Photosythesis - PowerPoint Presentation

Slide1

PhotosythesisSlide2

Which of the following is a correct

explanation for how carbons in a triose-phosphate can be said to be in a more reduced state than carbons in carbon dioxide? (See image on next slide.)

Carbons

in triose-phosphates have accepted more

electrons

, and have taken on a full negative

charge, relative

to

carbons

in carbon dioxide.

Carbons

in triose-phosphate have more bonds with

hydrogen

and fewer bonds with

oxygen

relative

to

carbons

in

carbon dioxide.

Converting

carbon in carbon dioxide into carbon in

triose- phosphate

is an endergonic process.

Carbons

in carbon dioxide donate their excess electrons to

NADP



as they are converted to carbons in triose-phosphate.

The

binding with a phosphate by the triose-phosphate makes it higher in

energy

relative to carbons in carbon dioxide

.Slide3
Slide4

Which of the following is a

correct explanation for how carbons in a triose-phosphate can be said to be in a more reduced state than carbons in carbon dioxide is?

Carbons

in triose-phosphates have accepted more

electrons

, and have taken on a full negative

charge, relative

to

carbons

in

carbon dioxide.

Carbons

in triose-phosphate have more bonds with

hydrogen

and fewer bonds with

oxygen

relative

to carbons in

carbon dioxide.

Converting

carbon in carbon dioxide into carbon in

triose- phosphate

is an endergonic process.

Carbons

in carbon dioxide donate their excess electrons to

NADP



as they are converted to carbons in triose-phosphate.

The

binding with a phosphate by the triose-phosphate makes

it

higher in

energy

relative to carbons in carbon dioxide

.Slide5

Which of the following INCORRECTLY matches a process with its typical location

?Oxygen gas is

produced

—

the

soluble space surrounded by the thylakoid

membranes

Activated chlorophyll donates an electron—in the thylakoid membranesNADPH is oxidized to NADP—the stroma of the chloroplastATP is produced—the space between the two chloroplast envelope membranesRUBISCO catalyzes carbon fixation—the stroma of the chloroplastSlide6

Which of the following INCORRECTLY matches a process with its typical location

?Oxygen gas is

produced

—

the

soluble space surrounded by the thylakoid

membranes

Activated chlorophyll donates an electron— in the thylakoid membranesNADPH is oxidized to NADP—the stroma of the chloroplastATP is produced—the space between the two chloroplast envelope membranesRUBISCO catalyzes carbon fixation—the stroma of the chloroplastSlide7

Of

the following events from the light reactions of photosynthesis, which would be expected to occur first?

Light-induced

reduction of the primary electron

acceptor

in the reaction center of PS II takes place.

While

being split, electrons are taken out of water.donation of electrons from reduced Pq to the cytochrome complexacceptance of electrons by Pc from the cytochrome complexPq gets electrons from the reduced primary electron acceptor of PS II.Slide8

Of

the following events from the light reactions of photosynthesis, which would be expected to occur first

?

Light-induced

reduction of the primary electron

acceptor

in the reaction center of PS II takes place.

While being split, electrons are taken out of water.donation of electrons from reduced Pq to the cytochrome complexacceptance of electrons by Pc from the cytochrome complexPq gets electrons from the reduced primary electron acceptor of PS II.Slide9

When

donating its activated electron, the chlorophyll in photosystem II (P680) is said to be a very powerful oxidizing agent. This is best

shown by its ability

to

make

use of a proton electrochemical gradient to drive the formation of ATP.

force

the oxidation of oxygen in water to oxygen gas.donate an electron to plastoquinone (Pq).absorb light energy to power redox reactions.force the reduction of NADP+ to NADPH.Slide10

When

donating its activated electron, the chlorophyll in photosystem II (P680) is said to be a very powerful oxidizing agent. This is best shown by its ability to

make

use of a proton electrochemical gradient to drive the formation of ATP.

force

the oxidation of oxygen in water to oxygen gas.

donate

an electron to plastoquinone (Pq).absorb light energy to power redox reactions.force the reduction of NADP to NADPH.Slide11

One good reason for carrying out the production of oxygen gas (O

2) in the space surrounded by the thylakoid membranes, and not in the stroma of the chloroplasts, is

that

this makes it easier for

O

2

to exit the chloroplast.that the hydrogen ions released can contribute to the H electrochemical gradient being generated.to reduce the concentration of O2 in the stroma so that organic matter located there is not oxidized by it.that the concentration of water in this space is high, making it easier to form O2 from the water.that carrying out this process in the stroma would tend to dry out this compartment and denature the enzymes

of the Calvin cycle

located there.Slide12

One good reason for carrying out the production of oxygen gas (O

2

) in the space surrounded by the thylakoid membranes, and not in the

stroma

of the chloroplasts, is

:

that

this makes it easier for O2 to exit the chloroplast.that the hydrogen ions released can contribute to the H electrochemical gradient being generated.to reduce the concentration of O2 in the stroma so that organic matter located there is not oxidized by it.the concentration of water in this space is high, making it easier to form O2 from the water.carrying out this process in the stroma

would tend to dry out

this compartment and denature the enzymes of the Calvin cycle

located

there

.Slide13

Which makes an INCORRECT comparison between the membrane and surrounding compartments indicated in mitochondria and chloroplasts by the boxes (see figure

)?

The

darker compartment

will

often be more positively charged and more acidic.

