6) and fructose (C6 H12 O6).
During ___________ _________, water from the cytoplasm breaks and produces oxygen bonds that chemically bind amino acids together. It creates biochemical energy.
Dehydration synthesis
Sunlight is a mixture of different ___________, many of which are visible to our eyes and make up the visible spectrum.
wavelengths
What is the order of colors from least to greatest wavelength on the visible spectrum?
Violet (450) Blue (500) Green (550) Yellow (600) Orange (650) Red (700)
How many types of chlorophyll are found in plants?
Two: Chlorophyll A and Chlorophyll B
Which regions of the visible spectrum do plants’ chlorophyll absorb light best?
Blue-Violet and the red region
Why do plants’ leaves look green?
Leaves reflect green light. They DO NOT absorb it.
Which chlorophyll is the most efficient for collecting sun energy?
Chlorophyll B
Plants contain red and orange pigments such as ________ that absorb light in the other regions of the spectrum.
carotene
*helpers or “accessories”- they aren’t essential, but they do help
Why do the red and orange pigments in leaves appear?
When the temperatures drop, the chlorophyll molecules break down and aren’t as overwhelming compared to the red and orange.
In which organelle does photosynthesis take place?
chloroplasts
Thylakoids are saclike photosynthetic membranes in the chloroplast. When thylakoids are interconnected and arranged in stacks, they are called what?
grana
Where are pigments located in the chloroplast?
Pigments are located in the thylakoid membranes.
When chlorophyll absorbs light, a large fraction of the light energy is transferred where?
electrons
When electrons have light energy transferred to them, what are they called?
High-energy electrons
What are electron carriers used for?
Plants use electron carriers to transport high-energy electrons from chlorophyll to other molecules.
*high-energy electrons are highly reactive and require a special “carrier”
The common carrier molecule NADP+ accepts and holds what?
NADP+ accepts and holds two high-energy electrons, along with a hydrogen ion (H+)
Once NADP+ accepts two high-energy electrons and a hydrogen ion, what is it converted to?
NADPH
Where does NADPH carry the high-energy electrons?
NADPH carries the high-energy electrons to chemical reactions elsewhere in the cell.
Photosynthesis uses the energy from sunlight to do what?
Convert water and carbon dioxide into high-energy sugars and oxygen.
Starches are produced when _____.
plants use the sugars generated by photosynthesis to produce complex carbohydrates (starches - carrots, corn kernels)
Light-dependent reactions use energy form sunlights to produce _____ and ____.
ATP (which is not yet ready to be used) and NADPH
Where do the light-dependent reactions take place?
The reactions take place within the thylakoid membranes of the chloroplast.
What is required as a source of electrons and hydrogen ions during the light-dependent reactions?
Water
What is released as a byproduct during the light-dependent reactions?
Oxygen
How do plants complete the process of photosynthesis?
Plants absorb carbon dioxide form the atmosphere and then produce sugars and other carbohydrates.
How are ATP and NADP used during the light-independent reactions?
ATP and NADPH molecules are produced in the light-dependent reactions are used to produce high-energy sugars from carbon dioxide.
Where do light-independent reactions take place?
Outside the thylakoids in the stroma
Why do chloroplasts contain so many membranes?
Most pigments lose the light energy as heat, but chloroplasts do not.
_________ are a physical barrier to separate the chemical reactions taking place.
Membranes
What does the chloroplast membrane do so energy isn’t lost?
“insulate” it
ATP and NADPH are necessary for the production of _______.
glucose
Photosystems are clusters of ___________ and ________.
chlorophyll and proteins
After the photosystems absorb sunlight and generate high-energy electrons, they are then passed to what?
The high-energy electrons are passed to a series of electron carriers.
The chemical formula showing the water molecules int he thylakoids being split is what?
2 H20 to 4H+ + O2
Where does the thylakoid membrane get new electrons for the chlorophyll to replace the 4 high-energy electrons?
