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Questions and Answers
What is the primary role of water in living organisms?
What structure do water molecules have?
Why is water considered a polar molecule?
What type of bonds form between water molecules?
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What characteristic allows water to be classified as the universal solvent?
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What characteristic of water allows it to have a high boiling point?
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Which property explains why ice floats on water?
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What causes cohesion in water molecules?
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How do water molecules exhibit adhesive properties?
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What is the main reason water is an excellent solvent for polar substances?
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What happens to the distance between molecules when kinetic energy increases?
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What property of water is responsible for capillary action in plants?
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Why is water unique in its density-temperature relationship?
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What happens to the structure of nonpolar molecules when mixed with water?
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What would happen if water behaved like most normal substances?
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Which ions are formed when water can ionize?
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At what temperature is water most dense?
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How does temperature affect the solubility of substances in water?
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What causes water molecules to not 'bounce out' as quickly as oxygen molecules?
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What is the relationship between the kinetic energy of water and its temperature?
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What is the effect of decreasing temperature on the density of water?
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What is the primary function of the Calvin Cycle in photosynthesis?
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Where do light-dependent reactions occur in plant cells?
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Which of the following products are released as byproducts of the light-dependent reactions?
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What substances are used as inputs during photosynthesis?
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Which substance serves as a long-term energy reserve for plants?
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How is cellulose relevant to plant structure?
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Which process directly converts light energy into chemical energy?
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What is the role of chlorophyll in photosynthesis?
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What is the primary process by which glucose is broken down in glycolysis?
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Where does the Krebs cycle occur within the cell?
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Which of the following products is generated during glycolysis?
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What role does oxygen play in the electron transport chain?
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How many ATP molecules are produced from one glucose molecule during the Krebs cycle?
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Which of the following describes the process that occurs during the electron transport chain?
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What is the end product of the breakdown of pyruvate if oxygen is present?
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Which molecule acts as a carrier of electrons produced during glycolysis and the Krebs cycle?
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Study Notes
Importance of Water
- Water is vital for all life, comprising 60-80% of most organisms.
- Functions in transporting materials (e.g., blood, sap), regulating temperature, and producing cell products (saliva, tears, sweat, stomach acids).
- Provides support and structure in organisms (e.g., jellyfish) and facilitates movement (e.g., hydraulic systems in worms and starfish).
Chemistry of Water
- Water (H2O) forms by two hydrogen atoms bonded to a single oxygen atom through covalent bonds, sharing electrons.
- The water molecule has a V shape with a bond angle of 104.5 degrees.
- Oxygen's larger size results in unequal electron sharing, creating slight electrical charges: negative at the oxygen end and positive at the hydrogen end.
Polar Nature of Water
- A polar molecule with distinct electrical charges allows it to dissolve many substances, earning it the title of "universal solvent."
- Hydrogen bonds form between the negative pole of one water molecule and the positive pole of another, creating unique properties for water.
Unique Properties of Water
- High boiling point of 100°C (212°F).
- Ice is less dense than liquid water, allowing it to float.
- Cohesion: attraction among water molecules keeps them together, forming puddles instead of droplets.
- Adhesion: water molecules stick to polar surfaces, influencing capillary action essential for plant water uptake.
Solvent Properties
- Water's hydrogen bonds enable it to dissolve ions and other polar substances easily, facilitating biological functions.
- Water organizes nonpolar molecules, influencing their shapes and behaviors in solutions (e.g., hydrophilic vs. hydrophobic).
Density and Temperature Relations
- Density is defined as mass per unit volume; water deviates from normal density behavior below 4°C, becoming less dense as it freezes.
- This decrease in density prevents bodies of water from freezing solid from the bottom up, critical for aquatic life survival.
- In winter, denser water remains beneath ice, allowing ecosystems to thrive.
Temperature & Solvent Dynamics
- Warm water can hold more dissolved solids than colder water, increasing solubility (e.g., hot water dissolves more salt).
- Oxygen depletion in warmer water occurs as oxygen molecules escape, necessitating diffusion from deeper areas to replace them.
Carbohydrate Synthesis in Plants
- Main process: Photosynthesis, involving light-dependent reactions and the Calvin cycle to convert light energy into glucose.
- Light-Dependent Reactions: Occur in chloroplast thylakoid membranes; water (H2O) is split, producing oxygen, ATP, and NADPH.
- Calvin Cycle: Takes place in chloroplast stroma, where carbon dioxide (CO2) is converted into glucose using stored energy.
Carbohydrate Metabolism in Animals
- Comprises glycolysis, the Krebs cycle, and the electron transport chain for energy production from carbohydrates, primarily glucose.
- Glycolysis: Converts glucose to pyruvate in the cytoplasm, generating ATP and NADH without oxygen.
- Krebs Cycle: Takes place in mitochondria, breaking down acetyl-CoA to produce ATP, NADH, FADHâ‚‚, and CO2 when oxygen is available.
- Electron Transport Chain: Located in the inner mitochondrial membrane, it produces significant ATP through oxidative phosphorylation using electrons from NADH and FADHâ‚‚.
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Description
This quiz explores the significance of water in biological systems and its unique chemical properties. Questions will cover topics like water's composition, its polar nature, and its role in supporting life and facilitating movement. Perfect for students studying biology or chemistry.
