PHOTOSYNTHESISPHOTOSYNTHESISPHOTOSYNTHESISPHOTOSYNTHESISstate what photosynthesis isstate what photosynthesis is

state the factors required for state the factors required for photosynthesisphotosynthesis

state the products of state the products of photosynthesisphotosynthesis

Check it!

Plants in Action

What is the process that uses the sun’s energy to make simple sugars?

Photosynthesis is the process in which green plants

use light to produce food green plants manufacture glucose

from water and carbon dioxide in the presence of sunlight trapped in their chlorophyll.

oxygen is released in the process glucose is stored as starch in the plant

+ +Carbon dioxide

Water Glucose Oxygen

Light energy from the sun

Trapped by chlorophyll

CARBON DIOXIDEfrom the air

WATERabsorb by the roots from the soil

CHLOROPHYLL a green pigment in the leaf of green plantabsorbs the sun’s energy

convert sun’s energy to glucose GLUCOSE

stored as starch in other parts of plant OXYGEN

release to the air

+ +

PlantsLeaves are green because they containthe pigment:

chlorophyll

Leaves have a Leaves have a large surface area large surface area to absorb as much to absorb as much light as possibleas possible

"Thanks for the Glucose!""Thanks for the Glucose!"

StomaThis opening how plants exchange

gases!Check it! Can you name the two

important gases that go in and out of the leaves?

Why are the Why are the stomata stomata located on the located on the underside of underside of leaves?leaves?

REQUIREMENTS OF PHOTOSYNTHESIS

chlorophylllight

carbon dioxide

water

To know whether photosynthesis is take place in

a plant :• We can test for the presence of starch in the

leaves

Step Purpose Boiling the leaf in the water

To break the cell wall

Heating the leaf in alcohol

To remove the chlorophyll in the cells

Dipping the leaf in hot water

To soften the leaf

Adding iodine solution onto the leaf

To test the presence of starch in the leaf

Alcohol was heated in a beaker of hot water

Method of heating is WATER BATH

Why should the alcohol be heated in this manner?

Alcohol is flammable, so it will catch fire

when heated directlly

If starch is present in a leaf, the leaf turns

blue black/dark blue when tested by iodine

solution

Lets see the video

Determining the requirements of photosynthesis

• To investigate whether carbon dioxide is required for photosynthesis

1. A potted plant was kept in the dark for two days

2. A potted plant was exposed to sunlight for two hours

3. Leaves X and Y were tested for the presence of starch

function potassium hydroxide pellets to absorb carbon dioxide in conical flask X

Determining the requirements of photosynthesis

• To investigate whether carbon dioxide is required for photosynthesis

Leaf Presence of carbon dioxide in

flask

Observation Inference

X Absent The leaf turn brown

Starch is not present, photosynthesis does not take place

Y Present The leaf turned blue black

Starch is present, photosynthesis takes place