crash course photosynthesis

If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

To log in and use all the features of Khan Academy, please enable JavaScript in your browser.

Unit 13: Photosynthesis

About this unit.

This unit is part of the Biology library. Browse videos, articles, and exercises by topic.

Intro to photosynthesis

• ATP: Adenosine triphosphate (Opens a modal)
• ATP hydrolysis mechanism (Opens a modal)
• Photosynthesis (Opens a modal)
• Breaking down photosynthesis stages (Opens a modal)
• Intro to photosynthesis (Opens a modal)
• Photosynthesis Get 3 of 4 questions to level up!

The light-dependent reactions

• Conceptual overview of light dependent reactions (Opens a modal)
• Light dependent reactions actors (Opens a modal)
• Photosynthesis: Overview of the light-dependent reactions (Opens a modal)
• Light and photosynthetic pigments (Opens a modal)
• The light-dependent reactions (Opens a modal)
• The light-dependent reactions Get 3 of 4 questions to level up!

The Calvin cycle

• Photosynthesis: Calvin cycle (Opens a modal)
• The Calvin cycle (Opens a modal)
• The Calvin cycle Get 3 of 4 questions to level up!

Photorespiration: C3, C4, and CAM plants

• Photorespiration (Opens a modal)
• C4 photosynthesis (Opens a modal)
• CAM plants (Opens a modal)
• C3, C4, and CAM plants (Opens a modal)
• Photorespiration Get 3 of 4 questions to level up!

Photosynthesis and Cellular Respiration: Crash Course Botany #5

Plants and trees may seem pretty passive, but behind the scenes, their cells are working hard to put on a magic show. In this episode of Crash Course Botany, we’ll explore how the processes of photosynthesis and cellular respiration work, why they’re so critical for all life on Earth, and how they’re helping us to forge a greener path to the future.

Nerdfighteria Wiki

Popular articles

crashcourse Photosynthesis: Crash Course Biology #8

• Description

YouTube:
Previous:
Next:

-->

View count:	8,348,182
Likes:	85,028
1,954
Comments:	6,174
Duration:	13:15
Uploaded:	2012-03-19
Last sync:	2024-05-13 06:15

MLA Full:	"Photosynthesis: Crash Course Biology #8." , uploaded by CrashCourse, 19 March 2012, www.youtube.com/watch?v=sQK3Yr4Sc_k.
MLA Inline:	(CrashCourse, 2012)
APA Full:	CrashCourse. (2012, March 19). [Video]. YouTube. https://youtube.com/watch?v=sQK3Yr4Sc_k
APA Inline:	(CrashCourse, 2012)
Chicago Full:	CrashCourse, "Photosynthesis: Crash Course Biology #8.", March 19, 2012, YouTube, 13:15, https://youtube.com/watch?v=sQK3Yr4Sc_k.

 Introduction

 1) water ( 1:16 ),  2) carbon dioxide ( 1:32 ),  3) sunlight/photons ( 1:43 ),  4) chloroplasts ( 1:57 ),  5) light reaction/light-independent ( 2:42 ),  a. photosystem ii ( 3:33 ),  b. cytochrome complex ( 5:54 ),  c. atp synthase ( 6:16 ),  d. photosystem i ( 7:06 ),  6) dark reactions/light-independent ( 7:55 ),  a) phase 1 - carbon fixation ( 8:50 ),   b) phase 2 - reduction ( 11:31 ),  c) phase 3 - regeneration ( 12:02 ),  conclusion ( 12:44 ), create account.

AP® Biology

Photosynthesis: ap® biology crash course.

• The Albert Team
• Last Updated On: March 1, 2022

There’s a lot of information in the Advanced Placement (AP) Biology photosynthesis unit that can distract you from remembering its most important concept: the transformation of light energy into chemical energy, and then its storage in the bonds of carbohydrates.

Instead of giving you a laundry list of processes and reactions, we are going to discuss the pathway of light energy in plants. We think a pathway is easier to remember and maintains the focus on energy transduction.

