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Unit 8: Energy Conversions in Cells

Name: _________________________________

Period: __________

Test Date: _______________________

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Table of Contents

Title of Page Page Number Due Date

Unit 8 Warm-Ups 3-4

Unit 8 KUDs 5-6

The Great Energy Caper 7-8

Starch Production in Photosynthesis Lab 9-12

Photosynthesis Notes 13-16

Photosynthesis Flow Chart 17

Exploring Cellular Respiration Demos 18-19

Aerobic Respiration Notes 20-22

Mitochondria Reading Activity 23-24

Anaerobic Respiration Notes 25-26

Anaerobic Respiration Lab 27-29

Energy Conversions Flow Chart 30

Unit 8 Vocabulary 31

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UNIT 7 WARM-UPS

Question: Answer: Question: Answer: Question: Answer: Question: Answer: Question: Answer:

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Question: Answer: Question: Answer: Question: Answer: Question: Answer: Question: Answer:

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Unit 8: Energy Conversions in Cells What should I understand, know and be able to do? Got it √ By the end of the unit I will UNDERSTAND that…

Energy conversions support the cycling of matter in an ecosystem.

By the end of the unit I will KNOW that…

The conversion of ADP to ATP is the means by which cells store and transfer energy. (9B)

Photosynthesis the process by which light energy is converted to chemical energy (glucose).

Glucose molecules bond together to form starch, a common storage molecule in plants.

Photosynthesis occurs in the chloroplast of a plant and includes both light-dependent reactions and light-independent reactions (dark reactions or the Calvin cycle).

Light energy is absorbed by chlorophyll in the thylakoid of the chloroplast.

During the light-dependent reactions of photosynthesis, energy is absorbed from sunlight and transferred to ATP, water molecules are broken down and oxygen is released.

During the light-independent reactions (dark reactions or Calvin cycle) of photosynthesis, ATP from the light-dependent reactions is used to build glucose (six carbon sugar) from carbon dioxide.

The rate of photosynthesis is related to the number of stomata.

The stomata are responsible for gas exchange (CO2, O2 and H2O) in the plant.

Cellular respiration is the process by which chemical energy (glucose) is converted to usable energy by the cell (ATP).

Both plants and animals perform cellular respiration.

Aerobic respiration occurs in the presence of oxygen; anaerobic occurs in its absence.

Glycolysis occurs in the cytoplasm and is required for both aerobic and anaerobic respiration.

Glycolysis breaks glucose (six carbon sugar) into pyruvate (three carbon sugar) to generate ATP.

Cellular respiration (the Kreb’s cycle or the Citric Acid Cycle and the electron transport chain) occur in the mitochondria in the presence of oxygen.

During the Kreb’s cycle (Citric Acid Cycle) and the electron transport chain, pyruvate (three carbon sugar) is broken down to release carbon dioxide, oxygen is used to make water molecules and a large number of ATP is generated.

Aerobic respiration produces more ATP compared to anaerobic respiration.

There are two types of anaerobic respiration: lactic acid fermentation and alcohol fermentation.

The energy stored in the chemical bonds of ATP is used by cells to do work.

At the conclusion of photosynthesis, energy is stored in the chemical bonds of glucose, a six carbon sugar. (4B)

The reactants (water, carbon dioxide and light energy) and products (glucose and oxygen) of photosynthesis.

The balanced equation for photosynthesis shows that six molecules of carbon dioxide and six molecules of water are required to produce one molecule of glucose.

At the conclusion of cellular respiration, energy is stored in the chemical bonds of ATP. (4B)

Cellular respiration is the inverse reaction of photosynthesis.

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The reactants (carbohydrates/glucose and oxygen) and products (water, carbon dioxide and energy/ATP) of cellular respiration.

By the end of the unit I will BE ABLE TO…

Label a chloroplast to indicate where the reactions of photosynthesis occur. (9B)

Label the mitochondria to indicate where cellular respiration occurs.

Given a scenario trace the flow of energy through photosynthesis and respiration.

Identify the reactants and products of photosynthesis.

Write the balanced chemical equation that represents photosynthesis.

Differentiate between the light-dependent and light-independent reactions of photosynthesis.

Explain the link between the light-dependent and light-independent reactions to the overall process of photosynthesis.

Identify the reactants and products of cellular respiration.

Write the balanced chemical equation that represents cellular respiration.

