PowerPoint Presentation

On PhotosynthesisFrom chapter l ife processes

Session-2015-16Term-1

CONTENTS1.Photosynthesis2.Photosynthesis

Overview3.Discovery of

Photosynthesis4.Why is

Photosynthesis important?

5.Photosystem Organization

6.Equation of photosynthesis

The process by which green plants make their own food (like glucose) from carbondioxide and water by using sunlight energy in the presence of chlorophyll, is called photosynthesis.Plants use sunlight to turn water and carbon dioxide into glucose. Glucose is a kind of sugar. Plants use glucose as food for energy and as a building block for growing.Autotrophs make glucose and heterotrophs are consumers of it.Makes organic molecules (glucose) out of inorganic materials (carbon dioxide and water).It begins all food chains/webs. Thus all life is supported by this process.It also makes oxygen gas!!Energy for all life on Earth ultimately comes from photosynthesis.

Overview of photosynthesisOxygenic photosynthesis is carried out by:cyanobacteria, 7 groups of algae, all land plants Photosynthesis is divided into:•light-dependent reactions-capture energy from sunlight.-make ATP and reduce NADP+ to NADPH.•carbon fixation reactions-use ATP and NADPH to synthesize organic molecules from CO2.

Autotrophic Process: Plants and plant-like organisms make their energy (glucose) from sunlight.Stored as carbohydrate in their bodies. Photosynthesis takes place in chloroplasts.•thylakoid membrane – internal membrane arranged in flattened sacs-contain chlorophyll and other pigments•grana – stacks of thylakoid membranes•stroma – semi-liquid substance surrounding thylakoid membranes. The work of many scientists led to the discovery of how photosynthesis works.

PLANTS ARE IN ACTIOIN FOR PHOTOSYNTHESIS

Importance of photosynthesisMakes organic molecules (glucose) out of inorganic materials (carbondioxide and water).It begins all food chains/webs. Thus all life is supported by this process.It also makes oxygen gas..ORGANIC FOOD- Photosynthesis is the only process which produces organic food from in organic raw materials. All organisms of the world are dependent on this organic food. Plants, which manufacture food, are called producers. Others, which are directly or indirectly dependent upon plants for food, are known as consumers. ENERGY- Photosynthesis converts solar energy into chemical energy. The whole living world uses this chemical energy for all the functions. FUELS- Wood, coal, petroleum and natural gas are all products of photosynthesis. CARBON DIOXIDE- Respiration and combustion add carbon dioxide into environment. By using carbon dioxide, photosynthesis helps in maintaining the concentration of the gas in the environment. OXYGEN- It supports life and combustion on the earth and is, therefore, being continuously consumed. Photosynthesis is the only process known to release oxygen into the atmosphere. USEFUL ARTICLES- A number of plant products produced as a result of photosynthetic activity are used in our daily life, e.g., timber oil, fibres, drugs, resins, rubber, etc.

PROCESS OF CHEMICAL REACTIONS IN PHOTOSYNTHESIS

CHEMICAL EQUATION FOR PHOTOSYNTHESIS

CARBON DIOXIDE + WATER GLUCOSE + OXYGEN

6CO2 + 6H2O + energy C6H12O6 + 6O2

sunlight

Absorbed by chlorophyll

Photosynthesis-starts to ecological food webs!

NECESSARY IN PHOTOSYNTHESIS

A. PHOTCHEMICAL PHASE (LIGHT OR HILL REACTIONS)

(a) PHOTOLYSIS OF WATER (b) FORMATION OF ASSIMILATORY

POWER

B. BIOSYNTHETIC PHASE(DARK AND BLACKMAN’S REACTIONS)

Discovery of Photosynthesis

The work of many scientists led to the discovery of how photosynthesis works.

