Unit 3 -Energy (photosynthesis, respiration, food webs) Flashcards
What is the 1st law of thermodynamics?
energy cannot be created nor destroyed
What is the 2nd law of thermodynamics?
when energy is converted from one form to another form some energy is lost as heat
What are the three parts of a photosystem and what are their functions?
a. Reaction center complex: Located centrally in a photosystem, this complex triggers the light reactions of photosynthesis. Excited by light energy, the pair of chlorophylls donates an electron to the primary electron acceptor, which passes an electron to an electron transport chain. b. Light-harvesting complex: captures light energy and transfers it to reaction center pigments in a photosystem. c. Primary electron acceptor: a specialized molecule that shares the reaction center complex with a pair of chlorophyll a molecules and that accepts an electron from them.
What is the name of the chlorophyll a at the reaction center of PS I called?
P700
In phase two, the reduction stage, what molecule will donate electrons, and so is the source of the reducing power?
NADPH
What is a C3 plant?
A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate.
What percent of energy is passed from each trophic level?
about 10%
What is photophosphorylation?
The process of generating ATP from ADP and phosphate by means of chemiosmosis, using a proton-motive force generated across the thylakoid membrane or the chloroplast or the membrane of certain prokaryotes during the light reactions of photosynthesis.
What is photosynthesis and why is it important?
The conversion of light energy to chemical energy that is stored in sugars or other organic compounds; in plants, algae, and certain prokaryotes. It is important because it is the primary consumer that starts the food chain; it is an energy source, where other animals get there food for energy.
What is the similarity and difference between photosystem I and II?
Light-capturing units in a chloroplast’s thylakoid membrane or in the membrane of some prokaryotes; I. it has two molecules of P700 chlorophyll a at its reaction center. II. it has two molecules of P680 chlorophyll a at its reaction center.
What is photorespiration?
A metabolic pathway that consumes oxygen and ATP, released CO2, and decreases photosynthetic output. EX: On a hot, dry day, when stomata close and the O2/CO2 ratio in the leaf increases, favoring the binding of O2 rather than CO2 by rubisco.
Why are the primary producers important?
They are autotrophs that make up the tropic level of an ecosystem that ultimately supports all other levels.
Who is a primary consumer? Give an example.
Herbivores; an organism that eats plants or other autotrophs. EX: cows, horses, zebras
What do producers do?
Organisms that produce organic compounds from CO2 by harnessing light energy (photosynthesis) or by oxidizing inorganic chemicals (chemosynthetic reactions carried out by some prokaryotes)
What is a pyruvate and where is it in cellular respiration?
A 3-carbon molecule (when glucose splits in two); in glycolysis and Krebs cycle
What are redox reactions?
A chemical reaction involving the complete or partial transfer of one or more electrons from one reactant another; short for reduction-oxidation reaction.
What is a reduction?
The complete or partial addition of electrons to a substance involved in a redox reaction.
Who are the secondary consumers? Give an example.
A carnivore that eats herbivores. EX: snakes, turtles
What is the stroma, what does it contain, and what is it involved in?
The dense fluid within the chloroplast surrounding the thylakoid membrane and containing ribosomes and DNA; it is involved in the synthesis of organic molecules from carbon dioxide and water.
What is the substrate?
The reactant on which an enzyme works.
What is the substrate-level phosphorylation?
The enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism.
Who are the tertiary consumers? Give an example.
A carnivore that eats other carnivores. EX: shark, hawk
What is allosteric regulation?
The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site.
What is hydrolysis and give one example of where it is used.
A chemical reaction that breaks between two molecules by the addition of water EX: disassembly of polymers to monomers
Why is carbon fixation important?
Because it is the initial incorporation of carbon from CO2 into an organic compound by an autotrophic organism (EX: a plant, another photosynthetic organism, etc.)
Why is the hydrogen gradient important in the production of ATP of cellular respiration?
As hydrogen moves back through the membrane through ATP synthase, the enzymatic activity of ATP synthase synthesizes ATP from ADP and P.
What is the reaction-center complex and what does it do?
A complex of proteins associated with a special pair of chlorophyll a molecules and a primary electron acceptor. Located centrally in a photosystem, this complex triggers the light reactions of photosynthesis.
What is entropy and how is it part of the 2nd law of thermodynamics?
Entropy is a measure of disorder or randomness in a closed system and the 2nd law of thermodynamics states that there is a natural tendency of any isolated system to degenerate into a more disordered state.
What is the difference between competitive inhibition and noncompetitive inhibition?
In competitive inhibition, a competitve inhibitior mimics the substrate, competing for the active site. In noncompetitive inhibition, a noncompetitive inhibitor binds to the enzymes away from the active site, altering the shape of the enzyme so that the active site functions less effectively
What is the function of enzymes and what macromolecule are they?
Enzymes speed up reactions by providing an alternative reaction pathway that requires less activation energy and they are mostly proteins.
What is an enzyme-substrate complex?
An enzyme-substrate complex is a temporary complex formed when an enzyme binds to its substrate molecule.
What is an exergonic reaction?
An exergonic reaction is when energy is released and these reactions usually don’t require energy to proceed so they occur spontaneously.
What is the function of FADH2?
FADH2 is a coenzyme that transfers electrons derived from glucose to ETC’s along with NADH in the mitochondrial membrane during cellular respiration.
What is fermentation and when is the only time it takes place?
Fermentation is a metabolic process that converts sugar into acids, gases or alcohol, such as lactic acid fermentation. Fermentation takes place when the ETC is unusable because there is no oxygen present.
What is a food chain and what is the order of the types of organisms?
The transfer of food energy up the trophic levels from its source in plants and other autotrophic organisms (primary producers) through herbivores (primary consumers) to carnivores (secondary, tertiary, quaternary consumers) and eventually to decomposers.
What does a food web show and what do the arrows represent?
A food web shows the interconnected feeding relationships in an ecosystem and the arrows represent which organism eats the other.
What process is the starting point for either fermentation or cellular respiration and what happens during this?
Glycolysis is a series of reactions that ultimately splits glucose into pyruvate, each glucose molecule is broken down into two pyruvate molecules.
What are grana and where are they located?
Grana are thylakoid sacs (where the light-dependent reactions from photosynthesis take place) stacked in columns and they are located in chloroplasts which are only in plant cells.
What is the difference between heterotrophs and autotrophs?
Autotrophs are organisms that produce their own organic molecules from CO2 and other raw materials while heterotrophs depend on other organisms to obtain their organic molecules, autotrophs are producers and heterotrophs are consumers,
What is induced fit?
It is caused by entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate.