Photosynthesis Flashcards
Produce their own food by using photosynthesis (or chemosynthesis) to produce organic molecules from inorganic inputs
Autotrophs
Must consume other organisms to get their food. Other organisms are the source of organic molecules.
Heterotrophs
Does photosynthesis make food for animals?
Yes
Does photosynthesis return CO2 to the atmosphere?
No - it returns oxygen
In plants, photosynthesis is carried out in ________ organelle
Chloroplast
A chloroplast contains flattened, membranous sacs called __________ that are stacked to form the ________. The fluid surrounding this is called the ________.
Thylakoids
Grana
Stroma
The green pigment __________ is found within the membrane of the _________, and it is here that _______ energy is captured.
Chlorophyll
Thylakoids
Light
What is the photosynthesis equation?
(6)CO2 + (6)H2O → C6 H12 O6 + (6)O2
What is the function of stomata?
Small openings/pores on the underside of leaves that allow for gas exchange to occur (take in CO2 and release O2).
What type of energy do plants use to convert water and carbon dioxide into glucose and oxygen?
Light Energy (solar)
What color is best absorbed by chlorophyll?
Violet, blue, and red
Why do leaves appear green?
The green light is reflected by the chlorophyll
Describe the function of a pigment.
Pigments are substances (proteins) that absorb light. They give color to objects based on which wavelengths they absorb v. reflect.
What is the primary pigment used in photosynthesis?
Chlorophyll (A and B)
Oxidized
Loses electrons
Reduced
Gain electrons
Where in the chloroplast is that pigment found?
Inside the thylakoid membrane
Where does the LDR take place?
Thylakoid membrane
Where does the Calvin Cycle take place?
Stroma
Energy-capturing reaction is (LR or CC)
LR
Carbon dioxide becomes a carbohydrate
(LR or CC)
CC
NADP+ takes up energized electrons
(LR or CC)
LR
NADPH and ATP are made (LR or CC)
LR
NADPH and ATP are used
(LR or CC)
CC
Molecule absorbing solar energy…
Chlorophyll
Each of the following is a product of photosynthesis EXCEPT
Carbon dioxide
Food energy
Oxygen
Carbohydrate
Carbon dioxide
Photosynthesis occurs best at wavelengths that are
Blue/Purple
The two major sets of reactions involved in photosynthesis are…
The light reaction and the Calvin cycle reaction
What are the inputs to the light reactions?
Water and light energy
Also NADP+ and ADP + P returning from the Calvin cycle
What are the outputs of the light reactions?
Oxygen, ATP, & NADPH
O2 is released and ATP & NADPH will be used in the Calvin cycle
The concentration of H+ ions in the thylakoid space is higher or lower than the lower H+ concentration in the stroma
Higher
What is the role of ATP in photosynthesis?
ATP provides the energy needed to power the Calvin cycle reactions
How is ATP produced in light reactions?
The electron transport chain pumps H+ from the stroma to the thylakoid space
H+ diffuses through ATP synthase
The diffusion of these H+ ions gives energy to ATP synthase to produce ATP from ADP + P
What is the role of NADPH in photosynthesis?
NADPH carries high-energy electrons and hydrogen atoms to the Calvin cycle reactions to aid in the production of organic molecules
How is NADPH produced in light reactions?
Energized electrons from photosystem 1 go to NADP Reductase proteins in the thylakoid membrane. NADP Reductase uses these electrons as well as the H+ in the stroma to reduce NADP+ into NADPH.
What is the role of the electron transport chain in light reactions?
The electron transport chain uses the electron energy to pump H+ ions from the stroma into the thylakoid space/lumen which is needed for ATP production.
Why is water an essential input to photosynthesis?
Water will replace the lost electrons in chlorophyll.
Site of light reactions…
Thylakoid membrane
What are the three phases/stages of the Calvin Cycle reactions?
Carbon fixation, Reduction, and RuBP Regeneration
What are the inputs to the Calvin Cycle reactions?
Carbon dioxide and ATP & NADPH from the light reactions
What are the outputs of the Calvin Cycle reactions?
Two G3P molecules
ADP + P and NADP+ will be returned to the light reactions to be charged up again
What atmospheric molecule is required for the Calvin Cycle reactions to make G3P as a product?
Carbon dioxide (need carbon to form organic molecules)
The Calvin Cycle produces two G3P molecules. What can these G3P molecules be used to build for the plant?
Simple sugar (ex: glucose), fatty acids, amino acids, polysaccharides (by combining simple sugars built-up)
What is the role of RuBP in the Calvin Cycle reactions?
What is the role of RuBP in the Calvin Cycle reactions?
This 6-carbon chain is cut in half for the reduction stage, eventually leading to G3P production.
RuBP must be regenerated for the cycle to continue as new CO2 is brought in.
Why are only 2 of the 12 G3P produced in the Calvin Cycle released? What happens to the remaining 10 G3P?
These 10 G3P are used in the Regeneration stage to regenerate more 5-carbon RuBP molecules to go on to fix more carbon dioxide and allow Calvin cycles to continue.
What is the function of the stomata on a leaf?
They are small pores/openings on the underside of the leaf that allows for gas exchange for the plant. They can also open or close to regulate and conserve water.
What type of photosynthesis adaptation (C4 v. CAM) will you likely see in plants in the desert?
CAM photosynthesis
What are environmental factors that can affect the rate of photosynthesis? (6)
Temperature
Amount/intensity of light
Wavelength or color of light
Time exposed to light
Amount of reactants available (carbon dioxide and/or water)
Leaves dropping
Carbon dioxide fixation occurs when CO2 combines with
RuBP
Photosystem 2 gets replacement electrons from
Water
Plants in hot, dry areas, such as grasses and fixation stage happen in a different cell from the rest of the Calvin cycle is…..
C4
Plants in temperate climates with high precipitation & carbon dioxide is fixed into a 3-carbon molecule in the fixation stage
C3
Stomata are closed during the day to conserve water & CO2 fixation at night and 4-carbon molecules are stored until daylight
CAM