Compare the products of anaerobic respiration to the products of aerobic respiration in terms of energy produced.

Analyze the relationship between photosynthesis and respiration. (4B)

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The Great Energy Caper

Topic: Using complete sentences, describe your ideal (perfect) burger with at least 4 ingredients. Be sure to include all the ingredients you like on your burger. Explain the energy flow of the ingredients in your burger.

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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The Great Energy Caper

Topic: Draw 4 flow charts that trace the energy flow of 4 of the ingredients in your burger. Answer the following questions: What is the origin of the energy for all the ingredients? How do plants transfer light energy from the sun to herbivores? How do herbivores use the energy they obtain from eating plants?

Example - Ingredient: French Fries

Ingredient 1:__________________________ Flow Chart:

Ingredient 2:__________________________

Flow Chart:

Ingredient 3:__________________________

Flow Chart:

Ingredient 4:__________________________

Flow Chart:

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Starch Production in Photosynthesis

Background: The ultimate source of energy used by living things comes from the sun. Autotrophs such as plants produce energy rich carbon compounds by converting radiant energy to chemical energy in the process of photosynthesis. Photosynthesis occurs inside a cell organelle called the chloroplast. The chloroplast is surrounded by a double membrane on the outside and stacks of membranes on the inside called grana. Each granum is made of stacks of sac-like membranes called thylakoids which contain the green pigment chlorophyll. Surrounding the grana is a gel-like matrix called the stroma. The stroma and thylakoid membranes are directly involved in the processes of photosynthesis.

Fig.1

The reactions of photosynthesis can be divided into two main sets of events called the light-dependent and light-independent or dark reactions. The light-dependent reactions occur in the membranes of the thylakoids and send their products to the stroma where the light-independent reactions take place. The light-independent reactions, called the Calvin cycle, convert carbon dioxide and water into glucose using energy from the light-dependent reactions. Figure 2 illustrates the basic processes of the Calvin cycle. Energy end products from the light-dependent reaction, such as ATP,

supply the energy needed for the Calvin cycle.

In the Calvin cycle, 6 carbon dioxide molecules are used to produce a single 6 carbon glucose. As glucose molecules become available, they are chemically combined through dehydration synthesis to create long chains of starch and cellulose. Starch is a common energy storage molecule in plant. These carbohydrates can be used by the plant to provide energy for cellular activities. Heterotrophs obtain this stored energy when they consume the plants as a food. Iodine is a specific stain for starch, producing a black color (actually a very dark blue) where starch is present.

Energy Rich Carbohydrates

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Purpose: In this activity, you will observe the use of the iodine-starch test to compare the amounts of starch produced in a leaf exposed to light with one that has been light-limited. Pre-lab Questions: 1. Hierarchy of Photosynthesis: Number the order of the diagrams in descending order (1=largest to 5= smallest) below to indicate where the Calvin Cycle takes place. Circle where the Calvin Cycle occurs.

______ ______ ______ ______ _______

2. What is the difference between the light-dependent and the light-independent (Calvin Cycle) reactions?

_____________________________________________________________________________________

_____________________________________________________________________________________

3. How do the light-independent reactions (Calvin Cycle) rely on the light-dependent reactions?

_____________________________________________________________________________________

_____________________________________________________________________________________

Video: https://www.youtube.com/watch?v=Vh3gvBX-DJo&feature=youtu.be

Procedure: Watch the video of the experiment making notes below.

Materials needed: Brief procedure:

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Observations: Draw a picture of your leaves indicating the different shades you observe.

Diagram of Leaf Kept in the Dark Diagram of Leaf Exposed to Light (non-photosynthesizing leaf) (photosynthesizing leaf)

Shade of leaf:___________________ Shade of leaf:____________________

Analysis:

1. What does Lugol’s iodine test for? _______________________________________________________

2. Describe similarities in the two leaves after they have been boiled and stained with Lugol’s iodine solution.

_____________________________________________________________________________________

_____________________________________________________________________________________

3. Describe the differences in the two leaves after they have been boiled and stained with Lugol’s iodine solution.

_____________________________________________________________________________________

_____________________________________________________________________________________

4. Which leaf contains the most starch, the one that had been covered or the one that was not covered? Explain your answer using evidence from the lab.

_____________________________________________________________________________________

_____________________________________________________________________________________

5. In this experiment, what is the purpose of removing, boiling and staining both a leaf that was kept in the light and a leaf that was kept in the dark?

