Biology - Photosynthesis

Name: Biology - Photosynthesis
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Olympiad, Foundation, NEET, AIIMS, CBSE, iGCSE, GCSE, MCAT, AP-Biology & More

Created bystudi live

Last updated 1/2022

English

English [Auto],

What you'll learn

What do we Know?
Early Experiments
Where does Photosynthesis take place?
How many Pigments are involved in Photosynthesis?
What is Light Reaction?
The Electron Transport
Where are the ATP and NADPH Used?
The C4 Pathway
Photorespiration
Factors affecting Photosynthesis

Course content

1 section • 16 lectures • 2h 2m total length

Introduction5:36
Explore how photosynthesis in green plants, an autotrophic process, uses carbon dioxide, water, sunlight, and chlorophyll to synthesize glucose stored as starch, via light and dark reactions.
HSK Pathway11:58
Describe the hatch-slack pathway for C4 photosynthesis, detailing two-stage carbon fixation in mesophyll and bundle-sheath chloroplasts and the formation of oxaloacetate and malate leading to glucose.
Structure of Chloroplast5:36
Explore the structure of the chloroplast, including outer and inner membranes, stroma, and grana interconnected by membranes; light reactions occur in the grana and dark reactions in the stroma.
Mechanism of Photosynthesis6:14
Explore the mechanism of photosynthesis, detailing light and dark reactions, photochemical and biochemical processes in chloroplasts, and C3 (Kelvin) and C4 cycles converting carbon dioxide to glucose.
Photosynthetic Pigments8:14
Explore photosynthetic pigments, including chlorophyll a, b, c, and e. Describe chlorophylls' properties, such as water insolubility, light absorption, and carotenoids like carotene and xanthophyll.
Nature of Light5:39
Describe how light behaves as a wave and a particle, forming photons with energy inversely related to wavelength, used in photosynthesis, while pigments absorb blue and red and reflect green.
Photoexcitation of Chlorophyll - a6:53
Chlorophyll a acts as the essential action center, undergoing photoexcitation by photons and transferring excited electrons through electron acceptors and carriers to synthesize ATP, stored later as starch.
Photosystem Pigment System6:56
Explore photosystem pigment system, including action center and harvesting complex with chlorophyll a and accessory pigments, contrasting 700 photosystem i and 680 photosystem ii cyclic and non cyclic phosphorylation.
Light Reaction-Non-cyclic Photophosphorylation10:47
Describe non cyclic photophosphorylation in the light reactions, detailing PSII and PSI, electron flow via coenzyme Q, cytochrome b6f, and plastocyanin, water splitting, ATP, and oxygen evolution.
Distinguish -Cyclic and Non-cyclic Photophosphorylation5:59
Compare cyclic and non cyclic photophosphorylation: cyclic produces ATP without water splitting or oxygen release, while non cyclic uses both photosystems, splits water, and releases oxygen.
Dark Reaction - Calvin Cycle Part - 17:17
explain the dark reaction, the Calvin cycle in the stroma, using atp and nadph from light reactions to fix co2 into glucose through four phases: fixation, reduction, synthesis, regeneration.
Dark Reaction - Calvin Cycle Part - 212:25
The lecture explains the Calvin cycle, from Rubisco-driven carbon dioxide fixation to glucose formation through RuBP regeneration, detailing carboxylation, reduction, synthesis, and regeneration phases.
Kranz Anatomy6:39
Explore Kranz anatomy in tropical C4 plants, where bundle sheath cells surround vascular bundles and house mesophyll and bundle-sheath chloroplasts for carbon fixation via pep carboxylase and rubisco.
Contribution by Some Scientists12:14
Scientists prove that oxygen in photosynthesis comes from water, not carbon dioxide, through experiments with isolated chloroplasts and isotopes, clarifying the role of NADP as the electron acceptor.
Interdependence of Light & Dark Reaction4:37
Show how the light and dark reactions in the chloroplast grana are interdependent, with cyclic and non cyclic photophosphorylation producing ATP and releasing water and oxygen to form glucose.
Significance of Photosynthesis5:19
Photosynthesis converts solar energy into chemical energy, providing food for all living beings and releasing oxygen, while supporting atmospheric balance and giving rise to economically important products and fossil fuels.

Requirements

Basic understanding of Biology

Description

SUMMARY

Green plants make their own food by photosynthesis. During this process carbon dioxide from the atmosphere is taken in by leaves through stomata and used for making carbohydrates, principally glucose and starch. Photosynthesis takes place only in the green parts of the plants, mainly the leaves. Within the leaves, the mesophyll cells have a large number of chloroplasts that are responsible for CO2 fixation. Within the chloroplasts, the membranes are sites for the light reaction, while the chemosynthetic pathway occurs in the stroma. Photosynthesis has two stages: the light reaction and the carbon fixing reactions. In the light reaction the light energy is absorbed by the pigments present in the antenna, and funnelled to special chlorophyll a molecules called reaction centre chlorophylls. There are two photosystems, PS I and PS II. PS I has a 700 nm absorbing chlorophyll a P700 molecule at its reaction centre, while PS II has a P680 reaction centre that absorbs red light at 680 nm. After absorbing light, electrons are excited and transferred through PS II and PS I and finally to NAD forming NADH. During this process a proton gradient is created across the membrane of the thylakoid. The breakdown of the protons gradient due to movement through the F0 part of the ATPase enzyme releases enough energy for synthesis of ATP. Splitting of water molecules is associated with PS II resulting in the release of O2 , protons and transfer of electrons to PS II.

In the carbon fixation cycle, CO2 is added by the enzyme, RuBisCO, to a 5- carbon compound RuBP that is converted to 2 molecules of 3-carbon PGA. This is then converted to sugar by the Calvin cycle, and the RuBP is regenerated. During this process ATP and NADPH synthesised in the light reaction are utilised. RuBisCO also catalyses a wasteful oxygenation reaction in C3 plants: photorespiration.

Some tropical plants show a special type of photosynthesis called C4 pathway. In these plants the first product of CO2 fixation that takes place in the mesophyll, is a 4-carbon compound. In the bundle sheath cells the Calvin pathway is carried out for the synthesis of carbohydrates.

Who this course is for:

Biology enthusiast
Beginners in Biology
NEET & MHT-CET aspirants
Those preparing for board and competitive exams State Board, CBSE, ICSE , IGCSE, MHT-CET & NEET