Photosynthesis

Uses solar energy to build sugar from CO2 & H2O

Carbon dioxide + Water Glucose + Oxygen

Chlorophyll

All Life on Earth Ultimately Depends on Solar Energy

6CO2 + 6H2O C6H12O6 + 6O2

Solar energy

Chloroplast

Stroma lamellae

Inner Membrane

Granum (stack of thylakoids)

Thylakoid

Outer Membrane

Stroma

Intermembrane space

fluid with enzymes

Extensively folded to increase

surface area

membrane with

chlorophyll

Pigments• Pigments absorb solar energy

• electrons in pigment become ‘excited’

high energy electron

• Green pigment chlorophyll reflects green light – absorbs blue and red

+-

H2O

O2

Chlorophyll in

Thylakoid membrane

Calvin CycleCarbon fixation

Stroma

NADP+

ADP + Pi

NADPH2

ATP

CO2

Glucose

Light-dependent Phase

Light-independent Phase

from water

More chloroplasts in the upper palisade cells, mostly around

the edges of the cells

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Key Words

Exercises

Quick Quiz

MCQ

Videos

Application questions

Stages of photosynthesi

sRecap

Extension

Key words• photosynthesis• plant• chloroplast• autotrophic• chlorophyll• pigment

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QUICK QUIZModified True/False If false, change the identified word or phrase to make the sentence or statement true. 1.  ADP is one of the principal chemical compounds that

living things use to store energy

2. If you grind up the chloroplasts found in spinach leaves into a liquid solution, the solution will have a green color.

3. The light-dependent reactions supply the Calvin cycle with CO2 and ATP.

One word answers

4. Photosynthesis requires light, water, CO2, and ____ 

5. The electrons that chlorophyll loses to the electron transport chain are replenished by _____ molecules

6. In many plants, the rate of photosynthesis ____ when the weather becomes very cold

 

Answers

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QUICK QUIZ1.  F - ATP is one of the principal chemical compounds

that living things use to store energy

2. T - If you grind up the chloroplasts found in spinach leaves into a liquid solution, the solution will have a green color.

3. F - The light-dependent reactions supply the Calvin cycle with NADPH2 and ATP.

One word answers

4. Photosynthesis requires light, water, CO2, and chlorophyll  

5. The electrons that chlorophyll loses to the electron transport chain are replenished by water molecules

6. In many plants, the rate of photosynthesis slows down when the weather becomes very cold (because enzymes become less active)

 

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ApplicationA student prepared two beakers with identical sprigs

of a water plant as shown below. She placed one beaker in the shade and the other beaker beside a fluorescent lamp. She then systematically changed the distance of the beaker from the lamp. She counted the bubbles given off by each sprig of the water plant.

1. If she later tested the air bubbles collected in the test tube, what would she find they are made of? How do you know?  

2. What do the student’s data show?   3. If the lamp were placed closer than 5cm from the water

plant, would the plant give off many more bubbles? Why or why not?

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Application Answer1. If she later tested the air bubbles collected in the test tube,

what would she find they are made of? How do you know?Oxygen – given off by photosynthesis

  2. What do the student’s data show?  

As the light is moved further away, the rate of photosynthesis decreases.

3. If the lamp were placed closer than 5cm from the water plant, would the plant give off many more bubbles?Why or why not? If the light was too close the plant might get too hot and the enzymes would become denatured.

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Revision question1. What are the products of the light-dependent reactions?  

2. What are the products of the Calvin cycle?

3. What chemical is converted to sugar?

   

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Revision question1.What are the products of the light-dependent reactions?

ATP, oxygen and NADPH   2. What are the products of the Calvin cycle?

sugars, NADP, ADP3. What chemical is converted to sugar?

