Photosythensis

Question 1

Photosynthesis:

Answer 1

the process of capturing light energy to power the production of glucose and oxygen from carbon dioxide and water.

Question 2

Structures involvedin photosytehnsis and theirfunctions

mesophyll cells
chloroplasts
chlorophyll
stomata
xylem

Answer 2

-Mesophyll cells- cells in the leaves containing large amounts of chloroplasts

-Chloroplasts- organelle where both stages of photosynthesis occurs

-Chlorophyll- pigment within the chloroplasts that captures light energy

-Stomata-pores on the surface of leaves that regulate gas exchange

-Xylem- tissues that draw water from the roots to the stem

Question 3

Structure of chloroplast and their functions

Answer 3

Thykloid-flattened sacs where light dependent reactions occur

stroma is the fluid part of the chloroplast where the light indepdnet stga occurs

Question 4

compare the stroma and the mitcodhonrial matrix

and where does each stgae of aeorbcui cellularrespiraiton occur

Answer 4

The stroma is the fluid inside chloroplasts where the Calvin cycle occurs during photosynthesis. WHereas,
The mitochdonrial matrix is the fluid inside mitochondria where the Krebs cycle takes place during cellular respiration.

ETC-occurs in cristae of mitcohdonrai
krebs cycle-occurs in the mitochdonrail matirx ofthe miotcndonrai

Question 5

LIght depedent stage

Answer 5

the first stage of photosynthesis where light energy splits water molecules into oxygen and H+ inside of the thylakoid membranes. Occurs in the thylakoid membranes of the chloroplast

Question 6

Input and outputs of the light dependent stage

Answer 6

Inputs:
12 H20
NADP+
18 ADP+Pi

Outputs:
6O2
NADPH
18 ATP

Question 7

explain the process of the light depdnent stage

Answer 7

During the light-dependent stage in the thylakoid membranes, sunlight is absorbed, causing electrons to excite and water to split into oxygen, protons(hydrogen), and electrons. Oxygen is released as a gas. The electrons reduce NADP+ to NADPH, while ATP is synthesized from ADP + Pi. ATP and NADPH travels to the stroma for the light indepdenet stage

Question 8

what is the light indepdnent stage

Answer 8

: is the 2nd stage of photosynthesis that does not require sunlight and occurs in the stroma of the chloroplasts. Carbon dioxide is fixed and reduced to form organic molecules, such as glucose, using ATP and NADPH generated in the light dependent reactions.

Question 9

inputs and outputs of the light independent stage

Answer 9

Inputs:
6CO2
NADPH
18 ATP

Outputs:
1 Glucose
NADP+
18 ADP+Pi
H20

Question 10

process of the light indepndet stageindependent stage

Answer 10

:In the light-independent stage (Calvin Cycle), carbon dioxide (CO2) from the atmosphere enters the stroma of chloroplasts.Then, C02 gets converted into glucose and other organic molecules using energy from ATP and reducing power from NADPH produced in the light depdenet stage. The output includes glucose, while ADP + Pi and NADP+ are recycled for further use in the light-dependent reactions

Question 11

What is glucose?

Answer 11

Glucose is the primary product of photosynthesis, and functions as a source of energy for aerobic cellular respiration, as it is stored as starch or is used to form more complex molecules such as cellulose.

IT IS USED TO MAKE ATP

In cellular respiration, Used in glycolysis to produce pyruvate. Contains hydrogen that is carried by coenzymes used to make ATP.

Question 12

Photoautotrophs

Answer 12

are organism capable of undertaking photosynthesis eg. algae and cyanobacteria.

Question 13

Photolysis

Answer 13

is the process whereby molecules are broken down by the action of light into molecules such as hydrogen and oxygen.

Question 14

Why does the light independent stage not require light?

Answer 14

because it is catalyzed by enzymes and coenzymes NADPH and ATP, from the light dependent stage.hy does the light independent stage not require light?

Question 15

Functions of ADP+Pi,
NADPH
NADP+

Answer 15

ADP+Pi: Inorganic phosphate combine together to form ATP, which is used to speed up the conversion of CO2 into glucose.

NADPH: carries the H+ in the calvin cycle needed to make glucose

NADP+: acts as an electron carrier, therefore facilitating the reduction of CO2 into glucose and it binds with H+ to form NADPH.

The function of NADPH and ATP in the light independent stage is to fix the carbon dioxide in the stroma into glucose and other organic molecules.

