# Photosynthesis in Higher Plants, Class 11 Biology | SwaVid Photosynthesis in Higher Plants, NCERT Class 11 Biology: notes with key ideas, key terms, common mistakes and 3 quick checks with worked answers. Canonical: https://www.swavid.com/cbse/class-11/biology/chapter/photosynthesis-in-higher-plants Source: https://www.swavid.com/cbse/class-11/biology/chapter/photosynthesis-in-higher-plants # Photosynthesis in Higher Plants ## Key terms ## Key ideas ## Common mistakes ## Quick checks ## Keep going ## Questions parents ask ## Class 11 Biology on SwaVid ### Early experiments in photosynthesis ### Chloroplasts and photosynthetic pigments ### Light reaction and electron transport ### Chemiosmotic hypothesis ### Calvin cycle or C3 pathway ### C4 pathway ### Photorespiration and external factors ### Next chapter ### Related chapter ### Related chapter ### All chapters SwaVid › CBSE › Class 11 › Biology › Photosynthesis in Higher Plants Notes written by SwaVid from the NCERT textbook. Class 11 Biology, Chapter 11. Key ideas, formulas and common mistakes. CBSE prints 12 marks for Unit IV, not for this chapter alone. Short answer. This chapter explains the process of photosynthesis in green plants, covering light absorption, electron transport, and carbon fixation. It demonstrates how solar energy is converted into chemical energy through the coordinated photochemical and biosynthetic pathways inside chloroplasts. Source: NCERT Biology (Reprint 2026-27) , Chapter 11, Photosynthesis in Higher Plants Joseph Priestley showed that plants restore air damaged by breathing animals. Jan Ingenhousz proved that sunlight is essential for this purification, and Julius von Sachs found that green plant parts make glucose stored as starch. T.W. Engelmann plotted the first action spectrum using green alga Cladophora, and Cornelius van Niel showed that oxygen comes from water rather than carbon dioxide. Photosynthesis occurs in chloroplasts, where the membrane system traps light to form ATP and NADPH, and the stroma synthesises sugar via enzymatic reactions. Leaf pigments separated by paper chromatography are chlorophyll a (bright or blue-green), chlorophyll b (yellow-green), xanthophylls (yellow), and carotenoids (yellow to yellow-orange). Chlorophyll a is the primary pigment responsible for trapping light. Photosystem II absorbs light at 680 nm, causing electrons to jump and pass through an electron transport chain to Photosystem I, which absorbs at 700 nm. This non-cyclic movement of electrons from PS II to NADP+ produces ATP and NADPH, with water splitting occurring at PS II. When only PS I is functional in stroma lamellae, cyclic photophosphorylation yields only ATP. ATP synthesis in chloroplasts is driven by a proton gradient across the thylakoid membrane. Protons accumulate inside the thylakoid lumen due to water splitting, plastoquinone transport, and NADP+ reduction on the stroma side. Movement of protons across the membrane through the F0 channel of ATP synthase into the stroma activates F1 to produce ATP. The biosynthetic phase uses ATP and NADPH to fix carbon dioxide into sugars in the stroma. The cycle has three stages: carboxylation of RuBP using RuBisCO to form 3-PGA, reduction of 3-PGA to triose phosphate using ATP and NADPH, and regeneration of RuBP. To produce one molecule of glucose, the Calvin cycle must turn 6 times. Plants adapted to dry tropical regions show Kranz anatomy with bundle sheath cells around vascular bundles. Primary CO2 fixation occurs in mesophyll cells via PEP carboxylase to form oxaloacetic acid, which is converted to malic acid. In bundle sheath cells, malic acid releases CO2 for RuBisCO in the Calvin cycle, preventing photorespiration. When RuBisCO binds oxygen instead of carbon dioxide, RuBP forms one molecule of PGA and one of phosphoglycolate in a wasteful process called photorespiration. Blackman's law of limiting factors states that if a chemical process is affected by more than one factor, its rate is determined by the factor nearest to its minimal value. Key factors affecting photosynthesis are light, carbon dioxide concentration, temperature, and water. Try each question first. Then tap it to see the answer. Fixation of 1 CO₂ requires 3 ATP and 2 NADPH in one cycle. A molecule of glucose has 6 carbon atoms, requiring 6 turns of the Calvin cycle. Total ATP = 6 × 3 = 18 ATP; Total NADPH = 6 × 2 = 12 NADPH. 6 turns, 18 ATP, and 12 NADPH Stroma lamellae membranes lack both Photosystem II and the NADP reductase enzyme. Because PS II is absent, electrons cannot flow from water to PS I. Without NADP reductase, electrons loop back to PS I, forming only ATP. Due to the absence of Photosystem II and NADP reductase in stroma lamellae The C3 Calvin cycle in bundle sheath cells uses 3 ATP per CO₂ fixed (18 ATP for 6 CO₂). The C4 pathway uses an additional 2 ATP per CO₂ fixed in mesophyll cells to regenerate PEP (12 ATP for 6 CO₂). Total ATP consumed = 18 + 12 = 30 ATP. 30 ATP Respiration in Plants . Cell: The Unit of Life . Plant Growth and Development . The 19 chapters of Class 11 Biology . CBSE does not give marks to one chapter. It prints 12 marks for Unit IV, Plant Physiology, which includes Photosynthesis in Higher Plants. No. They are written by SwaVid from the NCERT textbook. The CBSE curriculum is the reference for what is assessed. Respiration in Plants. SwaVid is an AI tutor for Indian students in Classes 6 to 12. It finds the earlier ideas a child missed, then teaches today’s chapter. Start free to see how it works. - Ch 11 NCERT book - 12 marks, Unit IV - 3 quick checks - Believing that the oxygen released during photosynthesis comes from carbon dioxide . Remember that Cornelius van Niel and water splitting experiments proved that released oxygen comes entirely from the photolysis of water in PS II. - Thinking that the dark reaction occurs only at night . Treat the dark reaction as the biosynthetic phase; it does not require darkness, but depends directly on the products of the light reaction (ATP and NADPH). - Assuming RuBisCO is absent in C4 plants . Recognise that C4 plants have both PEPcase and RuBisCO; PEPcase is in the mesophyll cells, while RuBisCO operates in the bundle sheath cells. - Mixing up the site of proton accumulation in mitochondria and chloroplasts . Protons accumulate in the intermembrane space in mitochondria during respiration, but in the thylakoid lumen inside chloroplasts during photosynthesis. ## Key Links - [CBSE](https://www.swavid.com/cbse) - [Class 11](https://www.swavid.com/cbse/class-11) - [Biology](https://www.swavid.com/cbse/class-11/biology/chapters) - [Start free →](https://www.swavid.com/signup) - [All 19 chapters](https://www.swavid.com/cbse/class-11/biology/chapters) - [NCERT Biology (Reprint 2026-27)](https://ncert.nic.in/textbook.php) - [Open notes](https://www.swavid.com/cbse/class-11/biology/chapter/respiration-in-plants) - [Open notes](https://www.swavid.com/cbse/class-11/biology/chapter/cell-the-unit-of-life) - [Open notes](https://www.swavid.com/cbse/class-11/biology/chapter/plant-growth-and-development) - [Class 11 Biology](https://www.swavid.com/cbse/class-11/biology/chapters) - [Start free →](https://www.swavid.com/signup)