_____________________________________________________________________________________

_____________________________________________________________________________________

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Conclusion:

1. Did the Calvin cycle take place in the cells located in the leaf that was covered and kept in the dark? How do you know?

_____________________________________________________________________________________

_____________________________________________________________________________________

2. Photosynthesis produces glucose. Lugol’s iodine solution tests for starch. What is the relationship between starch and glucose?

_____________________________________________________________________________________

_____________________________________________________________________________________

3. Why is it important to primary consumers, like you, that plants store energy as starch?

_____________________________________________________________________________________

_____________________________________________________________________________________

4. Describe where the light-dependent reactions occur in the chloroplast.

_____________________________________________________________________________________

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5. Describe where the light-independent reactions (Calvin Cycle) occur in the chloroplast.

_____________________________________________________________________________________

_____________________________________________________________________________________

6. Describe how the Calvin cycle is dependent upon the events of the light-dependent reactions.

_____________________________________________________________________________________

_____________________________________________________________________________________

7. Write a chemical equation that describes the process of photosynthesis.

_____________________________________________________________________________________

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Photosynthesis Notes

Starch is produced in the leaves of plants. What process produces starch in plants?

Where in the leaf does photosynthesis occur?

___________ ______________________ __________________ _____________

Observing Stomata

Leaf 1 Leaf 2 Leaf 3

Name of Leaf Cactus – live in hot, dry environment

Oak Tree Hibiscus – live in warm, tropical environments

Observations

Drawing

Observing Stomata Discussion Questions

Which leaf had the most stomata? Why do you think this was so?

What gases move in and out of the leaf stomata?

What does the number of stomata indicate about the rate of photosynthesis for a plant?

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PHOTOSYNTHESIS OCCURS IN THE CHLOROPLAST

Draw the process of photosynthesis below.

__________________________ are specialized organelles to carry out photosynthesis!

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Use your diagram to write the chemical equation of photosynthesis.

How do CO2 and H2O get converted into sugar?

Where?

We said that plants need energy from the sun. How does it get energy? _____________ _______________ is absorbed by the pigments in the thylakoid of the chloroplast.

The energy absorbed will split ________ into _________________ and ________________ during the light-dependent reactions.

The next set of reactions occurs in the ___________________. These are light-independent reactions.

Three main stages to photosynthesis • Stage 1 __________________________________________________________

• Stage 2 ___________ ___________________ is converted to ________________ ________________, which is

temporarily stored in _______ and energy carrier molecule NADPH

• Stage 3 The chemical energy stored in ATP and NADPH powers the formation of _____________________ _________________ (i.e. sugar), using carbon dioxide (CO2)

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How many molecules of carbon dioxide does it take to make one molecule of glucose?

Where is the energy stored?

What are the products of photosynthesis?

Where does the oxygen come from?

Summary:

STAGE What happens during this stage?

Where in the chloroplast does it happen?

What is produced in this stage?

Stage 1

Stage 2

Stage 3

Chemical Equation for Photosynthesis

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WORD BANK

Light

Light-dependent reaction

Products

Calvin Cycle Light

Energy

Reactants

chloroplast

H20

CO2

C6H1206

02

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Exploring Cellular Respiration

Demo 1: Energy Release and Transfer

1. What materials are being used in this demo?

a.

b.

c.

2. What is released during cellular respiration? _______________________

3. Temp of water before energy is released and transferred to water? ___________

4. Temp after energy is released and transferred? ________________

5. What does this increase in temperature in the water mean?

_______________________________________________________________________________

Demo 2: Water Release

1. What is the equation for cellular respiration?

_____________________________________________________________________________

2. If we capture what is released from the respiration of the corn chip into the upside down beaker, what

should be captured?

____________________________________________________________________________

3. After burning the corn chip was can you see in the beaker?

____________________________________________________________________________

4. What does the formation of this condensation mean?

____________________________________________________________________________

Demo 3: Carbon Dioxide Release

1. Other than water and energy, what is released during cellular respiration?

____________________________________________________________

2. How long did each corn chip burn?

In beaker: ____________________ Not in beaker: ____________________

3. Why do you think they burned for different times?

________________________________________________________________________________

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Write a 5 sentence summary explaining what you know about cellular respiration after observing these

demonstrations?

