Photosynthesis (Ch. 10) Flashcards
Photosynthesis converts ______________ to _____________.
Light energy……..sugar and other organic molecules
Distinguish between autotrophs and heterotrophs.
Autotrophs sustain themselves without eating anything from other human beings. They use CO2 and other inorganic raw materials from the environment. Producers.
Heterotrophs get organic material from compounds produced by other organisms. Consumers.
Where are chloroplasts mostly found?
Mostly found in the mesophyll, the tissue in the interior of the leaf.
Where does CO2 enter the leaf and oxygen exit?
Stomata – microscoping pores
What covers the chloroplasts?
An envelope of two membranes surrounding a dense fluid called the stroma (the stroma is the dense liquid)
What is suspended inside the stroma?
A third membrane system – sacs called thykaloids, which keeps the stroma away from thykaloid space.
What is chlorophyll?
The green pigment that gives leaves their color and lives in the thykaloid membranes of the chloroplast.
What is the overall photosynthetic equation?
6 CO2 + 12 H2O + light energy –> C6H12O6 + 6 O2 + 6 H2O
What is the relationship between the chemical equations of cell respiration and photosynthesis?
Cell respiration and photosynthesis are essentially opposites.
What happens to the molecules in the photosynthesis process?
C from CO2 goes to sugar
O from CO2 goes to sugar and water
H from water goes to sugar and water
O from water goes to oxygen
What are the two parts of the photosynthesis process?
- light reactions (“photo”)
- Calvin cycle (“synthesis”)
What do the light reactions of photosynthesis do? How? (overview)
Convert solar energy to chemical energy.
Water is split, providing electrons and protons and giving off O2 as a by-product.
Chlorophylls absorb light and drive the transfer of electrons from that hydrogen to an acceptor NADP+ (i.e. we reduce NADP+ to NADPH)
the light reactions generate ATP, using chemiosmosis to photophosphorylate ADP.
What is carbon fixation?
When the cell initially incorporates carbon from air CO2 into organic compounds.
What happens after CO2 carbon is fixed?
The Calvin cycle reduces the fixed carbon to carbohydrate by the addition of electrons. It uses electrons from NADPH, which got those electrons from the light reactions.
What wavelengths of light are visible?
380nm to 750nm
What are the different bands of light?
(short wavelength)
- Gamma rays
- X-rays
- UV
- Visible
- Infared
- Microwaves
- Radio waves
(long wavelength)
How are chlorophylls organized?
Chlorophylls are organized with other molecules into complexes called photosystems.
What is a photosystem?
A photosystem is composed of a reaction-center complex surrounded by several light-harvesting complex.
Describe a reaction-center complex and a light-harvesting complex
A reaction-center complex is an organized association of proteins holding a special pair of chlorophyll a molecules
A light-harvesting complex is various pigment molecules (chlorophyll a and b, carotenoid) bound to proteins
Describe how light leads to the primary electron acceptor to capture an electron.
Light excites chlorophyll in the light-harvesting complex of the photosystem; redox reactions carry the electrons through chlorophylls until they arrive at the pair of special chlorophylls in the reaction-center complex. Then the primary electron acceptor captures those electrons.
The Calvin cycle takes ______ and produces ______.
The Calvin cycle takes CO2 and produces sugar.
What sugar molecule does the Calvin cycle produce?
Glyceraldehyde 3-phosphate
What are the three steps of the Calvin cycle?
- Carbon fixation
- Reduction
- Regeneration of RuBP
Describe Carbon fixation
- Attach CO2 to a five-carbon sugar, RuBP
