Photosynthesis versus Cellular Respiration

Photosynthesis

video: Where do plants get their mass from? https://www.youtube.com/watch?v=2KZb2_vcNTg

Diagrams and much of the wording here is taken directly from

http://www.hobart.k12.in.us/jkousen/Biology/phobig.html

What is photosynthesis?

• Photosynthesis is a chemical reaction in which light energy is converted to chemical energy in glucose.  It is the means by which the energy in sunlight becomes usable to living things.  Living things can eat glucose, we can't eat sunlight.

Why is photosynthesis important?

• Two big reasons.  One product of photosynthesis is glucose (sugar), which provides the basis for most food chains.  The second product of photosynthesis is oxygen which comes in handy if you happen to be an aerobic organism that requires oxygen for survival.

Class handout: plant notes, Galoob, Biology leaf diagram and photosynthesis cartoon drawing

1.

http://www.ftexploring.com/me/photosyn1.html

Leaf structure• The top and bottom layers

are referred to as an epidermis. They are protective layers.

• The cuticle is a waxy surface that protects the leaf and prevents excess water loss.

• The mesophyll is the middle layer made of:

• Palisade: tightly packed oval cells

• Spongy layer: circular cells that are spread out allowing gases to circulate within the leaf.

Plant Veins transport materials between the roots and leaves.

  • Xylem: tubes to transport water and minerals from the roots up through the stem and into the leaves.

• Phloem: tubes to transport sugars made during photosynthesis down through the plant.

Stomates and Guard Cells: holes in the underside of leaves where gases go in and out.

• Plants respond to changes in temperature and humidity by opening and closing their stomata.

• Stomata: small openings on the lower epidermis

• Guard cells: surround the stomates and swell and shrink to open and close the stomates.

Chloroplasts

• The black dots in the cells of the mesophyll represent chloroplasts. The cells of the palisades have the most chloroplasts, therefore the greatest amount of photosynthesis happens there.

Questions 1-7 refer to the diagram to the left. 1.Write the number and name of the principal area of photosynthesis. 2.Write the number and name of the structure that regulates the opening and closing of stomates. 3.Which number indicates where oxygen exits the leaf? 4.Which numbers indicate the vascular tissue, which transport materials to and from the leaf? 5.What are the names of the vascular tissues? 6.Write the number and function of the cuticle. 7.What do the black dots represent?

Questions 9-10 DO NOT directly refer to the diagram9. a. What do plants require for photosynthesis? b. Where do they get these things from? c. What plant organs are involved in obtaining them? 10. a. What do plants produce as a result of photosynthesis? b. Where does the reaction take place?

c. What happens to the products?  

Leaf structure quiz

Leaf structure quiz1. Write the number and name of

the principal area of photosynthesis.

3 or 4 Palisades, ½ pt spongy layer, or mesophyll ½ pt

2. Write the number and name of the structure that regulates the opening and closing of stomates.

8 ½ pt Guard cells ½ pt

3. Which number indicates where oxygen exits the leaf? 9 ½ pt

4. Which numbers indicate the vascular tissue, which transport materials to and from the leaf? 5 and 6 ½ pt

5. What are the names of the vascular tissues? Xylem and phloem ½ pt each

6. Write the number and function of the cuticle.

1 ½ pt protection ½ pt

7. What do the black dotes represent? Chloroplasts ½ pt

9. a. What do plants require for photosynthesis? Need all 3 1 pt1. Sunlight, 2. Carbon dioxide/CO2,3. Water

b. Where do they get these things from? ½ pt1. The air, 2. and soil

c. What plant organs are involved in obtaining them? 1. leaves or stomates ( get CO2) ½ pt2. roots (get water) ½ pt

10. a. What do plants produce as a result of photosynthesis? 1. Glucose or sugar or carbohydrate, ¼ pt

2. Oxygen ¼ ptb. Where does the reaction take place?

Leaves or chloroplasts, or mesophyll ½ ptc. What happens to the products?

1. Glucose becomes part of plant used by plants or animals for energy ½ pt 2. Oxygen becomes part of air ½ pt

 

•Learning is not a spectator sport get off the bench and get in the game!

WHY are plants green? Do they contain other pigments?

