61 9macromicronutrientsinplants 120530224106 Phpapp01

8/11/2019 61 9macromicronutrientsinplants 120530224106 Phpapp01

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CHAPTER 6 : NUTRITION

6.9 Macronutrients &

Micronutrients in Plants


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LE RNING OUTCOMES List elements required by

plants, Classify elements required

by plants based on theamount needed,

Relate the effects ofmacronutrient deficiency inplants.

Explain the function of each

macronutrient in plants, State the function of

micronutrients & effects ofmicronutrient deficiency inplants.


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MACROnutr ien ts : needed in

LARGER quantities Carbon, Hydrogen, Oxygen,

Phosphorous, Potassium (Kalium),

Calcium, Magnesium & Sulphur. MICROnutr ients : needed in

SMALLER quantities. Boron, Molybdenum, Zinc,

Manganese, Copper & Ferum

Table 1
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Wilhelm Knop (scientist) successfully prepared a solution which can provide aplant with all the nutrients it needs

The solution is known as nops Solution.

Calcium nitrate, Ca(NO3)2 0.8g

Potassium nitrate, KNO3 0.2g

Potassium dihydrogen phosphate, KH2PO4 0.2g

Magnesium sulphate, MgSO4 0.2g

Ferum (III) phosphate, FePO4 Trace

Distilled water 1 litre


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LEARNING OUTCOMES

Describe the development that leads tothe discovery of photosynthesis, State the substances required for

photosynthesis,

State the substances produced fromphotosynthesis, Draw & label the cross section of leaf State the function of each part of the

leaf with respect to photosynthesis, Explain leaf adaptation to optimise

photosynthesis, Explain how plants from different

habitats are adapted to carry out

photosynthesis.


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The Disc ov ery o f Photos yn thes i s

1692 Dutch scientist, Van Helmont carried outan investigation to study the nutrition of plants. He filled a big pot with exactly 91kg of dry soil

planted a plant (2.4kg) the surface coveredwith a metal sheet with small holes to allowwater to enter Van watered the plants for 5years consistently plant (increased to 75kg),soil (decreased by 0.057kg)

Van Helmont concluded that the increase inweight of the plant came from the water & notthe soil.


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The Discovery of Photosynthesis

1772 Joseph Priestly carried out anexperiment using mouse, candle & plants.

The plant had changed the air in the container. 1770s Jan Ingenhouse discovered that a plant

could only change the air container if there waslight. He also discovered that only the greenparts of the plant were able to do so. (light &chlorophyll both play a part in photosynthesis0

1780s Jean Senebier showed that the plantsgave out oxygen when they were provided withCO 2


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PHOTOSYNTHESIS

The biochemical process throughwhich light energy is absorbedby chlorophyll, and is used to

fuel the synthesis of sugarmolecules

The process where organiccompounds are synthesised fromwater & carbon dioxide in the

presence of sunlight &

chlorophyll .


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STRUCTURE FUNCTION OF THE

PARTS OF A LEAF


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Adaptations of Leaf for OptimalPhotosynthesis

The internal structure of a leaf, the shape of aleaf & the arrangement of leaves on a plants areall adapted for obtaining optimum light & CO 2

Table 2 The shape of a leaf is also adapted forphotosynthesis. Most leaves are broad & thin.

Large surface area enables the leaf to absorb

maximum light & CO 2 The thinness light & CO 2 need not travel too

far to reach every mesophyll cell
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Adaptations of Leaf forOptimal Photosynthesis

The arrangement of leaves is alsoadapted to optimize photosynthesis .

Most plants spread out their leaves insuch a way that there is minimaloverlapping known as leaf mosaic every leaf can receive sunlight.