LIGHT: THE DRIVING FORCE OF PHOTOSYNTHESIS

When light hits an object, photons are reflected, transmitted, or absorbed. The term photon  here emphasizes the particle-like behavior of light, as opposed to the wave-like behavior of light. Reflection and transmission constitute what we perceive as color. Absorption is what allows photosynthesis.

Plants take advantage of the fact that some photons can be absorbed and use the energy of these photons for photosynthesis. This energy conversion takes place in the chloroplasts of the plant cell, where light energy is converted to chemical energy. Photons with more energy than a given electron in the chloroplast will transfer energy to the electron by the mechanism of diffusion. The electron then acts as an energy carrier, transferring its energy to be used for many reactions in photosynthesis.

We say that light is the driving force behind photosynthesis because light is the original provider of the energy used in the photosynthetic process. The first set of reactions in photosynthesis are called “light-dependent” reactions because they need light energy to start and continue. The second set of reactions are known as “light-independent” reactions as they function using the energy produced by the first set of reactions, but not the photons themselves.

We will highlight the key points you need to understand to fully take advantage of this surprisingly simple AP® Biology photosynthesis exploration. The first time, read through as if you are reading a story; this will give you the bigger picture, and it will help you avoid getting lost in the jargon. Next, read again focusing on the details; always keep in mind what the purpose of each system, enzyme and molecule is. This will help you understand the concepts instead of cramming for your AP® Biology exam.

THE LIGHT-DEPENDENT PHASE

Light absorption.

Once light energy (in the form of photons) has been absorbed by the chlorophyll and other pigments of the chloroplast, this energy needs to go somewhere. The energy is transferred to the photo systems of the chloroplast – bundles of chlorophyll pigments packed into thylakoids. Thylakoids are membrane-bound sacs inside chloroplasts where the light-dependent reactions of photosynthesis occur. The energy is carried by electrons; these electrons are known in this state as “excited” electrons. The excited electrons concentrate in the thylakoid membrane proteins, which power photosynthesis. The photosynthetic process begins in Photo system II – so called because this photo system was the second photo system discovered (don’t get confused – Photo system I is used later in photosynthesis!).

In Photo system II, light energy from photons splits water into its constituents:two H + ions,two electrons, and a single oxygen atom in a process known as photolysis. The electrons released are transferred to P680 molecules while the oxygen atoms combine to form O 2 , which is released into the atmosphere, and the H + molecules remain in the thylakoid membrane for later use in the conversion of NADP + to NADPH (remember this – we will come back to it later). P680 is a bundle of chlorophyll pigments located within Photo system II that acts as an oxidizing agent (currently no stronger oxidizing agent is known to exist!). The first stage of this reaction, the photolysis of water, occurs as follows:

2H 2 O ®4H + + O 2 + 4e –   

THE ELECTRON TRANSPORT CHAIN

At this stage, we introduce the electron transport chain, which is the mechanism by which electrons are transferred from the thylakoid membrane proteins to the NADP + molecule – all of this occurs to produce ATP and water necessary for the plant’s growth. The beginning of transport chain is Photo system II, where electrons are first excited by light. Electrons released by the reduction of NADH 2  then progress along the chain, where their energy is dissipated as heat or converted to ATP energy – the power of the cell. The reduction of NADP + occurs as follows:

NADP + + 2e – + 2H + ®NADPH + H +

ATP PRODUCTION

It is at this stage that photosynthesis can be broken into cyclical and non-cyclical processes. We will focus on non-cyclical photosynthesis.

Non-cyclical photosynthesis is described by the following equation:

2 H 2 O + 2 NADP + + 3 ADP + 3 P i + light → 2 NADPH + 2 H + + 3 ATP + O 2

Each molecule of chlorophyll absorbs one photon of light. This excess of energy causes the photon to release an electron into Photosystem II, where it changes the P680 molecule to a P680*. This releases the electron, which is passed through various molecules in the electron transport chain. The electron transport chain causes a proton gradient across the chloroplast membrane. This gradient is used to produce ATP from ADP during photo phosphorylation.

