Chapter 7 Photosynthesis
Compare the mechanisms that C3, C4, and CAM plants use to obtain and use carbon dioxide
-C3 (trees) and C4 plants (grasses) have their stomata open during the day and go through the calvin cycle -CAM plants (pineapple) have theirs open during nighttime.
Define autotrophs, heterotrophs, producers, and photoautotrophs
Autotrophs-make their own food through the process of photosynthesis, sustain themselves, do not consume organic molecules derived from other organisms, are called producers because they produce food for the biosphere. Heterotrophs-are consumers that feed on plants, animals and decompose organic material Producers-orgs that make organic food molecules from CO2 and H2O Photoautotrophs-are autotrophs that use the energy of light to produce organic molecules, most plants, algae and other protists, and some prokaryotes.
Compare photophosphorylation and oxidative phosphorylation
Both photophosphorylation and oxidative phosphorylation (oxphos) are processes cells use to make energy in the form of ATP. First the similarities: in both cases electrons are transferred through a series of membrane proteins. ... the protons flow back through a special enzyme (ATP-synthase) which makes ATP. Differences: when it occurs: oxphos occurs during cellular respiration ↔ photophosphorylation occurs during photosynthesis where it occurs: oxphos occurs inside mitochondria ↔ photophosphorylation occurs inside thylakoids (in chloroplasts) energy source: the energy source for oxphos is glucose ↔ the energy source for photophosphorylation sunlight. electron acceptor: in oxphos the final electron acceptor is molecular oxygen ↔ in photophosphorylation the final electron acceptor is NADP+
Describe the properties and functions of the different photosynthetic pigments
Chlorophyll a absorbs blue-violet and red light which chlorophyll b absorbs mainly blue and orange light. Purpose is to broaden the spectrum of light the photosystems can absorb as much as possible.
Compare the reactants and products of the light reactions and the Calvin cycle
Light reactions -reactants=H₂O and light -products=electrons (NADPH), ATP, and O₂ Calvin Cycle -reactants=CO₂, NADPH, and ATP -products=Sugar, ADP and a third phosphate group, and NADP
Describe the role of redox reactions in photosynthesis and cellular respiration
Photosynthesis: -6CO₂ is reduced to C₆H₁₂O₆ -6H₂O is oxidized to 6O₂ Cellular respiration: -C₆H₁₂O₆ is oxidized to 6CO₂ -6O₂ is reduces to 6H₂O 6CO2+ 6H20 -----------> C6H12O6 + 6O2 (photosynthesis) C6H12O6 + 6 O2 ----------> 6 CO2 + 6 H2O (cellular respiration)
Explain how photosystems capture solar energy
Pigments found in the stroma attract protons and absorb them. They pass the energy from molecule to molecule until it reaches the reaction center. The reaction center contains chlorophyll a moleculesand a molecule called the primary electron receptor, which is capable of accepting electrons and becoming reduced. The solar-powered transfer of an electron from the reaction center chlorophyll a to the primary electron acceptor is the first step of the light reactions.
Explain how plants produce oxygen
Plants produce oxygen by splitting water. This was discovered when H₂O with a heavy isotope of oxygen was tracked and found in oxygen and not other products.
Describe the structure of chloroplasts and their location in a leaf
Two outermost membranes surround interior stroma Inner thylakoid membrane system Light-dependent reactions occur at the thylakoid membrane system Light-independent reactions occur in the stroma scattered in cytoplasm. mainly found in the interior tissue of the leaf.
Explain how the electron transport chain and chemiosmosis generate ATP, NADPH, and oxygen in the light reactions
Water is split and provides O₂ as a product as well as an electron for the photosystem which is then excited. When an excited electron falls down the chain, it releases energy that aids in the synthesis of ATP by chemiosmosis (the active transfer of H⁺ through a permeable membrane). After photosystem II, the excited e⁻ from that process is passed through a short electron transport chain to NADP⁺ changing it to NADPH.
