Foundations of Biology

Objectives

• Describe the properties of living organisms

• Describe the major taxonomic groups of living organisms

• Apply the scientific method to investigate biological problems

Unifying Themes of Biology

Theme 1: Organization

Biological organization refers to the hierarchical structure of life, from molecules to the biosphere. Understanding these levels helps explain how complex living systems are structured and function.

Topic 1: 10 Levels of Organization

There are ten recognized levels of biological organization, each representing increasing complexity.

Topic 2: Emergent Properties

Emergent properties are characteristics that arise from the interaction and arrangement of parts within a system, not present in individual components.

• Structure: The arrangement of parts in an organism or system.

• Function: The specific role or activity performed by a structure.

• Example: The heart is made of muscle cells (structure) that work together to pump blood (function).

Topic 4: Cell is the Basic Unit of Life

Cells are the fundamental units of life. All living organisms are composed of cells, which can be classified as eukaryotic or prokaryotic.

Theme 2: Evolution Determines Classification

Evolutionary relationships are the basis for classifying and naming organisms. Classification reflects shared ancestry and evolutionary history.

• Domains: The highest taxonomic rank; three domains are Bacteria, Archaea, and Eukarya.

• Prokaryotic cells are found in Bacteria and Archaea; eukaryotic cells are found in Eukarya.

• Kingdoms: Eukarya is further divided into kingdoms such as Plantae, Animalia, Fungi, and Protists.

Theme 3: DNA is the Genetic Information

DNA stores genetic information in all living organisms, determining traits and enabling inheritance.

• Location in eukaryotic cells: DNA is found in the nucleus.

• Prokaryotic cells: DNA is located in the nucleoid region.

• Composition: DNA is composed of nucleotides (adenine, thymine, cytosine, guanine).

• Trait differences: Variations in DNA sequences explain differences in traits, such as fur color in mice.

Theme 4: Energy Transformations

Energy flows and cycles through biological systems, enabling life processes.

Topic 1: Energy Flow in 2 Steps

• Step 1: Energy enters ecosystems as sunlight.

• Step 2: Energy is converted by producers (e.g., plants) and transferred through consumers.

• Energy cannot be reused indefinitely; it is lost as heat at each transfer.

Topic 2: Chemical Cycling in 2 Steps

• Step 1: Chemical nutrients are taken up by producers from the environment.

• Step 2: Nutrients are passed to consumers and decomposers, cycling back to the environment.

Scientific Process

Six Major Steps of The Scientific Process

The scientific method is a systematic approach to investigating questions and testing hypotheses in biology.

1. Question: Identify a problem or question to investigate.

2. Hypothesis: Propose a tentative explanation or prediction.

3. Prediction: State how an independent variable will affect a dependent variable.

4. Experiment: Design and conduct a test to gather data.

5. Evaluate results: Analyze data to determine if it supports the hypothesis.

6. Conclusions: Draw conclusions and communicate findings.

Practice: Analyze a Scientific Question

Example: "Does Camouflage Affect Predation Rates on Two Populations of Mice?"

• Independent variable: Camouflage (presence or absence)

• Dependent variable: Predation rate

• Hypothesis example: Camouflage affects survival.

• Prediction example: Light colored mice will experience lower predation rates on the beach than inland environments.

• Experimental design: Use control and experimental groups (camouflaged vs. non-camouflaged models) in different habitats.

Data Analysis Example

In the provided experiment, models of mice (light and dark, camouflaged and non-camouflaged) were placed in beach and inland habitats. The percentage of attacked models was measured to test the hypothesis.

Conclusion: Camouflage reduces predation rates, supporting the hypothesis.

Additional info: The experiment demonstrates the application of the scientific method and the importance of adaptation in evolution.