• http://mw.concord.org/modeler/ • Harvesting light activity• Chlorophyll doesn’t absorb light in the

green region of the spectrum. • Molecular workbench activity:

harvesting light for photosynthesis: http://www.concord.org/projects/sam#curriculum (our projects, SAM, Activities, “harvesting light”)

• 2 minute video why do leaves change color: http://www.youtube.com/watch?v=IPvbl1mu7kM

Class handout: Photosynthesis background knowledge

Photosynthesis Background Knowledge questions

• Question: What is the complete name of the molecule that is made and used by almost every cell to fuel biological processes?

• Adenosine triphosphate

• Abbreviation: ATP

Question: What part of the molecule contains weak bonds=high chemical energy?

The phosphate groups are added or lostATP (tri 3 phosphate) to ADP (di 2 phosphate)

What type of chemicals are in our food that eventually are used to

create ATP?

• Carbohydrates like glucose

What did each of the following scientists discover about plant

growth?• Van Helmont: most of the mass that a

plant gains comes from water not soil.

• Priestly: plants release oxygen

• Ingenhousz: light is necessary for a plant to produce oxygen

Describe the process of photosynthesis including reactants

and products.

• Light energy + 6CO2 + 6H2O C6H12O6 + 6O2

• Purpose: Energy Storage in bonds of glucose sugar

• Reactants: 6CO2 + 6H2O

• Products: C6H12O6 + 6O2

Why are light and chlorophyll needed for photosynthesis?

• They allow a plant to take water and CO2 to make high energy sugar

Why are plants green?

• Chlorophyll doesn’t absorb light in the green region of the spectrum.

• Molecular workbench activity: harvesting light for photosynthesis: http://www.concord.org/projects/sam#curriculum (our projects, SAM, Activities, “harvesting light”)

• 2 minute video why do leaves change color: http://www.youtube.com/watch?v=IPvbl1mu7kM

Using the graph below what colors of light does chlorophyll a absorb?

Chlorophyll B? • Chlorophyll a: violet and red

• Chlorophyll b: blue and red.

Using the graph below, how well would a plant grow under pure

yellow light? Explain

• The plant would not grow well because neither chlorophyll a nor b absorbs much light in the yellow region of the visible spectra.

Summarize the light-dependent reactions. What are the reactants

and products?

Reactants: H2O ADP+P NADP+

Products: O2 ATP NADPH

What reactions make up the Calvin cycle ( or light –independent

reactions)? • CO2 sugar

• ATP ADP + P

• NADPH NADP+

What is the function of NADPH?

• It traps energy from sunlight into a chemical form

• NADPH holds 2 high energy electrons along with a hydrogen ion (H+)

How is light converted into chemical energy during

photosynthesis? • In the light dependent reactions

chloroplasts use light and H2O to change ADP and NADP+ to O2 , ATP, and NADPH

• In the Calvin cycle or light independent reaction CO2 is changed into high energy sugar by using the energy in ATP an NADPH

Based on the lab experiment, can the complete process of

photosynthesis take place in the dark? Explain your answer.

• No, because ATP and NADPH won’t be produced to be used in the calvin cycle.

List factors that affect photosynthesis

• Amount of water

• Temperature

• Intensity of light

Factors affecting photosynthesisThree factors can limit the speed of photosynthesis: light intensity, carbon dioxide concentration and temperature.

Light intensityWithout enough light, a plant cannot photosynthesize very quickly, even if there is plenty of water and carbon dioxide. Increasing the light intensity will boost the speed of photosynthesis.                                                                                             Carbon dioxide concentrationSometimes photosynthesis is limited by the concentration of carbon dioxide in the air. Even if there is plenty of light, a plant cannot photosynthesize if there is insufficient carbon dioxide.       

                                      TemperatureIf it gets too cold, the rate of photosynthesis will decrease. Plants cannot photosynthesize if it gets too hot.If you plot the rate of photosynthesis against the levels of these three limiting factors, you get graphs like the ones above.In practice, any one of these factors could limit the rate of photosynthesis.

Photoinhibition: reduction in photosynthesis as a result of low lightEnzymes are less active at low temperatures and destroyed at high temperatures

• As carbon dioxide increases this is beneficial for photosynthesis.However because it is a greenhouse gas increased carbon dioxide will cause more infrared heat energy to be trapped in the earth’s atmosphere and cause a increase in temperature. An increase in temperature decreases photosynthesis

Cellular Respiration and Fermentation

• Chemical process where food energy is broken down to release energy. – Cellular respiration: when oxygen is used– Fermentation: releases energy from food

without using oxygen.

• http://www.youtube.com/watch?v=nGRDa_YXXQA&feature=player_embedded

Write the overall equation for cellular respiration

C6H12O6 + 6O2 Usable energy (ATP) + 6CO2 + 6H2O

Glycolysis followed by cellular respiration

2. 1.

