Biology Ch. 6 Photosyntesis

Front 1

autotroph

Back 1

organism that uses sunlight energy or energy stored in chemical bonds of inorganic compounds to create organic compounds

Front 2

Hetertroph

Back 2

organism that must get energy from food instead of directly from the sun

Front 3

Biochemical Pathway

Back 3

a complex series of chemical reactions in which product of one reaction is consumed in the next reaction

Front 4

state the equation for photosynthesis

Back 4

6CO2 + 6H2O ____C6H12O6 + 6O2

Front 5

Name the two stages for Photosynthesis

Back 5

1. LIGHT REACTIONS-sun energy converted to chemical energy, temporarily stored in ATP and NADPH
2. CALVIN CYCLE- organic compounds are formed using CO2 and store chemical energy of ATP and NADPH

Front 6

where do the light reactions take place

Back 6

On the folded inner membrane, THYLAKOID, of the chloroplast

Front 7

Visible spectrum

Back 7

seen when white light is passed thru a prism separating its components into its component colors, the visible spectrum

Front 8

what happens when white light strikes an object/

Back 8

the component colors can be transmitted, absorbed, or reflected

Front 9

what happens when a pigment absorbs a color

Back 9

the pigment will subtract the other colors from the visible spectrum and the reminder, absorbed color will be reflected or transmitted

Front 10

VISIBLE SPECTRUM

Back 10

ranges from violet to red

_____________________
400nm 700nm

Front 11

Name 2 most common types of chlorophyll
Where are they located?

Back 11

chlororphyll a
chlorophyll b (acessory pigment- helps capture light energy)
both are located in the membrane of the thylakoid of the chloroplast

Front 12

Difference between chlorophyll a and chlorophyll b
Name similarity between the two

Back 12

chlorophyll a absorbs less blue but more red than chlorophyll b
Neither a or b absorbs much green light; green is reflected or transmitted

Front 13

Carotenoids

Back 13

an accessory pigment, found in the thylakoid, assist in capturing sunlight and can be yellow, orange and brown

Front 14

Where are chlorophylls most abundant on a plant

Back 14

leaves

Front 15

what is more abundant in the fruit of a plant

Back 15

accessory pigment, yields color to the fruit

Front 16

What is a photosystem?

Back 16

The cluster of a few hundred pigment molecules and the proteins they are embedded in.
(2 types: photosystem I and photosystem II)

Front 17

What do the accessory pigments (Yellow, orange, and brown carotenoids) do?

Back 17

They absorb (sun)light and pass the acquired energy to chlorophyll a.

Front 18

Name the sequences of the light reactions in proper order (4)

Back 18

1. photosystem II
2. Electron transport chain
3. Photosystem I
4. Electron transport chain

Front 19

1. What happens in the photosytem II step of the light reactions?

Back 19

Light 'excites' electrons in chlorophyll a molecules. This causes the electrons to leave the chlorophyll a. This is an oxidative reaction.

Front 20

Where do the light reactions, 1st step of photosynthesis, take place?

Back 20

Within the thylakoid membrane, which is an extension of the inner membrane of the chloroplast. (AKA: grana-sing., granum- pl.)

Front 21

What happens in step 2 of the light reactions?

Back 21

Electrons that left chlorophyll are moved to the primary electron acceptor.

Front 22

What happens in step 3 of the light reactions?

Back 22

The primary electron acceptor donates the electrons to the electron transport chain ( a series of molecules in the thylakoid membrane) The energy lost in the transfer of the electrons is used to move protons H+ into the thylakoid.

Front 23

What happens in step4 of light reactions?

Back 23

Light is again absorbed by photosystemI (concurrent with absorption by photosystem II). Electrons lost by the cholorphyll a molecules move to yet again another primary electron acceptor, and the electrons are replaced in the chlorophyll a by another electron transport chain. These electrons are on the stromal side of the thylakoid membrane and they combine with a proton and NADP+ reduce it to NADPH.

Front 24

What is NADP+?

Back 24

an organic molecule that accepts electrons during oxidation/reduction reactions
(think of the electron transport chain of photosystem II)

Front 25

What replacement step in the light reactions is necessary for photosynthesis to occur?

Back 25

The electrons from chlorophyll molecules in photosystem II must replace the electrons that leave chlorophyll molecules in photosystem I by the enzymatic splitting of water molecules into protons, electrons, and oxygen.

Front 26

What is the thylakoid?
(Greek 'thylakus' meaning pocket)

Back 26

the folded (into grana/granum) inner membrane of a chloroplast

Front 27

Give an equation for the thylakoid's splitting of water molecules.

Back 27

2H O ----- 4H+ + 4e- + O

Front 28

Say the equation of Water splitting in words

Back 28

For every 2 molecules of water that are split 4 electrons become available to replace those lost by the chlorophyl a in photosystem II. The resulting 4 protons (H+) are left inside the thylakoid and the oxygen diffuses out of the chloroplast and can leave the plant---making our world more oxygen rich.

Front 29

Is oxygen needed for photosynthesis to occur?

Back 29

No. But nonetheless plants need oxygen to live so as to perform cellular respiration.

Front 30

How is ATP made during the light reactions?

Back 30

Through a process of CHEMIOSMOSIS.