After the reaching the plastocyanin, the electrons move into the P700 of the Photo system I, converting it to P700*. At this stage, the electrons are further excited by light energy absorbed by the Photo system I. The electrons travel further along the electron transfer chain, from the Photo system I to membrane-bound iron sulfur proteins to ferredoxin molecules, losing part of their energy to molecules of the ETC at each stage. This energy is used to further the proton gradient across the chloroplast membrane, and the electron reduces the NADP+ molecule to NADPH.

Systems seek to restore the equilibrium of concentrations, so by chemiosmosis, extraneous protons are forced back to the outer membrane of the thylakoid. The channel that the extraneous protons exit the membrane through is known as ATP synthase. This motion of protons rotates the ATP synthase protein and phosphorylates ADP to ATP.

In the diagram below, the transfer of an electron from excitation by a photon of light energy (far left) through Photo systems II and I, to the formation of ATP and NADPH is depicted. It should be noted that the electrons travel in one direction, while the NADPH and ATP produced are used in the furthering of the photosynthetic cycle.

Image Source: Wikimedia Commons

Figure 1: The movement of electrons along the electron transfer chain.

Losing electrons causes both photo systems to have a positive charge and become strong oxidizing agents, so they oxidize surrounding water molecules to obtain their electrons. This breaks the molecular bonds of water and dissociates it into its components, oxygen and hydrogen, which are released and used to form NADPH. This all occurs in the thylakoid membrane of the cell.

If you’re familiar with cellular respiration , you may be experiencing déjà-vu! Indeed, the process of ATP production is similar for both cellular respiration and photosynthesis . This AP® Biology photosynthesis review can also help bolster your understanding of cellular respiration.

KINETIC, POTENTIAL, AND THEN CHEMICAL ENERGY

We’ve discussed how water molecules are used to create the proton gradient, but this gradient is also created by regular diffusion. Some of the energy from electrons moving down the electron transport chain is converted to kinetic energy in order to bring in hydrogen ions released into the thylakoid membrane during the photolysis of water (remember, we discussed this at the start of the article).

Once in the inner space of the chloroplast, the kinetic energy of hydrogen is considered potential energy because of its position in the proton gradient. Potential energy can be considered as energy that is available to use for work.

We consider potential energy to be converted to the chemical energy in ATP bonds because it was usedto turn ADP into ATP by rotating ATP synthase.

LIGHT INDEPENDENT REACT®IONS

The released hydrogen protons are also used to reduce carbon dioxide into glucose in the second set of reactions in photosynthesis, called the Calvin cycle. This process also uses the ATP and NADPH’s stored energy to perform this reduction. The reaction is as follows:

3 CO 2 + 9 ATP + 6 NADPH + 6 H + → C 3 H 6 O 3 -phosphate + 9 ADP + 8 Pi + 6 NADP + + 3 H 2 O

Most plants can put three carbon dioxide molecules into an enzyme called ribulose bis-phosphate carboxylase (RuBisCo) to produce PGAL. ATP and NADPH are used to convert sugar back and forth from RuBisCo, but the final output is one PGAL. PGAL stores the energy for later conversion to sugars.

Therefore, the chemical energy that was carried by ATP and NADPH become stored in PGAL.

THE CALVIN CYCLE

The Calvin Cycle occurs in three main parts: fixation, reduction, and regeneration. During fixation, a RuBisCoenzyme catalyzes a reaction between 3 CO 2 molecules and three ribulose biphosphate (RuBP) molecules. This forms six molecules of 3-phosphoglyceric acid (3-PGA). The cycle completes three times, during each of which one RuBP and one CO 2 molecule interact. This is known as carbon fixation. During reduction, the ATP and NADPH created in the first stage of photosynthesis are used to convert the 3-PGA to glyceraldehyde 3-phosphate (PGAL). ATP is converted back to ADP in this reaction, and NADPH is converted back to NADP + . These products are recycled in the first phase of photosynthesis – the light-dependent phase. During regeneration, PGAL is exported to produce food products such as carbohydrates. This occurs in a 1:5 ratio: for every turn of the Calvin Cycle, two PGAL molecules are created. As it takes three turns of the cycles to use all RuBP molecules, six molecules of PGAL are created. One is exported, while five are used to regenerate RuBP. The one PGAL expelled collects in the cytosol. Once several have collected, PGAL molecules react to form sugar, in the form of six-carbon phosphates, which in turn react to form sucrose.

