Every objective will NOT necessarily be covered during class time; you will be independently responsible for some of them.

  1. List uses of free energy by living things, and the consequences of a free energy deficit
  2. Contrast the energy acquisition methods of autotrophs (including specifically photoautotrophs and chemoautotrophs) and heterotrophs, and give examples of organisms from each
  3. Explain the utility of coupled reactions in living systems
  4. Identify coupling within redox reactions
  5. Connect oxidation and reduction with electron gain or loss, and within the context of metabolic reactions, energy gain or loss
  6. Explain the ADP/ATP cycle and phosphorylation in terms of energy storage or donation, reaction coupling, and oxidation or reduction
  7. Explain what about the structure of ATP makes it a suitable energy transfer molecule
  8. Diagram and label the structure of a chloroplast, locating the sites of different stages of photosynthesis
  9. Model the steps of the light reactions of photosynthesis, explaining how this process captures, converts, and stores energy
  10. Identify the roles of ATP synthase and chemiosmosis in photosynthesis
  11. Identify the roles of carbon fixation and rubisco in the Calvin Cycle
  12. Identify the functional products, byproducts, reactants, and purpose of the light reactions
  13. Identify the functional products, byproducts, reactants, and purpose of the Calvin Cycle
  14. Identify the functional products, byproducts, reactants, and purpose of photosynthesis as a whole
  15. Explain why photosynthetic organisms on Earth are typically green
  16. Explain why plants conduct more photosynthesis than they do respiration
  17. Diagram and label the structure of a mitochondrion, locating the sites of different stages of cellular respiration
  18. Identify the functional products, byproducts, reactants, and purposes of each of the stages of cellular respiration
  19. Identify the functional products, byproducts, reactants, and purposes of cellular respiration as a whole
  20. Compare and contrast photosynthesis and respiration as performed in prokaryotes vs. in eukaryotes
  21. Explain why glycolysis must be followed either by aerobic cellular respiration or anaerobic fermentation
  22. Contrast alcoholic and lactic acid fermentation
  23. Identify the roles of ATP synthase, chemiosmosis, and oxidative phosphorylation in respiration
  24. Give examples of how energy-related pathways in biological systems are sequential and may be entered at multiple points in the pathway
  25. Explain how the stages of cellular respiration can be utilized to catabolize or anabolize a variety of metabolites besides glucose
  26. Explain the relationship between metabolic rate per unit of body mass and the size of a multicellular organism
  27. Contrast endothermy and ectothermy in terms of metabolic rate and body temperature patterns and characteristic organisms
  28. Explain the role of photosynthesis in the history of Earth’s atmosphere*

  • = self-study

Enduring Understandings

Enduring Understandings are the College Board's AP Biology course concepts that you need to know for the AP exam. Below, you'll find those Enduring Understandings relevant to this unit. Numbering and lettering matches the document linked from the main page of this website.
Every Enduring Understanding will NOT necessarily be covered during class time; you will be independently responsible for some of them.