CO2 and H2O

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Exercise

• Workbook pp73-7• Pathfinder pp49-50 q 1, 2, 6

Extra READING• Pathfinder p50, Excellence in Biology 126-130

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Videos

• http://www.youtube.com/watch?v=2xNwZCk2CHY • http://

videos.howstuffworks.com/discovery/29603-assignment-discovery-photosynthesis-video.htm

• http://www1.teachertube.com/viewVideo.php?title=Photosynthesis&video_id=62625

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Question 1

Which of the following is NOT a part of an ATP molecule?

a. adenine

b. ribose

c. chlorophyll

d. phosphate

 

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Question 2

Energy is released from ATP when

a. a phosphate group is formed

b. adenine bonds to ribose

c. ATP is exposed to sunlight

d. a phosphate group is removed 

 

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Question 3

Different plants are placed under a bell jar with a burning candle. The candle remains lighted for different periods of time. What would be a logical conclusion from these experiments?

a. different plants require different amounts of water

b. different plants require different amounts of oxygen

c. different plants require different amounts of carbon dioxide

d. different plants require different amounts of light

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Question 4

Photosynthesis uses sunlight to convert water and carbon dioxide into

a. oxygen and high energy sugars

b. high energy sugars

c. ATP and oxygen

d. oxygen

 

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Question 5

Which of the following are used in the overall reactions for photosynthesis?

a. carbon dioxide

b. water

c. light

d. all of the above 

 

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Question 6

All of the following are parts of an ADP molecule EXCEPT

a. structure D

b. structure C

c. structure B

d. structure A  

 

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Question 7

In the overall equation for photosynthesis, six molecules of carbon dioxide result in six molecules of

a. glucose

b. oxygen

c. water

d. ATP 

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Question 8

Plants gather the sun’s energy with light-absorbing molecules called

a. pigments

b. thylakoids

c. glucose

d. chloroplasts 

 

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Question 9

The stroma is the space that surrounds

a. plant cells

b. chloroplasts

c. thylakoids

d. all of the above   

 

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Question 10

Where do the light-dependent reactions take place?

a. in the stroma

b. in the thylakoid membranes

c. outside the chloroplasts

d. only in chlorophyll molecules

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Question 11

The Calvin cycle takes place in the

a. chlorophyll molecules

b. photosystems

c. thylakoid membranes

d. stroma 

 

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Question 12

How does the Calvin cycle differ from the light-dependent reactions?

a. It requires light

b. It takes place in chloroplasts.

c. It takes place in the stroma.

d. It takes place in the thylakoid 

 

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Question 13

Which of the graphs represents the effect of light intensity on the rate of photosynthesis?

 

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Question 14

If carbon dioxide is removed from a plant’s environment, what would you expect to happen to the plant’s production of high-energy sugars?

a. More sugars will be produced.

b. Fewer sugars will be produced.

c. The same number of sugars will be produced but without carbon dioxide.

d. Carbon dioxide does not affect the production of high-energy sugars in plants.

 

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Correct

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Incorrect

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Light Dependent Reaction

Find definitions for the following terms:

Photoionisation, photophosphorylation & photolysis.

Where do these processes take place? What is the difference between cyclic &

non-cyclic phosphorylation.

EXTENSION

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Carotenoids

• Yellow – orange

• Transfer energy to chlorophyll.

• Often not reabsorbed during autumn

EXTENSION

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Both mitochondria & chloroplasts contain DNA & may have arisen from endosymbiosis

EXTENSION

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a waste product of photosynthesis

Solar energy

organic molecule with chemical potential energy

Inorganic molecules

oxygen as a waste product

Chlorophyll• Absorbs all wavelengths except green

• Reflects green light appears green

• Reabsorbed before leaves fall

Chlorophyll in grana

Photolysis - light dependant stage

oxygen

hydrogen

NADP

NADPH2

Energy

ADP + Pi ATP

Splits water

by-product

light-independent

phase

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Electron Transfer• Electrons excited by solar energy• Transferred down a chain of

receptors• Release energy with each transfer• ADP ATP • energy in ATP used to make sugars

Electron Transfer

1 electron excited by solar energy photon

2 electron passed along from carrier to carrier

3 electron excited by solar energy photon

4 electron passed to NADPH

e-

ATP

ATP

ATP

NADPH

Electron Transfer Chain

Carbon fixation - light independent stage

Calvin Cycle(carbon fixation)

In the stroma

CO2

CH2O

from air

from light-dependent

phase

6 cycles needed to make C6H12O6

H2

Energy

NADPH2

ATP

123456 123456

C6H12O6

Photosynthesis & Respiration in plants

Draw an overview of photosynthesis

Summarise the factors needed

Highlight key ideas in the workbook

Pair up and teach each other

Work through NCEA questions

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THE END

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