Photosynthesis

Question 1

Photosynthesis waste product

Answer 1

Oxygen

Photosynthesis changed earths atmosphere

Evolved after to use the oxygen as the final electron acceptor in electron transport

Question 2

Heterotrophs and autotroph

Answer 2

Autotroph: primary producers, phototrophes use photosynthesis , produce all their nutrients
Heterotrophs: eat something else to get nutrients

Question 3

Origin of chloroplast and mitochondria

Answer 3

Serial endosymbiosis

One prokaryote engulf another prokaryotes that started producing energy, they’re exist together until the second prokaryote became the mitochondria

Endosymbiosis: Symbiotic relationship in which the smaller species- the symbiont- live inside the larger species

Mitochondria came first because all living things have mitochondria

Question 4

Dessiccation

Answer 4

Dessiccation:

Waxy cuticle and stoma (to allow gas to enter and leave leaf) help with preventing it

With evolution of plants on ground, these are needed

Water leaves stoma through adhesion and cohesion

Question 5

Chloroplast

Answer 5

Mostly in mesothelioma, every where that’s green has chloroplast tho (including stems and unripe fruits)

2 membranes

Stroma: fluid inside
Thylakoids:folded scars of membrane in stroma
Grana: stacking of 10-29 thylakoids

Question 6

Joseph Priestly

Answer 6

Placed plant inside a cloche with a candle, leading it to burn for much longer than without a plant,

Concluded that the plant “repaired injured air”

Question 7

Photosynthesis

Answer 7

6 CO2 + 6 H2O = C6H12O6 + 6O2

looks like inverse of cellular respiration

Plants do both, photosynthesis when day, respiration when night/dark

Question 8

Cornelius van Niel

Answer 8

Studied anarobic bacteria that use H2S instead of water in photosynthesis
They produced sulfur as water, rather than oxygen
He supposed that CO2 + 2H2S = CHO + H2O +2S so bacteria split hydrogen sufuld

He proposed that plants split water and not co2 to produce water

Using isotopes of oxygen in CO2 and water lead them to confirm it (when isotope was in water, it was found alter in oxygen, but not when it comes from co2)

So oxygen comes from splitting water

Question 9

Respiration vs phtosynthesis

Answer 9

Photosynthesis is an endergonic reaction ( needs energy, energy comes from the sun)

Question 10

Light reactions

Answer 10

Convert solar energy to chemical energy by splitting water into o2 and reducing NADP+ into NADPH
light absorbed by chlorophyll drives the transfer of the electron and hydrogen ions from water to NADP+
H+ and electrons come from water

Using chemiosmosis, to power the addition of a phosphate group to ADP, called photophosphorylation

Light energy converted into chemical energy into the form of NADPH and ATP

Do not produce any sugars, just produce NADPH and ATP

Question 11

Dark reaction or Calvin cycle

Answer 11

Occurs in the stroma

Fixes atmospheric CO2 into carbohydrate, called carbon fixation

enzymes of the cycle further reduce the fixed carbon - by adding high - energy electrons to it

NADPH produced by light reactions that provides the high energy electrons for reduction in the Calvin cycle and ATP from the light reactions provides chemical energy that powers several of the steps in the Calvin cycle

Question 12

Photon

Answer 12

Packets of energy (of light)

Question 13

Quantum

Answer 13

The energy of a photon is a quantum and is inversely proportional to the wavelength of the light; the longer the wavelength , the less energy per photon

Question 14

Pigment

Answer 14

Take ?. And bounce electrons to a higher state of energy

Substances that absorb visible light

Chloroplast doesn’t use green light

Question 15

Why do leaves change colour

Answer 15

As temperature gets colder, synthesis of nucleorophyl slows down and pigments are no longer hidden

Question 16

Action spectrum

Answer 16

profiles the relative effectiveness of different wavelengths of radiation in driving the process of photosynthesis

Rate of photosynthesis (y) depending on wavelength of light (x)

prepared by illuminating chloroplasts with light of different colors and then plotting wavelength against some measure of photosynthetic rate, such as CO2 consumption or O2 release.

Question 17

Absorption spectrum

Answer 17

Amount of absorption (y) depending of wavelength of light (x)

Question 18

Accessory pigments

Answer 18

everything but chlorophyll a

Question 19

Primary pigment

Answer 19

Chlorophylle a

Question 20

Accessory pigments

Answer 20

Carotenoids
Caratines
Zenataphile

Accessory pigments such as carotenoids and chlorophyll b absorb light that chlorophyll a cannot absorb, and extend the range of light useful for photosynthesis

Question 21

Light and photosynthesis

Answer 21

When light is absorbed, the energy of the photons is captured by the pigment and is used to boost the energy of the electrons - it changes the configuration of electrons by boosting them to higher - energy orbitals

The only photons absorbed are those whose energy is exactly equal to the energy difference between the ground state and an excited state, and this energy difference varies from one kind of molecule to another.

When electron drops to the ground state again to be more stable, energy is lost as light, creating fluorescence, but in native environment of chloroplast, not what happens

Question 22

Photosynthesis

Answer 22

Excited electrons bumped up to an electron carrier

Question 23

Phtosystem

Answer 23

In Thylakoids membrane, chlorophyll molecules are organized into photsystems

composed of a reaction-center complex surrounded by several light- harvesting complexes.

