Introduction to Biology & The Scientific Method Lecture Notes
General Biology 1 Course Information
Foundations of Biology
Definition of Biology: The study of living organisms and their specific interactions with one another and their non-living environments.
Organism: A term used to describe any individual form of life.
Characteristics of Life: Eight identified traits define a living entity:
Order/Organization
Sensitivity or response to the environment
Reproduction
Adaptation
Growth and development
Regulation and homeostasis
Energy processing
Evolution
Hierarchical Organization of Living Systems
Cellular Level:
Atoms: The basic building blocks of matter.
Molecule: Groups of atoms bonded together.
Macromolecule: Large molecules like DNA or proteins.
Organelle: Specialized structures within a cell (e.g., mitochondria).
Cell: The fundamental unit of life. All living organisms are composed of cells.
Unicellular: Organisms consisting of a single cell.
Multicellular: Organisms composed of many cells organized into specialized structures.
Organismal Level:
Tissue: Groups of similar cells working together.
Organ: Different tissues grouped together to perform a specific function.
Organ System: A group of organs working together.
Organism: The individual living entity.
Populational Level:
Population: A group of individuals of the same species living in the same area.
Species: A group of similar organisms capable of interbreeding.
Community: Different populations of species living together in an area.
Ecosystem: A community of living organisms interacting with their physical, non-living environment.
Biosphere: The global sum of all ecosystems; the zone of life on Earth.
Classification of Cells
Eukaryotic Cells: These contain membrane-enclosed organelles. The largest organelle is typically the nucleus.
Prokaryotic Cells: These are simpler structures that lack a nucleus and other membrane-enclosed organelles.
Characteristics of Life: Detailed Mechanisms
Sensitivity and Response to Stimuli:
Organisms respond to various environmental stimuli.
Movement toward a stimulus is categorized as a positive (+$) response.\n - Movement away from a stimulus is categorized as a negative (-) response.\n- **Reproduction and Inheritance**:\n - Both single-cell and multicellular organisms reproduce through cell division.\n - This process involves DNA replication and mitosis, resulting in the passage of genes to offspring. In mitosis, this produces two diploid cells.\n- **Adaptation**:\n - This is the ability of a living organism to adjust to or fit into its environment.\n - A trait is only considered an adaptation if it enhances the organism’s chance of survival for the purpose of reproduction.\n - **Example**: Deep-sea fish have specialized retinas dominated by rods and reflective properties, which are adaptations for vision in extremely dim light.\n- **Growth and Development**:\n - Genes provide specific instructions that direct the growth and development of organisms.\n - This ensures offspring exhibit many of the same traits as their parents.\n- **Regulation and Homeostasis**:\n - Organisms utilize regulatory mechanisms to coordinate internal functions, respond to stimuli, and cope with environmental stressors.\n - **Homeostasis**: The specific process of maintaining stable internal conditions despite external changes.\n- **Energy Processing**:\n - All organisms require energy for metabolic activities.\n - Some organisms (autotrophs) capture energy from the sun and convert it into chemical energy.\n - Others (heterotrophs) utilize chemical energy found in the molecules they ingest as food.\n\n# Evolution and Natural Selection\n\n- **Evolution**: The process by which organisms adapt to changing environments through natural selection.\n- **Stabilizing Selection**: Favors the average phenotype and selects against extreme variations.\n - **Example**: Robins typically lay a clutch of 444$$ may result in no viable offspring.
Directional Selection: Favors one extreme of the phenotypic spectrum, often following an environmental change.
Example: Prior to the Industrial Revolution, light-colored moths were better camouflaged in pristine environments. The soot produced during the Industrial Revolution darkened the environment, shifting selection favor toward dark-colored moths.
Diversifying (Disruptive) Selection: Favors extreme phenotypes over the average phenotype.
Example: In certain environments, gray rabbits and dappled (white and gray) rabbits are better camouflaged and survive better than pure white rabbits.
The Nature of Science and Reasoning
Goal of Science: To understand the natural world through observation and reasoning.
Descriptive Science: Much of science begins with observation and description, such as the classification of life or the sequencing of the human genome.
Deductive Reasoning: Uses general principles to make specific predictions.
Example: Eratosthenes used deductive reasoning to estimate the circumference of the Earth.
Inductive Reasoning: Uses specific observations to develop general conclusions.
The Scientific Method
The Scientific Method is a systematic approach to gaining knowledge about the natural world.
Hypothesis: A possible explanation for an observation.
It must be testable to determine its validity.
It allows for the formation of predictions.
It is often tested in multiple ways.
It is iterative; hypotheses are refined or changed as new data is acquired.
Experimental Design:
Experiments test the hypothesis and must be designed to isolate and test only one variable at a time.
Control Group: The group that remains unmanipulated for comparison.
Test Group: The manipulated group.
Process Example:
Observation: A light bulb does not light up.
Question: Is the light bulb blown?
Hypothesis: The light bulb is blown.
Prediction: If I replace the light bulb and it lights up, then the hypothesis is supported.
Experiment: Replace the bulb.
Results and Analysis: If the new bulb lights up, the hypothesis is supported. If it does not, the hypothesis is not supported and must be revised.
Report: Share the findings.