Jan Baptista van Helmont (1580-1644)Joseph Priestly (1733-1804)Jan Ingen-Housz (1730-1799)F. F. Blackman (1866-1947) C. B. van Niel (1897-1985) Robin Hill (189-1991)

Robert hill C. B. van Niel Joseph Priestly

C. B. van Niel Jan Ingen-Housz F. F. Blackman

Scientists researched on photosynthesis

Types Of Photosynthesis

Light Reaction(photochemical reaction)

Dark Reaction(biosynthetic reaction)

FACTORS HELPING FOR PHOTOSYNTHESIS

LIGHT (SUNLIGHT) CHLOROPHYLL WATER AND MINERALS CARBONDIOXIDE TEMPERATURE NITROGEN

LIGHT It is the source for energy for photosynthesis. Light is visible part of the electromagnetic radiations. It has a

wavelength of 390-760 nm. Photosynthetically active radiations or PAR are 400-700 nm.Natural source of light is sun but artificial light can also provide energy

to plants for their photosynthesis. plants absorb light mostly in violet-blue and red parts of the light.Violet-blue light carries light carries more energy as compared to red

light Plants growing under shade of others receive mostly green and some

violet light.They have lower rates of photosynthesis. Light has two functions, photolysis of water and excitation of

chlorophyll to emit electrons. Photolysis of water produces oxygen, protons and electrons and

electrons and protons help in producing ATP and NADPH2.

CHLOROPHYLL A green colour pigment possesses by plants for absorption of light is called as chlorophyllThe green dots present on the leaves are calledcell organelle called chloroplast which contain chlorophyll.It is absorbed and conserved into light energy. It takes part in conversion of light energy. There are 3 types of photosynthetic pigments- (i) green chlorophylls (ii) orange coloured carotenes (iii) yellowish xanthophylls It is a primary photosynthetic pigment Other pigments absorb light energy of variouswavelengths and hand the energy to chlorophyll,a pigment through resonance.

Images of chlorophyll

WATER Land plants absorb water from soil through their roots.The absorbed water is transported to photosynthetic areas of xylem and minerals are also transported alongwith water. they are used in synthesis of different organic substances like sulphur in proteins, phosphorous in nucleic acids, magnesium in chlorophyll etc. 99% of absorbed water is lost through transpiration and only a small quantity of water is used in photosynthesis as hydrogen donor. For this, water splits into its components with the help of light energy. the phenomenon is called photolysis of water and oxygen is evolved.

CARBONDIOXIDE Land plants obtain it from atmosphere while aquatic plants absorb the same from water. Atmosphere contains over 0.036% of carbondioxide. It enters the leaves through stomata function as turgor-operated valves. Their guard cells thicker on the inner side and thinner on the outer side. K+ ions are closure of stomata. It generally remain open during the daytime. As, carbondioxide is used internally in photosynthesis is occurring. During day time the leaves can also use a small quantity of carbondioxide produced internally through respiration. At night, the carbondioxide evolved in respiration remains unutilised. The stomata get closed which prevents loss of water through transpiration. During evening and early morning, when light intensity is low, the rate of photosynthetic utilisation of carbon dioxide may just balance respiratory release of the gas. At this time the leaves neither obtain carbondioxide from outside nor release the gas. The light intensity wherein the photosynthesizing organ neither absorbs carbondioxide nor releases the same is called compensation point.

TEMPERATURE Photosynthetic takes place between 5 degree centigrade to 45 degree centigrade. The rate of photosynthesis is maximum at 30 degree centigrade. So, photosynthesis start at 5 degree centigrade, increase till30 degree centigrade and decrease at 45 degree centigrade. At high temperature, enzymes of the chlorophyll are inactive so photosynthesis stops at that temperature

NITROGEN It is an essential element which is used in the synthesis of proteins and other compounds. This is taken in the form of inorganic nitrates and nitrites or as inorganic compounds which have been prepared by bacteria (rhizobium) from atmospheric nitrogen.

SYSTEM AND TYPES OF LIGHT ENERGY

A CLEAR VIEW OF THE CHLOROPHYLL

23

WAVELENGTH OF THE DIFFERENT LIGHT ABSORPTION BY CHLOROPHYLL

LIGHT behaves as if it were composed of "units" or "packets" of energy that travel in waves. These packets are photons.The wavelength of light determines its color.