Question 24

Antenna/ light harvesting complexes

Answer 24

Passes resonance energy

Absorbes photon, resonance energy transferred from pigment molecule to pigment molecule within complex

Use energy from light to boost one electron up to a primary electron acceptor

Used to reduce carbohydrate

Passes them to special

Question 25

Photosyntheme 2 and 1, Z scheme, linear electron flow

Answer 25

2: Absorbs 680 nm
1: 700nm

Photon received by secondary pigments, electrons are ejected by chlorophyll, (a, b?) into an electron tranport chain, electrons from splitting of water goes into the hole, the electron ejected is used to pump H+ and used to fill hole in P1

P1 gets photon, same thing as P2 but produces NADPH, hole filled by electrons from P2

2 gets its electrons I. The special things, go to primary electron acceptor

Hole is left, as electrons are lost, so water is split

Electrons from 2 get to 1, fill the hole in the special whatever, as the electron go up and reduce NADP+ to NADPH

Part of it goes to the cyclic flow that doesn’t reduce NADP+ but instead is accepted by Fd and then a complex, then back to 1, produces atp, (cyclon electron flow, reduces light damage)

Some only have 1, so don’t synthesize sugar

NADPH used on cyclic reactions, fixes CO2 into glucose

Electrons pumped by atp synthase into stroma used to reduce NADP+ to go into the Calvin cycle

Question 26

Differences photosynthesis and oxidative phosphorylation

Answer 26

Some electron carriers are similar
Atp synthase are alike

In mitochondria, electrons are extracted from organic molecules being oxidized, in chloroplast, electron source is water
Chloroplast do not need food to make atp, photo système capture light energy and use it to drive electrons to the top of transport chain
Mitochondria uses chemiosmosis to transfer chemical energy from food to atp, chloroplast transform light energy into chemical energy
Chloroplast, hydrogen pumped into empty space in thylakoid (lumen), then goes back down into stroma

So stroma becomes matrix in atp synthase drawing, thylakoid space becomes intermembrane space

Question 27

Calvin cycle

Answer 27

Similar the kerbs cycle, but opposite

Reduces NADPH and ATP

Produces glucose

Uses carbon dioxide

1-carbon fixation
2- reduction
3- regeneration of CO2 acceptor

Has to go around 3 times to get a net of a three carbon

Plants that use it are called C3 plants

Fixation: uses 6 ATP and 6 NADPH

réduction: produces G3P,

régénération: uses 3 ATP

Output is 1 G3P per 3 cycles, can be used to make glucose or sucrose or anything

Question 28

How efficient is photosynthesis

Answer 28

Requires absorption of 4 photons by each phtosystem

So about 30%, however, on cloudy days. Goes to 0.1%-3%

Question 29

Warburg effect and Phtorespiration

Answer 29

Increase of O2 slows down photosynthesis in C3 plants

Close up the stomata when hot and dry to avoid loosing water, but keeps O2 inside

Even if CO2 and O2 concentrations outside are relatively constant, inside the cell, when the stomata closes in a hot day, there will be more a oxygen inside the cell, the stomata don’t open to let them out and let Czo2 enter, and photosynthesis stops cause there’s nothing to fix (?) wastes CO2 originally fixed by calvin cyclecalled lhtorespiration

Fixes CO2 by rubisco using O2

Can be protective against light damage to the plant

C4 plants don’t do photrespiration

Question 30

Turning off light

Answer 30

When lights turned off, difference in pH between thylakoid membrane and stroma goes back to no difference

Question 31

Experiment Calvin did

Answer 31

Radioactive C in CO2 was found in a 3 carbon molecule, but the missing 2 carbon molecule was not found, instead a 5 carbon molecule was found (enzyme adding CO2 into 5 carbon molecule is rubisco), produces 6 carbon molecule that’s very unstable and splits

Question 32

C4 plants

Answer 32

Don’t do photorespiration

Experiment of Calvin was done to prove the 3 carbon product, but some plants produced a 4 carbon

Larger bundle sheet cels, contains mesophyll cells as opposed C3

In bundle cell, normal Calvin cycle occurs

C4 plants have another enzyme in the mesophyll, instead of rubisco, PEP carboxalase which does not fix oxygen
Very similar to kerbs cycle

Rubisco saturated with CO2, so never photorespiration

Takes more ATP to produce glucose that a C3 that comes from cyclic electron transport
So only have an advantage against C3 plants when it’s hot and stomata are closed

Uses nitrogen more efficiently because they saturate their rubisco

Climate change will affect C3 and C4 plants very differently. If CO2 increases, C3 advantaged, if temperature increases, C4 advantaged

Question 33

Crassulancean acid metabolism

Answer 33

Desert plant

At night, open stomata and fix CO2 into malade,

At day, stomata close, they

Instead of the physical separation of C4 between CO2 fixation and release, there is a temporal Segoe ration (night and day)

Use water more efficiently, grow very slowly though

Question 34

What happens to product of photosynthesis

Answer 34

Produces sucrose

A lot is used to make cellulose

Put in fruits

Then rest is put into starch