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Photosynthesis

andRespiration

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Lesson ObjectivesDefine photosynthesis

State the word equation for photosynthesis

State that enzymes are involve in

photosynthesis.

[Factors that will affect the enzyme action]

State the presence of stomata wheregaseous exchange on plants takes place.

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3

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Where does the wood come from?

An experiment carried out byJean Baptistevan Helmont (1580-1644)

4

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This is an extract from van Helmont

s diary

I took an earthenware pot in which I put 90 kg of earththat had dried in a furnace.

I moistened it with rain water and implanted in it a trunk of

a willow tree weighing 3 kg. I planted it in the garden andcovered the earth with an iron lid punched with many

holes to allow rain water in.

At length, after 5 years, the tree did weigh 76kg. I again

dried the earth in the vessel and found it weighed almost

90kg. Therefore 73kg of wood, bark and roots arose out ofwater only.

5

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THINK-PAIR-SHARE

PHOTOSYNTHESIS AND ENZYMES

What was the change in mass of the tree?

What was the change in mass of the soil?

What did van Helmont conclude from theexperiment?

Do you agree with his conclusion?

What other explanations could there be for theresults he found?

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What is Photosynthesis?

Photosynthesis is a process to produce organicfood substances by using light energyandinorganicsubstances

Chlorophyllor some other photosyntheticpigments in the plant absorb light from thesurrounding environment and the Sun.

The energy absorbed is used to drive thereaction.

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General overview of Photosynthesis

During photosynthesis, green plants(1) Trap sunlight with a green pigment called

chlorophyll

(2) Take in carbon dioxide through tiny

openingscalled stomata(singular: stoma)(3) Take in water from the soil through root

hairs

To form carbohydrates such as glucose,which is usually converted to starch.

Light energy Chemical energy

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Pictorial representation

Entrance of carbon dioxide isthrough the stomata of the leaf

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Photosynthesis

What are involved?

Chlorophyll

SunlightCO2

Water

Equation:

6CO2+ 6H2O C6H12O6+ 6O2

Light energy

Chlorophyll

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How do we test for the starch that

plants make from glucose?

To test for starchyou add iodine solution. If starch ispresent the yellowish brown iodine solution

changes to a blue black colour.

11

Pear stained with iodinesolution

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Photosynthesis

Equation:

6CO2+ 6H2O C6H12O6+ 6O2

Light energy

Chlorophyll

Enzymesare involve in the process of

photosynthesis.

Can you recall some of the factors thatcan affect enzyme action?

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RECALL!

What are the factors that affect enzyme action?

Temperature. Very low temperature enzymes are

inactive Optimum temperature enzymes work

fastest rate

High temperature enzymes denature

pH

Extreme pH enzymes denature

Optimum pH enzymes are active.

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Lesson Objectives

Define respiration

State the word equation for respiration

State the use of energy in the human body.

State that enzymes are involve in respirationand the factors that will affect the enzymeaction of respiration.

Discuss the experiment to show respiration in

living things. State the differences between photosynthesis

and respiration.

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Why do Living Things Respire?

Light energy is converted to chemical energyby the process photosynthesis and stored inglucose

Respiration is the breakdown (oxidation) offood with the RELEASE of energy in living cells.

Energy released is used for

1. Contraction and relaxation of muscles to

bring about movement

2. Excretion of waste products from body

3. Growth and reproduction

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So where does respiration take

place?In our mitochondria!

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Definition of RespirationBreakdown(oxidation) of food

substances (molecules) to release

energy.Carbon dioxide and water released

as waste products

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Where do we get the energy to

do work?

FOOD

DIGESTION

ABSORPTION INTO

BLOODSTREAM

TRANSPORT TO ALL CELLS

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GLUCOSE

+CARBONDIOXIDE

+ WATER

+ OXYGEN ENERGY

WasteProducts of

AerobicRespiration

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GLUCOSE

+CARBONDIOXIDE

+ WATER

+ OXYGEN ENERGY

Glucose is not burnt!

but OXIDISED

This reaction is facilitated by the actionof ENZYMES.

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Overall equation for aerobic

respiration of glucose

The process is more complicated thanequation shown

Respiration is carried out in series of

enzyme-catalysed reactions

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GLUCOSE

+CARBONDIOXIDE

+ WATER

+ OXYGEN ENERGY

Is the energy requiredonly for exercise?

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What processes in our bodiesrequire energy?

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Examples of energy consuming

processes in organismsSynthesis of new protoplasm for growth and repair

Synthesis of proteins from amino acids

Active transport in absorption of food substancesby small intestines

Muscular contractions (heartbeats and respiratorymovements)

Transmission of nerve impulses

Cell division

During respiration, energy is also released as heat to

keep body warm

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All living things (animals& plants ) carry out

respiration ALL THE

TIME.

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Finally, a little more

exercise.

