P H O T O S Y N T H E S I S

Metabolism involves either using energy to build up molecules or breaking down molecules in which energy is stored. When molecules are built, energy is stored in the chemical bonds of those molecules. When molecules are broken down, the energy stored in the chemical bonds is released.

What is photosynthesis? Photosynthesis is the process by which light energy is converted to chemical energy.

Organisms that convert light energy into chemical bond energy are called autotrophs. Most autotrophs are photosynthetic, like plants.

*Some organisms actually do Chemosynthesis, rather than photosynthesis. This process involves making their own food by oxidizing inorganic (nonliving) compounds. Such as bacteria, which live near volcanic ocean vents, swamps or hot springs.

Yellow Stone National Park Hot Spring Deep sea volcanic vent

+ + + How does photosynthesis work? Solar energy Carbon Dioxide Water Carbohydrate Oxygen

Photosynthesis utilizes only the visible light spectrum.

Energy from the sun travels in the form of discrete packages called photons. These photons hit the pigment molecules, called chlorophyll, inside the chloroplasts. These molecules are exited and start the photosynthesis reaction. The reason plants look green is because this is the color of light that bounces back to us.

Fall leaf colors are made by the absence of chlorophyll and the presence of pigments called carotenoids and xanthans. These pigments absorb different wavelengths than chlorophyll, so that plants are able to absorb more light during photosynthesis.

Most living creatures depend on photosynthesis, directly or indirectly, in order to survive. Plants use it to make their own food. Animals eat plants and other animals, which eat plants.

Most animals are heterotrophs, which literally means “other eating.” they depend on plants or other animals for their food.

Plants are called Primary Producers, because they are at the bottom of the food chain; they produce the first food in the chain. Almost all other living organisms depend on plants for energy. They are also called autotrophs, because they make their own food.

Photosynthesis

Photosynthesis Gas Exchange Stomata (singular, stoma) are openings in a leaf or stem that enable gas exchange to occur. Each stoma is opened and closed by two guard cells. Transpiration is the process by which plants release water vapor into the air through stomata. If too much water is lost, a plant wilts.

Photosynthesis

Inner Structure of the Chloroplast:

Light Dependent Reaction: This reaction takes place during the daytime. During these reactions, chlorophyll, green pigment within the thylakoid membranes, absorbs solar energy and energizes electrons. This energy is captured and later used for ATP production.

Light dependent reactions take place in the thylakoid membrane inside the chloroplast .

The chemical reaction to memorize: 6CO2 + 6H2O (+ light energy) = C6H12O6 + 6O2   

Photosynthesis: The Origin Cyanobacteria (blue-green algae) were probably the first photosynthetic organisms Cyanobacteria raised the oxygen concentration in the atmosphere from 1% to 21%

Chloroplasts All photosynthetic organisms except cyanobacteria have chloroplasts Cyanobacteria essentially are chloroplasts

Photosynthesis in review: Conversion of light energy into chemical energy stored in organic compounds. What does that mean?????????

Photosynthesis Light from the sun hits the leaves of plants and trees. This causes chemical reactions to occur which provides energy for the cells of the plants.

Capturing Light Energy Photosynthesis Capturing Light Energy Photosynthesis is the process by which plants algae, and some bacteria use sunlight, Carbon dioxide, and water to make food. Chlorophyll is a green pigment that captures light energy by photosynthesis. Chlorophyll is located in structures called grana. Grana are stacks that are found in the chloroplasts of a plant cell.

Capturing Light Energy, continued Photosynthesis Capturing Light Energy, continued Making Sugar The light energy captured by chlorophyll is used to help form glucose molecules. In turn, oxygen gas (O2) is given off by plant cells. Photosynthesis can be summarized by the following chemical equation:

Photosynthesis: The Basic Plan Water, taken up by the roots, and carbon dioxide, entering through the stomata meet in the chloroplast Chemical reactions, powered by light energy, produce glucose

Grana are made up of flattened sacs called thylakoids. Chloroplasts are located in the leaves of plants. They absorb light from the sun to begin the process of photosynthesis. The chloroplast has 2 membranes which surround it : the outer membrane and the inner membrane. Grana are made up of flattened sacs called thylakoids. The fluid-like solution found inside the membranes is called the stroma.

Light reactions take place in the thylakoid membrane Light reactions take place in the thylakoid membrane. There are several steps involved in a light reaction.

Light independent reaction (Also called the Calvin Cycle): These reactions take place at nighttime. There are three cycles to this kind of reaction. 1. Carbon dioxide fixation is the method of generating organic molecules. 2. Reduction 3. Regeneration of CO2 acceptor

The equation you need to memorize: 3 RuBP 5 PGAL 3 ADP + P 3 ATP

Light independent reactions take place in the stroma, the space inside the chloroplast, which surrounds the thylakoids.

Terms to know: Photosynthesis Thylakoid Granum Stroma Stomata Photosystem Herbivore Carnivore Primary Producer Autotroph Heterotroph ATP Photon Chlorophyll

Be able to describe or write the equation for the following: 1. Photosynthesis Light and Dark Reactions 2. Equations for the above 3. Explain why leaves appear to be green 4. Tell what part of the light spectrum is used for photosynthesis 5. Explain where the light and dark reactions take place 6. Explain one other method autotrophs use to synthesize inorganic molecules into useable organic “food”

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