Class 11 Biology - BIHAR
Photosynthesis in Higher Plants
The chapter Photosynthesis in Higher Plants explores how green plants use sunlight to synthesize organic food from carbon dioxide and water. For Bihar (BSEB) Class 11 students, this is a core physiological chapter vital for understanding energy flow in living organisms. Board exams frequently test mechanisms of light reaction, Calvin cycle, C3 and C4 pathways, and factors affecting photosynthesis. Mastering this chapter helps secure high marks in both objective and long-answer botany questions.
Start Learning FreeKey Concepts
Site of Photosynthesis
Photosynthesis primarily takes place in the chloroplasts of green leaves, specifically within the thylakoids (light reaction) and the stroma (dark reaction).
Pigment Systems
Chlorophyll a, chlorophyll b, carotenoids, and xanthophylls absorb light energy at different wavelengths, forming Photosystem I (PSI) and Photosystem II (PSII).
Light Reaction (Photophosphorylation)
Occurs in thylakoid membranes, involving splitting of water (photolysis), release of oxygen, and formation of ATP and NADPH.
Calvin Cycle (C3 Pathway)
The biochemical pathway occurring in the stroma where CO2 is fixed into glucose using ATP and NADPH generated during the light reaction.
C4 Pathway (Hatch-Slack Pathway)
An adaptation in tropical plants to minimize photorespiration, featuring Kranz anatomy where initial CO2 fixation produces a 4-carbon compound.
Important Formulas
Board Exam Info
In the Bihar (BSEB) Class 11 Biology exams, this chapter typically carries around 6 to 8 marks. Questions frequently include objective multiple-choice questions, short-answer questions on differences between C3 and C4 plants, and long-answer questions explaining the light reaction or Calvin cycle.
Frequently Asked Questions
C3 plants form a 3-carbon compound (PGA) as the first stable product and lack Kranz anatomy, whereas C4 plants form a 4-carbon compound (OAA) and possess specialized Kranz anatomy to reduce photorespiration.
C3 plants form a 3-carbon compound (PGA) as the first stable product and lack Kranz anatomy, whereas C4 plants form a 4-carbon compound (OAA) and possess specialized Kranz anatomy to reduce photorespiration.
Why is Photosystem II called so if it functions first?
PSII was discovered and named second chronologically after PSI, even though electrons flow from PSII to PSI during non-cyclic photophosphorylation.
What is Blackman's Law of Limiting Factors?
It states that if a chemical process is affected by more than one factor, its rate is limited by the pace of the slowest factor, i.e., the factor closest to its minimum value.
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