AUTOTROPHS• All organisms require a source of energy.• There are two types of autotrophs:

• 1. Chemoautotrophs (or chemotrophic autotroph),

2. Photoautotrophs

Chemoautotrophs

• (Gr:chemical, auto= self, troph (nourishment) in addition to deriving energy from chemical reactions, synthesize all necessary organic compounds from carbon dioxide.

• Chemoautotrophs use inorganic energy sources, such as hydrogen sulfide, elemental sulfur, ferrous iron, molecular hydrogen, and ammonia. Most are bacteria that live in hostile environments such as deep sea vents and are the primary producers in such ecosystems.

PHOTOSYNTHESIS

• Autotrophic Process: Plants and plant-like organisms make their energy (glucose) from sunlight.

• Stored as carbohydrate in their bodies.

• 6CO2 + 6H2O +light energy C6H12O6 + 6O2

Why is Photosynthesis important?

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!!

Photosynthesis-starts to ecological food webs!

Plants use the pigment chlorophyll to absorb light energy 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.

Photo-synthesisPhoto-synthesismeansmeans "putting together with light.""putting together with light."

Why do some plants appear green?• Green plants are green because they contain a pigment

called chlorophyll. Chlorophyll absorbs certain wavelengths of light within the visible light spectrum.

• chlorophyll absorbs light in the red (long wavelength) and the blue (short wavelength) regions of the visible light spectrum.

• Green light is not absorbed but reflected, making the plant appear green.

• Chlorophyll is found in the chloroplasts of plants. There are various types of chlorophyll structures, but plants contain chlorophyll a and b.

How do we know that plants make carbohydrates from just carbon dioxide water and light energy?• For example:

Jan Baptisa van Helmont (1648) planted a willow branch weighing 5 pounds into 200

pounds of soil and then after 4 years the tree weighed 169 lbs. and the soil was still

nearly 200 lbs.

Experiments!Experiments!

Photosynthesis

Carbon dioxide + water glucose + oxygen

sunlightsunlight

absorbed by chlorophyllabsorbed by chlorophyll

66COCO22 + + 66HH22O + energy O + energy C C66HH1212OO66 + + 66OO22

As can be seen from the equation for photosynthesis, the wood, bark, and root came from water and carbon dioxide.

Check it!

Plants in Action

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

Answer the following:

1. How does the leaf get the raw materials for photosynthesis?

•A) carbon dioxide

•B) water

•C) light energy

2. How does the plant utilize the glucose produced in the process of photosynthesis?

Plant leaves have many types of cells!

Cross-section of a leaf

Plant Cells

The photograph below is an elodea leaf X 400. Individual cells are clearly visible. The tiny green structures within the cells are chloroplaststhis is where photosynthesis

happens.                                    

PlantsLeaves are green

because they contain

the pigment:

chlorophyllchlorophyll

Leaves have a Leaves have a large surface area large surface area to absorb as much to absorb as much light as possiblelight as possible "Thanks for the Glucose!""Thanks for the Glucose!"

Chloroplasts make the oxygen too!

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?

PHOTOSYNTHESIS

• Absorbing Light Energy to make chemical energy: glucose!• Pigments: Absorb different colors of white light

(ROY G BIV)• Main pigment: Chlorophyll a

• Accessory pigments: Chlorophyll b and Carotenoids

• These pigments absorb all wavelengths (light) BUT green!

PHOTOSYNTHESIS

• Why do we see green? • Green color from white light

reflected NOT absorbed• Chloroplast: organelle

responsible for photosynthesis• Chlorophyll: located within

Chloroplast• Green pigment

Photosynthesis

Glucose provides the energy and carbon needed to make other plant materials like wax and proteins.

• In plants and simple animals, waste products are removed by diffusion. Plants, for example, excrete O2, a product of

photosynthesis.

EQUATION FOR PHOTOSYNTHESIS

6CO6CO22 + + 6H6H22OO + + ENERGYENERGY CC66HH1212OO66 + + 6O6O22

CARBON CARBON DIOXIDEDIOXIDE

WATERWATER

GLUCOSEGLUCOSE

OXYGENOXYGEN

The end!

PHOTOSYNTHESIS

• What affects photosynthesis?• Light intensity: as light increases, rate of

photosynthesis increases

PHOTOSYNTHESIS

• What affects photosynthesis?• Carbon Dioxide: As CO2 increases, rate of

photosynthesis increases

PHOTOSYNTHESIS

• What affects photosynthesis?• Temperature:

• Temperature Low = Rate of photosynthesis low

• Temperature Increases = Rate of photosynthesis increases

• If temperature too hot, rate drops

Check it!

1. The process that uses the sun’s energy to make simple sugars is _____________.

A. Cellular respiration

B. Glycolysis

C. Photosynthesis

D. Photolysis

Check it!

2. The function accomplished by the light-dependent reactions is ______________.

A. Energy storage

B. Sugar production

C. Carbon fixation

D. Conversion of sugar