Name
Class
Date
8.3 The Process of Photosynthesis
Lesson Objectives
Describe what happens during the light-dependent reactions.
Explain what happens during the light-independent reactions.
Identify factors that affect the rate at which photosynthesis occurs.
The chart below shows key terms from the lesson. Complete the chart by writing the
definitions.
Term
Definition
ATP synthase
Found in the thylakoid membrane, assembles ATP as H+ move from
thylakoid space out to the stroma
Calvin cycle
Reactions that occur in the stroma. Carbon dioxide is taken in, energy
from the light reactions is also required (ATP and NADPH) and sugars
are produced.
Electron transport
chain
Found in the thylakoid membrane, these carriers pass along high energy
electrons and eventually pass them to NADPH.
Photosystem
Cluster of 100s of pigments including chlorophylls and antenna
pigments. They convert light energy to chemical energy.
BUILD Understanding
Flowchart A flowchart is a way to show the steps in a process. As you read, complete the
flowchart to show the steps involved in the light-dependent reactions of photosynthesis.
Light is absorbed by
the pigments
Water provides
electrons as it is split
light-dependent
reactions
The proton gradient is
used to drive ATP
synthesis
Oxygen is made as a
waste product from
splitting water
NADPH captures the
high energy electrons
Light-Dependent and Light-Independent Reactions
Photosynthesis involves two sets of reactions. The light-dependent reactions need sunlight.
They use energy from this sunlight to produce energy-rich compounds, like ATP. The lightindependent reactions use these energy-rich compounds to produce sugars from carbon
dioxide.
Complete the T-chart. Write the phrases in the box that belong in each side of the chart.
Use energy from the sun
Take place in the stroma
Use carbon dioxide
Take place in thylakoids
Produce oxygen
Require water
Produce sugars
Also called Calvin cycle
Convert ADP into ATP
Light-dependent Reactions
Light-independent Reactions
Use energy from the sun
Use carbon dioxide
Produce oxygenConvert ADP into ATP
Produce sugars
Take place in thylakoids
Take place in the stroma
Require water
Also called Calvin cycle
The Light-Independent Reactions: Producing
Sugars
Both ATP and NADPH are produced by the light-dependent reactions of photosynthesis. The
Calvin cycle uses the energy in ATP and NADPH to produce high-energy sugars. A model of
the Calvin cycle is shown below.
Follow the directions.
1. Circle the places where ATP and NADPH are used.
2. Draw an X over the two 3-carbon molecules that are removed from the cycle to produce
sugars, lipids, and other compounds.
Calvin Cycle
Sugars and other compounds
Answer the questions.
3. Circle the letter of each statement that is true about the Calvin cycle.
A. The main products of the Calvin cycle are six carbon dioxide molecules.
B. Carbon dioxide molecules enter the Calvin cycle from the atmosphere.
C. Energy from ATP and high-energy electrons from NADPH are used to convert 3carbon molecules into higher-energy forms.
D. The Calvin cycle uses 6 molecules of carbon dioxide to produce a single 6-carbon
sugar molecule.
4. Why are the reactions of the Calvin cycle also called the light-independent reactions?
Although they use ATP and NADPH from the light reactions, the Calvin cycle does not
directly require light.
Chapter Vocabulary Review
Crossword Puzzle Complete the puzzle by entering the term that matches the
description.
Across
Down
4. energy carrier cells use to transport high-energy electrons 1. liquid part of the inside of a
chloroplast
6. cluster of pigments and proteins that absorbs light
7. a saclike photosynthetic membrane found in chloroplasts
8. energy carrier made as a result of photosystem II
9. process of using the sun’s energy to make food
10. man who worked out the light-independent reactions
2. chemical that absorbs light
for photosynthesis
3. light-absorbing chemical
5. organism that makes its
own food
For Questions 11–16, complete each statement by writing the correct word or words.
11. The light-dependent reactions occur in thylakoid membranes.
12. Carbon dioxide is used to make sugars in the light-independent
reactions.
13. The light-independent reactions are also called the Calvin cycle.
14. ATP Synthase spins to provide the energy for adding a phosphate group to ADP.
15. Electron transport chains move high-energy electrons between photosystems.
16. An animal that obtains food by eating other organisms is called a(n)heterotroph.