___________________________________________________________________________________________

___________________________________________________________________________________________

___________________________________________________________________________________________

___________________________________________________________________________________________

___________________________________________________________________________________________

___________________________________________________________________________________________

___________________________________________________________________________________________

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AEROBIC Cellular Respiration Notes

What did we learn in yesterday’s lab?

• Sugar (carbohydrates) were broken down • Oxygen must be present • Carbon dioxide was released • Water was released

What process breaks down sugars? ____________________________________

Let’s look at the process of cellular respiration in general. Label the diagram below using the ppt.

Use your diagram to write the chemical equation for Aerobic cellular Respiration.

Reactants Products

What goes _____ What is ____________

_______ + ___________ _______ + _______ + energy

How do the Carbohydrates break down? _________________________________________

Where? ___________________________________

Just as photosynthesis uses the structure of the chloroplast to facilitate the process, ____________________________

____________________ uses the structure of an organelle called the __________________________________.

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Label the following diagram using the ppt notes.

How does glucose enter the cell? _______________________________________

• A process called ______________________________ breaks the 6 carbon glucose into two 3 carbon

______________________________. What is produced? _______________________

_____________________

• THE PYRUVATES ENTER THE KREB’S CYCLE IN THE MITOCHONDRIA (A.K.A. _______________ ____________________) What is produced? _______________________ ____________________

• ELECTRON TRANSPORT CHAIN ACROSS INNER MEMBRANES OF MITOCHONDRIA. What is produced____________________ _________________________

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WHAT IS ATP???

• ATP (adenosine triphosphate) – a ______________________________ with two extra

_____________________-_____________ phosphate groups.

• ______________ + ______ → ________ + _____ + __________________ o How cells release energy from ATP: By releasing a phosphate group, the energy stored between the two

can now be released.

SUMMARY: Stages of Aerobic Cellular Respiration

There are “3” stages in aerobic cellular respiration:

• Glycolysis - _______________________________ • Kreb’s cycle (aka Citric Acid Cycle) • Electron transport chain- ______________________________

According to the equation, what is the energy source? ________________________________

Where does the carbon dioxide come from? ______________________________________

How many molecules of water are created? __________

The oxygen on the reactant side forms which molecule on the product side? _________________________

Stage of cellular respiration

Where is the process happening?

What is going into the stage?

What is being produced in this stage?

Glycolysis

Krebs Cycle

Electron Transport Chain

Chemical Equation for Cellular Respiration

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Mitochondria Reading Activity

Mitochondria are the powerhouses of the cell because they “burn” or break the chemical bonds of glucose to release energy to do work in a cell. Remember, this energy originally came from the sun and was stored in chemical bonds by plants during photosynthesis. Glucose and other carbohydrates made by plants during photosynthesis are broken down by the process of aerobic cellular respiration (requires oxygen) in the mitochondria of the cell. This releases energy (ATP) for the cell. The more active a cell (such as a muscle cell), the more mitochondria it will have. The mitochondria are about the size of a bacterial cell and are often peanut-shaped. Mitochondria have their own DNA and a double membrane like the nucleus and chloroplast. The outer membrane is smooth, while the inner membrane is convoluted into folds called cristae in order to increase the surface area.

Label the outer membrane and the cristae on figure 3. This greatly increases the surface area of the membrane so that carbohydrates (simple sugars) can combine with oxygen to produce ATP, adenosine triphosphate (the energy molecule of the cell). The electron transport chain takes place across the membranes of the cristae (crista, singular). Inside the folds or cristae is a space called the matrix that contains enzymes needed for the Kreb's Cycle. Label the matrix on figure 3.

FIGURE 3 - MITOCHONDRIA

Adenosine triphosphate (ATP) is the energy molecule used by all cells to do work. It is a nucleotide consisting of a nitrogen-containing base (adenine, thymine, cytosine, or guanine), a 5-carbon sugar, and 3 phosphate groups. ATP is able to store and transport chemical energy within cells. The LAST TWO phosphate groups (PO4), are joined by HIGH-ENERGY bonds. When these bonds are broken, energy is released for cells to use and ADP forms. Enzymes help to break and reform these high-energy bonds.

ON THE BACK SIDE: In Figure 4, label the 5-carbon sugar RIBOSE. LABEL the nitrogen-base. LABEL the 3 phosphate groups, and LABEL the 2 high-energy bonds.

