Water Properties Quiz

Water Properties

• Water's molecular structure (H₂O) involves polar covalent bonds, enabling hydrogen bonding.
• Cohesion: Water molecules stick together, creating high surface tension.
• Adhesion: Water molecules bond to other surfaces, crucial for capillary action.
• Surface tension allows some organisms to walk on water.
• Capillary action: Water moves in plant xylem against gravity due to cohesion and adhesion.
• Heat of vaporization: High energy needed for water to vaporize helps regulate temperature.
• Specific heat: Water absorbs much heat without significant temperature change, regulating climates.
• Water is a universal solvent, dissolving many polar and ionic substances.
• Ice is less dense than liquid water, insulating aquatic life.
• Water's properties facilitate nutrient transport, blood circulation, and temperature regulation in various ecosystems.

Carbon Properties

• Carbon's tetravalence allows it to form diverse, stable bonds with various elements.
• Isomers: variations in structure, connectivity, and spatial arrangement (cis/trans, enantiomers).
• Functional groups (e.g., hydroxyl, carboxyl, amino) provide diverse functions for various carbon-based molecules.

Biological Macromolecules

• Dehydration synthesis: Forms covalent bonds by removing water; hydrolysis breaks polymers by adding water.
• Macromolecules are formed from monomers (carbohydrates, lipids, proteins, nucleic acids).
• Covalent bonds join monomer units: glycosidic (carbohydrates), ester (lipids), peptide (proteins), phosphodiester (nucleic acids).
• Nucleic acids encode genetic information; DNA is double-stranded, RNA single-stranded.
• Protein structure: primary (linear sequence), secondary (alpha helix/beta sheet), tertiary (3D shape), and quaternary (multiple polypeptide subunits).
• Amino acids have an amino group, carboxyl group, hydrogen, and variable R group, defining properties.
• Disulfide bridges: Covalent bonds between cysteine residues stabilize protein structure.
• Polysaccharides: diverse functions; starch (plants), glycogen (animals), cellulose (plant cell walls), chitin (fungi).
• Lipids: All nonpolar due to C-H bonds. Diverse forms: phospholipids (membranes), cholesterol (membrane fluidity), fats (energy storage), steroid hormones (signaling).
• Glucose isomers: Alpha (starch/glycogen) and beta (cellulose).

Cell Organelles and Structure

• Organelle functions: nucleus (genetic material), mitochondria (ATP), chloroplasts (photosynthesis), ER (protein/lipid synthesis), Golgi (protein modification/sorting), lysosomes (macromolecule digestion).
• Eukaryotic vs. prokaryotic cells: Eukaryotes have a nucleus and membrane-bound organelles; prokaryotes do not.
• Plant vs. animal cells: Plant cells have cell walls and chloroplasts, animal cells have lysosomes and centrioles.
• Endosymbiotic theory: Mitochondria and chloroplasts evolved from free-living bacteria, evidenced by their double membranes and DNA.
• Endomembrane system: pathway for protein processing involving ER, Golgi, vesicles.
• Surface area to volume ratio: crucial for efficient nutrient/waste transfer.

Transport Across Cell Membranes

• Phospholipid bilayer structure: hydrophilic heads, hydrophobic tails; forms cell membranes.
• Membrane components: phospholipids, proteins, cholesterol, glycoproteins, glycolipids.
• Passive transport: diffusion (down concentration gradient), facilitated diffusion (proteins assist).
• Active transport: requires energy (ATP) to move molecules against the gradient.
• Gap junctions (animal cells) vs. plasmodesmata (plant cells): connect cells, facilitating communication.
• Sodium-potassium pump: pumps 3 Na+ out, 2 K+ in using ATP, crucial for nerve function.
• Endocytosis and exocytosis: transport large molecules in and out of cells.
• Transport mechanisms: gases (simple diffusion), ions (ion channels), small polar molecules (facilitated diffusion), macromolecules (endocytosis), nonpolar molecules (simple diffusion).
• Osmosis is passive water movement across the membrane.
• Aquaporins facilitate water movement.

Enzymes and Thermodynamics

• Enzyme structure: active site for substrate binding, allosteric site for regulation.
• Induced fit model: Enzymes adjust their shape to fit substrate.
• Enzyme activity is affected by temperature and pH.
• Enzymes lower activation energy, increasing reaction rates.
• Competitive vs. noncompetitive inhibitors: competitive bind to the active site; noncompetitive bind elsewhere.
• Feedback inhibition: regulatory mechanism where product inhibits enzyme.
• Catabolic vs anabolic reactions: catabolic breaks down, anabolic builds up molecules.
• Denaturation: usually irreversible loss of enzyme function due to extreme conditions.
• First and second laws of thermodynamics: Energy conservation (first law), increase in entropy (second law).
• Cooperativity : increased efficiency due to combined substrate interaction.

Cellular Respiration

• Cellular respiration breaks down glucose in the presence of oxygen to produce ATP.
• Respiration involves glycolysis, Krebs cycle, and oxidative phosphorylation.
• Fermentation is an anaerobic process producing less ATP.
• Mitochondrial structure: outer membrane, inner membrane (ETC), and matrix (Krebs cycle).
• Cellular respiration locations: glycolysis (cytoplasm), Krebs (matrix), oxidative phosphorylation (inner mitochondrial membrane).
• Overall equation: Glucose + O₂ → CO₂ + H₂O + energy (ATP). Electron carriers (NADH & FADH2) are crucial to cellular respiration.

Photosynthesis

• Photosynthesis converts light energy into chemical energy (glucose).
• Chloroplast structure: thylakoids (light reactions), stroma (Calvin cycle).
• Chlorophyll and other pigments absorb light energy.
• Light-dependent reactions produce ATP and NADPH.
• Calvin cycle uses ATP and NADPH to convert CO₂ into glucose.
• Photorespiration is an inefficient process reducing overall photosynthesis.
• The product of photosynthesis is needed for cellular respiration, and vice versa.

Cell Communication

• Cell signaling: autocrine, paracrine, synaptic, endocrine.
• Signal transduction pathways: series of events transmitting signals into cells.
• Second messengers (e.g., cAMP, Ca²⁺) amplify signals within cells.
• Hormones are signaling molecules in endocrine signaling.
• Negative feedback mechanisms help stabilize internal conditions (e.g., insulin/glucagon, calcium homeostasis).

Mitosis and Meiosis

• Mitosis produces two identical daughter cells; meiosis produces four genetically diverse haploid cells.
• Cell cycle phases: G1, S, G2, M (mitosis).
• Cytokinesis: division of the cytoplasm.
• Cyclins and CDKs regulate cell cycle progression.
• Mitosis phases: Prophase, Metaphase, Anaphase, Telophase.
• Genetic variation in meiosis results from crossing over and independent assortment.

General Note

• These notes cover fundamental concepts in biology. Further study and practice are important for a full understanding.