32 terms

Biology Chapter 8

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Adenosine triphosphate (ATP)
compound used by cell to store and release energy
Heterotroph
organism that obtains food by consuming other living things; also called a consmer
Autotroph
organism that is able to capture energy from sunlight or cheicals and use it to produce its own food from inorganic compounds; also called a producer
Photosynthesis
process used by plants and other autotrophs to capture light energy and use it to power chemical reactions that convert carbon dioxide and water into oxygen and energy rich carbohydrates such as sugars and starches
Pigments
light absorbing molecules
Chlorophyll
principal pigment of plants and other photosynthetic organisms
Thylakoids
saclike photosynthetic membranes found in the chloroplasts
Stroma
fluid portion of the chloroplast, outside of the thylakoids
NADP
(nicotinamide adenine dinucleotide phosphate) carrier molecule that transfers high energy electrons from chlorophyll to other molecules
Light dependent reactions
set of reactions in pohtosynthesis hat use energy from light to prduce ATP and NADPH
Light independent reactions
set of reactions in photosynthesis that do not require light; energy from ATP and NADPH is used to build high energy compounds such as sugar; also called the Calvin cycle
Photosystems
clusters of chlorophyll and proteins
Electron transport chain
series of electron carrier proteins that shuttle high energy electrons during ATP generating reactions
ATP synthase
spans the membrane and allows H+ ions to pass through it
Calvin cycle
light-independent reactions
ATP is an abbreviation for the compound adenosine triphosphate. Cells use ATP to store and release energy.
What is ATP and what is its role in the cell?
ATP can release and store energy by breaking and re-making the bonds between its phosphate groups
How does the structure of ATP make it an ideal source od energy for the cell?
ADP and ATP are like batteries because they store energy in the chemical bonds they have. ADP has only two phosphate groups, so it's like a partially charged battery. ATP has three phosphate groups, so it is like a fully charged battery and has more bonds available for storing energy.
Explain how ADP and ATP are each like a battery. Which one is "partially charged" and which one is "fully charged" Why?
The ultimate source is the sun
What is the ultimate source of energy for plants?
Heterotrophs obtain energy by feeding on other living things. Autotrophs make their own food using photosynthesis
How do heterotrophs obatin energy? How is this different from how autotrophs obtain energy?
Decomposers consume the remains of living things for energy and cannot make their own food, and mushrooms cannot make their own food.
Why are decomposers, such as mushrooms, considered heterotrophs and not autotrophs?
Photosynthetic organisms capture energy from sunlight by using pigments
Why are pigments such as chlorophyll needed for photosynthesis?
Plants would grow very slowly if at all because pigments do not absorb energy well under the yellow spectrum
How well would a plant grow under pure yellow light? Explain your answer.
NADPH can carry the high energy electrons that were produced by light absorption in chlorophyll to chemical reactions eleswhere in the cell
What is the function of NADPH?
Light energy absorbed by pigments pro- duces high-energy electrons that are used to convert NADP+ and ADP to the compounds NADPH and ATP, trapping the energy in chemical form.
How is light energy converted into chemical energy during photosynthesis?
Because photosynthesis depends on the conversion of NADP+ to NADPH to carry electrons to chemical reactions in other parts of the cell, the process could not occur efficiently if there were a shortage of NADP+ in the cells of plants.
How wuold photosynthesis be affected if there were a shortage of NADPH in the cells of plants?
Photoaynthesis uses energy of sunlight to convert water and carbon dioxide into high energy sugars and oxygen
Describe the overall process of photosynthesis, including the reactants and products.
The light-dependent reactions use energy from sunlight to produce oxygen and convert ADP and NADP+ into the energy carri- ers ATP and NADPH
Summarize what happens during the light dependent reactions of photosynthesis.
(1) Light energy is absorbed by electrons in the pigments and water molecules are split into H+ ions, oxy- gen, and electrons. (2) High-energy elec- trons (from the splitting of water) move down the electron transport chain, where energy from the electrons is used to pump H+ ions into the thylakoid space. (3) At the end of the chain, NADP+ molecules pick up the high-energy electrons along with H+ ions to become NADPH
Put the events of the light dependent reactions in the order in which they occur and describe how each step is dependent on the step that comes before it.
The Calvin cycle is another name for the light-independent reactions in which ATP and NADPH from the light-dependent reactions are used to produce high-energy sugars. It is named for Melvin Calvin, who worked on its details.
What is the Calvin cylce?
The light-dependent reactions require light and water, occur in the thylakoids, and produce ATP and NADPH. The light-independent reactions require carbon dioxide, occur in the stroma, and produce high-energy sugars
List at least three differences between light dependent and light independent reactions of photosynthesis
Temperature, light intensity, and availability of water
What are the three primary factors that affect the rate of photosynthesis?