PHOTOSYSTEM

ANATOMY OF THE PLANT CEL CHLOROPLAST

DIFFERENTIATION OF CHLOROPHYLL

SYSTEM OF ENTRY AND EXIT OF THE GASES THROUGH CHLOROPHYLL

Light reactions The reaction of this phase is driven by light energy :-They are of 2 types- (i) Photolysis of water:- Light energy is divided into different components and the steps requires as oxygen evolving complex like manganese ion(Mn), calcium (Ca), chlorine (Cl). (ii) Formation of assimilatory power:- Electrons released by photolysis of water are picked up by chlorophyll. A molecule on absorption light energy. Each chlorophyll molecule throws out an electron with gain of the energy. This is known as the primary reaction of photosynthesis which converse light energy into chemical energy. The energy is used in the formation of ATP(adenosine tri phosphate) from ADP and phosphate with the help of the light energy is called phospharylations.

ADP + Pi ATP The electrons ultimately activate NADP(nicotinamide dinucleotide phosphate ) and it combine with hydrogen to form NADPH2.

NADP+ + 2e- + 2H+ (NADPH+H+) Both ATP and NADPH2 form assimilatory power of reaction.

DARK REACTIONS It is actually light independent reaction which can occur both in light and as well in

dark. It requires the energy and reducing power contained in assimilatory power of light

reaction. The common pathway of the biosynthetic phase is Kelvin cycle which convert

carbondioxide into glucose by a series of reaction. Carbondioxide combines ribulose biphosphate in the presence of enzyme ribulose

biphosphate carboxylaze or rubisco. It produces two molecules of phosphoglyceric acid (PGA).

RuBP+ CO2 2GPA This glucose then converts into starch and stored in the leaves or flow in the phloem

as liquid glucose. in the presence of ATP, phosphoglyceric acid is reduced by NADPH2 to form

glyceraldehydrade phosphate. PGA+ATP+ NADPH2 GAP+NADP+ADP+Pi

12 PGA6RuBP 12ATP

NADPH2

12NADP

12ADP+12 P1

12GAP

6RuMP

GLUCOSE

CALVIN CYCLE

6 CO2

6ADP

6ATP

DIGRAM OF THE CALVIN CYCLE

BROAD DIGRAM OF CALVIN CYCLE

DARK REACTION

SOME IMPORTANT NOTESphoton: a particle of light

-acts as a discrete bundle of energy.-energy content of a photon is inversely proportional to the wavelength of the light.

photoelectric effect: removal of an electron from a molecule by light-occurs when photons transfer energy to electrons.

Pigments: molecules that absorb visible lightEach pigment has a characteristic absorption spectrum, the range and efficiency of photons it is capable of absorbing.chlorophyll a – primary pigment in plants and cyanobacteria-absorbs violet-blue and red light .chlorophyll b – secondary pigment absorbing light wavelengths that chlorophyll a does not absorb.accessory pigments: secondary pigments absorbing light wavelengths other than those absorbed by chlorophyll a.-increase the range of light wavelengths that can be used in photosynthesis.-include: chlorophyll b, carotenoids, phycobiloproteins.-carotenoids also act as antioxidants.

In sulfur bacteria, only one photosystem is used for cyclic photophosphorylation1. an electron joins a proton to produce hydrogen.2. an electron is recycled to chlorophyll -this process drives the chemiosmotic synthesis of ATP.In chloroplasts, two linked photosystems are used in noncyclic photophosphorylation-1. photosystem I

-reaction center pigment (P700) with a peak absorption at 700nm.2. photosystem II

-reaction center pigment (P680) has a peak absorption at 680nm.Photosystem II acts first:-accessory pigments shuttle energy to the P680 reaction center.-excited electrons from P680 are transferred to b6-f complex-electron lost from P680 is replaced by an electron released from the splitting of water.The b6-f complex is a series of electron carriers.-electron carrier molecules are embedded in the thylakoid membrane.-protons are pumped into the thylakoid space to form a proton gradient.

THE ENDTHANK YOU FOR LOOKING MY PRESENTATION

IN FULL COOPERATION

NAME- CHNMAYA PATTNAIKCLASS- X – “B”ROLL-36SCHOOL- KENDRIYA VIDYALAYA NO.1, CUTTACK