What does it mean that water is a polar molecule?
It means that water has an unequal sharing of electrons: the oxygen side has a slightly negative charge, while the hydrogen sides have slightly positive charges.
How do hydrogen bonds work in water?
The slightly positive hydrogen of one water molecule is attracted to the slightly negative oxygen of another water molecule, forming hydrogen bonds.
What are cohesion and adhesion?
Cohesion = water molecules sticking to each other. Adhesion = water molecules sticking to other surfaces.
What property of water allows insects to walk on its surface?
Surface tension, which is due to cohesion (the stickiness between water molecules), forming a “skin” at the top.
What does it mean that water is a solvent?
That water can dissolve many other substances, especially polar molecules or ionic compounds, because its polarity helps surround and separate charged parts.
Why is water less dense as ice than as liquid water?
When water freezes, molecules form a stable, hexagonal lattice due to hydrogen bonding. This lattice spreads them further apart than in liquid water, making ice less dense.
What is high specific heat, and why is it important?
Specific heat is the amount of heat required to raise the temperature of a unit mass by one degree. Water’s high specific heat means it resists temperature changes, which helps stabilize environments and living things.
What is evaporative cooling, and how does water enable it?
Evaporative cooling happens when water evaporates (changes from liquid to gas), taking heat with it. This cools surfaces, like when you sweat or when water evaporates from the ground.
How does water work against gravity in plants?
Through cohesion (water molecules stick together) and adhesion (water sticks to the walls of xylem), allowing water to move up from roots to leaves.
Which part of the water molecule is more negative? Which is more positive?
Oxygen is more negative; hydrogens are more positive.
Why is carbon called the “backbone of life”?
Carbon can form 4 covalent bonds, allowing it to create complex and diverse molecules (chains, rings, branches).
What are the types of bonds carbon can form?
Single, double, and triple covalent bonds.
Why is carbon versatile in forming biological molecules?
It bonds with many elements (CHNOPS), can form stable long chains, branched molecules, and rings.
What’s the difference between hydrocarbons and organic molecules with functional groups?
Hydrocarbons = only C and H. Functional groups = add specific chemical properties (polarity, reactivity, solubility).
What is a functional group?
A specific cluster of atoms attached to carbon skeletons that give molecules unique properties.
What is the hydroxyl group (-OH)?
Polar, makes compounds soluble in water; found in alcohols and sugars.
What is the carbonyl group (C=O)?
Found in aldehydes (at end of chain) and ketones (in middle); important in sugars.
What is the carboxyl group (-COOH)?
Polar, acidic; found in amino acids and fatty acids. Can donate H⁺ ions.
What is the amino group (-NH₂)?
Basic, polar, found in amino acids; can accept H⁺ to become -NH₃⁺.
What is the phosphate group (-PO₄²⁻)?
Negatively charged, important for energy transfer (ATP, nucleic acids).
Which functional group makes molecules more hydrophilic?
Hydroxyl, carboxyl, amino, phosphate (all polar).
Which functional group is found in sugars?
Hydroxyl (-OH) and carbonyl (C=O).
What are the monomers of carbohydrates?
Monosaccharides (simple sugars, e.g., glucose, fructose, galactose).
What bond links monosaccharides?
Glycosidic linkage (formed by dehydration synthesis).
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Biochemistry42
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Lipids22
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Proteins25
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Enzymes11
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Nucleic acids10
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Carbohydrates23
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Cell membrane25
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Metabolism & energy36
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Aerobic respiration:harvesting chemical energy11
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Glycolysis pathway10
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Genetic Discoveries18
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Structure of DNA20
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DNA replication29
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Transcription30
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Translation19
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Mutation and Gene expression11
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Gene expression22
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Biotechnology9
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Population Ecology62
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Homeostasis intro25
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Neuron and synapse17
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Reflex arc/action potential26