In the image below, the interaction between the light-dependent and light-independent reactions is shown. The products of the light reactions used in the Calvin Cycle can be seen, as are the products of the Calvin Cycle which are then reused in the light reactions.

Figure 2: The interaction between the light-dependent and -independent parts of photosynthesis.

After a long trip, the spare light energy settles down and is stored in PGAL!

When the plant needs energy to perform metabolic processes, sugars created by photosynthesis are broken down and the chemical energy is released, much in the same way as food is broken down for energy in animal cells. In this way, light energy (as well as a few other products – can you name them?) is used to create carbohydrates that can be stored and used as “food” energy.

We mentioned that there are similarities explored in photosynthesis and respiration. Can you name other aspects of cellular processes that are similar to those mentioned in this crash course of AP® Biology photosynthesis?

Need help preparing for your AP® Biology exam?

Albert has hundreds of AP® Biology practice questions, free response, and full-length practice tests to try out.

Interested in a school license?​

Popular posts.

AP® Score Calculators

Simulate how different MCQ and FRQ scores translate into AP® scores

AP® Review Guides

The ultimate review guides for AP® subjects to help you plan and structure your prep.

Core Subject Review Guides

Review the most important topics in Physics and Algebra 1 .

SAT® Score Calculator

See how scores on each section impacts your overall SAT® score

ACT® Score Calculator

See how scores on each section impacts your overall ACT® score

Grammar Review Hub

Comprehensive review of grammar skills

AP® Posters

Download updated posters summarizing the main topics and structure for each AP® exam.

• school Campus Bookshelves
• menu_book Bookshelves
• perm_media Learning Objects
• login Login
• how_to_reg Request Instructor Account
• hub Instructor Commons

Margin Size

• Download Page (PDF)
• Download Full Book (PDF)
• Periodic Table
• Physics Constants
• Scientific Calculator
• Reference & Cite
• Tools expand_more
• Readability

selected template will load here

This action is not available.

10.6: Video- Photosynthesis (Crash Course #8)

• Last updated
• Save as PDF
• Page ID 46426

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)

( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)

\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)

\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

\( \newcommand{\Span}{\mathrm{span}}\)

\( \newcommand{\id}{\mathrm{id}}\)

\( \newcommand{\kernel}{\mathrm{null}\,}\)

\( \newcommand{\range}{\mathrm{range}\,}\)

\( \newcommand{\RealPart}{\mathrm{Re}}\)

\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

\( \newcommand{\Argument}{\mathrm{Arg}}\)

\( \newcommand{\norm}[1]{\| #1 \|}\)

\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)

\( \newcommand{\vectorA}[1]{\vec{#1}}      % arrow\)

\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}}      % arrow\)

\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

\( \newcommand{\vectorC}[1]{\textbf{#1}} \)

\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)

\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)

\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)

Hank explains the extremely complex series of reactions whereby plants feed themselves on sunlight, carbon dioxide and water, and also create some by products we’re pretty fond of as well.

A YouTube element has been excluded from this version of the text. You can view it online here: pb.libretexts.org/fob2/?p=122

Contributors and Attributions

• Crash Course Biology Videos. Provided by : Crash Course. Located at : https://www.youtube.com/user/crashcourse . License : All Rights Reserved . License Terms : Standard YouTube license

Influence of lowered temperature on the resistance and functional activity of the photosynthetic apparatus of wheat plants

• Plant Physiology
• Published: 29 March 2011
• Volume 38 , pages 132–137, ( 2011 )

Cite this article

• Yu. V. Venzhik 1 ,
• A. F. Titov 1 ,
• V. V. Talanova 1 ,
• S. A. Frolova 1 ,
• A. V. Talanov 1 &
• Ye. A. Nazarkina 1  

