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Questions and Answers
What is the primary mechanism by which energy from sunlight is transformed for ecosystem maintenance?
Which process is characterized by the building up of complex molecules from simpler ones?
In what way is energy released during catabolism?
Which structure within plant cells is primarily responsible for conducting photosynthesis?
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How does energy transfer occur in a typical food web?
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What is the net energy output of glycolysis per glucose molecule?
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Which product is formed during alcoholic fermentation?
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In the absence of oxygen, pyruvate is primarily converted into which of the following?
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Which of the following correctly outlines the processes that occur in the presence of oxygen?
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What role does lactic acid play in lactic acid fermentation?
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What is the primary function of the dark reactions in photosynthesis?
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Which of the following processes occurs in all living organisms at all times?
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Where does cellular respiration primarily take place in eukaryotic cells?
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Which stage of cellular respiration involves the breakdown of glucose into pyruvic acid?
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Which statement best describes anaerobic respiration?
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What is produced as a byproduct of cellular respiration?
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Which type of pathway does glycolysis represent in metabolic processes?
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Which of the following best describes the role of enzymes in cellular respiration?
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Study Notes
Energy and Metabolism
- All life depends on a continuous input of energy.
- Energy is vital for sustaining life processes like movement, growth, reproduction, and secretion.
- The first law of thermodynamics states that energy can be transformed but not created or destroyed.
- Energy within ecosystems is transformed from sunlight by photoautotrophs, the primary producers.
- These organisms convert light energy into chemical energy stored in bonds.
Energy Transfer
- Energy flows through ecosystems via feeding.
- This begins with primary producers, then primary consumers, followed by secondary, tertiary, and quaternary consumers.
Metabolism
- Metabolism is the sum of all chemical reactions occurring in a biological system.
- Anabolism is the process of building complex molecules from simpler ones.
- Catabolism is the process of breaking down complex molecules into simpler ones.
Energy in Metabolism
- Energy is used to form bonds between molecules. This energy is stored as potential energy and can be released during catabolism.
Catabolism
- Catabolism involves the breakdown of complex molecules into simpler ones.
- Examples include the dark reactions in photosynthesis which rely on the products of the light reactions.
Respiration
- Respiration occurs in all living things constantly.
- It involves the breakdown of glucose into carbon dioxide, water, and ATP.
- The chemical energy of bonding is released as free energy (ATP).
- Cellular respiration takes place in mitochondria.
Respiration (Energy Harvesting)
- This is the process by which organisms obtain energy from organic molecules.
- Cellular processes release energy, producing carbon dioxide which is transported to the lungs.
- This involves breaking down sugar or other organic compounds for cellular work.
- It is the oxidation of food molecules, releasing energy as ATP.
- Respiration can be anaerobic(without oxygen) or aerobic(with oxygen).
Energy Harvesting (cont'd)
- The enzymes for cellular respiration are located in the plasma membrane of prokaryotes and within the mitochondria of eukaryotes.
- Respiration occurs in two stages:
- Glycolysis: glucose is broken down into pyruvic acid.
- Citric Acid Cycle/Tricarboxylic Acid Cycle (TCA)/Krebs Cycle: complete oxidation of pyruvic acid into carbon dioxide and water.
Glycolysis
- Glycolysis is the breakdown of glucose (6 carbons) into two 3-carbon molecules called pyruvic acid.
- It is the first step in both aerobic and anaerobic energy-harvesting reactions.
- Does not require oxygen.
- Occurs in the cytoplasm of cells.
- It is found in all living organisms (prokaryotes and eukaryotes).
Energy Output: Glycolysis
- Each glucose molecule produces two ATP net, two NADH, and two molecules of pyruvic acid.
Fermentation
- Occurs in the cytosol/cytoplasm.
- In the absence of oxygen (O2), pyruvate is reduced by coenzymes to lactate or ethyl alcohol.
- Lactic acid fermentation uses lactic acid as an electron acceptor.
- Alcoholic fermentation occurs in yeasts and some plant cells.
Fermentation (cont'd)
- It is essential for brewing beverages from sorghum, grapes, barley, etc.
- Fermentation yields lactic acid or alcohol and 2 ATP.
In the Presence of Oxygen
- Three things occur when oxygen is present:
- Pyruvate oxidation
- Citric Acid Cycle (Tricarboxylic Acid Cycle or Krebs Cycle)
- Oxidative phosphorylation (Electron Transport Chain)
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Description
This quiz covers the fundamental concepts of energy and metabolism in biological systems. It addresses the laws of thermodynamics, the flow of energy in ecosystems, and the processes of anabolism and catabolism. Test your understanding of how energy is crucial for life processes and the chemical reactions that occur within organisms.