Water molecules split to provide for the chlorophyll.
What is the byproduct of the light-dependent reactions?
Oxygen
Where does the electron transport chain get the energy used to pump the positive hydrogen ions from the stroma into the thylakoid space?
The high-energy electrons give their energy to the proteins in the chain.
Do the high-energy electrons contain as much energy as they move through the transport chain?
No. The high-energy electrons gradually lose energy.
How do the electrons become reenergized during photosystem I?
The pigments in photosystem I use light energy to reenergize the electrons
Do the reenergized electrons become as “hyped-up” as they were before the chain?
No, but they come close.
Why does the stroma become negatively charged relative to the space within the thylakoid as the hydrogen ions move?
As water molecules are split, hydrogen ions accumulate within the thylakoid. The buildup of the positive Hydrogen ions makes the stroma negatively charged.
What is the protein that spans the thylakoid membrane and allows positive hydrogen ions to pass through it?
ATP synthase
ATP synthase starts reactions and is, therefore, an ______.
enzyme
The difference in both charge and H+ ion concentration across the membrane is called what?
gradient
What powers the H+ ions to pass through the ATP synthase and forces it to rotate?
the gradient
True or false: ATP could not be made if ATP synthase didn’t rotate.
True
The movement of protons through the ATP synthase is called ____________.
chemiosmosis
The light-independent reactions are also called the ____ _______ and the _____ cycle.
“dark reactions” and the Calvin cycle
Plants us the energy that ATP and NADPH contain to build what to be stored for a long time?
sugars and carbohydrate compounds
The CO2 molecules combine with Carbon5 compounds to produce what to continue the cycle?
Carbon3 compounds
- CO2 + C5
Are the Carbon3 compounds stable?
Yes. They are stable.
Fill in the blanks
For every _ carbon dioxide molecules that enter the cycle, a total of __ 3-carbon compounds are produced.
__ (CO2) to __ C3
6 (CO2) to 12 C3
_ of the __ 3-carbon molecules are removed from the cycle to use as the building blocks for the plant to make sugars, lipids, and other compounds.
2 of the 12 3-carbon molecules are removed from the cycle to use as the building blocks for the plant to make sugars, lipids, and other compounds.
The remaining __ 3-carbon molecules are converted back into _ 5-carbon molecules to begin the next cycle.
The remaining 10 3-carbon molecules are converted back into 6 5-carbon molecules to begin the next cycle.
What does the Calvin cycle do?
The Calvin Cycle uses six molecules of carbon dioxide to produce a single 6-carbon sugar molecule.
6 CO2 to become C-C-C-C-C-C (C6 sugar molecule)
The light-dependent reactions ___ the energy of sunlight in chemical form.
trap
The light-independent reactions use that energy to do what?
The light-independent reactions use that energy to produce stable, high-energy sugars from carbon dioxide and water.
Are photosystem 1 and 2 always operating at the same time?
Yes
Where is NADPH produced?
In the stroma
When carbon dioxide enters the cell into the stroma, what does it combine with?
Hint: It’s the 5-carbon compound that’s an enzyme.
Rubisco
Why do the 6 molecules of carbon6 change to 12 molecules of a carbon3 compound?
Th 6 C6 compounds are UNSTABLE. The 12 C3 compounds are STABLE.
What is the first stable 3 carbon compound that is made from the 6 C6 called?
PGA
When the ATP and NADPH carry to the 12 molecules of the 3 Carbon compound, they are zapped to a higher energy level and become G3P. What two events happen?
1) 2 molecules of PGAL (6 C) become 1 molecule of glucose
2) 10 molecules of PGAL (30 C) are separated
What are the 10 PGAL used for?
They become 6 Carbon5 compounds of rubisco.
Why is the PGAL transfer to rubisco essential for the Celvin cycle to continue?
To continue the cycle, rubisco is needed in one of the first steps (when it combines with the CO2 from the air). If the rubisco was not present, then the cycle would not continue.
