Chap 10: Photosythesis

Question 1

Photosynthesis

Answer 1

Occurs in plants, algae, certain other protists, & some other prokaryotes

The ability to use sunlight to combine CO2 & H2O to make food

Redox process in which H2O is oxidized and CO2 is reduced

Question 2

Heterotrophs

Answer 2

Get their food from eating others

Eat food energy other organisms+organic molecules

Make energy directly through respiration

Glucose + Oxygen—> CO2+ H2O+ ATp

Question 3

Autotrophs

Answer 3

Produce their own energy

Convert energy of sunlight

Build organic molecules (CHO) fromCO2

Make energy & synthesize sugars through photosynthesis

CO2 + H2O + light energy —> glucose + oxygen

Question 4

What does it mean to be a plant?

Answer 4

Collect light energy
- transform it into chemical energy

Store light energy
-in a stable form to be moved around the plant or stored

Need to get building block elements from the environment
- C, H, O, N, P, K, S, Mg

Produce all organic molecules needed to growth
- carbs, proteins, lipids, nuclei acid

Question 5

What parts of the plant obtains raw materials ?

Answer 5

Sunlight: Leaves: solar collectors

CO2: stomates: gas exchange

H2O: uptake from roots

Nutrients: N, P, Fe etc. : uptake from roots

Question 6

Chlorplasts

Answer 6

Double membrane
Stroma
- fluid-filled interior
thylakoid sacs
grana stacks

Splits H2O into hydrogen and oxygen, incorporating the electrons of hydrogen into sugar molecules

Structurally similar to and likely evolved from photosynthetic bacteria

The structural organization allows chemical reactions of photosynthesis

Question 7

What does the thylakoid membrane contains ?

Answer 7

Chlorophyll molecules
Electron transport chain
ATP synthase

Question 8

What are the 2 parts of photosynthesis?

Answer 8

Light reactions(photo part)

Calvin Cycle(the synthesis part)

Question 9

Light Reactions

Answer 9

In the thylakoids
- split H2O
-Release O2
-Reduce NADP+ to NADPH
-Generate ATP from ADP by photophosphorylation

Question 10

Calvin Cycle

Answer 10

Forms sugar from CO2, using ATP and NADPH

Begins w/ carbon fixation, incorporating CO2 into organic molecules

Question 11

Light

Answer 11

A form of electromagnetic energy a.k.a electromagnetic radiation

Travels in rhythmic waves

Question 12

Wavelength

Answer 12

Distance b/tw crests of waves

Determines the type of electromagnetic energy

Question 13

Photosynthetic Pigment

Answer 13

substances that absorb visible light

different pigment absorbs different wavelengths of light

wavelength that are not absorbed are reflected or transmitted

leaves appear green b/c chlorphyll reflects and transmitts

Question 14

Spectrophotometer

Answer 14

measures a pigments ability

Question 15

What did Theodor W. Englelmenn 1st demonstrate?

Answer 15

the action spectrum of photosynthesis

Question 16

How did Theodor demonstrate the action spectrum of photosynthesis?

Answer 16

He exposed different segments of filamentous alga to different wavelengths

areas that received wavelengths favorable to photosynthesis produced excess O2

used the growth of aerobic bacteria cluster along the alga as a measure of O2 production

Question 17

What is the main photosynthetic pigment?

Answer 17

chlorophyll a

Question 18

What do accessory pigments do for plants?

Answer 18

Broadens the spectrum used for photosynthesis

Question 19

Carotenoids

Answer 19

accessory pigment excessive light that would damage chlorophyll

Question 20

What happens to a pigment that absorb light?

Answer 20

The pigment goes from a ground state to an excited state, which is unsable

Question 21

What is the role of sunlight?

Answer 21

moves the electrons, runs the pumps , pumps the proton, builds the gradient, drives the flow of protons through the ATP synthase, bonds P to ADP, generates the ATP

Question 22

Where are the pigments found?

Answer 22

embedded in the thylakoid membrane

Question 23

How are pigments arranged?

Answer 23

in a photosystem, collection of molecules

Question 24

What does chlorophyll a absorb the best & the worst?

Answer 24

Best: red & blue wavelengths
Worse: green wavelenghs

Question 25

How many photosystems are in thylakoid membranes

Answer 25

2

Question 26

Photosystem II

Answer 26

chlorophyll a , absorbs 680 nm, wavelengths red light

Question 27

Photosystem I

Answer 27

chlorophyll b, absorbs 700, wavelengths red light

Question 28

What happens when the PS II absorbs light ?

Answer 28

excited electrons passes through the chlorophyll to “primary electron acceptor”

need to replace the electron in chlorophyll

enzymes extracts electrons fromH2O & supplies them to chlorophyll
- splits H2O
-O combines w/ another O creating O2
-O2 is release to the atmosphere

Question 29

What does the EC produce w/ light energy

Answer 29

ATP & NADPH

Question 30

Cyclic photophosphorylation

Answer 30

If PS I can’t pass electron to NADP…it cycles back to PS II & makes more ATP, but no NADPH

coordinates light reactions to Calvin cycle

Calvin cycle uses more ATP than NADPH

Question 31

Noncyclic Photophosphorylation

Answer 31

Light reactions elevate electrons in
2 steps (PS II & PS I)
-PS II generates energy as ATP
- PS I generate reducing power as NADPH

Question 32

Calvin Cycle

Answer 32

Occurs in stroma

The ATP and NADPH made in light reactions are used to power the process of carbon fixation

CO2 combines with 5C ribulose biphosphate (RuBP) to make a very unstable 6C compound which splits immediately into 2 3C G3P.

For every 1 CO2 which enters the Calvin cycle, 1 G3P molecule is created.

After 3 CO2 enter into the Calvin cycle (and 3 “turns” of the Calvin Cycle), 2 G3P molecules will be made.

The G3P that leaves will be reduced to glucose

The 5CO2 that stay in the Calvin cycle are rearranged using ATP to reconstruct RuBP