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D PT TION OF PL NTS FROM DIFFERENT H BIT TS FOR

PHOTOSYNTHESIS

Two main aspects : The distribution of stomata The distribution of chloroplasts

Examples : Hibiscus : land Water lily : water surface Hydrilla : in the water Cactus : desert


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6 11:

THE MECHANISMOF

PHOTOSYNTHESIS


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LEARNING OUTCOMES

To identify the parts of chloroplastrelated to photosynthesis,

To explain the light reaction & dark

reaction of photosynthesis, To compare & contrast light reaction& dark reaction in photosynthesis,

To relate light reaction with darkreaction in photosynthesis,

To write an equation to representthe process of photosynthesis


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Photosynthesisoccurs in in thechloroplasts ofmesophyll cells &guard cells of theleaf.

Consist of two part :stroma & grana

Each granumcontain chlorophyllthat absorb energyof sunlight


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The process of photosynthesis is dividedinto two :

Light reaction Dark reaction

Lig ht reac t ion : occurs in the granum (containchlorophyll) photolysis of water

Dark react io n : occurs in the stroma (gel-likematrix contain enzymes) CO 2 is reduced tocarbohydrate in a process called fixation of CO 2

(reduction of CO 2)


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LIGHT REACTION Occurs in granum Chlorophyll captures light excites the

electrons of chlorophyll to higher level Light energy is used to split the water molecules

hydroxyl ions + hydrogen ions (photolysis ofwater)

4H 2O 4H + + 4(OH) -

The hydrogen ions combine with the electronsreleased by chlorophyll to from hydrogen atoms 4(H)+ + 4 electrons 4(H)

sunlight

chlorophyll


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LIGHT REACTION

The hydrogen atom are used indark reaction

toreduce CO 2. Each hydroxyl ion loses an electron to the

chlorophyll hydroxyl groups combine

together to form H 2O & O 2 4(OH) - - 4 electrons 4(OH) 4(OH) 2H 2O + O 2

Oxygen is released into the atmosphere & laterused for cellular respiration

Energy released from the excited electrons isused to form ATP


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DARK REACTION

Occurs in the stroma of the chloroplast Hydrogen atoms from light reaction areused in dark reaction to reduce carbondioxide to basic units of glucose (CH

2O)

Involves a series of complex chemicalreactions which require enzymes CO

2 + 4(H) (CH

2O) + H

2O

Six units of (CH2O) combine together toform a molecule of glucose


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DARK REACTION

6(CH 2O) C 6H12 O 6 Glucose is converted into starch, cellulose,

sucrose & lipids. When combined with

nitrogen protein Overall process :12H 2O + 6CO 2 C 6H12 O 6 + 6O 2 + 6H 2O

Water + carbon dioxide glucose + oxygen + water

sunlight

chlorophyll

sunlight

chlorophyll


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COMPARISON OF LIGHT REACTION& DARK REACTION

LIGHT REACTION DARK REACTION

SIMILARITIESBoth occur in the chloroplast

Both involve chemical reactions

Both are reactions related to photosynthesisBoth occur during the day

DIFFERENCESOccurs in granum Occurs in stroma

Requires sunlight Does not require sunlight

Involves photolysis of water Involves reduction of carbon dioxide

Produces water & oxygen Produces glucose

Substance required in reaction iswater

Substance required in reaction iscarbon dioxide


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6 12 :

FACTORS AFFECTINGPHOTOSYNTHESIS


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LEARNING OUTCOMES Identify the factors affecting the rate

of photosynthesis, Identify the factor that limits the rate

of photosynthesis at different lightintensities,

Explain the effects of temperature &concentration of CO2 on the rate ofphotosynthesis,

Explain the difference in the rate ofphotosynthesis in plants throughout theday based on the changes in lightintensity & temperature,

Identify some ways to meet the need ofincreasing the productivity of cropsbased on factors affecting the rate ofphotosynthesis.


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CONCENTRATION OF CO 2 Conc. of CO2 in theatmosphere varies between

0.03% to 0.04% Light intensity & temperature

are kept constant the rate

of photosynthesis increasesuntil a saturation point is reach After this point, any further

increase in the conc. of CO2has no effect on the rate ofphotosynthesis

Limited by other factors (lightintensity), not enough toincrease the rate ofphotosynthesis

Effect of concentration of CO2 on therate of photosynthesis

0

2

4

6

8

10

1 2 3 4 5 6 7 8 9 10 11

concentration of CO2

r a t e o

f p

h o

t o s y n t

h e s

i s


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LIGHT INTENSITY Temperature &concentration of CO2 are

kept constant, the rate ofphotosynthesis can beincreased by increasing the

light intensity up to the lightsaturation point. After this point, any further

increase in light intensityhas no effect on the rate ofphotosynthesis (limitingfactor : CO2 conc.)

