Scientific Method and Experimental Design

Key Vocabulary and Concepts

The scientific method is a systematic approach to investigation, involving observation, hypothesis formation, experimentation, and analysis. Understanding key terms is essential for designing and interpreting experiments.

• Precision: The degree to which repeated measurements under unchanged conditions show the same results.

• Accuracy: How close a measurement is to the true or accepted value.

• Dependent Variable: The variable being tested and measured in an experiment; it is affected by changes in the independent variable.

• Independent Variable: The variable that is changed or controlled in a scientific experiment to test its effects on the dependent variable.

• Controlled Experiment: An experiment in which only one variable is changed at a time, while all others are kept constant.

• Hypothesis: A testable statement or prediction about the relationship between variables.

Metric System and Measurement

• Metric units include grams (mass), liters (volume), and meters (length).

• Common prefixes: kilo-, centi-, milli-, micro-, nano-.

• Scientific notation is used to express very large or small numbers.

Graphing and Data Analysis

• X-axis: Independent variable.

• Y-axis: Dependent variable.

• Types of graphs: bar graph, line graph, scatter plot, pie chart.

Scientific Method Steps

• Observation

• Hypothesis

• Experiment

• Conclusion

Laboratory Equipment

• Graduated cylinder

• Molecular pipette

• Electronic balance

• Meter stick

Atoms, Molecules, and Chemical Reactions

Key Vocabulary and Concepts

Understanding atomic structure and chemical reactions is fundamental to biology, as all living things are composed of atoms and molecules.

• Atomic structure: Atoms consist of protons, neutrons, and electrons. The periodic table provides information about atomic number and mass.

• Molecular structure: Molecules are formed by atoms bonded together; types of bonds include covalent, ionic, and hydrogen bonds.

• Chemical reaction: A process in which substances (reactants) are transformed into new substances (products).

• Solution: A homogeneous mixture of two or more substances.

• Electrolyte: A substance that produces ions when dissolved in water and conducts electricity.

• Solvent: The substance in which the solute is dissolved (often water in biological systems).

• Solute: The substance dissolved in the solvent.

Applications and Examples

• Be able to diagram atoms using information from the periodic table.

• Predict products of a mixture of ionic compounds when mixed in an aqueous solution.

• State possible physical changes that can occur from a chemical reaction.

• Determine the formula for compounds from combinations of ions.

• Write the structural formula for an organic compound from its chemical formula.

Density and the Scientific Method

Key Vocabulary and Concepts

Density is a physical property that relates mass and volume. It is commonly used in scientific investigations to identify substances and analyze experimental results.

• Density: The mass per unit volume of a substance.

• Displacement: A method for measuring the volume of an object by the amount of water it displaces.

• Meniscus: The curved surface of a liquid in a container, used for accurate volume measurement.

Formulas

• Density formula:

Applications

• Calculate the volume of an object using displacement or geometric formulas.

• Measure mass using a balance.

• Determine density using mass and volume measurements.

Buffers

Key Vocabulary and Concepts

Buffers are solutions that resist changes in pH when acids or bases are added. They are important in maintaining stable conditions in biological systems.

• pH: A measure of the hydrogen ion concentration in a solution.

• Buffer: A solution that minimizes changes in pH.

• Acid: A substance that increases the concentration of hydrogen ions () in a solution.

• Base: A substance that decreases the concentration of hydrogen ions in a solution.

Applications

• Calculate the pH of an acid or base from a given concentration of .

• Understand how buffers work and predict the effect of adding acid or base to a buffered solution.

Introduction to Microscopes

Compound Microscope Parts and Functions

Microscopes are essential tools in biology for observing cells and microorganisms. Understanding their parts and functions is crucial for proper use.

• Parts: base, arm, oculars, revolving nosepiece, objective lenses, stage, coarse adjustment knob, fine adjustment knob, condenser, iris diaphragm, lamp.

• Field of view (FOV): The area visible through the microscope.

• Depth of field: The thickness of the specimen that is in focus.

• Resolution: The ability to distinguish two points as separate.

Microscope Calculations

• Calculate total magnification:

• Determine FOV diameter for a given objective.

• Know what types of samples are viewed on a compound microscope versus a dissecting microscope.

Cell Structure and Function

Key Vocabulary and Concepts

Cells are the basic units of life. Understanding their structure and function is fundamental to biology.

• Cytoplasm streaming: Movement of the fluid substance within a cell.

• Cilia: Hair-like structures that aid in movement.

• Pseudopodia: Temporary projections of eukaryotic cell membranes or cytoplasm used for movement or feeding.

• Photosynthesis: The process by which plants and some other organisms convert light energy into chemical energy.

• Thylakoid: Membrane-bound compartments inside chloroplasts, site of the light-dependent reactions of photosynthesis.

Cell Types and Staining

• Distinguish between plant cells and animal cells (no cell wall in animal cells).

• Recognize common stains used to visualize cells.

• Identify cell types:

  • Cyanobacteria – Oscillatoria

  • Amoeba

  • Spirogyra

  • Onion cell

  • Epithelial (Cheek Cell)

  • Paramecium

  • Elodea

Diffusion and Osmosis

Key Vocabulary and Concepts

Diffusion and osmosis are passive transport processes that move substances across cell membranes, essential for maintaining cellular homeostasis.

• Diffusion: Movement of molecules from an area of higher concentration to an area of lower concentration.

• Osmosis: Diffusion of water across a selectively permeable membrane.

• Hypotonic solution: Lower solute concentration compared to the cell; water enters the cell.

• Hypertonic solution: Higher solute concentration compared to the cell; water leaves the cell.

• Isotonic solution: Equal solute concentration inside and outside the cell; no net water movement.

• Crenation: Shrinking of animal cells in a hypertonic solution.

• Plasmolysis: Shrinking of plant cell cytoplasm in a hypertonic solution.

• Concentration gradient: Difference in concentration of a substance across a space.

• Solvent: Substance that dissolves the solute.

• Solute: Substance dissolved in the solvent.

• Solution: Homogeneous mixture of solute and solvent.

Applications and Examples

• Understand results of diffusion experiments using solutions like sucrose and starch.

• Explain how substances move across membranes and the effect of concentration gradients.

• Predict direction and rate of osmosis and diffusion based on solution type.

• Recognize visual effects of different solution concentrations on plant cells.

HTML Table: Comparison of Solution Types

This table summarizes the effects of different solution types on cells.