Chapter 8Photosynthesis

Ch. 8-1 Energy & Life

• All living things need energy

• Plants capture energy from sunlight to produce food (autotrophs)

• Animals get energy from food (heterotrophs)

Chemical Energy

• One of the most imp. compounds that living things use to store energy – ATP

• ATP – adenosine triphosphate• Has 3 parts: →• When the bond

is broken b/t the2nd & 3rd phosphateenergy is released

ATP – ADP cycle

• When ATP gives up some energy, it’s converted to ADP (adenosine diphosphate)

• ADP doesn’t

have much

energy, so

it must be

re-converted

to ATP again

Ch. 8-2 Investigating Photosynthesis

• Van Helmont – discovered that plants gain most of their mass from water

Investigating Photo

• Priestly – discovered oxygen• ←his expt.

Ingenhousz – showed that

plants give off O2 only when exposed to light

•

Equation for Photosynthesis

• 6 CO2 + 6 H2O → C6 H12 O6 + 6 O2

• carbon dioxide + water → glucose + oxygen

Light & Photo• Plants gather sunlight with light-absorbing molecules

called pigments *necessary for photosynthesis!• Main pigment is chlorophyll• Chlorophyll absorbs light only in certain parts of the

visible spectrum

• Two types of Chlorophyll:

• Chlorophyll a - absorbs blue-violet and red light.

• Chlorophyll b - absorbs blue and red light.

• Green light is not absorbed! It’s reflected!

Light & Photo• Plants do not

absorb lightwell in the green part ofthe spectrum.Why?(green lightis reflected byplants, which is why they appear green)

• A pigment will be the color of the spectrum of light that it CANNOT absorb!

http://www.sciencelearn.org.nz/Science-Stories/Harnessing-the-Sun/Sci-Media/Animations-and-Interactives/The-electromagnetic-spectrum

Accessory Pigments:

Their purpose is to absorb light where chlorophyll does not – they absorb green light! (They complete the absorption spectrum)

• Carotenoids: which produce orange, red, and brown colors in such things as carrots, cranberries, grapes, and rutabagas

• Anthocyanins: produce purple, blue and red colors, such as: concord grapes, blueberries, and plums.

• Xanthophylls: produce yellow colors, such as in corn and daffodils

stoma

Ch. 8-3 The Reactions of Photo

• Take place in the chloroplasts• Parts of a chloroplast:

thylakoids: sac-like photosyntheticmembranesgranum(a) – stacksof thylakoidsstroma – spaceoutside thylakoid

http://www.mhhe.com/biosci/bio_animations/02_MH_Photosynthesis_Web/ great review video

Steps of Photosynthesis• Two main parts:

1. Light-dependent reaction2. Light-independent reaction (Calvin Cycle)

6 CO2 + 6 H2O → C6 H12 O6 + 6 O2

(2) (1) (2) (1)

Electron Carriers• When light excites electrons (e-) in chlorophyll, they gain

energy• These high-energy e- require a special carrier • NADP+ is one e- carrier• It is like an uncharged battery (like ADP)• It turns to NADPH when charged

• http://www.mhhe.com/biosci/bio_animations/02_MH_Photosynthesis_Web/

Light-Dependent Reaction

• Take place in the grana / thylakoid membrane (with chlorophyll)

• Raw materials: light, water, ADP & NADP+(unchargedbatteries)

• Products: ATP, NADPH (chargedbatteries)

& O2 (given off into air)• Video Slower animation

http://www.sumanasinc.com/webcontent/animations/content/harvestinglight.html

http://www.science.smith.edu/departments/Biology/Bio231/ltrxn.html

Step 2 – Light Independent Reaction (Calvin Cycle)

• Raw materials: ATP, NADPH & CO2

• Products: C6H12O6

• Takes place in the stroma

Calvin Cycle – add to picture• Uses ATP and NADPH from the light reactions to produce high-energy sugars such

as glucose.

• Uses 6 molecules of CO2 to produce one 6-Carbon sugar.

• The sugar is either then used for immediate energy or to build larger molecules such as cellulose or starch.

• Calvin cycle video clip

• http://highered.mcgraw-hill.com/sites/0070960526/student_view0/chapter5/animation_quiz_1.html

• Calvin cycle animation

• http://faculty.nl.edu/jste/calvin_cycle.htm

Overview of Photosynthesis

Factors Affecting Photosynthesis

a. Amount of water

b. Temperature (photo depends on enzymes

that work best at 0°C to 35°C (32oF to 95oF)

c. Light Intensity

d. CO2 concentration

e. surface area of leaves

Factors Affecting Photo

Photosynthesis Review Round 1

Number your paper 1-8.

