Introduction to Biology and Scientific Inquiry: Study Notes

Introduction to Biology and Scientific Inquiry

What is Life?

Life is defined by a set of characteristics shared by all living organisms. These characteristics, when considered together, distinguish living things from non-living matter.

• Acquire and Use Materials and Energy: Organisms obtain necessary materials (nutrients, minerals) and energy from their environment to sustain life processes. Energy can be obtained through:

  • Photosynthesis: Capturing sunlight energy and converting it to a storable form.

  • Consumption: Obtaining energy by eating other organisms.

• Maintain Organized Complexity: Living organisms use energy to maintain a stable internal environment (homeostasis) and build complex biological molecules and structures.

• Sense and Respond to Stimuli: Organisms detect and respond to changes in their environment, such as light, temperature, or chemicals.

• Grow: Organisms increase in size and often in the number of cells.

• Reproduce: Organisms produce offspring, passing on genetic information to the next generation.

• Evolve: Populations of organisms change over generations through genetic variation and natural selection.

The Cell: The Basic Unit of Life

All living organisms are composed of cells. The cell is the smallest unit that can carry out all life processes.

• Plasma Membrane: Encloses the cell, regulating passage of materials in and out.

• Genetic Material: Contains instructions for cell function (DNA).

• Cytoplasm: Fluid interior containing organelles and molecules.

Levels of Biological Organization

Life can be studied at various levels of complexity, from the simplest atomic structures to the entire Earth.

• Atom: The smallest particle of an element retaining its properties.

• Molecule: Atoms bonded together.

• Cell: The smallest unit of life.

• Tissue: Groups of similar cells performing a specific function.

• Organ: Structure composed of different tissues working together.

• Organ System: Groups of organs that cooperate to perform major functions.

• Organism: An individual living thing.

• Population: A group of individuals of the same species living in an area.

• Community: Populations of different species living in the area.

• Ecosystem: A community plus its non-living environment.

• Biosphere: All ecosystems on Earth, encompassing all living and non-living components.

Classification of Organisms

Biologists classify organisms based on their evolutionary relationships.

Domains of Life

• Domain Bacteria: Prokaryotic organisms.

• Domain Archaea: Prokaryotic organisms, often found in extreme environments.

• Domain Eukarya: Eukaryotic organisms (protists, plants, fungi, animals).

Cell Types

• Prokaryotic Cells:

  • No nucleus or membrane-bound organelles.

  • Found in domains Bacteria and Archaea.

• Eukaryotic Cells:

  • Have a nucleus and membrane-bound organelles.

  • Typical of plants, animals, fungi, and protists.

Binomial Nomenclature

• A two-name system for scientific classification, developed by Linnaeus.

• The first name refers to the genus (capitalized), the second to species (lowercase).

• Example: Homo sapiens

Evolution

Evolution is the genetic change in a population over time. It explains the diversification of life on Earth.

Key Concepts

• Common Ancestry: Similarities among different organisms (in anatomy, physiology, DNA, embryology) are evidence of shared evolutionary history.

• Mutation: Changes in DNA sequences that can lead to genetic variation. Mutations can be inherited if they occur in reproductive cells.

• Natural Selection: Differential survival and reproduction of organisms with advantageous traits, leading to adaptation.

• Adaptation: Traits that are beneficial in a specific environment and increase an organism's reproductive success.

Evidence for Evolution

• Embryological Similarities: Early embryonic stages of different species can show striking similarities, indicating common ancestry.

• Genetic Similarities: Humans and chimpanzees share over 95% of their DNA.

• Fossils: Preserved remains of past organisms provide a record of life's history.

Drivers of Evolution

• Diversity of Habitats: Different environments exert different selective pressures.

• Natural Phenomena: Shaping forces of a population include weather, food supply, and predators.

• Human Activities: Human activities (e.g., fossil fuel burning) impact evolution through environmental change.

• Introduction of Change: Mutations, genetic drift, and selection events expose advantageous adaptations.

What is Science?

Science is a systematic inquiry into the natural world, using observation and experimentation.

Principles of Science

• Natural Causality: Events have natural explanations.

• Uniformity: Natural laws are consistent across time and space.

• Objective Evidence: Scientific findings are independent of bias.

The Scientific Method

A systematic process for investigating phenomena.

1. Observation: Noticing a specific phenomenon.

2. Question: Asking why or how the phenomenon occurs.

3. Hypothesis: An informed, testable explanation for the observation.

4. Prediction: A specific, outcome expected if the hypothesis is true.

5. Experiment: Testing the prediction under controlled conditions.

6. Conclusion: Determining whether the experimental results support or refute the hypothesis.

Controlled Experiments

• Control Group: A baseline where all variables are held constant.

• Experimental Group: One variable is changed to test its effect.

• Placebo: An inactive substance used as a control group in medical studies.

• Blind Studies: Participants do not know which group they are in.

• Double-Blind Studies: Both participants and data collectors have no group assignment knowledge.

Scientific Theories

• A general and reliable explanation of important natural phenomena, developed through extensive, reproducible observations and experiments.

• Examples: Cell Theory (all living organisms are composed of cells).

Reasoning in Science

• Inductive Reasoning: Generalizing from specific observations to form theories (from specific to general).

• Deductive Reasoning: Generating hypotheses from well-supported generalizations or theories (from general to specific).

Historical Context

• Spontaneous Generation: The disproven idea that life arises from non-living matter.

• Biogenesis: The current view that all life comes from pre-existing life.

• Cell Theory: All living organisms are composed of cells; cells are the basic unit of life.

• Cellular Organization: A distinction is made between prokaryotic cells (no nucleus) and eukaryotic cells (with nucleus and organelles).