Topic 7

Introduction to Biology 241

  • Course Title: BIOL 241 - Energy Flow in Biological Systems

  • Instructor Contact: paul.galpern@ucalgary.ca

  • Important Note: Image content is in the public domain or licensed for use at the University of Calgary.

Course Overview

  • Primary Focus: Energy flow in biological systems

    • Unit 1: Molecular Energy Transformations

    • Unit 2: Cellular Energy Transformations

    • Unit 3: Energy Allocation in Organisms

      • 7. Energy Budgets

      • 8. Thermoregulation

      • 9. Locomotion

      • 10. Reproduction/Population Growth

    • Unit 4: Energy Flow in Ecosystems

Energy Budgets

Objectives of Energy Budget Calculations

  1. Calculation of Energy Components:

    • Assess how biomass changes are affected by different energy budget components.

  2. Trade-off Relationships:

    • Understand the positive relations and trade-offs between components of the energy budget in relation to an organism's life history.

  3. Significance of Resting Metabolism:

    • Explore why resting (basal) metabolism is a crucial part of energy allocation.

Importance of Metabolic Rates

  1. Measurement of Metabolic Rate:

    • Explain why metabolic rate is a key metric for measuring organism energy use.

    • Discuss methods to measure metabolic rate.

  2. Scaling with Body Size:

    • Examine how metabolic rate varies with body size, and the implications of this scaling.

  3. Comparison of Metabolic Rates:

    • Compare absolute vs. mass-specific metabolic rates across different organisms.

  4. Graphical Representation:

    • Relate log-transformed variables to original graphs and predict relationships.

Energy Expenditure Factors

Factors Influencing Energy Use

  • Activity Levels: Organisms allocate energy differently based on various functions such as growth, reproduction, and maintenance.

Size and Energy Needs

  • Comparison of Organism Sizes:

    • Larger animals require more total energy but less energy per gram compared to smaller animals.

  • Plant Growth Rates:

    • Fast-growing plants have higher energy demands to support their rapid growth.

Environmental Influence on Energy Needs

Thermoregulation Strategies

  • Endotherms (e.g., polar bears) require more energy than ectotherms (e.g., American alligator).

  • Environmental factors significantly influence the energy needs of organisms.

Mass and Energy Expenditure

  • Mass Ranges in Organisms:

    • Mass varies across many orders; for example, from Salmonella sp. (1x10^-12 g) to blue whales (2x10^8 g).

  • Impact of Size on Behavior:

    • Size affects peristaltic movement, dietary habits, and feeding frequency.

  • Scaling Studies:

    • The relationship between mass and metabolic parameters.

Surface Area to Volume Relationships

  • Volume Calculation:

    • Volume affects the exchange of matter and energy; larger organisms must develop adaptations to increase surface area for efficiency.

Energy Budget Equation

  • Formulating Energy Equations:

    • Energy IN = Energy ASSIMILATION + Energy EXCRETION

    • Energy ASSIMILATION = Energy RMR + Energy ACTIVITY + Energy PRODUCTION

    • Energy OUT = Energy RMR + Energy ACTIVITY + Energy PRODUCTION + Energy EXCRETION.

Metabolic Rate Definitions

  • RMR (Resting Metabolic Rate):

    • The energy consumption rate of the organism at rest.

  • BMR (Basal Metabolic Rate):

    • Metabolism at complete rest, lowest energy expenditure.

  • SMR (Standard Metabolic Rate):

    • Measured at a specific temperature in ectotherms.

  • FMR (Field Metabolic Rate):

    • Measured in wild animals, reflects metabolic rate while active.

Impact of Body Size on RMR

  • Kleiber's Law:

    • The relationship of energy expenditure with body mass, slope varies.

    • Biologically significant for understanding energy demands across species.

Energy Requirements for a 20 kg Cat

  • EnergyIN, EnergyEXCRETION, and EnergyASSIMILATION:

    • Considerations on kitty's energy budget based on dietary intake and waste production.

Conclusion

  • Understanding energy budgets is crucial for assessing how organisms function, their behaviors, environmental impacts, and evolution in relation to their energy needs.