General Biology: Foundations, Scientific Method, and Chemistry for Life

Biology: Study of Life

What Does It Mean to Be Alive?

• Order: Living things display complex organization. Example: The head of a sunflower shows ordered structure.

• Utilization of Energy: All living organisms require energy to perform activities. Examples: Running, walking, and internal actions. Anything that has calories will fuel us.

• Reproduction: Living things produce offspring. Key Points:

  • Union of sperm and egg = fertilization

  • A fertilized egg becomes a zygote, which develops into a new organism.

• Growth and Development: Organisms grow and develop according to specific instructions encoded in their DNA. Example: A zygote develops into a multicellular human made up of trillions of cells.

• Response to the Environment: Living things respond to stimuli. Example: Sweating to cool off or shivering to heat up.

• Homeostasis: Maintenance of a stable internal environment despite changes in the external environment. Examples: Temperature, sleep, hunger, and heart rate are regulated.

• Populations and Organisms: Populations consist of members of a species within an area that can breed. Key Points:

  • Organisms inherit traits from parents via DNA.

  • Only organisms that reproduce sexually pass on DNA.

• DNA: The universal molecule of heredity. Key Points:

  • All organisms use DNA, except some viruses which use RNA.

  • Example: HIV is a virus that uses RNA.

  • All viruses require a host cell to replicate.

Cellular Organization

Unicellular vs. Multicellular

• Unicellular: Organisms made of one cell (e.g., bacteria).

• Multicellular: Organisms made of many cells (e.g., humans).

Types of Cells

• Prokaryotes: Cells without a nucleus (e.g., bacteria).

• Eukaryotes: Cells with a nucleus (e.g., plants, fungi, protists, animals).

Cell Type	Nucleus	Examples
Prokaryote	No	Bacteria
Eukaryote	Yes	Plants, Fungi, Protists, Animals

Biological Hierarchy

• Biosphere: All ecosystems on Earth.

• Ecosystem: All living and nonliving things in an area.

• Community: All populations in an area.

• Population: Group of organisms of the same species in an area.

• Organism: An individual living thing.

• Organ System: Group of organs working together (e.g., respiratory system).

• Organ: Structure with a specific function (e.g., lungs).

• Tissue: Group of similar cells (e.g., simple squamous epithelial tissue).

• Cell: Smallest unit of life.

Taxonomy and Classification

Domains and Kingdoms

• Three Domains:

  • Eukarya: Includes kingdoms Plantae (producers), Animalia (consumers), Fungi (decomposers), Protista (miscellaneous group).

  • Bacteria

  • Archaea

Taxonomic Hierarchy

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species (most exclusive)

• Species: Group of organisms with similar characteristics that can reproduce fertile offspring.

• Naming: Binomial nomenclature (Genus species, italicized; e.g., Homo sapiens).

Scientific Method

Methods of Scientific Inquiry

• Discovery Science: Making observations and drawing conclusions.

• Hypothesis-Driven Science: Formulating and testing hypotheses. Steps:

  1. Observation

  2. Question

  3. Hypothesis (statement)

  4. Prediction

  5. Test

  6. Results

  7. Conclusion

Variables in Experiments

• Independent Variable (IV): The variable that is changed or controlled.

• Dependent Variable (DV): The variable measured to assess the effect of the IV.

• Control Group: Group not exposed to the IV.

• Experimental Group: Group exposed to the IV.

• Controlled Variables: Factors kept constant.

Types of Data

• Qualitative: Descriptive data.

• Quantitative: Numerical and measurable data.

Type of Data	Description
Qualitative	Descriptive, non-numerical
Quantitative	Numerical, measurable

Graphing Results

• Graphs visualize data; every graph should have a descriptive title.

• Axes: X-axis (independent variable), Y-axis (dependent variable).

• Include units and scale.

Experimental Design Example

• Hypothesis: Fertilizer will increase tomato plant growth.

• Control group: No fertilizer.

• Experimental group: Fertilizer applied.

• Measured variable: Height or mass of tomato plants.

Chapter 2: Chemistry for Biology

Matter and Elements

• Matter: Anything that has mass and occupies space.

• Elements: Pure substances that cannot be broken down further. Examples: Sodium (Na), Oxygen (O).

• Compounds: Substances formed by chemical bonds between elements. Examples: $\text{NaCl}$, $\text{H}_2\text{O}$

Atoms

• Atom: Smallest unit of an element retaining its properties.

• Subatomic Particles:

  • Protons: Positive charge, found in nucleus, mass = 1 AMU.

  • Neutrons: No charge, found in nucleus, mass = 1 AMU.

  • Electrons: Negative charge, found in electron cloud, negligible mass.

Particle	Charge	Location	Mass (AMU)
Proton	+1	Nucleus	1
Neutron	0	Nucleus	1
Electron	-1	Electron cloud	~0

Atomic Number and Mass Number

• Atomic Number: Number of protons in the nucleus.

• Mass Number: Sum of protons and neutrons.

• Equation: $\text{Mass Number} = \text{Number of Protons} + \text{Number of Neutrons}$

Isotopes

• Isotope: Atoms of the same element with different numbers of neutrons.

• Example: Carbon isotopes: $^{12}\text{C}$, $^{13}\text{C}$, $^{14}\text{C}$

Periodic Table

• Lists all known elements, organized by atomic number.

• Biologically relevant elements include: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Calcium (Ca), Magnesium (Mg), Sulfur (S), Potassium (K), Sodium (Na), Chlorine (Cl), Phosphorus (P).

States of Matter

• Solid

• Liquid

• Gas

Additional info:

• Scientific method steps and experimental design are foundational for all biological research.

• Understanding atomic structure is essential for grasping molecular biology and biochemistry.