Study Guide for Lab Exam 2 Biology 105A Fall 2025

Study Guide for Lab Exam 2 Biology 105A Fall 2025 Instructor: Pelkki

Laboratory 1: Evolution

  1. Geologic Time

    • Concept: Refers to the immense timescale over which Earth's geological and biological history has occurred.

    • Age of the Earth: Approximately 4.5 billion years old.

  2. Lines of Evidence Used to Study Evolution
    a. Fossil Evidence

    • Definition of Fossils: Preserved remains or traces of organisms from the past, typically found in sedimentary rock layers.

    • Sedimentary Rock Layers: Fossils are typically found in layers that are arranged in a sequence where older layers lie beneath younger layers.

    b. Anatomical Evidence

    • Comparison of Physical Structures: Analyzing structure similarities and differences among organisms to determine evolutionary relationships.

    • Lab Focus: Specific anatomical structures studied to illustrate evolutionary concepts.

    c. Molecular Evidence

    • Genetic Information: Evolutionary relationships can also be traced through genetic codes, where proteins are formed from DNA sequences.

    • Electrophoresis Apparatus: Used to separate proteins from blood serums of various animals; understanding how to interpret these separations is crucial.

      • Interpretation of Protein Separation:

        • Similar columns of separated proteins suggest a closer evolutionary relationship.

        • Significant differences in columns indicate a divergence in evolutionary paths.

  3. Understanding Evolutionary Trees

    • Evolutionary Tree Analysis: Students should be prepared to analyze and interpret the evolutionary tree presented in the exam.

Goals for the Laboratory Session

  • Gain an understanding of geologic time.

  • Understand information scientists utilize to describe evolution.

  • Ability to interpret evolutionary trees.

  • Enhance observational skills.

Laboratory 2: Classification and Diversity of Life

  1. Definition of a Species

    • A species is often defined as a group of organisms that can interbreed and produce fertile offspring.

  2. Scientific Names

    • Recognition of Scientific Names: Knowledge of how to recognize scientific names based on a two-part naming system.

      • Components: Each scientific name is composed of a genus name and a species epithet.

    • Classification Scheme Levels: The hierarchy consists of domain, kingdom, phylum, class, order, genus, and species, each representing a level of biological classification.

  3. Dichotomous Key

    • Definition: A tool that allows for the identification of organisms through a series of two-part statements.

    • Construction: Built using pairs of descriptive statements that lead the user to the correct identification.

  4. Recognition of Related Organisms

    • Students should be able to recognize and differentiate related organisms from written descriptions.

Goals for the Laboratory Session

  • Gain a perspective of the diversity of life on Earth.

  • Understand the classification system.

  • Use dichotomous keys to identify organisms.

Laboratory 3: Symbiosis

  1. Types of Interactions between Species

    • Memorize the five types of symbiotic interactions and their effects on each species involved (refer to Table 3.1).

  2. Definition of Coevolution

    • Co-evolution: The process where two or more species influence each other's evolutionary path through selective pressures.

  3. Recognition of Species Interaction

    • Be able to identify and name a species interaction based on a given written description.

Goals for the Laboratory Session

  • Understand interactions between various species.

  • Learn different categories of species interactions.

  • Enhance observational skills.

  • Proper use of a compound light microscope.

Laboratory 4: Predators and Prey

  1. Predation

    • Understanding Predation: Knowledge of the interaction type known as predation and its characteristics within the ecosystem.

  2. Organism Strategies

    • Various strategies used by organisms to mitigate predation risk, including those used by plants.

    • Specific Strategies and Effectiveness:

      • Camouflage Strategy: Organisms blend into their environment to avoid detection.

      • Warning Coloration Strategy: Bright colors signal to predators that an organism is toxic or unpalatable.

      • Mimicry Strategy: One species evolves to resemble another species to gain a survival advantage.

  3. Graph Interpretation

    • Be prepared to read and analyze graphs generated from lab experiments regarding predator-prey dynamics.

Goals for the Laboratory Session

  • Comprehend predator-prey relationships.

  • Experience prey defense strategies.

  • Understand bar graph creation and analysis methods.

Laboratory: Loss of Biodiversity Game

  1. Key Definitions

    • Biodiversity: The variety of life in the world or a particular habitat or ecosystem.

    • Extinction: The end of existence of a species, resulting in the permanent loss of that species.

    • Extirpation: The local extinction of a species in a specific area but not globally.

    • Ecosystem Services: Benefits provided by ecosystems to humans, including clean air, water, and pollination.

  2. Human Impact

    • Identify ways humans contribute to the loss of biodiversity, including habitat destruction, pollution, and climate change.

  3. Understanding Ecosystem Services

    • Familiarize with examples and the importance of ecosystem services presented in class.

  4. Graph Trends

    • Be prepared to discuss major trends seen in graphs related to:

      • Species that are not invasive or introduced.

      • Introduced/invasive species.

  5. Graph Construction

    • Understand how to construct and answer questions regarding the graph created during the Loss of Biodiversity game.

Goals for the Laboratory Session

  • Understand predator-prey relationships.

  • Experience the effectiveness of prey defense strategies.

  • Learn how to create and utilize information from bar graphs.