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photosynthesis
Section 8.2 Photosynthesis..basics and light and dark reactions
Question | Answer |
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What is the energy conversion done by some types of autotrophs called photoautotrophs | they convert light energy into chemical energy ( energy is stored in the chemical bonds of glucose, a carbohydrate) |
What is the overall chemical equation for photosynthesis ( not necessary to be balanced but include reactants , products, and information over the arrow | carbon dioxide combines with water in the presence of light, chlorophyll, and enzymes to produce glucose and oxygen |
What names are given to the two phases of photosynthesis | light reaction and calvin cycle (also called dark reaction) |
give a general description of the light reactions of photosynthesis | light energy is absorbed and converted into chemical energy in the form of ATP and NADPH to be used for the second phase of photosynthesis |
give a general description of the dark reactions of photosynthesis or the calvin cycle ( light-independent reactions) | the ATP and NADPH made in the light reactions are used to make glucose when they are combined with carbon dioxide |
What can happen to glucose once it is formed | it can join with other glucose molecules to make starch ( a polysaccharide for storage)... or they can also be used to make other organic molecules such as proteins, lipids, and nucleic acids |
What is the organelle associated with photosynthesis | chloroplast |
Name two energy storage molecules associated with photosynthesis | ATP and NADPH |
What organelle captures the light during photosynthesis | chloroplast |
The chloroplast has flattened saclike membranes that are arranged in stacks... what are the flattened membranes and the stacks called. .what happens in these structures | the flattened stacks are the thylakoids... and the stacks are the grana... they are the site of the light reaction |
What name is given to the portion of the chloroplast where the light-independent ( dark reactions... or calvin cycle ) occur. Give a brief description | stroma... it is a fluid filled space in the chloroplast |
What are pigments | they are light absorbing- colored molecules in the thylakoid membrane of the chloroplast...different pigments absorb specific wavelengths of light |
What are the major light absorbing pigments in plants.. and what colors do they absorb most strongly and which do they reflect | chlorophyll ( several types ), they absorb in the violet-blue region of the visible spectrum and reflect light in the green region of the spectrum |
why do plants that contain chlorophyll appear green to the human eye | because they reflect the light in the green region of the spectrum |
True or False Chlorophylls are the only pigments in plants that are associated with photosynthesis | false... their are other pigments called accessory pigments that allow plants to trap additional light energy |
What group of accessory pigments provide the colors or carrots and sweet potatoes and reflect most light in the yellow , orange and red regions... they absorb in the blue and green region | carotenoids ( you may have heard of beta - carotene) |
Explain why many leaves change color in the autumn or fall? | chlorophylls are more abundant than other pigments and hide the colors of the other pigments. as trees prepare to lose their leaves before winter, the chlorophyll molecules break down, allowing the other colors to show or appear |
What is found in the thylakoid membrane that helps with the light reactions... explain this special structure | the thylakoid has a large surface area with space for many electron-transporting molecules, pigments, and proteins ... these have an important role in froming NADPH and ATP... in a structure called an electron transport chain |
What is split during the light reaction... and how did this happen? | the light absorbed by the thylakoid membrane is used to split water into hydrogen ions that go into the thylakoid space and oxygen that is released. an electron from this process moves into the electron transport chain... to transfer energy.. |
What is produced during the light reaction that is important to most of the inhabitants on earth | oxygen |
What is the first event in the light reaction | the light energy strikes chlorophyll and excites the electrons that start the events of the light reaction |
What happens as electrons are moving through the thylakoid membrane electron transport chain | they pump H+ into the thylokoid space which will be used later to make ATP... and they help form NADPH |
What is NADPH | it is an energy- storage molecule something like ATP |
How is ATP made during the light reaction | there are many hydrogen ions in the thylakoid space ( inside the thylakoid disk) and they move across the thylakoid membrane through ATP synthase providing energy to hook a phosphate to ADP |
what is ATP synthase | it is a structure in the thylakoid membrane that is responsible for making the ATP... as hydrogen goes across the membrane it provides the energy to hook a phosphate (P) to ADP to make ATP ( ADP is adenosine diphosphate)...ATP is triphosphate |
How is splitting of water important to the light reaction of photosynthesis | it provides electrons that initiate the electron transport chain and provides H+ to drive ATP synthesis using ATPsynthase |
What is another name for the light-independent or dark reactions of photosynthesis | Calvin Cycle |
ATP and NADPH are energy molecules, Why is it necessary to make them into glucose in the second stage of photosynthesis | they are not stable enough to store chemical energy for long periods of time. Glucose is more stable for this long term storage |
What is the purpose of the Calvin cycle | it uses the ATP and NADPH made during the light reactions to form glucose... this set of reactions need to use carbon dioxide also to provide the carbon for glucose |
What is the first part of the calvin cycle? explain this portion | it is called carbon fixation ... Carbon dioxide combines with something called RuBP ... to form PGA... this will continue to be reaaranged... the carbon is being put into a molecule that can be rearranged into glucose |
What is happening in the second part of the calvin cycle | this is a series of reactions that rearrange the PGA into G3P using the products of the light reactions (ATP AND NADPH)... the G3P will go on to make glucose and other products... |
Describe the third step of the calvin cycle | Some of the G3P leaves the cycle to be used to make glucose and other organic compounds... MOST of the remaining G3P is coverted to more RuBP which will keep the cycle going and will be able to combine with more carbon dioxide to fix carbon ... |
How do plants use the sugars formed during the calvin cycle ( describe 2 things) | they used them as a source of energy ( they will need to be used for cellular respiration at some point in time).. and they also can be building blocks for complex carbs such as cellulose etc. |