Collaboration Teams - Members share responsibility for posting refined answers to the guided readings - succinct, relevant, clear, and with pictures or a video to compliment.
When contributing to the reading guide, follow these steps:
1) First complete the reading guide on your own from the cells unit page.
2) Write your response to a question in word and then copy it. Be sure to upload pictures and/or video for each question.
3) Click on the edit button and then go to the appropriate question and paste your answer below it. Sign your contribution with your first name and last initial and TEAM COLOR
4) Save the page by selecting "Save with comment" from the Save dropdown. Enter a comment (e.g. "I answered chp 26 question 3" - Tom S.) then click Save.

14-15, 20
6-8, 21

1. Label the diagram below.


Brett S.
This is a song about photosynthesis.
Alina Dyak

2. Explain the experiment reasoning that Van Niel used to understand photosynthesis.
That bacteria uses photosynthesis and slits H2's and uses the H to make sugar.
He also believed that plants split water from the hydrogen s and releases oxygen as a by product. All organisms need oxygen for photosynthesis
. light_reactions
2 H2A + CO2 → 2A + CH2O + H2O ^^^^he was the first to discover the light reaction
this is how the experiment is expressed
Brett S.

3. Use the diagram to label and identify the two broad stages of photosynthesis.


Brett S.

4. What is carbon fixation?
Carbon fixation is the initial incorporation of carbon into organic compounds *It occurs during Photosynthesis, while The Calvin Cycle also uses carbon fixation.
-Dahlia M.

external image 14_39_04_carb_fix_cycle.jpg

5. What is a photon?

A photon is biology's way of representing light as a molecule instead of a wavelength. It gives light a physical representation that can react with the environment. For example, in photosynthesis, light from the sun excites an electron to begin the plant's light-dependent reactions. Instead of simply saying that light traveling at a wavelength of 400 nm hits the plant, we say that a photon of 400 nm is emitted from the sun and hits the plant.
-Sam V
light as a wavelength
light as a wavelength
a photon of light
a photon of light
I chose the first picture to show how light is represented as a wave with varying color based on its wavelengths. In contrast, the second picture shows light as a single particle at around 600 nm (yellow light).

6. Why are leaves green?
The reason why we see leaves as green is because when we look at a leaf, the chlorophyll (the pigment found in leaves/plants) absorbs violet, blue, and red lights. However, the chlorophyll reflects the color green. This causes us to see leaves as green in our eyes

external image SB9-4.JPG
external image Green%20Leaves1186090534-800x600.jpg

.The picture on the left shows how mostly all of the colors from sunlight are absorbed
into the leaf. However the green is reflected to our eyes.

- Mike G

7. Describe Engelmann’s experiment and explain its results.

An action spectrum is prepared by making chloroplasts glow with light of different colors and then plotting wavelength against some measure of photosynthetic rate, such as CO2 consumption of O2 releases. Engelmann used bacteria to measure rates of photosynthesis in filamentous algae. Engelmann's experiment determined which wavelengths of light are most effective at causing photosynthesis.

external image wt0701d.jpg

Engelmann shot light onto the spiral chloroplast saw that oxygen-seeking bacteria introduced into the system collected in the region of the spectrum where chlorophyll pigments absorb. This action spectrum showed the effectiveness of light absorbed by accessory pigments in driving photosynthesis.

-Yellow Group

8. What is the difference between an absorption spectra and action spectrum?

The absorption spectra are the range of a pigment’s ability to absorb various wavelengths of light. The action spectrum is a graph that depicts the relative effectiveness of different wavelengths of radiation in driving a particular process.

This video shows the absorption spectra in a cool way

-Yellow Group

9. What happens to chlorophyll when it is hit by light? How does this relate to potential energy
The colors responding to the absorbed wavelengths disapear but energy can't, when the light hits the chlorophyll. One of the electrons has more energy when a molecule absorbs a photon of lights.
Tyler Hanssens

The molecule absorbs a photon of the light, but it can only absorb a photon with the exact same energy as the difference between the ground state and the excited state of the molecule. A particular compound absorbs only photons corresponding to specific wavelengths.

Sam Barton

10. Identify the following parts of a photosystem:

a. Photosystem -  composed of a reaction center surrounded by a anumber of light-harvsting complexes.

b. Light harvesting complex - consists of pigment molecules bound to particular proteins.
- The number and variety of pigment molecules enable light to be harvested over a larger portion of the spectrum.
Sam B
c. Reaction center - a protein complex that includes two special chlorophyll a molecules.

d. Primary electron acceptor- a specialized molecule sharing the reaction center with the pair of reaction-center chlorophyll
enables use of energy from light to boost an electron to a higher level
-sam b.


The light-dependent portion of photosynthesis is carried out by two consecutive photosystems (photosystem I and photosystem II) in the thylakoid membrane of the chloroplasts. The photosystems are driven by the excited chlorophyll molecules.