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FIGURE 4 – ATP MOLECULE

Questions:

1. Why are mitochondria called the powerhouse of the cell? __________________________

_______________________________________________________________________

2. How would the number of mitochondria in an insect's wing compare to the amount found in other cells in an insect's body? Explain your answer.___________________________

______________________________________________________________________________ ______________________________________________________________________________

3. What product of photosynthesis is used in cellular respiration? ______________________

4. What cell process occurs in the mitochondria? ___________________________________

5. Why do some cells have MORE mitochondria? Give an example. ____________________ ______________________________________________________________________________ ______________________________________________________________________________

6. Name 2 other organelles besides the mitochondria that contain DNA & have a double membrane.

______________________________ & _____________________________

7. What simple sugar is broken down in the mitochondria? ___________________________

8. What does ATP stand for? ___________________________________________________

9. What three main things make up an ATP molecule?

________________________ _______________________ _______________________

10. When ATP loses a phosphate group ______________________ is released for cells and a molecule of

_________________ forms.

11. How many high-energy bonds does ATP contain? ________

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Anaerobic Respiration – Background Info & Notes

BACKGROUND INFORMATION – Read for Warm Up! The process of fermentation is a component of anaerobic respiration, which is when respiration takes place in the absence of oxygen. In yeast cells, when this process occurs, it is called alcoholic fermentation. The products of this type of respiration are carbon dioxide and ethyl alcohol, as shown below:

C6H12O6 2C2H6O2 + 2CO2

This process is of particular interest to humans, since it is the source of the alcohol in wine and beer. This particular process only produces about 12% alcohol, which is enough to destroy the yeast cells, which are producing the alcohol. Upon conclusion of anaerobic respiration, if the products of this process are exposed to air, Acetobacter bacteria present in the air will convert the ethyl alcohol into acetic acid. This is why wine that has been in a cellar for a very long time will not taste like wine, but rather like vinegar.

This process occurs in animal cells as well, but of course, animals do not produce ethyl alcohol. Instead, a process known as lactic acid fermentation takes place, and lactic acid rather than ethyl alcohol is produced. As a result of this kind of fermentation, muscle cramps and soreness occur due to the buildup of lactic acid in the muscle cells.

NOTES: ANAEROBIC RESPIRATION

In the anaerobic cellular respiration labs we completed, what conditions were different from aerobic cellular respiration?

______________________________________________

Anaerobic Cellular Respiration

What happens when there is not enough oxygen for aerobic respiration to occur?

• A) ___________________________________

• B) ___________________________________

What is the name of this process? _____________________________

Fermentation (aka Anaerobic Cellular Respiration): An anaerobic process needed to continue making ATP through glycolysis.

2 types of fermentation

• ___________________________________

• ___________________________________

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Lactic Acid Fermentation

Organisms that go through this process:

• ________________________

How we make buttermilk

• ________________________

Ever felt sore after an intense workout? ________________________

Where in the cell does this process take place? _____________________________

How much energy do you create? ________________________________________

What is your energy source? ___________________________________________

Is this process aerobic or anaerobic? _____________________________________

Alcoholic Fermentation

Organisms that go through this process: _______________________

Can you think of a process in which we use yeast?

• ______________________________

• _______________________________

Where in the cell does this process take place? ____________________________

How much energy do you create? _____________________________________

What is your energy source? _______________________________________

Is this process aerobic or anaerobic? _____________________________

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Anaerobic Respiration Lab PART I PROCEDURE

1. Obtain one Ziploc→ bag. 2. Place one “spoonful” of yeast into the bag. Set aside. 3. Obtain 7-9 large grapes and test the pH of the grapes by squeezing the juice of one grape onto a pH strip.

Record the pH of the grape juice in the data table. 4. Place all the grapes into the Ziploc→ bag and seal bag. 5. Using your fingers, GENTLY crush each grape to release the grape juice. Make sure the grape juice mixes with

the dry yeast. 6. Open the bag and smell the juice in the bag by wafting. Record your observation in the data table. 7. Close the bag, making sure you squeeze out any air. Record your observations about the appearance of the bag

in the data table. 8. Let the bag sit on your lab table at room temperature for about 35 minutes. 9. Record your observations about the appearance of the bag in the data table. 10. Open the bag. Allow some of the juice to touch the pH strip. Record the pH in the data table. 11. Smell the juice in the bag. Record your observation in the data table.

