Scientific Method/ Basic Life/Chemistry

Scientific Method

• Purpose of the Scientific Method: To systematically investigate observations, solve problems, and test hypotheses.

• Steps of the Scientific Method:

  1. Observation

  2. Question

  3. Hypothesis

  4. Experiment

  5. Data Collection

  6. Conclusion

  7. Communication of Results

• Independent Variable: The factor being manipulated.

• Dependent Variable: The factor being measured.

• Control Group: Group without experimental treatment, used as a baseline.

• Experimental Group: Group receiving treatment.

• Key Terms:

  • Hypothesis: A testable statement.

  • Theory: A well-supported explanation.

  • Sample Size: Number of subjects in an experiment.

  • Trial: Repetitions of an experiment.

  • Standardized Variable: Kept constant across groups.

  • Placebo: Inactive substance in control group.

  • Peer Review: Evaluation by experts before publication.

Basics of Life

• Properties of Life: Order, metabolism, homeostasis, growth, adaptation, response, reproduction.

• Levels of Organization:

  1. Chemical

  2. Cell

  3. Tissue

  4. Organ

  5. Organ System

  6. Organism

• Homeostasis: Maintenance of stable internal conditions.

• Homeostatic Control Mechanism:

  • Stimulus → Receptor → Control Center → Effector → Response

• Feedback Mechanisms:

  • Negative Feedback: Opposes change (e.g., temperature regulation).

  • Positive Feedback: Enhances change (e.g., blood clotting).

Chemistry

• Atom Structure: Protons, neutrons, electrons.

• Atomic Terms:

  • Atomic Symbol: Letter representation.

  • Atomic Number: Number of protons.

  • Atomic Mass: Protons + Neutrons.

  • Isotope: Same element, different neutrons.

• Common Biological Elements: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N).

• Valence Shell: Outer electron shell involved in bonding.

• Chemical Bonds:

  • Nonpolar Covalent: Equal electron sharing.

  • Polar Covalent: Unequal electron sharing.

  • Ionic: Electron transfer.

  • Hydrogen: Weak attraction between molecules.

• Ions:

  • Ion: Charged particle.

  • Anion: Negatively charged.

  • Cation: Positively charged.

• Chemical Reactions:

  • Endergonic: Absorbs energy.

  • Exergonic: Releases energy.

• Enzymes: Speed up chemical reactions by lowering activation energy.

• Water Properties: Cohesion, adhesion, high heat capacity, solvent properties.

• Hydrophilic vs. Hydrophobic:

  • Hydrophilic: Water-attracting.

  • Hydrophobic: Water-repelling.

• pH Scale:

  • Acid: pH < 7.

  • Base: pH > 7.

  • Neutral: pH = 7.

• Compounds vs. Mixtures:

  • Compound: Chemically bonded elements.

  • Mixture: Physically combined substances.

• Types of Mixtures:

  • Solution: Homogeneous, small particles.

  • Colloid: Medium particles, does not settle.

  • Suspension: Large particles, settles over time.

• Solvent vs. Solute:

  • Solvent: Dissolving medium.

  • Solute: Substance being dissolved.

• Organic vs. Inorganic Compounds:

  • Organic: Contains carbon (e.g., glucose).

  • Inorganic: Lacks carbon (e.g., water).

• Monomers vs. Polymers:

  • Monomer: Single unit.

  • Polymer: Chain of monomers.

• Organic Macromolecules:

  • Carbohydrates:

    • Monosaccharides (e.g., glucose).

    • Disaccharides (e.g., sucrose).

    • Polysaccharides (e.g., starch, glycogen, cellulose).

  • Lipids:

    • Triglycerides: Energy storage.

    • Phospholipids: Cell membrane component.

    • Steroids: Hormones (e.g., cholesterol).

  • Proteins:

    • Examples: Enzymes, antibodies.

    • Levels of Folding: Primary, secondary, tertiary, quaternary.

  • Nucleic Acids:

    • Examples: DNA, RNA.