Front 31

What does chemiosmosis rely on in the light reactions?

Back 31

It relies on a concentration gradient of protons across the thylakoid membrane.

Front 32

Explain the concentration gradient of protons across the thylakoid membrane. What does this gradient represent?

Back 32

Protons are hypertonic inside the thylakoid as compared with the stroma. This leads to potential energy.

Front 33

What does the enzyme ATP synthetase do?

Back 33

It takes the energy potential from the proton concentration gradient across the thylakoid membrane and adds a phosphate to ADP to yield ATP. (It converts the potential energy of the proton concentration gradient into chemical energy stored in ATP)

Front 34

What products of energy currency result from the first stage of photosynthesis, the light reactions?

Back 34

ATP and NADPH

Front 35

What is the product of chemiosmosis?

Back 35

ATP

Front 36

What is the name of the second stage of photosynthesis? What does it do?

Back 36

THE CALVIN CYCLE
The Calvin cycle takes energy from ATP and NADPH (which were results of the light reactions) and uses it to produce organic compounds.

Front 37

What is the most common way plants produce organic compounds? What are these plants called?

Back 37

The Calvin cycle
C3 plants

Front 38

Carbon fixation

Back 38

the incorporation of CO2 into organic compounds

Front 39

Calvin cycle
Where does this occur?

Back 39

a series of enzyme-assisted chemical reactions that produces a 3-carbon sugar----- this occurs within the stroma of the chloroplast.

Front 40

Stoma (sing)
Stomata (pl)

Back 40

major passageways through which CO2 enters and O2 leaves a plant.....located on the undersurface of leaves....used to reduce water loss when air is hot and dry

Front 41

stoma

Back 41

Greek meaning mouth

Front 42

Step 1 of Calvin cycle

Back 42

3 molecules of CO2 combines with a 5 carbon molecule, RuBP, to create an unstable 6 carbon molecule that immediately splits into two 3 carbon molecules, 3-PGA, 3-phoshoglycerate

Front 43

Step 2 of Calvin Cycle

Back 43

The two 3-PGA converted into another 3 carbon molecule, two of G3P, glyceraldehyde 3-phosphate.this requires a phosphate from ATP and a proton, H+, from NADPH. THe ADP, NADP+ and phosphate that is released can be used again in the light reactions to make more ATP and NADPH

Front 44

Step 3 of Calvin cycle

Back 44

one of the G3P molecules leaves the Calvin cycle to make organic compounds, carbohydrates (stored energy for later use)

Front 45

Step 4 of Calvin cycle

Back 45

the remaining G3P molecules are converted back into RuBP through the addition of phosphate groups from ATP; these RuBP can be reused in the cycle.

Front 46

What happens when a plant partially closes its stomata

Back 46

The plant reduces water loss, and O2 levels rise (produced from light reactions) and CO2 falls (consumption by Calvin cycle)

Front 47

Name alternative pathways for plants to fix carbon, make organic compounds, in 1. wet, hot tropical climates and 2. hot dry, desert conditions

Back 47

1. C4 pathway
these plants have a special enzyme that can fix CO2 into four carbon compounds even when stomata are partially closed( CO2 low, and O2 high)
2. CAM pathway (crassulacean pathway)stomata opened at night and closed in day, slow growers and require least water

Front 48

What 2 living organisms can perform photosynthesis? Where does it take place?

Back 48

It can occur in plant cells and algae. It takes place in the chloroplasts.

Front 49

Describe the global greenhouse effect

Back 49

Since Industrial Revolution of the 1850's atmospheric concentrations of CO2 have risen, largely as a consequence of burning fossil fuels, releasing CO2 as a gas. This CO2 gas retains some of the Earth's heat.. the warming can reduce precipitation...leading to more desert

Front 50

Is photosynthesis a static series of steps?

Back 50

No it is two steps, light reactions, and Calvin cycle that work together as one continuous cycle.

Front 51

Light Reactions....AKA:

Back 51

light dependent reactions

Front 52

Calvin cycle.....AKA:

Back 52

light-independent reactions or dark reactions (but actually take place in the daytime, because that is when light reactions must take place)

Front 53

Give the simplest equation for photosynthesis

Back 53

CO2 + H2O---------(CH2O) + O2

CH2O= generic carbohydrate

Front 54

C6H12O6

Back 54

Glucose

Front 55

Give equation for photosynthesis using glucose as the carbohydrate

Back 55

6CO2 + 6H2O-------C6H12O6 +
6O2

Note glucose is NOT a direct product of photosynthesis, but does play key role in cellular respiration

Front 56

What 3 factors affect photosynthesis?

Back 56

Light intensity, Carbon Dioxide (CO2) levels, and temperature

Front 57

How does light intensity affect photosynthesis?
(this is same relationship with Carbon Dioxide)

Back 57

It is a direct relationship that hits a plateau. This is because at first the increased intensity of the light will excite more electrons in both photosystems, but at some point all of the available electrons are excited and the maximal rate of photosynthesis is reached.

Front 58

How does temperature affect photosynthesis?

Back 58

There is a direct relationship until a certain range then an indirect relationship at a certain temperature that makes the enzymatic catalyst ineffective, and the stomata close to limit water loss and CO2 entry into the plant