DATA & OBSERVATIONS

Initial Observations Observations after 35 minutes

pH of grape juice

Observation of smell

Observation of appearance

PART II PROCEDURE

1. One member of your team will be the timekeeper while the other member will do the exercising. 2. Rest your elbow on the table. Open and close your hand as rapidly and forcefully as you can, counting the

number of times you can do this in 20 seconds. In the table provided, record the number of times you closed your hand.

3. Repeat step 2 nine more times and record the results of each trial in the table. 4. Reverse roles and repeat steps 2 and 3.

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DATA & OBSERVATIONS Trial Number of Closures

Student 1 Student 2

1

2

3

4

5

6

7

8

9

10

Prepare a graph with the results. Plot the number of closures per trial versus the number of trials. Remember: Always put the independent variable on the x-axis.

Which is the independent variable (number of trials or number of closures)? ________________________________

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DATA ANALYSIS 1. Which kind of respiration is occurring in the yeast cells? How do you know? ________________________________ is occurring in the yeast cells because__________________________________ _________________________________________________________________________________________________ 2. Which type of respiration is occurring in your muscle cells? Why does this occur? ________________________________is occurring in our muscle cells because__________________________________ _________________________________________________________________________________________________ 3. What is present as a product in the ziplock that might have caused the pH of the solution to change? _________________________________________________________________________________________________ 4. What are some commercial applications of this experiment? __________________________________________________________________________________________________

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Photosynthesis & Cellular Respiration WORD BANK

Energy

H20

CO2

C6H1206

02

Photosynthesis

Sunlight

H20

CO2

C6H1206

02

Animal & Plant Cells

Anaerobic Respiration

Alcoholic Fermentation

Yeast

Lactic Acid Fermentation

Bacteria & Muscle Cells

2 ATP

Chloroplasts inside plant cells

Aerobic Respiration

Cellular Respiration

36 ATP

Unit 8 Vocabulary – Energy Conversion in Cells

1. Aerobic – process that requires oxygen to occur 2. Alcoholic Fermentation – anaerobic process that breaks down sugars for energy when oxygen isn’t present; produces alcohol; occurs in yeast 3. Anaerobic – process that does not require oxygen to occur 4. ATP (Adenosine Triphosphate) – high-energy molecule that contains, within its bonds, energy that cells can use 5. Calvin Cycle – process by which a photosynthetic organism uses energy to synthesize simple sugars from CO2 6. Cellular Respiration – process of producing ATP by breaking down carbon-based molecules when oxygen is present 7. Chemical Equation – symbolic representation showing the kind and amount of the starting materials and products of a reaction. 8. Chlorophyll – light-absorbing pigment molecules in photosynthetic organisms 9. Chloroplast – organelle composed of numerous membranes that are used to convert solar energy into chemical energy; contains chlorophyll 10. Cristae – inner membrane of the mitochondrion where the electron transport chain occurs 11. Electron Transport Chain – series of proteins in the thylakoid and mitochondrial membranes that aid in converting ADP to ATP by transferring electrons 12. Glucose - high energy sugar formed in photosynthesis & broken down in cellular respiration to produce energy for cells 13. Glycolysis – anaerobic process in which glucose is broken down into two molecules of pyruvate and two net ATP are produced 14. Grana – stack of thylakoid membranes in chloroplasts 15. Kreb’s Cycle – process during cellular respiration that breaks down a carbon molecule to produce molecules that are used in the electron transport chain 16. Lactic Acid Fermentation – anaerobic process that breaks down sugars for energy when oxygen is not present; produces lactic acid; occurs in muscle cells and bacteria 17. Matrix – inner space of the mitochondria where the Kreb’s Cycle occurs 18. Membrane – thin layer surrounding a cell or a cell part that regulates what enters or exits the cell or cell part or in which chemical reactions occur 19. Mitochondria – bean-shaped organelle that supplies energy to the cell and has its own ribosomes & DNA 20. Photosynthesis – process by which light energy is converted to chemical energy; produces sugar and oxygen from carbon dioxide and water 21. Products – substance formed in a chemical reaction 22. Reactants – substance that is changed by a chemical reaction 23. Stomata – pores in the cuticle of a plant through which gas exchange occurs 24. Stroma – region outside the thylakoid membranes in chloroplast; site of Calvin Cycle 25. Thylakoid – saclike photosynthetic membranes found in chloroplasts; site of Light-dependent reactions