Photosynthesis

&

Cellular Respiration

Directly or indirectly, nearly all the energy for life comes from the SUN

Heterotrophs

can not make its own food and must obtain energy by eating other living organisms

Autotrophs

Captures energy to make their own food!

BUT HOW?

How do organisms obtain energy?

The Big Idea…

Photosynthesis vs.

Respiration

Cellular respiration takes place within

all living things

Only cells that contain chlorophyll can

perform photosynthesis

Ex. Plants, plant-like Protista, Eubacteria

Photosynthesis and cellular respiration form a

cycle in which the products of one metabolic

pathway form the reactants of the other

metabolic pathway

Photosynthesis produces oxygen

and glucose.

Cellular respiration produces carbon

dioxide and water.

A continuous cycle…

Photosynthesis vs.

Respiration

Photosynthesis

Photosynthesis

Anabolic pathway in which

light energy from the Sun is

converted to chemical energy

for use by the cell.

ANABOLIC = chemical reactions that use

energy to build larger molecules from smaller

ones

What is the equation for the chemical

reaction of photosynthesis?

Six molecules of carbon dioxide react with six

molecules of water, in the presence of solar

energy, to form 1 molecule of glucose and six

molecules of oxygen.

What is the equation for the chemical

reaction of photosynthesis?

E

And you can also think of it this

way…

Describe photosynthesis

Takes place in the chloroplasts, using chlorophyll,

the green pigment in plants

Chlorophyll turns water (H2O) into hydrogen and

oxygen when energized by sunlight

CO2 combines with the

stored energy in the

chloroplasts through a

chemical reaction to make

glucose

Carbon dioxide initially enters the leaf

through holes called stomata, and excess

water can exit through the stomata

Pea Leaf Stoma, Vicea sp. (SEM x3,520). This image is copyright Dennis Kunkel at www.DennisKunkel.com

Describe photosynthesis

We cannot absorb energy from our star. We

must get our food from autotrophs, the first

step in the food chain

Why is this important to us?

Remember…

So what is

cellular

respiration?

Cellular Respiration

Catabolic pathway in which

organic molecules are broken

down to release energy for use

by the cell.

Performed by all living organisms!

CATABOLIC = chemical reactions that release

energy by breaking down large molecules

into smaller molecules

Cellular Respiration

Do you remember which organelle provides

energy for the cell?

The mitochondria!

What is the chemical equation for

cellular respiration?

-E

See page 233 in your book for a good

picture of the metabolic pathways

between chloroplasts and

mitochondria