Class 11 Biology - HARYANA
Photosynthesis in Higher Plants
The chapter 'Photosynthesis in Higher Plants' for Class 11 Haryana (BSEH) students explores how green plants manufacture their own food using sunlight, water, and carbon dioxide. You will study the site of photosynthesis, the role of pigments like chlorophyll, and the two main phases: light-dependent reactions and light-independent reactions (Calvin cycle). The chapter also covers alternative pathways like C4 and CAM pathways, and factors affecting the rate of photosynthesis. Mastering this chapter is crucial for board exams as it features frequently in both conceptual questions and diagram-based evaluations.
Start Learning FreeKey Concepts
Site of Photosynthesis
Photosynthesis takes place in the chloroplasts, specifically within the thylakoids (light reactions) and the stroma (dark reactions).
Pigment Systems
Chlorophyll a, chlorophyll b, xanthophylls, and carotenoids absorb light energy and transfer it to reaction centers, forming Photosystem I (PSI) and Photosystem II (PSII).
Light Reaction (Photophosphorylation)
A process driven by light energy where ATP and NADPH are produced through non-cyclic and cyclic electron transport chains, along with the photolysis of water.
Calvin Cycle (C3 Pathway)
The biochemical pathway occurring in the stroma where CO2 is fixed into sugars using the ATP and NADPH generated during light reactions, with RuBisCO acting as the key enzyme.
C4 Pathway (Hatch-Slack Pathway)
An adaptation seen in tropical plants with Kranz anatomy that minimizes photorespiration by initially fixing CO2 into a 4-carbon compound.
Important Formulas
Board Exam Info
In the Haryana (BSEH) Class 11 Biology board exam, this chapter typically carries around 4 to 6 marks. Expect 1-mark objective questions, 2-mark conceptual questions (like differences between C3 and C4 plants), and 3 to 5-mark descriptive questions often involving diagrams of the Calvin cycle, Z-scheme, or chloroplast structure.
Frequently Asked Questions
What is the difference between C3 and C4 plants?
C3 plants form a 3-carbon compound (PGA) as the first stable product and lack Kranz anatomy. C4 plants form a 4-carbon compound (oxaloacetic acid), possess Kranz anatomy, and are better adapted to high temperatures and dry conditions without significant photorespiration.
Why is Photosystem II called PSII even though it acts first in non-cyclic photophosphorylation?
Photosystems are named in the chronological order of their discovery, not the order in which they function during the light reaction.
What is Kranz anatomy?
Kranz anatomy is a specialized leaf structure found in C4 plants where the vascular bundles are surrounded by two rings of cells: inner bundle-sheath cells and outer mesophyll cells.
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