BIO 353 CELL BIOLOGY CELLULAR RESPIRATION LAB NOTES ARIZONA STATE UNIVERSITY
Big Idea 2: Biological systems utilize free energy and molecular building blocks to grow, to reproduce and to maintain
dynamic homeostasis.
• Enduring understanding 2.A: Growth, reproduction and maintenance of the organization of living systems require free
energy and matter.
• Enduring understanding 2.B: Growth, reproduction and dynamic homeostasis require that cells create and maintain
internal environments that are different from their external environments.
• Enduring understanding 2.C: Organisms use feedback mechanisms to regulate growth and reproduction, and to maintain
dynamic homeostasis.
• Enduring understanding 2.D: Growth and dynamic homeostasis of a biological system are influenced by changes in the
system’s environment.
Learning Objectives:
LO 2.1 The student is able to explain how biological systems use free energy based on empirical data that all organisms
require constant energy input to maintain organization, to grow and to reproduce.
LO 2.2 The student is able to justify a scientific claim that free energy is required for living systems to maintain organization, to
grow or to reproduce, but that multiple strategies exist in different living systems.
LO 2.24 The student is able to analyze data to identify possible patterns and relationships between a biotic or abiotic factor
and a biological system (cells, organisms, populations, communities or ecosystems).
Science Practices employed by activity:
• Science Practice 2: The student can use mathematics appropriately
• Science Practice 5: The student can perform data analysis and evaluation of evidence
• Science Practice 6: The student can work with scientific explanations and theories
AP Biology Lab - Cell Respiration
This investigation uses respirometry techniques to calculate the rate of oxygen consumption (cellular
respiration) in germinating pea seeds. The effect of temperature and whether a seed has broken dormancy are
quantified and graphed. The ideal gas law and its concepts are reviewed and applied.
Objectives
• Understand the relationships between temperature, pressure and volume.
• Study the effects of diffusion through a semipermeable membrane
• Quantify oxygen consumption rates in germinating peas under different conditions
• Predict the effect of temperature and germination state on the rate of cell respiration
Background
Each individual cell is responsible for the energy exchanges necessary to sustain its ordered structure. Cells
accomplish this task by breaking down nutrient molecules to generate ATP (adenosine triphosphate), which
can then be used to run cellular processes that require energy. This process is called cellular respiration which
requires nutrient molecules and oxygen. Carbon dioxide and water are products of the series of reactions
involved in cellular respiration.
C6H12O6 + 6O2 → 6CO2 + 6H2O
There are several methods of indirectly measuring the rate of cellular respiration in organisms. One method
involves monitoring changes in temperature; since the process of respiration is exergonic (produces heat).
Another method is to measure either the oxygen consumption or the carbon dioxide production. Respirometers
are devices that measure these types of gas volume changes, and therefore provide information about the rate
of cellular respiration.
In order to be able to use a respirometer, you will need to use the ideal gas law, which describes the
relationship between temperature, pressure and volume. (PV = nRT)
Where P is the pressure of the gas, V is the volume of the gas, n is the number of molecules of gas, R is the
gas constant, and T is the temperature of the gas (in K)
This law implies the following important concepts about gases:
1. If temperature and pressure are kept constant, then the volume of the gas is directly proportional to the
number of molecules of gas.
2. If the temperature and volume remain constant, then the pressure of the gas changes in direct
proportion to the number of molecules of gas present.