1. Name the energy storage molecule (the charged battery)._______2. What are organisms called that can produce their own food?

_______3. What molecule can be compared to a partially charged battery?

________4. Name the ultimate source of energy for plants & animals._____5. What are organisms called that get energy from other animals &

plants? ________6. What is the location of the high energy bond in ATP? _________7. What is the simple sugar that stores great amounts of energy?

________8. The 3 parts of ATP are: ________, _________ & 3 _________.

Answers – Exchange papers with a partner

Answers – Round 1

• 1. ATP• 2. Autotroph• 3. ADP• 4. The sun• 5. Heterotrophs• 6. Between the 2nd & 3rd phosphate• 7. Glucose• 8. Adenine, ribose, 3 phosphates

Photosynthesis Review Round 2

• Number your paper 1-4• Match each scientist with their contribution to

photosynthesis:

1. Plants gain most of their mass through water.

2. Using a candle & a jar, he observed that plants

produce a gas that kept the candle burning.

3. Found that plants need sunlight to produce oxygen.

4. Traced the path in plants that produces glucose; known as the light-independent reaction.

Priestly Ingenhousz van Helmont Calvin

Answers – Exchange papers with a partner

Answers – Round 2

• 1. van Helmont

• 2. Priestly

• 3. Ingenhousz

• 4. Calvin

Photosynthesis ReviewRound 3

• Number your paper 1-9.

• 1. Write the equation for photosynthesis in symbols.• 2. Write the equation for photosynthesis in words.• 3. Plants gather light with molecules called _______; the main one

in plants is ____________.

• 4. Two areas of the visible spectrum that chlorophyll absorbs light well from are ______ & ______.

• 5. Photosynthesis occurs in the _________ of plants.• 6. Photosynthetic membranes in the chloroplasts are called

___________.• 7. A ______ is a stack of thylakoids.• 8. The _________ is the space outside the grana. • 9. _______ can be compared to a device used to transfer hot

coals.

• Answers – Exchange papers with a partner.

Answers – Round 3

• 1. 6CO2 + 6H2O + light → C6H`2O6 + 6O2

• 2. carbon dioxide + water + light → glucose + oxygen

• 3. pigment; chlorophyll• 4. blue & red• 5. chloroplasts• 6. thylakoids• 7. granum• 8. stroma• 9. NAPD+

Photosynthesis Review

Round 4

Number your paper 1-9. 1. The part of photosynthesis that requires light is called the

_____________ reaction.2. The part of photosynthesis that does not require light is called the

_______ cycle.3. Name 4 raw materials of the light- dependent reaction: ______,

______, ______ & ______.4. Name 3 products of the light-dependent reaction:

______, ______ & ______.5. Name 3 raw materials of the Calvin cycle: _____, ______ &

________6. Name 1 product of the Calvin cycle: ________.7. The light-dependent reaction takes place in the _______.8. The Calvin cycle takes place in the ________.9. Name 3 factors that affect the rate of photosynthesis:

• Answers – Exchange papers with a partner.

Answers – Round 4

1. light-dependent2. Calvin cycle (light-independent)3. Light, water, ADP & NADP+

4. ATP, NADPH, & O2

5. ATP, NADPH & CO2

6. C6H12O6 (glucose)7. grana8. stroma9. 9. temperature, light & water

Photosynthesis Review Round 5

• Number your paper 1-8. Multiple Choice:1. Which of the following is an autotroph:

A. cheetah B. mushroomC. fern D. frog

2. One of the most important compounds that living things use to store energy is:A. DNA B. ATPC. H2O D. CO2

3. Which scientist discovered oxygen?A. Van Helmont B. CalvinC. Priestly D. Ingenhousz

4. The products of photosynthesis are:A. sugar & oxygen B. water & CO2

C. oxygen & hydrogen D. sugar & carbon dioxide

Photosynthesis Review Round 5

5. Which substance from the light-dependent reaction of photosynthesis is a source of energy for the Calvin cycle?

A. ADP B. H2O

C. NADPH D. CO2

6. In which structures in a chloroplast does the Calvin cycle take place?

A. stroma B. grana

C. thylakoid D. stacks of pancakes

7. The leaves of a plant appear green because chlorophyll:

A. reflects blue light B. absorbs blue light

C. reflects green light D. absorbs green light

8. Which molecule stores the most amount of energy?

A. ADP B. ATP

C. fat D. glucose

Answers – Round 5

1. C 2. B3. C4. A5. C6. A7. C8. D

• Answers – Exchange papers with a partner