A. Growth, reproduction and maintenance of the organization of living systems require free energy and matter.
1. All living systems require a constant input of free energy.
  • a. Life requires a highly ordered system.
  • b. Order is maintained by constant free energy input into the system.
  • c. Loss of order or free energy flow results in death.
  • d. Increased disorder and entropy are offset by biological processes that maintain or increase order.
  • e. Living systems do not violate the second law of thermodynamics, which states that entropy increases over time.
  • f. Order is maintained by coupling cellular processes that increase entropy (and so have negative changes in free energy) with those that decrease entropy (and so have positive changes in free energy).
  • g. Energy input must exceed free energy lost to entropy to maintain order and power cellular processes.
  • h. Energetically favorable exergonic reactions, such as ATP -> ADP, that have a negative change in free energy can be used to maintain or increase order in a system by being coupled with reactions that have a positive free energy change.
  • i. Energy-related pathways in biological systems are sequential and may be entered at multiple points in the pathway.
  • j. Organisms use free energy to maintain organization, grow and reproduce.
  • m. There is a relationship between metabolic rate per unit body mass and the size of multicellular organisms – generally, the smaller the organism, the higher the metabolic rate.
  • n. Excess acquired free energy versus required free energy expenditure results in loss of mass and, ultimately, the death of the organism.
2. Organisms capture and store free energy for use in biological processes.
  • a. Autotrophs capture free energy from physical sources in the environment.
  • b. Photosynthetic organisms capture free energy present in sunlight.
  • c. Chemosynthetic organisms capture free energy from small inorganic molecules present in their environment, and this process can occur in the absence of oxygen.
  • d. Heterotrophs capture free energy present in carbon compounds produced by other organisms.
  • e. Heterotrophs may metabolize carbohydrates, lipids and proteins by hydrolysis as sources of free energy.
  • f. Fermentation produces organic molecules, including alcohol and lactic acid, and it occurs in the absence of oxygen.
  • g. Different energy-capturing processes use different types of electron acceptors.
  • h. The light-dependent reactions of photosynthesis in eukaryotes involve a series of coordinated reaction pathways that capture free energy present in light to yield ATP and NADPH, which power the production of organic molecules.
  • i. During photosynthesis, chlorophylls absorb free energy from light, boosting electrons to a higher energy level in Photosystems I and II.
  • j. Photosystems I and II are embedded in the internal membranes of chloroplasts (thylakoids) and are connected by the transfer of higher free energy electrons through an electron transport chain (ETC).
  • k. When electrons are transferred between molecules in a sequence of reactions as they pass through the ETC, an electrochemical gradient of hydrogen ions (protons) across the thylakoid membrane is established.
  • l. The formation of the proton gradient is a separate process, but it is linked to the synthesis of ATP from ADP and inorganic phosphate via ATP synthase.
  • m. The energy captured in the light reactions as ATP and NADPH powers the production of carbohydrates from carbon dioxide in the Calvin cycle, which occurs in the stroma of the chloroplast.
  • n. Photosynthesis first evolved in prokaryotic organisms; scientific evidence supports that prokaryotic (bacterial) photosynthesis was responsible for production of an oxygenated atmosphere; prokaryotic photosynthetic pathways were the foundation of eukaryotic photosynthesis.
  • o. Cellular respiration in eukaryotes involves a series of coordinated enzyme-catalyzed reactions that harvest free energy from simple carbohydrates.
  • p. Glycolysis rearranges the bonds in glucose molecules, releasing free energy to form ATP from ADP and inorganic phosphate, and resulting in the production of pyruvate.
  • q. Pyruvate is transported from the cytoplasm to the mitochondrion, where further oxidation occurs.
  • r. In the Krebs cycle, carbon dioxide is released from organic intermediates, ATP is synthesized from ADP and inorganic phosphate via substrate level phosphorylation and electrons are captured by coenzymes.
  • s. Electrons that are extracted in the series of Krebs cycle reactions are carried by NADH and FADH2 to the electron transport chain.
  • t. The electron transport chain captures free energy from electrons in a series of coupled reactions that establish an electrochemical gradient across membranes.
  • u. Electron transport chain reactions occur in chloroplasts (photosynthesis), mitochondria (cellular respiration) and prokaryotic plasma membranes.
  • v. In cellular respiration, electrons delivered by NADH and FADH2 are passed to a series of electron acceptors as they move toward the terminal electron acceptor, oxygen. In photosynthesis, the terminal electron acceptor is NADP+.
  • w. The passage of electrons is accompanied by the formation of a proton gradient across the inner mitochondrial membrane or the thylakoid membrane of chloroplasts, with the membrane(s) separating a region of high proton concentration from a region of low proton concentration. In prokaryotes, the passage of electrons is accompanied by the outward movement of protons across the plasma membrane.
  • x. The flow of protons back through membrane-bound ATP synthase by chemiosmosis generates ATP from ADP and inorganic phosphate.
  • y. In cellular respiration, decoupling oxidative phosphorylation from electron transport is involved in thermoregulation.
  • z. Free energy becomes available for metabolism by the conversion of ATP->ADP, which is coupled to many steps in metabolic pathways.

A. Interactions within biological systems lead to complex properties.
2. The structure and function of subcellular components, and their interactions, provide essential cellular processes.
  • g. Mitochondria specialize in energy capture and transformation.
  • h. Mitochondria have a double membrane that allows compartmentalization within the mitochondria and is important to its function.
  • i. The outer membrane is smooth, but the inner membrane is highly convoluted, forming folds called cristae.
  • j. Cristae contain enzymes important to ATP production; cristae also increase the surface area for ATP production.
  • m. Chloroplasts are specialized organelles found in algae and higher plants that capture energy through photosynthesis.
  • n. The structure and function relationship in the chloroplast allows cells to capture the energy available in sunlight and convert it to chemical bond energy via photosynthesis.
  • o. Chloroplasts contain chlorophylls, which are responsible for the green color of a plant and are the key light-trapping molecules in photosynthesis. There are several types of chlorophyll, but the predominant form in plants is chlorophyll a.
  • p. Chloroplasts have a double outer membrane that creates a compartmentalized structure, which supports its function. Within the chloroplasts are membrane-bound structures called thylakoids. Energy-capturing reactions housed in the thylakoids are organized in stacks, called "grana," to produce ATP and NADPH2, which fuel carbon-fixing reactions in the Calvin cycle. Carbon fixation occurs in the stroma, where molecules of CO2 are converted to carbohydrates.

Textbook Reference

This is the part of your textbook that covers the material for this unit.
Ch. 6-8.

Relevant Files

Here, you'll find files for this course. Copies of lecture notes will go here, as will others.

Part 1, Photosynthesis:
Part 2, Respiration:


These connect to materials on other teachers' websites that you may find helpful. Generally speaking, I put links to helpful review materials - like video lectures summarizing the material - towards the top, and links to interesting extensions towards the bottom.
Cellular Respiration Song- May help you remember it!
John Kyrk Animations: Light Reactions, Calvin Cycle, Glycolysis, (Krebs Cycle (Citric Acid Cycle) and Electron Transport Chain
Cellular respiration simulation, investigate what happens to ATP production in the presence and absence of oxygen.
In-depth explanation of the processes of cellular respiration and fermentation.
Cellular Respiration simulation
Pictorial outline of Cellular Respiration
Cellular Respiration overview
Good general review notes of Cell Resp & Photosynthesis
MIT Hypertextbook on Cell Resp
Great animation of the Electron Transport Chain
More Cell Respiration Animations from Taylor Univ.
Photosynthesis Movie- Step by Step
Determine how wavelength and light intensity affect the light reactions of photosynthesis using this simulation
Calculate your Calories
Calorie Content in Foods
Food Composition
Activity Calorie Calculator