Photosynthesis

Objective 1• To trace the primary food source in

a food chain to the green plant

The Primary Food Source

• Green plants always found at the beginning of the food chain.

• Why?

• The only organisms that can produce their own food

• They are called producers

Objective 2• To define photosynthesis

PHOTOSYNTHESIS

• Photo = light• Synthesis = building up

DEFINITION

PhotosynthesisProcess by which plants use water & carbon dioxide to make carbohydrates in the

presence of light and chlorophyll.

Oxygen is given off during the process.

Objective 3• To understand the conditions

necessary for plants to make their own food

INTRODUCTION

Yummy!!!What are the similarities

between baking a cake and photosynthesis?

REQUIREMENTS

• Raw materials– Carbon dioxide– Water

• Conditions– Chlorophyll– Light energy

Answers• Review 1

1. An organism that make its own food, e.g. green plant

2. They make their own food by photosynthesis

• Review 21. Textbook pg 19

• Review 3– Raw materials: water & carbon dioxide– Conditions: sunlight & chlorophyll– End products: oxygen & glucose

Objective 4• To outline the process of

photosynthesis by which plants manufacture carbohydrates using raw materials

• To state that food is stored as starch in the plant

CARBON DIOXIDE

• From air• Enters leaf by diffusion• Pores: Stomata/Stoma• Found underside of the leaf

Carbon dioxide

WATER

• From soil• Absorb by root hair• Enter by osmosis• Transport by xylem vessel

Soil

Water

Water

Root Hair

To Xylem Vessel

Water

Water

CHLOROPHYLL

• Structure: Chloroplast• Green pigment: Chlorophyll• Absorb light energy

Leaf

Plant Cell

Chloroplast

LIGHT ENERGY

• Chlorophyll absorbs light energy from sun

• Light energy converted into chemical energy

• Chemical energy is needed to convert carbon dioxide to carbohydrate

• Series of chemical reactions

Xylem

H2O

CO2

H2O

H2O

CO2

Carbon Dioxide +Water

Light

ChlorophyllGlucose + Oxygen

O2

O2

Surroundings

STARCH

WORD EQUATION

CARBON DIOXIDE + WATER

GLUCOSE + OXYGEN LIGHT ENERGY CHLOROPHYLL

Review 4

1. Water, carbon dioxide, sunlight2. Chlorophyll3. It absorb the sunlight/light energy4. Chloroplasts5. The root hair absorb the water by osmosis6. Xylem vessel7. It enters through the stomata by diffusion8. Carbon dioxide + water glucose +

oxygen

Light energy

Chlorophyll

Objective 5• To state the conditions that affect

the rate of photosynthesis

LIMITING FACTORS

• Rate of photosynthesis is affected by:– carbon dioxide, – light intensity and – temperature

LIGHT INTENSITY

• Higher light intensity, faster the rate of photosynthesis

• After awhile, the rate will remain constant

• Due to limiting factors such carbon dioxide concentration or temperature

CARBON DIOXIDE

• Carbon dioxide in the air is 0.03%• Increasing the carbon dioxide

concentration to 0.1% increases the rate of photosynthesis

• After awhile the rate will remain constant due to limiting factor such as temperature and light intensity

TEMPERATURE

• Temperatures below 40°C, as it rises, the rate of photosynthesis is faster

• At 40°C, photosynthesis begins to decrease

• As temperature rises above 40°C, photosynthesis stop as the enzymes denatured

Other important things that plant need to grow

• Minerals– Found in soil and fertilizers– Magnesium: chlorophyll formation– Nitrogen: for making proteins

Objective 6• To compare the conditions for

healthy growth of ornamental plants and large scale crop productions

Ornamental Plants

• Use for decoration

• Usually grown in greenhouses

Ornamental Plants• Conditions needed

– Types of soil – sand, organic matter– Minerals – artificial or natural fertilizers– Humidity - humid conditions better, by

spraying and misting– Temperature - warm– Light - bright– Carbon dioxide – burning fuels– Water – watering plants– Pests – hand pick/pesticides

Large scale crops

• Includes rice, wheat, vegetables

• Relies on farming methods and agricultural technology

• Plant in open field

Large scale crops

• Light, humidity, temperature and water – cannot be controlled

• Fertilizers – mostly used artificial fertilizers, machines

• Pests – planes to spray pesticides over farm areas

Experiment Question

Experiment: Testing for starch in green leaves

• What does hot water do to the leaf?– Kills the leaf to stop photosynthesis

• What does the alcohol do to the leaf?– Breaks down chlorophyll – take the green colour

out of the leaf

• What is the original colour of iodine?– brown

• What does it mean when iodine turn blue-black?– Starch is present