Can be increased byincreasing the CO2 conc.

Effect of light intensity on the rate ofphotosynthesis at different levels of

CO2 concentration

02

4

6

8

10

1 2 3 4 5 6 7 8 9 10 11light intensity

r a t e

o f p h o t o s y n t h e s i s

karbon dioksida tinggikarbon dioksida rendah


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TEMPERATURE Dark reaction involves

enzymes The rate of photosynthesis

increases as the temperatureincrease enzymes moreactive

Optimum temp. is between30 oC to 35 oC

>40oC, the rate of reactiondecrease enzymesdenatured photosynthesisstops

If the light intensity is too low,any increase in temperaturewill not increase the rate ofphotosynthesis

Effect of temperature on the rate ofphotosynthesis at different light intensity

0

2

4

6

8

10

12

1 2 3 4 5 6 7 8

temperature

r a

t e o f p h o t o s y n t h e s i s


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RELATIONSHIP BETWEEN THE RATE OFPHOTOSYNTHESIS THROUGHOUT THE

DAY WITH THE CHANGES IN LIGHTINTENSITY & TEMPERATURE

Closely related & change throughout the

day Light intensity high, the temperature is

also high.

Tropical country, LI & T are at theirmaximum at noon time. The rate ofphotosynthesis is also maximum.


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If temperature increases above 40 oC, the rate ofphotosynthesis decreases.

In temperate country (4 seasons), LI & T changethroughout the year.

Winter : LI & T are very low. Photosynthesishardly occurs

Autumn : the rate of photosynthesis is at itslowest plants shed their leaves & lightintensity as well as the temperature are very low

Summer : LI & T are at their optimum level forphotosynthesis, the rate of photosynthesis is atits max.


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Summer is the best time for agricultural To overcome the problem, the plants need

to be planted in greenhouse. In a greenhouse, the conc. of carbon

dioxide, temperature & light intensity are atoptimum levels for photosynthesis.

The rate of photosynthesis is at itsmaximum throughout the year, ensure thecrop production throughout the year.


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6.13 Practising a Caring AttitudeTowards Plants

Must be thankful to plants & practise a caringattitude towards them

Why? Plants produce food as a source of energy for

us, maintaining the oxygen & carbon dioxidecontent in atmosphere

Without plants, there will be more CO2 & lessO2 in the atmosphere cause global warming

Not destroy forests @ chop down plantsindiscriminately. Should grow more plantsaround us.


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6.14 Technology in FoodProduction

To improve the quality & quantity of foodproduction in Malaysia through : Direct seeding from rice

Hydroponics & aeroponics Breeding Tissue culture Genetic engineering Soil management Biological control


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6 15 : TECHNOLOGICAL

DEVELOPMENT IN FOODPROCESSING


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Fresh food can last only for a short time,easily spoilt.

Need to be processed in order to lastlonger

Technology for food processing : Changing raw food materials to other forms Adding certain chemical


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The necessity for food processing are : Destroying m/organisms Extending the lifespan of food Avoiding food wastage Diversifying the uses of food, like milk & dairy

products Ensuring sufficient food supply because

processed food can last longer & they can be

easily sent to places with insufficient foodsupply


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FOOD PROCESSINGMETHODS

Cooking (to kill the bad bacteria) Using salt, sugar & vinegar (osmosis) Fermentation process (yeast is used glucose

ethanol + CO2) Drying (dehydration) Pasteurisation (heated to certain temp and

rapid cooling) Canning (sterilised at high temp, above 120oC,

the container is vacuum to kill bacteria,prevent bacteria from growing)

Refrigeration (slow down the action ofmicroorganism, temp low to -15oC)

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