Ch. 10 Photosynthesis Flashcards
What are autotrophs?
“Self-feeders” they sustain themselves without eating anything derived from other living beings
Plants 🌱
What are heterotrophs?
Unable to make their own food; live on compounds produced by other organisms “other feeder” eat living organism (plant or animal)
Is photosynthesis carried out by autotrophs or heterotrophs?
Autotrophs
What were the earliest organisms to carry out photosynthesis?
Cyanobacteria
What is the balanced equation for photosynthesis?
6 CO2 + 12 H2O -> C6H12O6 + 6 O2 + 6 H2O + Light energy
Where do the reactants of photosynthesis enter plants?
Stomata: small openings in their leaves
Xylem cells: transport water and minerals from roots to the rest of the plant
Where do the products of photosynthesis exit from plants?
Stomata: small regulated openings in their leaves
Phloem cells: transport sugars from leaves to the rest of the plant
How are water and minerals transported from roots to the rest of the plant?
Through Xylem cells
How is sugar transported from leaves to the rest of the plant?
Through Phloem cells
Where in the plant does photosynthesis occur?
In chloroplasts, most photosynthesis takes place in leaves
What is the relationship between the length of a wavelength and the energy it carries?
Longer wavelengths have lower energy
Shorter wavelength have higher energy
What are pigments?
Pigments are molecules which absorb certain wavelengths of visible light and reflect other wavelengths
What are the main pigments used in photosynthesis?
Chlorophyll A and Chlorophyll B
What does an absorption spectrum show?
Absorption of light by chloroplast pigments (Chlorophyll A, Chlorophyll B, and Carotenoids)
What does an action spectrum show?
Rate of photosynthesis
What type of relationship exists between the two spectra?
In graph on slide 12 the rate of photosynthesis and light absorbed are low in this same area where green is and high between purple and blue
What is the relationship between the wavelength(s) a pigment absorbs, and the color(s) the pigment reflects?
Leaves appear green because chlorophyll reflects and transmits (does not absorb) green light.
What happens when a photon of light strikes a photosynthetic pigment?
An electron within the molecule becomes excited (jumps up)
What happens to the excited electron?
The excited electron may be passed on to another molecule or return to ground state
What is the relationship between the light reactions and the Calvin Cycle in photosynthesis?
The light reactions provide ATP and NADH to the Calvin Cycle
Understand that H atoms split to form electrons (e-) and protons (H+).
H gain/loss represents electron gain/loss in these oxidation-reduction reactions.
During photosynthesis, water is oxidized and carbon dioxide is reduced. This happens through two major oxidation/reduction reactions which are…
During light reactions and The Calvin Cycle
During the light reactions…
H2O is oxidized (O2 remains), and NADP+ is reduced (this forms NADPH)
During the Calvin Cycle…
NADPH is oxidized (NADP+remain), and CO2 is reduced (this forms CH2O, a sugar) Some oxygen from the CO2 is reduced to create new H2O molecules
What is a photosystem?
A light-capturing unit located in the thylakoid membrane of the chloroplast consisting of a reaction-center complex surrounded by numerous light-harvesting complexes. There are two types of photosystems, I and II; they absorb light best at different wavelengths.
What occurs in a photosystem?
A proton strikes a pigment molecule in a light-harvesting complex, the energy is passed from molecule to molecule until it reaches the reaction-center complex
Where do the light reactions take place? Be specific.
Takes place in the Thylakoid inside the Chloroplast
Photosystem II:
What molecules DIRECTLY supply the electrons which go through the electron transport chains? Be specific.
Water (H2O), electrons comes from the splitting of water molecule
Photosystem II:
What replenishes the electron lost by the chlorophyll molecule in Photosystem II? Be specific
Electrons are replenished by H atoms from splitting of water molecules
Photosystem II:
What happens to the energy generated when the electrons go through the electron transport chain?
Electrons are passed by the protein in the membrane and they give off energy (ATP)
Photosystem II
From where are the protons pumped? Where are they pumped to? And, where do they diffuse back to?
Protons come from the H atom (hydrogen) in the splitting of water. They are pumped into the Thylakoid Space (inner thylakoid). They are diffused to the ATP synthase and back into the Calvin Cycle
Photosystem II:
What protein molecule (enzyme) do the protons diffuse through which releases the energy to rebuild ATP?
ATP synthase
Photosystem I:
What replenishes the electron lost by the chlorophyll molecule in Photosystem I? Be specific.
Electrons are replenished by electrons in the electron transport chain.
Where does the Calvin Cycle take place? Be specific.
ATP and NADPH are produced in the stroma, where the Calvin cycle takes place
What does “carbon fixation” mean?
The process by which photosynthetic organisms convert inorganic carbon in the atmosphere into organic carbon compounds used by living organisms
At the beginning of the Calvin Cycle, what molecule does CO2 join?
Ribulose biphosphate (RuBP)
What enzyme catalyzes this reaction?
RuBisCO
What two 3-carbon molecules are produced?
3-Phosphoglycerate
What molecule is oxidized in order for reduction to take place? What is produced as the result of reduction?
NADPH is oxidized and an organic compound is reduced to form Glyceraldehyde-3-phosphate (G3P), a sugar
What sugar (carbohydrate) is produced by the cycle? How many carbons does this sugar have?
G3P, contains 3 carbon
What molecule is regenerated at the end of the cycle?
RuBP
What are the three phases of the Calvin Cycle?
- Carbon fixation (inorganic carbon is converted to organic carbon)
- Reduction (NADPH oxidized + organic compound reduced = G3P
- Regeneration of RuBP, the CO2 acceptor