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Summing Up

1. Respiration is the breakdown of

________________ with the release of _______ inall living cells.

food substances energy

4. The glucose is not burnt but _________.

2. ________ + oxygen energy + _________

+ ________.

glucose

carbon

dioxide

water

oxidised

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Uses of the energy

Musclecontraction

Growth and

repair

Activetransport

Production

of heat

Transmission

of nerveimpulses

Proteinsynthesis

Cell

division

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Difference between

photosynthesis and respirationFactor Photosynthesis Respiration

Where does it

take place?

In the cells containing

chloroplast

In all living cells

When does it

take place?

Only when sunlight is

available

All the time

What happens

to oxygen?

Oxygen gas is

produced

Oxygen gas is

used up.

What happensto chemical

energy?

Chemical energy isstored in foods

Chemical energyis released from

food.

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Experiments: Respiration in action!

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Experiments: Respiration in action!

Jar Content Purpose

A Potassiumhydroxide solutn

To absorbcarbon dioxide from air

B Lime water The limewater should remain clear toshow that no more carbon dioxide fromair to interferethe experimental result.

C Living organism When living organisms carry outrespiration, they producecarbon

dioxide.

D Limewater White precipitate is formed in limewaterto show that carbon dioxide isproduced by living organisms when theycarry out respiration.

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Lesson Objectives Identify on diagrams the structure and function

of the respiratory system.

Describe the structure of the alveoli and how it

is adapted to its function.Explain the process of gaseous exchange

between alveoli and blood capillaries using

diffusion.

State the difference in the compositions of

inhaled and exhaled air.

Discuss the differences between breathing and

respiration.

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Cellular Respiration

Cellular respiration

A chemicalprocess by which

energy is releasedfrom breaking downof food in cells.

glucose + oxygen

carbon dioxide +water + energy

released

ExternalRespiration

Aphysicalprocessby which oxygen(required forrespiration) carbondioxide, a wasteproduct of respirationare exchanged.

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Involves 2 processes: Breathing

a muscular, pumping action that takes inair from the atmosphere and moves it to

the lungsGaseous Exchange

diffusionof oxygen and carbon dioxide

from a region of higherconcentration to a

region of lowerconcentrationbetween lungs and blood

between bloodand tissue cells

External Respiration

ExternalResp.

http://www.unis.org/UNIScienceNet/BodyCells_cap.jpghttp://www.unis.org/UNIScienceNet/BodyCells_cap.jpghttp://www.unis.org/UNIScienceNet/BodyCells_cap.jpghttp://www.unis.org/UNIScienceNet/BodyCells_cap.jpg

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O2

CO2

1

CO2

O2

Cell

Capillary

Respiration in human involves 3

related process

2

3

Cellular respiration

Breathing

Transport of gases bythe circulatory system

3

2

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~ Breathing

~ Gaseous

exchange

The chemical

change that

takes placein all living

cells

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Parts of Human

Respiratory System

Lungswhich lie in thethorax (chest cavity)

Protected byrib cageRibs may be moved by

intercostal muscles

A sheet of muscle, the

diaphragm, lies belowthe lungs

It separates the thorax from

the abdomen

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39

(dome-shaped

when relaxed)

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In our lungs

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Components of

Respiratory System (cond)

nostrils and mouth

pharynx (throat)larynx (voice box)

trachea (windpipe)

bronchi

bronchiolesair sacs (alveoli)in

lungs

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The air sacs(alveoli) are

richly supplied

with bloodcapillaries.Gaseous

exchange takes

place here.

In our lungs

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Human Gas Exchange System

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Human Gas Exchange System:

Alveoli (air sacs)

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How are the lungs adapted for

efficient gas exchange?Numerous alveoli in

lungs

One cell thick

alveolar wall

Thin film of moisturecovers surface ofalveolus

Walls of alveoli arerichly supplied withblood capillaries

Provides large surfacearea for gaseousexchange

Provides short diffusiondistance for gases,hence faster rate ofdiffusion

Allows oxygen to

dissolve in it Flow of blood maintains

the concentrationgradient of gases

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Gas Exchange in the Alveoli

Occurs by diffusion

Blood entering the lungs has lowerconcentration of oxygen and higher

concentration of carbon dioxide as comparedto atmospheric air entering alveoli in lungs.

Concentration gradient for oxygen and carbondioxide is set up between bloodand alveolar

airOxygen diffuses from alveolar air into blood

capillaries and carbon dioxide from bloodcapillaries into alveolar air

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Diffusion gradient is maintained by

Continuous flow of blood through capillary.

Moves the O2rich blood away.

Brings in CO2rich blood to the alveolus

Movement of air in and out of alveolus.

Brings in O2rich air.Removes CO2from alveolus

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Difference between breathing

and respirationBreathing Cellular Respiration

It is a physical

process as no newsubstances areformed

It is a chemical

process as newsubstances areformed.

Energy is not released Energy is released

It takes place outsidethe cells

It takes place insidethe cells.

It does not involveenzymes.

It involves enzymes.

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Differences in the composition of

inspired air and expired air

Substance Inhaled air Exhaled air

Oxygen 21% 16%

Carbon

dioxide

0.04% 4%

Water

vapour

Low High

Temperature At room

temperature

Close to body

temperature