Question 16

VWhere does H+, NADP+, NADPH, ADP+Pi and ATPcome from,

Answer 16

the source of H+ is water because its produced when sunlight is absorbed in the thykloid memrbanes which causes water to split into 02 and H+ moleucles
NADPH comes frm NADP+ from the light dependent stage of phootyshtensis
ATP comes from ADP+Pi in the light dependent stage of photoysthesnis

Question 17

The role of H+ in photoyshtensis and celluarlrepsiraiton:

Answer 17

The role of H+ is that it is carried by coenzymes NADP+ to become NADPH a high energy carrying molecule used in the light independent stage of the stroma to create glucose in photosythensis
The role of H+ is that it is carried by coenzymes NAD+ to become NADH for the electron transport chain in cellular repsriation

Question 18

What is the role of sunlight, chlorophyll, water, ATP and Rubisco.in photosythensis

Answer 18

Light Provides energy to split water into oxygen and hydrogen ions in photoynsythesnis

Chlorophyll captures light energy needed to drive photosyteshnsis

Water is split to produce hydrogen ions. the hydrogen and electrons are transferred to produce high energy carrying molecules NADPH and ATP

NADPH carries H+ ions in the calvin cycle needed to make glucos

a pivotal enzyme in the light independent stage of photosythensis as it either binds to C02 to produce a 3C molecule and facicilate furhter reactions in photosytehnsis process or other times, it binds to oxygen, initating photorespiration

Question 19

Photorespiration what is it and when deos photorepsiration occur in c3 plants and why is it a wasteful process

Answer 19

a wasteful process in C3 plants that is intitiated by RuBisCO binding with oxygen instead of C02 due to high 02 concentrtaion asa result of the stomata closing, thereofre negatively impacting C3 plants where this occurs BECAUSE no glucose is produced

photorespiration occurs when the stomata closes or increased water loss in hot and dry weather

Photorespiration is a wasteful process because it uses up ATP and NADPH, without creating glucose,therefore impacting plant growth and productivty.

Question 20

how does temperature affect RuBisCO

Answer 20

RuBisCO’s affinity changes as temperature changes because as temperature increases, the bonds holding the RuBisCO together lossen, so the active site of RuBisCO is no longer complementary to the C02, therefire RuBisCO will have a greater affinity towards oxygen–photorepsoraiton occurs

In lower temperatures, RuBisCO has a greater affinity towards CO2–photostyehsnsi ocucrs, not photorespraiton but if temp is too loew it becomes inactiev

In Hot temperatures, RuBisCO will just denature and will not be able to function at all—no processes can occur

Question 21

How does substrate concentration affect photorespiration

Answer 21

On a hot or windy day, the stomata will close to prevent water loss, then 02 from the light dependent reaction i strapped in the leaves so there will be higher 02 concentrtion,so RuBisCO will bind to more oxygen than C02, therefore more photorespiration occurs

Question 22

compare the calvin cycle and photorepsriaotn

Answer 22

In the calvin cycle:
-Photosynthesis is completed
-Glucose is produced
-Plants can survive and grow
- Rubisco binds to CO2

In photorespiration:
-energy is wasted in reactions
-no photosynthesis=no glucose produced
-plants survival and growth suffers
- Rubisco binds to O2

Question 23

Carbon fixation

Answer 23

a
light independent stage. –is the process in living organisms, where inorganic carbon typically within carbon dioxide is fixed into organic compoudsn like glucose.

Question 24

RuBisCO

Answer 24

a pivotal enzyme in the light independent stage of photosythensis as it either binds to C02 to produce a 3C molecule and facicilate furhter reactions in photosytehnsis process or other times, it binds to oxygen, initating photorespiration

Question 25

How is RuBisCO involve din the reduction of CO2.

Answer 25

Rubisco catalyzes the fixation of CO₂ by combining it with RuBP, initiating the Calvin cycle, where CO₂ is later reduced to form sugars using ATP and NADPH.

Question 26

What are c3, c4 and CAM plants and the Differences between C3, C4 and CAM plants

in relation to adapted or not adapted to photorepsraiton, location of light dependent/independent stage and whether the stomata is open during the day or the night

Answer 26

C3 plants are plants that have not adapted to photorespiration

C4 plants minimses photorespiration

CAM plants have adapted to decrease photorespritaiton

C3 plants do not decrease photorespiration, both the light depdnetn and indepdent stage occur in the mesophyll cell,s stomata is open during the day and closedat night.

C4 plants reduce photorespiraiton, the light depdent stage occurs in the mesophyll cells of the chloroplast and the light indepdnetn stage occur sin the bundle sheath cells of the chloropalst, stomat is opening during the day, disavdantgae is that it reuqires energy

CAM plants do reduce photopresiaiton, both the light dependt nand indpnedt tsage occur in the mesophyll cells but the light depdent stgae occurs during the day and the light idnpednt stgae duringhte night, the stomata is open at night and the disvatngae is that it requires enegry.

