General Biology Study Notes: The Science of Life & The Chemical Basis of Life

The Science of Life

Introduction to Biology

Biology is the scientific study of life, encompassing the structure, function, growth, origin, evolution, and distribution of living organisms. Understanding biology involves exploring the properties and processes that define living things.

• Biology: The study of life and living organisms.

• Organism: Any living thing composed of cells, capable of metabolism, growth, response to stimuli, and reproduction.

• Homeostasis: The ability of an organism to maintain stable internal conditions.

• Evolutionary Adaptation: Changes in organisms over generations that enhance survival and reproduction.

Properties of Life

All living things share several fundamental properties that distinguish them from non-living matter.

• Order: Living things are organized into cells and complex structures.

• Regulation: Ability to maintain homeostasis.

• Growth and Development: Organisms grow and develop according to genetic instructions.

• Response to Environment: Ability to respond to stimuli.

• Energy Processing: Use of energy to power activities and chemical reactions.

• Reproduction: Production of offspring.

• Evolutionary Adaptation: Populations evolve over time.

Levels of Organization

Biological organization ranges from molecules to the biosphere.

• Cell: Basic unit of life.

• Organism: Individual living entity.

• Population: Group of organisms of the same species.

• Community: Different populations living together.

• Ecosystem: Community plus its physical environment.

• Biosphere: All ecosystems on Earth.

Classification of Life

Organisms are classified into domains and kingdoms based on shared characteristics.

• Three Domains: Bacteria, Archaea, Eukarya

• Six Kingdoms:

  • Domain Bacteria

  • Domain Archaea

  • Domain Eukarya:

    • Protists

    • Fungi

    • Plantae

    • Animalia

Scientific Inquiry and Methods

Science uses systematic methods to investigate natural phenomena.

• Scientific Method: A process for experimentation that is used to explore observations and answer questions.

• Steps:

  1. Observation

  2. Question

  3. Hypothesis

  4. Experiment

  5. Analysis

  6. Conclusion

• Hypothesis: A testable statement based on observations.

• Controlled Experiment: An experiment in which only one variable is changed at a time.

• Variables:

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

  • Dependent Variable: The variable that is measured.

  • Control Group: The group that does not receive the experimental treatment.

Claim, Evidence, Reasoning (CER)

CER is a framework for scientific explanation and argumentation.

• Claim: A statement or conclusion that answers a question.

• Evidence: Scientific data that supports the claim.

• Reasoning: Explanation that connects the evidence to the claim.

The Chemical Basis of Life

Properties of Water

Water is essential for life due to its unique chemical and physical properties.

• Polarity: Water molecules have a partial positive charge on one side and a partial negative charge on the other, making them polar.

• Electronegativity: Oxygen is more electronegative than hydrogen, causing unequal sharing of electrons.

• Hydrogen Bonds: Weak bonds that form between the partially positive hydrogen atom of one water molecule and the partially negative oxygen atom of another.

Cohesion and Adhesion

Cohesion and adhesion are important for water movement in plants and other biological systems.

• Cohesion: Attraction between water molecules due to hydrogen bonding.

• Adhesion: Attraction between water molecules and other substances.

• Example: Water moving up plant stems (capillary action).

Surface Tension

Surface tension is the result of cohesion at the surface of water, allowing it to resist external force.

• Example: Insects walking on water.

Capillary Action

Capillary action is the ability of water to flow in narrow spaces without the assistance of external forces.

• Example: Water rising in a thin tube or plant xylem.

Specific Heat and Heat of Vaporization

Water has a high specific heat and heat of vaporization, which helps regulate temperature in organisms and environments.

• Specific Heat: Amount of heat required to raise the temperature of water by one degree Celsius.

• Heat of Vaporization: Amount of heat required to convert water from liquid to gas.

• Example: Sweating cools the body as water evaporates.

Summary Table: Properties of Water

Property	Description	Biological Importance
Polarity	Unequal sharing of electrons creates partial charges	Allows formation of hydrogen bonds
Cohesion	Water molecules stick to each other	Surface tension, transport in plants
Adhesion	Water molecules stick to other substances	Capillary action
Specific Heat	High energy required to change temperature	Temperature regulation
Heat of Vaporization	High energy required for evaporation	Cooling mechanisms

Additional Key Terms

• Metabolism: All chemical reactions in living organisms that maintain life.

• Autotroph: Organism that produces its own food (e.g., plants via photosynthesis).

• Heterotroph: Organism that obtains food from other organisms.

• Sexual Reproduction: Offspring produced by fusion of gametes.

• Asexual Reproduction: Offspring produced without gamete fusion.

• Taxonomy: The science of classifying organisms.

Formulas and Equations

• Photosynthesis: $6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$

• Cellular Respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}$

Example: Scientific Method Application

• Observation: Plants grow towards light.

• Hypothesis: Light affects plant growth direction.

• Experiment: Place plants in different light conditions.

• Analysis: Measure growth direction.

• Conclusion: Plants exhibit phototropism.

Additional info: Some explanations and examples have been expanded for clarity and completeness.