3.

4.

6.

5.

7.

What are the three main stages of cellular respiration called?

• Glycolysis

• Krebs cycle

• Electron transport chain

Where does the glucose for cellular respiration come from?

• Food!

How do you know that this series of reactions occurs in the presence of

oxygen? • A large amount of energy is released.

What does glycolysis supply to the Krebs cycle and to the electron transport chain?

• Pyruvic acid • NADH

What stages of cellular respiration occur in the mitochondria?

• Krebs cycle and Electron Transport Chain

Where in the cell does glycolysis take place?

• cytoplasm

Glycolysis is an energy consuming process and an energy releasing

process, explain

• 2 ATP are used

• 4 ATP are produced

What does glycolysis supply to the Krebs cycle?

What does it supply to the electron transport chain?

• Pyruvic acid

• NADH (electrons)

The Krebs cycle is aerobic what does that mean?

• Requires oxygen

Where does the Krebs cycle take place?

• mitochondria

In the Krebs cycle pyruvic acid is broken down into what?

• Carbon dioxide

How many ATP molecules are generated for every one turn of the Krebs cycle?

• 1ATP

How many ATP molecules are generated for every one turn of the

Krebs cycle? • 1ATP

Where is the most of the chemical energy in pyruvic acid transferred as a result of the Krebs cycle?

• to NADH

Where does the electron transport chain take place?

• Mitochondria

What builds up on the intermembrane space of the mitochondria?

• H+ ions

What happens to the ATP synthases spins?

• Changes ADP to ATP

How many ATP molecules total are produced from glycolysis, the Krebs

cycle, and the electron transport chain?

• 36 net

• 38 total

Website:

• http://www.sumanasinc.com/webcontent/animations/content/cellularrespiration.html lesson with questions embedded throughout

• Fermentation questions

Why is the process of cellular respiration and the process of fermentation discussed in the same chapter? They are ways of releasing energy from pyruvic acid made in glycolysis.

What does anaerobic mean? Without oxygen

What are two type of fermentation? Alcoholic and lactic acid

Pyruvic acid NADH

alcohol CO2 NAD+

Lactic acid NAD+

What is the point of producing the NAD+? To keep glycolysis happening

Why types of organisms do alcoholic fermentation? How have humans benefited? Microorganisms like yeast (think bread)

What types of cells in humans do lactic acid fermentation? When? How would you know? Muscles during bursts of activity when oxygen isn’t available – feel the lactic acid burn!

Cellular respiration

Using stored in glycogen

stored ATP

Lactic acid fermentation

Cellular respirationBreaking down fat

• What does breathing hard during after exercise have to do with cellular respiration?

• It provides oxygen to your cells.

• If someone is exercising for weight control how long must they exercise and why?

• More then 20 minutes to start to burn “fat”

CHEMICAL SYMBOLS

•C CARBON

•O OXYGEN

•H HYDROGEN

Prentice Hall Biology page 232

Comparing Photosynthesis & Cellular Respiration

•Photosynthesis•Light energy + 6CO2 + 6H2O C6H12O6 + 6O2

•Purpose: Energy Storage in bonds of glucose sugar•Reactants: 6CO2 + 6H2O •Products: C6H12O6 + 6O2

•Location: Chloroplasts•Happens in plants

•Cellular Respiration•C6H12O6 + 6O2 Usable energy (ATP) + 6CO2 + 6H2O •Purpose: Energy release •Reactants: C6H12O6 + 6O2

•Products: 6CO2 + 6H2O •Location: Mitochondria•Happens in plants and animals

CHEMICAL FORMULAS• CO2 CARBON DIOXIDE

– One carbon two oxygen

• 6H2O WATER – 6 molecules of two hydrogen one oxygen

• C6H12O6GLUCOSE SUGAR– Six carbon, twelve hydrogen, six oxygen

• 6O2 OXYGEN– 6 molecules of two oxygen

• Cell Respiration rap: http://www.youtube.com/watch?v=vlZZUtpyCgQ&feature=related&safety_mode=true&persist_safety_mode=1

• Glucose sugar sugar: http://www.youtube.com/watch?v=jJvAL-iiLnQ&feature=related&safety_mode=true&persist_safety_mode=1

• Photosynthesis rap: http://www.youtube.com/watch?v=Wi60tQa8jfE&feature=related&safety_mode=true&persist_safety_mode=1