The

flow of electrons between items in the membrane results in protons being pumped from the darker to the lighter compartments.The lighter compartment is where much of the carbon metabolism is done.This membrane has an ATP synthase in it.The lighter compartments are both similar to the cytosolic compartment of bacteria.Slide14

Which makes an INCORRECT comparison between the membrane and surrounding compartments indicated in mitochondria and chloroplasts by the boxes (see figure

)?

The

darker compartment

will

often be more positively charged and more acidic.

The

flow of electrons between items in the membrane results in protons being pumped from the darker to the lighter compartments.The lighter compartment is where much of the carbon metabolism is done.This membrane has an ATP synthase in it.The lighter compartments are both similar to the cytosolic compartment of bacteria.Slide15

The net reactions for some aerobic respiratory processes in mitochondria, and for some reactions of photosynthesis in the chloroplast are given below

.

Pyruvate

import and the Citric acid cycle

:

Pyruvic acid + FAD + 4NAD

+

+ ADP + Pi ÷ 3CO2 + FADH2 + 4NADH + 4H++ ATP The Calvin cycle:3CO2 + 9ATP + 5H2O + 6NADPH  Glyceraldehyde 3-phosphate + 9ADP + 8Pi + 6NADP+ + 3H+ The following are descriptions of proposed similarities between these two sets of reactions. Which is FALSE?Both alter the redox state of carbons.Both take place in a soluble space that is homologous to a

bacterial cytoplasmic space.Both

involve a three carbon organic acid, either as a substrate or as a product.Both couple very exergonic reactions to drive forward endergonic reactions of smaller net magnitude.Both

involve various types of nucleic acids in the exchange of

hydrogens

.Slide16

The net reactions for some aerobic respiratory processes in mitochondria, and for some reactions of photosynthesis in the chloroplast are given below

.

Pyruvate

import and the Citric acid cycle

:

Pyruvic acid + FAD + 4NAD

+

+ ADP + Pi ÷ 3CO2 + FADH2 + 4NADH + 4H++ ATP The Calvin cycle:3CO2 + 9ATP + 5H2O + 6NADPH  Glyceraldehyde 3-phosphate + 9ADP + 8Pi + 6NADP+ + 3H+ The following are descriptions of proposed similarities between these two sets of reactions. Which is FALSE?Both alter the redox state of carbons.Both take place in a soluble space that is homologous to a

bacterial cytoplasmic space.Both

involve a three carbon organic acid, either as a substrate or as a product.Both couple very exergonic reactions to drive forward endergonic reactions of smaller net magnitude.Both involve various types of nucleic acids in the exchange of hydrogens.Slide17

The enzyme

rubisco catalyzes the fixation of carbon (see reaction on next slide). Considering all the carbons involved, is the production of 3-PGA a net oxidation, reduction, or neither, and why

?

Oxidation

. Adding a carbon dioxide makes the products more oxidized.

Reduction

. Adding the

hydrogens from the water results in a more reduced condition.Reduction. The carbon in the carbon dioxide has been slightly reduced.Neither. There is no change in the total C–O and C–H bonds between the products and reactants.Oxidation. The RuBP acts as oxidizing agent in this reaction.Slide18
Slide19

The enzyme

rubisco catalyzes the fixation of carbon (see reaction on next slide). Considering all the carbons involved, is the production of 3-PGA a net oxidation, reduction, or neither, and why

?

Oxidation

. Adding a carbon dioxide makes the products more oxidized.

Reduction

. Adding the

hydrogens from the water results in a more reduced condition.Reduction. The carbon in the carbon dioxide has been slightly reduced.Neither. There is no change in the total C–O and C–H bonds between the products and reactants.Oxidation. The RuBP acts as oxidizing agent in this reaction.Slide20

One way in which photosynthesis as done in a typical C

4 plant differs from that in a C3 plant, is that the C

4

plant

does

not produce any oxygen gas at all.

actively pumps oxygen gas away from the cells that contain rubisco.avoids the use of rubisco entirely; instead, it uses PEP carboxylase to catalyze all carbon fixation.keeps its stomata more open, so that more CO2 can enter the plant.carries out the Calvin cycle only in the chloroplasts of bundle-sheath cells.Slide21

One way in which photosynthesis as done in a typical C

4 plant differs from that in a C3 plant, is that the C

4

plant

does

not produce any oxygen gas at all.

actively pumps oxygen gas away from the cells that contain rubisco.avoids the use of rubisco entirely; instead,it uses PEP carboxylase to catalyze all carbon fixation.keeps its stomata more open, so that more CO2 can enter the plant.carries out the Calvin cycle only in the chloroplasts of bundle-sheath cells.Slide22

In CAM plants, CO

2 istemporarily fixed in phloem cells and later permanently fixed in the bundle-sheath cells.

mainly obtained from oxidative respiratory processes.

temporarily fixed at night and later permanently fixed during the day.

fixed into organic matter just by the action of the enzyme

rubisco

.

brought up to the leaves through air spaces in the stem so that the stomata of the leaves can be kept shut to prevent water loss.Slide23

In CAM plants, CO

2 istemporarily fixed in phloem cells and later permanently fixed in the bundle-sheath cells.

mainly obtained from oxidative respiratory processes.

temporarily fixed at night and later permanently fixed during the day.

fixed into organic matter just by the action of the enzyme

rubisco

.

brought up to the leaves through air spaces in the stem so that the stomata of the leaves can be kept shut to prevent water loss.