Light reactions, cyclic and non-cyclic photophosphorylation, chemiosmosis
- The reaction centre in PS II has an absorption maxima at Answer: 2. 680 nm Key idea: The reaction centre of PS II is P680, with absorption maximum at 680 nm. The reaction centre of PS I is P700 (70... 1
- Which of the following combinations is required for chemiosmosis? Answer: 2. membrane, proton pump, proton gradient, ATP synthase Key idea: Chemiosmosis needs a membrane, a proton pump, a proton gradient an... 1
- Which one of the following is not true regarding the release of energy during ATP synthesis through chemiosmosis ? It involves : Answer: 3. Breakdown of electron gradient In chemiosmosis, a proton gradient (not an electron gradient) drives ATP synthesis. Protons move a... 1
- Which of the following statements is incorrect ? Answer: 4. Cyclic photophosphorylation involves both PS I and PS II. Find the incorrect statement. Cyclic photophosphorylation involves only... 1
- In light reaction, plastoquinone facilitates the transfer of electrons from : Answer: 1. PS-II to Cytb ₆ f complex In the Z-scheme, electrons from PS II go to plastoquinone (PQ), then to the Cyt b6f complex, then plast... 1
- Oxygen is *not* produced during photosynthesis by Answer: 1. Green sulphur bacteria Green sulphur bacteria perform anoxygenic photosynthesis using H ₂ S, so they release no oxygen. Cycas (pl... 1
- Which of the following is *not* a product of light reaction of photosynthesis ? Answer: 3. NADH The light reaction makes ATP and NADPH and releases O ₂ from photolysis of water. NADH is a respiration carrier, not a produ... 1
- Emerson's enhancement effect and Red drop have been instrumental in the discovery of : Answer: 2. Two photosystems operating simultaneously Key idea: Red drop and Emerson's enhancement effect showed that two light reactions wor... 1
- In a chloroplast the highest number of protons are found in : Answer: 2. Lumen of thylakoids Key idea: During the light reactions, protons build up inside the thylakoid lumen. They come from water split... 1