October 07, 2014
1.
ATP and NADP+ are products of the light reactions that are utilized in the Calvin cycle.
False
ATP and NADPH are the products of the light reaction. Light is absorbed by chlorophyll and drives the transfer of electrons from water to NADP+, forming NADPH.
October 07, 2014
2. The leaves of a particular plant appear to be reddish yellow, which means it absorbs mostly red and yellow wavelengths of visible light.
False
If it absorbed the light, you wouldn't be able to see those colors. That means the pigments in that plant reHlect red and yellow wavelengths of light. Carotenoids are accessory pigments in plants that reHlect red, yellow, and orange lights. October 07, 2014
3. In photosystem II, electrons derived from water Hill the electron vacancies.
True
The key to the light reactions is a Hlow of electrons through the photosystems in the thylakoid membrane. This is called noncyclic electron +low. Light that strikes PSII starts photolysis. This reaction splits water molecules into oxygen, electrons, and H+. New electrons from water replace the electrons released from the photosystems reaction center.
October 07, 2014
4. Chemiosmosis is involves the establishment of a proton gradient across the thylakoid membrane.
True
Chemiosmosis is the process in which chloroplasts transform light energy into chemical energy in ATP. An electron transport chain uses the Hlow of electrons to pump protons across the thylakoid membrane. A proton gradient is created within the thylakoid space that can be utilized by ATP synthase to phosphorylate ADP to ATP. October 07, 2014
October 07, 2014
5. The pH of the stroma is lower than the pH within the inner thylakoid space (lumen).
False
The pH of the stroma is higher than the pH of the lumen. The pH of the lumen becomes acidic (pH=4) while the stroma has a pH of about 8. By a combination of photolysis and electron transport, H+ is now more concentrated in the inner thylakoid compartment than in the stroma. This is what makes it more acidic. October 07, 2014
6. The light reactions supply the Calvin cycle with CO2 to produce sugars, and the Calvin cycle supplies the light reactions with sugars to produce ATP. False
The light reactions supply the Calvin cycle with ATP and NADPH to produce sugars. The CO2 from the air is incorporated into organic molecules in carbon Hixation. The Calvin cycle supplies the light reactions with NADP+ and ADP, to produce ATP. The sugar is a bi-­‐product of the reaction. October 07, 2014
7. In photosynthesis, the terminal electron acceptor is NADP+.
True
The primary electron acceptor of PS I passes the excited electrons along to another electron transport chain, which transmits them to NADP+, which is reduced to NADPH.
The high-­‐energy electrons of NADPH are now available for use in the Calvin cycle. October 07, 2014
8. Compared to C3 plants, C4 plants can continue to Hix CO2 even at relatively low CO2 concentrations and high oxygen concentrations.
True
C4 plants can close their stomata on hot, dry days but the CO2 level doesn't decline as much because the plants Hix carbon twice in photosynthesis. Lowers the photosynthetic efHiciency.