Photosynthesis in Higher Plants

Everyone is familiar with the basic principles of photosynthesis. Various processes are involved in photosynthesis in higher plants, but the principle remains the same. Sunlight is used for synthesizing organic compounds by this physicochemical process. As oxygen is released into the atmosphere, it compounds organic compounds.

The process of photosynthesis uses light energy to synthesize organic compounds in green plants. It is an anabolic process regulated by enzymes.

1. Life on earth depends on photosynthesis as it is the primary source of food, and it is responsible for releasing carbon dioxide into the atmosphere.
2. The process of photosynthesis requires chlorophyll. It can only be found on the green parts of leaves and in the presence of light.

Chloroplasts are found in the mesophyll cells of the leaves, where photosynthesis occurs. Photosynthesis involves four pigments:

1. Chlorophyll a
2. Chlorophyll b
3. Xanthophylls
4. Carotenoids

The process of photosynthesis in higher plants

Photosynthesis in higher plants involves the following processes:

1. Light Reaction
2. Dark Reaction

Light Reaction

1. In the presence of light, this phenomenon occurs.
2. Light wavelengths are absorbed by pigments and ATP is produced.
3. Absorption of light, splitting of water, oxygen release, and formation of ATP and NADPH are all involved in the process.
4. A protein-bound pigment molecule from a light-harvesting complex is located within two different photosystems. Antennae containing accessory pigments are attached to each photosystem's reaction center, which consists of chlorophyll molecules.
5. It is P-700 for PS-I, as chlorophyll a has an absorption peak of 700 nm, while it is P-680 for PS-II, as chlorophyll a has an absorption peak of 680 nm.

Dark Reaction

When there is no light, this process takes place in the chloroplast stroma. The process involves the following cycles:

Calvin Cycle (C3 Cycle)

The steps of this cycle include:

1. In a carbon-fixation process, ribulose-1, 5-bisphosphate combines with carbon dioxide to form 3-phosphoglyceric acid, a 3-carbon compound. In this process, a protein enzyme called RuBisCO is involved.
2. Glyceraldehyde-3-phosphate is formed by the reduction of one molecule of carbon dioxide with two molecules of ATP and NADPH.
3. A series of reactions occur to form glucose from glyceraldehyde-3-phosphate molecules, and RuBP regenerates to continue the cycle.

C4 Cycle (Hatch and Slack Pathway)

1. The pathway follows a cycle.
2. Mesophyll cells and Bundle Sheath cells contain enzymes involved in the C4 pathway.
3. Through this pathway, plants produce a chemical compound containing four carbons from atmospheric carbon dioxide.
4. Carbon dioxide is primarily taken up by phosphoenolpyruvate, which is located in the mesophyll cells. Phosphoenolpyruvate carboxylase is responsible for the reaction.
5. In the resulting mesophyll cells, aspartic acid and malic acid are formed and transported to the bundle sheath cells. Three-carbon molecules are released and carbon dioxide is released as a result of the breakdown of C4 acids.
6. They are then converted into phosphoenolpyruvate in the mesophyll cells and end the cycle.
7. Calvin's cycle is completed when carbon dioxide enters the bundle sheath cells.

Class 11 Biology Notes: Photosynthesis in higher plants

You can download the CBSE class 11 notes for Chapter 13 Photosynthesis in higher plants in PDF format for free. Revision sheets for Photosynthesis in higher plants class 11 Notes Biology are available online so that you can score high on exams. Here are the class 11 notes on Photosynthesis in Higher Plants written by a team of expert teachers. The revision notes make it easy to revise the whole chapter in a few minutes. One of the best tips teachers recommend during exam time is reviewing notes.

Photosynthesis in higher plants neet questions

1. The process making the major difference between C3 and C4 plants is (NEET – II 2016)

A. respiration

B. Calvin cycle

C. photorespiration

D. glycolysis

ANS: Photorespiration

2. The stomatal opening is where water vapor leaves the plant leaf. During photosynthesis, carbon dioxide diffuses into the plant through the same stomatal opening. Choose one of the following explanations. (NEET – I 2016)

A. It is possible for both processes to occur simultaneously since the diffusion coefficient of water and CO2 differs

B. Both processes cannot happen simultaneously

C. One happens during the day and the other during the night

D. One happens during the day and one during the night

ANS: A. Both processes can happen together because the diffusion coefficient of water and CO2 is different

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3. Emerson’s enhancement effect and Red drop have been instrumental in the discovery of (NEET – I 2016)

A. two photosystems operating simultaneously

B. oxidative phosphorylation

C. photophosphorylation and cyclic electron transport

D. photophosphorylation and non-cyclic electron transport

ANS: A. two photosystems operating simultaneously

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4. In Kranz anatomy, the bundle sheath cells have (Mains 2011)

A. thick walls, many intercellular spaces, and few chloroplasts

B. Small cells without intercellular spaces and several chloroplasts

C. Cell walls are thin, there are many intercellular spaces and there are no chloroplasts

D. thick walls, no intercellular spaces, and a large number of chloroplasts

ANS: D. thick walls, no intercellular spaces, and a large number of chloroplasts

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