-Kelly Sinclair

11. What are the steps in noncyclic electron flow in photosynthesis?

1. Photon of light strikes a pigment molecule until it reaches the chlorophyll and exicites one of the electrons to a higher energy state.

2. This electron is captured by the primary electron acceptor.

3. An enzyme comes along and spits a water molecule into two electrons, two hydrogen ions, and an oxygen atom. The electrons are supplied to the chlorophyll molecules, which replaces an electron lost to the primary electron acceptor. The oxygen atom combines with another oxygen atom, creating oxygen gas.

4. Each electron passes from photosystem II to phosystem I via the electron transport chain. The chain is made up of an electron carrier, a cytochrome complex, and a protein called plastocyanin.

5. The fall of electrons to a lower energy level provides energy for the synthesis of ATP.

6. Light energy was transferred to photosystem I, which excites an electron of one of the two chlorophyll molecules there.

7. The photoexcited electrons are passed from photosystem I's primary electron acceptor down another electron transport chain through a carrier protein.

8. The enzyme NADP reductase transfers electrons from the carrier protein to NADP. Two electrons are required for its reduction to NADPH.



12. What is cyclic electron flow?

Cyclic electron flow is the path that electrons may take, under certain conditions, that consists of only photosystem I, not photosystem II. This flow does generate ATP but there is no production of NADPH and no release of oxygen. The cyclic electron flow makes up the difference of ATP that the Calvin cycle uses.


This picture explains the path electrons take during the cyclic electron flow. The faded out part is the normal flow of electrons called the noncyclic electron flow, but the area that is still in color is only the cyclic electron flow. It is a cycle that keeps generating ATP.


13. Use the diagram below to assist – but also write a response – compare and contrast chemiosmosis in mitochondria and chloroplasts. flipped_md_wht.gif


14. Use the diagram below to summarize the activities in the light reactions of photosynthesis.

A photon from light hits photosystem 2, exciting the electrons. (The electron come from a split water molecule). Oxygen gas is given off. The excited electrons travel down the electron transport chain, and pump H+ molecules into the inner thylakoid space. The electrons are then passed, to photosystem 1, and excited again by another photon. The electrons are passed down another electron transport chain, which pumps a few more H+ into the thylakoid space, then the electrons get passed to a molecule of NADP+ and reduced to NADPH. The H+ in the thylakoid then diffuse back into the stroma through a molecule of ATP Synthase. The hydrogen molecules allow the synthase to turn ADP into ATP.

-Ashley A

15. Describe and explain the overall purpose of the Calvin cycle and each phase listed below:
a. Calvin cycle - Consumes ATP as energy to consume NADPH as reducing power for adding high energy electrons to make sugar from simpler molecules

b. Carbon fixation  uses CO2 molecules one at a time. Enzyme catalyzing this step is rubisco, adds a five carbon sugar which then splits in half later

c. Reduction each molecule of the carbon receives a phjosphate group from ATP

d. Regeneration  carbon skeletons of five molecules of G3P are rearranged into three molecules of RuBP and uses three more molecules to do so which allows it to be ready for CO2 again
external image calvin_cycle.jpg


16. Label the diagram below of the Calvin Cycle.

17. What is a plant’s most valuable resource and why did plants need to evolve adaptations for hot, arid climates?

the plants most valuable resource is water, they don't want to dehydrate. the CO2 required for photosynthesis enters a leaf via the stoma which is the main avenue for transpiration of the evaporation of water. on dry days plants close their stomas to stop the water from escaping, they don't want to loss water.
Alecia Seliga

18. Why is photorespiration such a “waste”? flipped_md_wht.gif

19. Use the diagram below to explain C4 plants.

C4 plants calvin cycle in photosythesis occurs in the mesophyll cells in the leaves, it creates carbon fixation, which is CO2 combined together with 4 carbon atoms


Alecia Seliga

20. What are CAM plants and what is their “advantage”?
CAM plants are plants that open their stoma during the night and close their stoma during the day. During the night, the stoma is opened, it takes up CO2 and incorporates it into organic acids. Thus, desert plants (CAM plants) advantage is that they can conserve water and prevent CO2 from entering the leaves during the day (because their stoma is closed).
external image C4-and-CAM-plants.jpg external image DancingCactus_1_.gifSmiley-02-june.gif
found this picture comparing a regular plant with a CAM plant. I think it might be the same one from the textbook and the dancing cactus is there just because it is a CAM plant
external image cam.gif
This picture shows the contrast between what happens during the day and the night in the cell.

-Fernanda Robles

21. Use the diagram below to summarize the activities of photosynthesis.

Photosynthesis.pngReally good video about photosynthesis. Try to read and listen to the lyrics because it really explains the process well.

-Mike G.