Biology 100/101
Lecture 7
(Print Version)

Announcements &

Lecture Objectives

Photosynthesis Web Resources

Basic Reaction
of Photosynthesis

Biomes and Productivity

The Big Picture

Light Dependent

Calvin Cycle

(What to Know)

Lecture Syllabus

IB 100/101 Home Page


Text Readings  in Biology, Hoefnagels

    Chapter 4, The Energy of Life
    Chapter 5, Photosynthesis

You have open access (no log-in or password needed) to instructional materials on the Text web site. Select "Resources" from the upper left of the page and select the text chapter you want.


You may also ask questions and see answers to your classmates' questions in Moodle in the "Talk to Ed" forum.


The content of today's lecture will help you complete this assignment:

After studying this material you should be able to:

  1. Explain how the process of photosynthesis is involved in net primary production and an increase in plant biomass.

  2. Draw a sketch of a chloroplast, identify the structural components, and indicate where the photosynthetic energy transformations of the light reactions and the Calvin cycle take place.

  3. List the inputs (raw materials) and outputs (products) of the light dependent reactions and the Calvin Cycle.

  4. Describe how the light-dependent reactions and Calvin Cycle are chemically and energetically linked.

  5. Describe the role of enzymes in the process of photosynthesis.

  6. Explain how the following factors affect photosynthesis: stomatal opening, temperature, light intensity, water availability, and CO2 availability.

  7. Explain what the plant does with the carbohydrate that is produced by photosynthesis.

Web Resources, Photosynthesis:

Initiative will put Illinois at forefront of farm bioenergy production

A collection of animations for Photosythesis from the Smith College Biology 231 Web Page

The whole story of the Photosynthesis light dependent reactions (Virtual Cell Animation)


CO2 + H2O + --- Light
---> Heat + Simple
(Organic Compounds)
+ O2

(Cellular) Respiration

O2 + Simple
(Organic Compounds)
----> Heat + Usable
+ CO2 + H2O

Lecture activity

  • Get into groups with one or two other students. Each person will turn in her/his own paper.

  • From your understanding of biomes and the basic equation of photosynthesis, write down the factors you predict to be limiting the rate of photosynthesis and Net Primary Productivity (NPP) for trees in:

  • Biomes of North America

    • Taiga (boreal forests - bright blue area on the map)

    • Deserts (tan area on the map)

    • Tropical forests (dark green area in Mexico and central america)

    • Map of Global NPP

PRINT YOUR NAME and SIGN your name on the top of your paper.
Pass your paper to the aisle when asked to do so.

Photosynthesis, the big picture

The Light-Dependent Reactions

The conversion of light energy from the sun into usable chemical energy (ATP & NADPH) in the thylakoid membrane of the chloroplasts of plants

The Calvin Cycle

The production of carbohydrate (sugar) from CO2, using the energy of ATP and NADPH produced by the light dependent reactions of Photosynthesis

  • Photosynthesis: light reactions and Calvin Cycle (Text fig. 5.9, page 108)

  • Calvin Cycle (Text, Pg. 110, fig. 5.11)

    • Cyclic series of enzyme reactions

    • Addition of CO2 to a 5 carbon compound (RuBP)

    • Rubisco (the enzyme that fixes CO2)

    • Enzyme action (Text, Pg. 87, fig. 4.10)

  • Animation of the Calvin Cycle from Smith College

  • Summary of energy transformation enzyme reactions in the Calvin Cycle

    • Addition (fixing) of gaseous CO2 to RUBP, a 5 carbon compound in the stroma of chloroplasts.

    • Energy input from ATP
      (ATP from the light reactions ---> ADP + Phosphate back to the light reactions)

    • Addition of H+ and energy from NADPH
      (NADPH from the light reactions ---> NADP back to the light reactions

    • Production of carbohydrates for storage, transport, and biosynthesis

    • Recycling of 5 carbon compound (RUBP) to fix more CO2

    • Photosynthesis: Summary (Text, Pg. 106, fig. 5.7)

Plant anatomy: structural and functional integration of cellular activity

Photosynthesis: Summary

This is what it all distills down to - (Hoefnagels, Pg. 106, fig. 5.7)