Concept Check and Summary 8.2

Summary 8.2

-Chloroplasts like chemical factories, with energy from the sun, coverting it to energy for plants
-Sunlight is a form of electromagnetic energy which travels in waves
-distance between two adjacent waves is called wavelength
-range of types of electromagnetic energy, from short gamma rays to long wavelengths of radio waves is electromagnetic spectrum

-Different forms of electromagnetic energy have different wavelengths, shorter ones have more energy
-visible light are wavelengths that your eyes see as different colors are only a small fraction of thespectrum
-Visible light consists of wavelengths from about 400 nanometers to about 700 nm
-Shorter wavelengths have more energy than longer wavelengths.

-pigments and substance's color is due to chemical compounds called pigments
- light shines on a material that contains pigments: they can be absorbed, transmitted, or reflected
-the chloroplast pigments do not absorb green light well asmost of the green light passes through the leaf (is transmitted) or bounces back (is reflected), looking green because the green light is not absorbed.

-using paper chromotography, you could observe the different pigments in a green leaf

-he pigments dissolve in the solvents and are carried up the strip

-Different pigments travel at different rates, depending on how easily they dissolve and how strongly they are attracted to the paper

-within the thylakoid membrane, chlorophyll and other molecules are arranged in clusters called photosystems which contains a few hundred pigment molecules

-Each time a pigment molecule absorbs light energy, one of the pigment's electrons gains energy becoming very unstable

-Almost immediately,the excited electron falls back to the ground state and transfers the energy to a neighboring molecule, the energy "jumps" from molecule to molecule until it arrives at what is called the reaction center of the photosystem.

-Two photosystems are involved in the light reactions: first photosystem traps light energy and transfers the electrons to an electron transport chain, releases oxygen as a waste product, and also releases hydrogen ions.

- releases energy which the chloroplast uses to make ATP.

-mechanism of ATP production is very similar to ATP production in cellular respiration as electron transport chain pumps hydrogen ions across a membrane

-main difference is that in respiration food provides the electrons for the electron transport chain, while in photosynthesis electrons from chlorophyll travel down the chain.

- second photosystem can be thought of as the "NADPH-producing photosystem."photosystem produces NADPH by transferring excited electrons and hydrogen ions to NADP⁺

Concept Check 8.2

1. Explain why a leaf appears green.

A leaf appears green because the pigments located in the chlorphylls of the leaf do not absorb green light, therefore reflecting and bouncing off the light. When light shines on a material that contains pigments, three things can happen to the different wavelengths: they can be absorbed, transmitted, or reflected. The pigments in the leaf's chloroplasts absorb blue-violet and red-orange light very well. But the chloroplast pigments do not absorb green light well. Most of the green light passes through the leaf (is transmitted) or bounces back (is reflected) as leaves look green because the green light is not absorbed.

2. Describe what happens when a molecule of chlorophyll a absorbs light.

When a molecule of chlorophyll a which absorbs lightmainly blue-violet and red light and reflects mainly green light, it turns the substance into a green color. Chlorophyll a plays a major role in the light reactions of photosynthesis. Also, chlorphyll a is present in the reaction center which consists of a chlorophyll a molecule located next to another molecule called a primary electron acceptor. The primary electron acceptor is a molecule that traps the excited electron from the chlorophyll a molecule.

3. Besides oxygen, what two molecules are produced by the light reactions?

Besides oxygen, this process also releases hydrogen ions and NADPH molecules.

4. Where in the chloroplast do the light reactions take place?

The light reactions take place in both cases across a membrane—the inner mitochondrial membrane in respiration and the thylakoid membrane in photosynthesis.

Concept Check and Summary 8.1

Summary 8.1
-the chloroplasts is the cellular organelle where photosynthesis takes place
-chloroplasts contain chemical compounds called chlorophyll's that give these organelles a green color
-the leaves contain the most chloroplasts and are the site for most photosynthesis
-the chloroplasts are concentrated in the cells of the mesophyll, the inner layer of tissue, within a leaf
-Stomata, the tiny pores on the surface of the leaf letting CO2 enter the leaf and oxygen exit the leaf through this pore
-The veins carry water and nutrients from roots to the leaves delivering organic molecules produced in the leaves to other parts

-This is photosynthesis in cellular organelles

-chloroplast's structure is important like a mitochondria
-Have an inner and an outer membrane with a thick fluid called stroma in inner membrane
-disk-shaped sacs called thylakoids are in the stroma are many
-thylakoids are in stacks, grana


-the opposite of cellular respiration occurs in photosynthesis
-Electrons from water are boosted by the energy from sunlight allowing chlorplasts to use elecrtrons CO2 and hydrogen ions to produce sugar

-Photosynthesis occurs in two main stages: the light reactions and the Calvin cycle

-The light reactions convert the energy in sunlight to chemical energy.

- chlorophyll capture light energy to remove electrons from water splitting into oxygen and hydrogen ions

-oxygen is waste making energy rich products NADPH and ATP.

-The Calvin Cycle makes sugar from carbon dioxide, hydrogen ions and the electrons carried by NADPH

- enzymes for the Calvin cycle are outside the thylakoids, dissolved in the stroma.

-ATP made by the light reactions provides the energy to make sugar

- Calvin cycle does not directly require light to begin

-Calvin cycle requires two inputs supplied by the light reactions, ATP and NADPH.

Concept Check 8.1
1. Draw and label a simple diagram of a chloroplast that includes the following structures: outer and inner membranes, stroma, thylakoids.

http://www.helpsavetheclimate.com/chloroplast1.gif

2. What are the reactants for photosynthesis? What are the products?
The reactants for photosynthesis are 6 Carbon Dioxide molecules and 6 Water molecules. The products are glucose and 6 oxygen molecules.

3. Name the two main stages of photosynthesis. How are the two stages related?
The two main stages of photosynthesis are the light reactions and the Calvin cycle. The two stages are related in that they are both working together to make photosynthesis a possible action and that they both concert sunlight into chemical energy used for plants. These stages both help create ATP using sunlight and the Calvin cycle follows the stage of the light reaction.

Vocabulary Section 8.1-8.2

8.1 Section Vocabulary
Chloroplast: the cellular organelle where photosynthesis takes place
Chlorophyll: A type of chemical compounds that chloroplasts contain, which give these organelles a green color. All green parts visible contain chloroplasts and can carry out photosynthesis
Stroma: A thick fluid of the inner membranes of a chloroplast which has a inner and outer membrane, similar to the mitochondria matrix.
Thylakoids: Suspended in the stroma are many disk-shaped sacs. They each have a membrane surrounding an interior space, arranged in stacks called grana.
Light reactions: Convert the energy in sunlight to chemical energy
Calvin Cycle: makes sugar from the atoms in carbon dioxide plus the hydrogen ions and high energy electrons carried by NADPH. the enzymes for the Calvin cycle are located outside the membrane and dissolved in the stroma.
8.2 Section Vocabulary

Wavelength: the distance between two adjacent wave
Electromagnetic spectrum: The range of types of electromagnetic energy, from the very short wavelengths of gamma rays to the very long wavelengths of radio waves
Pigments: a substance's color is due to chemical compounds
Paper chromatography: a laboratory technique which allows people to observe the different pigments in a green leaf
Photosystems: within the thylakoid membrane, chlorphyll and other molecules are arranged in clusters, each containing a few hundred pigments molecules including chlorphyll.