Exam 2 Study Flashcards
What are the sources of energy available to chemo- and photo-autotrophs and heterotrophs?
Chemo-autotrophs use inorganic compounds, photo-autotrophs use sunlight, and heterotrophs consume organic substances.
What is the first law of thermodynamics?
Energy cannot be created or destroyed, only transformed.
What is the second law of thermodynamics?
In any energy transfer, the total entropy of a closed system can only increase.
How does the movement of electrons relate to the flow of energy in chemical reactions?
The movement of electrons during chemical reactions transfers energy.
What do free energy diagrams represent?
They illustrate the energy changes during biochemical reactions.
What are exergonic reactions?
Reactions that release energy.
What are endergonic reactions?
Reactions that absorb energy.
Define oxidation reactions.
Reactions involving the loss of electrons.
Define reduction reactions.
Reactions involving the gain of electrons.
What are anabolic reactions?
Reactions that build larger molecules from smaller ones.
What are catabolic reactions?
Reactions that break down larger molecules into smaller ones.
What is the significance of coupled reactions in living cells?
They allow energy from exergonic reactions to drive endergonic reactions.
Why is ATP considered the universal energy currency of life?
ATP provides a readily available form of energy for cellular processes.
What is activation energy?
The energy required to initiate a chemical reaction.
How can activation energy be overcome?
By increasing temperature or using catalysts.
What role do enzymes play in chemical reactions?
Enzymes catalyze reactions, lowering activation energy.
How does temperature affect enzyme catalysis?
Changing temperature can increase or decrease enzyme activity, affecting functional ranges.
How can enzyme function be controlled?
Through inhibitors that decrease enzyme activity.
What are endergonic steps in aerobic respiration?
Steps that require energy input, such as the synthesis of ATP.
What are exergonic steps in aerobic respiration?
Steps that release energy, such as glycolysis.
What is the role of enzymes in aerobic respiration?
They control the rate and efficiency of the metabolic pathways.
What is the electron transport chain (ETC)?
A series of complexes that transfer electrons and produce ATP.
How is a proton gradient established in aerobic respiration?
By pumping protons across the membrane during electron transport.
Why is oxygen necessary for aerobic respiration?
Oxygen serves as the final electron acceptor in the ETC.
What is the purpose of fermentation?
To produce energy when oxygen is not available.
What is the energetic advantage of aerobic respiration over fermentation?
Aerobic respiration generates more ATP per glucose molecule.
What evidence supports the universality of glycolysis?
Glycolysis is found in nearly all living organisms, indicating its ancient evolutionary origin.
How do non-carbohydrate food sources fit into aerobic respiration?
They can be converted into intermediates that enter the metabolic pathways.
What is the importance of photosynthesis in ecosystems?
Photosynthesis provides energy for the food chain.
What is the evolutionary history of photosynthesis?
Photosynthesis likely developed over 2.5 billion years ago, impacting life evolution.
How does energy transfer from light to chemical energy during photosynthesis?
Light energy is captured and converted to high-energy electrons for carbohydrate synthesis.
What are the two systems involved in photosynthesis?
Light capture and conversion to high-energy electrons, followed by carbon fixation.
What are the inputs and outputs of the light-harvesting steps in photosynthesis?
Inputs: light, water; Outputs: oxygen, high-energy electrons.
How does the ETC in photosynthesis compare to that in aerobic respiration?
Both involve electron transfer but differ in inputs and final electron acceptors.
What is carbon fixation?
The process of converting inorganic CO2 into organic compounds.
What is the critical role of Rubisco?
Rubisco catalyzes the first step of carbon fixation but has rate limitations and is involved in photorespiration.
What connects the light-harvesting reactions to the Calvin cycle?
The high-energy electrons produced in the light-harvesting reactions.
Why do photosynthetic organisms store their products as complex carbohydrates?
To provide a stable energy source for later use.