54 Accesses

14 Citations

Explore all metrics

The dynamics of cold resistance and the activity of the photosynthetic apparatus (PSA) of wheat germs at 4°C were studied. It was shown that in the first hours of cold, a certain functional readjustment to the changed conditions takes place in the plant organism. A decrease in the activity of the PSA and cessation of the linear growth of the leaf are registered at this stage along with an increase in resistance, as well as an increase in the coefficient of non-photochemical quenching of the fluorescence of chlorophyll. In one to four days, when resistance reaches its maximum, photosynthesis and the rate of electron transport are stabilized, the chlorophyll content in the lightcollecting complex increases, and the growth recommences. The final stage of adaptation (days 4–7) is characterized not only by the steady level of resistance but also by new functional organization of the PSA, which allows the plants to endure the lowered temperature successfully.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price includes VAT (Russian Federation)

Instant access to the full article PDF.

Rent this article via DeepDyve

Institutional subscriptions

Similar content being viewed by others

Recent Advances in Plant Drought Tolerance

Drought Tolerance Strategies in Plants: A Mechanistic Approach

Drought Stress in Plants: An Overview

Praktikum po fiziologii rastenii (A Practical Course in Plant Physiology) Tret’yakov, N.N., Ed., Moscow: Agropromizdat, 2003.

Google Scholar  

Anikiev, V.V. and Kutuzov, F.F., New Method for Determination of the Lamina Area in Cereals, Fiziol. Rast. , 1961, vol. 44, pp. 375–377.

Aroca, R., Irigouen, J., and Sanches-Diaz, M., Photosynthetic Characteristics and Protective Mechanisms Against Oxidative Stress during Chilling and Subsequent Recovery in Two Maize Varieties Differing in Chilling Sensitivity, Plant Sci. , 2001, vol. 161, no. 4, pp. 719–726.

Article   CAS   Google Scholar  

Balagurova, N.I., Drozdov, S.N., and Khilkov, N.I., Metod opredeleniya ustoichivosti rastitel’nykh tkanei k promorazhivaniyu (Method for Determination of Freezing Tolerance of Plant Tissues), Petrozavodsk: KFAN SSSR, 1982.

Bubolo, L.S., Paleeva, T.V., and Kislyuk, I.M., Effect of the Temperature of Growth and Short-Term Acclimation on Cell Ultrastructure, Photosynthesis, and Respiration of Leaves of Tradescantia albiflora (Commelinaceae), Bot. Zh. , 1988, vol. 73, no. 1, pp. 45–54.

Caemmerer, S. and Farquhar, G.D., Some Relationships between the Biochemistry of Photosynthesis and the Gas Exchange of Leaves, Planta , 1981, vol. 153, no. 2, pp. 376–381.

Article   Google Scholar  

Demmig-Adams, B. and Adams, W.W., Photoprotection in an Ecological Context: The Remarkable Complexity of Thermal Energy Dissipation, N. Phytol. , 2006, vol. 172, no. 1, pp. 11–21.

Gavrilenko, V.F. and Zhigalova, T.V., Bol’shoi praktikum po fotosintezu (An Extended Practical Course in Photosynthesis), Moscow: Akademiya, 2003.

Gray, G.R., Savitch, L.V., Ivanov, A.G., and Huner, N.R., Photosystem II Excitation Pressure and Development of Resistance to Photoinhibition, Plant Physiol. , 1996, vol. 110, no. 1, pp. 61–71.

PubMed   CAS   Google Scholar  

Hendrickson, L., Förfter, B., Furbank, R.T., and Chow, W.C., Processes Contributing to Photoprotection of Grapevine Leaves Illuminated at Low Temperature, Physiol. Plant. , 2004, vol. 121, no. 2, pp. 272–281.

Article   PubMed   CAS   Google Scholar  

Hurry, V.M., Strand, A., Tobiason, M., et al., Cold Hardening of Spring and Winter Wheat and Rape Results in Differential Effects on Growth, Carbon Metabolism and Carbohydrate Content, Plant Physiol. , 1995, vol. 109, no. 2, pp. 697–706.

Klimov, S.V., Astakhova, V.N., and Trunova, T.I., Relationship between Cold Hardiness of Plants and Photosynthesis, Fiziol. Rast. , 1997, vol. 44, no. 6, pp. 879–886.

Klimov, S.V., Astakhova, V.N., Davydenko, S.V., and Trunova, T.I., Effect of Cold on the Function and Structure of the Photosynthetic Machinery of Winter Wheat and Rye, Fiziol. Rast. , 1992, vol. 324, no. 6, pp. 1339–1344.

Klimov, S.V., Bioenergetic Aspects of Adaptation and Tolerance of Wintering Cereals to Frost, Usp. Sovrem. Biol. , 1987, vol. 104, no. 2, pp. 251–264.

Klimov, S.V., Cold Hardening of Plants-The Result of Maintenance of an Increased Photosynthesis/Respiration Ratio at Low Temperatures, Izv. Akad. Nauk, Ser. Biol. , 2003, no. 1, pp. 57–62.

Krol, M., Ivanov, A.G., Jansson, S., et al., Greening under High Light or Cold Temperature Affects the Level of Xanthophyll-Cycle Pigments, Early Light-Inducible Proteins, and Light-Harvesting Polypeptides in Wild-Type Barley and the Chlorina F2 Mutant, Plant Physiol. , 1999, vol. 120, no. 1, pp. 193–203.

Lichtenthaler, H.K., Chlorophylls and Carotenoids-Pigments of Photosynthetic Biomembranes, Methods Enzymol. , 1987, vol. 148, no. 2, pp. 350–382.

Maslova, T.G. and Popova, I.A., Adaptive Properties of Plant Pigment Systems, Photosynthetica , 1993, vol. 29, no. 2, pp. 195–203.

CAS   Google Scholar  

Maxwell, K. and Johnson, G.N., Chlorophyll Fluorescence—A Practical Guide, J. Exp. Bot. , 2000, vol. 51, no. 345, pp. 659–668.

Miroslavov, E.A., Structural Adaptation of Plants to Cold Climate, Bot. Zh. , 1994, vol. 79, no. 2, pp. 20–26.

Mokronosov, A.T., Gavrilenko, V.F., and Zhigalova, T.V., Fotosintez. Fiziologo-ekologicheskie i biokhimicheskie aspekty (Photosynthesis: Physiological and Biochemical Aspects), Moscow: Akademiya, 2006.

Oliveria, J.G., Alves, P.L., and Magalhes, A.C., The Effect of Chilling on the Photosynthetic Activity in Coffee ( Coffea arabica L.) Seedlings. The Protective Action of Chloroplastid Pigments, Brazil. J. Plant Physiol. , 2002, vol. 14, no. 1, pp. 95–104.

Rapacz, M., Gasior, D., Zweirzykowski, Z., et al., Changes in Cold Tolerance and the Mechanisms of Acclimation of Photosystem II to Cold Hardening Generated by Anther Culture of Festuca pratensis × Lolium multifolium Cultivars, N. Phytol. , 2004, vol. 162, no. 1, pp. 105–114.

Rodchenko, O.P., Maricheva, E.A., and Akimova, G.P., Adaptatsiya rastushchikh kletok kornya k ponizhennym temperaturam (Adaptation of Growing Root Cells to Low Temperatures), Novosibirsk: Nauka, 1988.

Sherstneva, O.A., Maslova, T.G., Mamushina, N.S., et al., Photosynthetic Machinery and Light-Dependent Absorption of Xanthophylls in Leaves of Ephemeroid Plants at Different Stages of Plant Ontogeny, Bot. Zh. , 2007, vol. 92, no. 1, pp. 72–80.

Strand, A., Hurry, V., Hences, S., et al., Acclimation of Arabidopsis Leaves Developing at Low Temperature. Increasing Cytoplasm Vellum Accompanies Increased Activities of Enzymes in the Calvin Cycle and in the Sucrose-Biosyntheses Pathway, Plant Physiol. , 1999, vol. 119, no. 4, pp. 1387–1397.

Titov, A.F., Akimova, T.V., Talanova, V.V., and Topchieva, L.V., Ustoichivost’ rastenii v nachal’nyi period deistviya neblagopriyatnykh temperatur (Tolerance of Plants at the Beginning of Exposure to Adverse Temperatures), Moscow: Nauka, 2006.

Trunova, T.I., Plant and Low-Temperature Stress, in 64-e Timiryazevskoe chtenie (The 64th Timiryazev Memorial Lecture), Moscow: Nauka, 2007.

Venzhik, Yu.V., Frolova, S.A., Koteeva, N.K., et al., Structural-Functional Characteristics of Triticum aestivum L. (Rosaceae) Plants at the Initial Stage of Hardening, Bot. Zh. , 2008, vol. 93, no. 9, pp. 39–49.

Yamasaki, T., Yamakawa, T., Yamane, Yo., et al., Temperature Acclimation of Photosynthesis and Related Changes in Photosystem II Electron Transport in Winter Wheat, Plant Physiol. , 2002, vol. 128, no. 3, pp. 1087–1097.

Download references

Author information

Authors and affiliations.

Institute of Biology, Karelian Scientific Center, Russian Academy of Sciences, ul. Pushkinskaya 11, Petrozavodsk, 185910, Russia

Yu. V. Venzhik, A. F. Titov, V. V. Talanova, S. A. Frolova, A. V. Talanov & Ye. A. Nazarkina

You can also search for this author in PubMed   Google Scholar

Corresponding author

Correspondence to V. V. Talanova .

Additional information

Original Russian Text © Yu.V. Venzhik, A.F. Titov, V.V. Talanova, S.A. Frolova, A.V. Talanov, Ye.A. Nazarkina, 2011, published in Izvestiya Akademii Nauk, Seriya Biologicheskaya, 2011, No. 2, pp. 171–177.

Rights and permissions

Reprints and permissions

About this article

Venzhik, Y.V., Titov, A.F., Talanova, V.V. et al. Influence of lowered temperature on the resistance and functional activity of the photosynthetic apparatus of wheat plants. Biol Bull Russ Acad Sci 38 , 132–137 (2011). https://doi.org/10.1134/S1062359011020142

Download citation

Received : 01 December 2009

Published : 29 March 2011

Issue Date : April 2011

DOI : https://doi.org/10.1134/S1062359011020142

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Chlorophyll
• Chlorophyll Content
• Winter Wheat
• Chlorophyll Fluorescence
• Relative Growth Rate
• Find a journal
• Publish with us
• Track your research

Crash of a Douglas DC-8-62 in Moscow: 61 killed

• Share full article

Advertisement

Supported by

Fake News Reports and Videos Seek to Undermine the Paris Olympics

Russian propagandists are spoofing broadcasters and mimicking French and U.S. intelligence agencies to stoke fear about security at the Games.

By Julian E. Barnes and Steven Lee Myers

Julian E. Barnes, who covers U.S. intelligence agencies, and Steven Lee Myers, who covers misinformation, have been reporting on Russian efforts to influence the 2024 presidential election.

With its athletes barred from competing in the Summer Olympics under the country’s flag, Russia has turned its fury on the Games and this year’s host, Paris.

Russian propagandists have created an hourlong documentary, spoofed news reports and even mimicked French and American intelligence agencies to issue fake warnings urging people to avoid the Games, according to a report released on Sunday by Microsoft.

The report details the disinformation campaign created by a group the company calls Storm-1679. The campaign appears to have accelerated since March, flooding social media with short videos raising alarms about possible terrorist attacks and stoking fears about safety.

The operation, while aimed at the Games, is using various techniques to spread disinformation that could also be employed in European and U.S. elections.

American and French officials have tracked the campaign. One American official said that Russian disinformation, spread by the Kremlin via social media, continued to threaten the security of the United States and its allies.

The group has also tried to goad fact checkers into examining its claims, hoping to use the attention to spread the disinformation to new audiences as it is called out.

We are having trouble retrieving the article content.

Please enable JavaScript in your browser settings.

Thank you for your patience while we verify access. If you are in Reader mode please exit and  log into  your Times account, or  subscribe  for all of The Times.

Thank you for your patience while we verify access.

Already a subscriber?  Log in .

Want all of The Times?  Subscribe .