Question 27

What 2 coenzymes does RuBisCO have and what role do they have in RuBisCO

Answer 27

RuBisCO uses the conenzymes ATP AND NADPH to convert CO2 into C6H12O6.

In RuBisCO, NADPH provides the reducing power(donates electrons) required to convert C02 into glucose, whilst ATP supplies the energy required for the process.

Question 28

Advantages vs disadvantages of C4 plants

Answer 28

Advantages:
minimises photorespiration due to constant high C02 concentration in the cells
-Able to photosynthesis in hot environments

Disadvantages: is that C02 needs ATP to convert pyruvate into PEP, therefore more energy is used compared to C3

Question 29

bundle sheath cells

Answer 29

a type of plant cell where most of the Calvin cycle in C4 plants occurs

Question 30

what environments conditions increase photorespriation

Answer 30

tdrier environments with little water because theirs little water stomata will close to prevent water loss, so rate of photosynthesis decreases as C02 cannot be exchanged, so build up 02 so high 02 concentration rubisoc binds to intitaitng photorepsriaiton

Question 31

what happens if theres too much light or too much C02

Answer 31

extremely high light intensity can lead to high temp which can cause photoresp, bc stomata will close to prevent water loss so c02 cannot diffuse out, high 02 concetration, rubisco will consequentially bind to 02.
extremely high co2 decreases the PH of the cells environment, therefore making it more acidic, therefore inhibiting enzyme activity denature decreaisnf photosytensis and high C02 means more phootyshteniss occurs so higher 02 concentration which means rubisco binds to 02 more meaning more photorepsriaiton, decreased photosythensis

Question 32

c. Explain why the oxygen concentration in the air surrounding the plants decreased during the first 10 minutes of the experiment.

Answer 32

There was no light reaching the plant for the first 10 minutes. Therefore the plant was
not photosynthesising, but still undergoing cellular respiration. Therefore oxygen was
used in aerobic respiration. In this process, oxygen is used, hence the decrease in the
graph.

Question 33

how do inhibitors impact the rate of photorespiration

Answer 33

Competitive inhibitors bind to the active site of an enzyme, directly competing with the substrate, which slows down enzyme activity. Their effect can be overcome by increasing substrate concentration.

Non-competitive inhibitors bind to a different site (allosteric site) on the enzyme, changing its shape and reducing its activity. This effect cannot be overcome by increasing substrate concentration.

Question 34

“How do C4 plants optimize carbon fixation in photosynthesis?”

Answer 34

C4 plants optimise carbon fixiation in photosytehnsis by sepearting intitial C02 fixiation in the mesophyllcells from the calvin cycle in the bundle sheath cells,

Question 35

Limiting Factors in Photosynthesis:
being light intensity. carbon dioxdieconcentraiton, temperature and water avalibiilty

Answer 35

Light Intensity: As light intensity increases, the rate of photosynthesis increases until it reaches a saturation point. Beyond this point, further increases do not enhance the rate, indicating that other factors may be limiting.

Carbon Dioxide Concentration: Higher concentrations of carbon dioxide generally lead to increased photosynthesis rates, up to a saturation point. This shows that carbon dioxide can be a limiting factor if its concentration is low.

Temperature: Photosynthesis is temperature-sensitive. Each enzyme involved has an optimal temperature range. Deviations from this range can decrease the rate of photosynthesis, indicating that temperature can be a limiting factor.

Water Availability: Insufficient water can limit photosynthesis as it is essential for the photosynthetic process. Water stress can close stomata, reducing carbon dioxide intake.

Question 36

how do differetn wavelenghts effect the rateof photoyshtenis

Answer 36

Violet ,blue and redwavelengths of light increase the rate of photosythensis because these wavelengths are absorbed by plants

Green and yellow light decreases the rate of photosythensis because green and yellow wavelengths are reflected in green plants, therefore photosytehnsis occurs less effienctly

Question 37

how does pH effect the rate of hpotysthenis

Answer 37

pH H levels above or below the optium will cause enzymes to denature, so photoysthensis will not occur

Enzymes at optimum temperature will allow enzymes to work optimally theroefre high photosythensis rates

Question 38

How does C02 affect the rate of photosytehnsis

Answer 38

When C02 concentration is high, increased rate of photosynthesis until point X, the saturation point is reached

However too much C02 will cause the cell to be tooPH acidic for the enzymes, therefofe enzymeswill denature resulting rate of photosytenhnsis decreasing

Question 39

Competitive inhibitors

Answer 39

bind to the active site of enzymes to prevent the catalysis of substrates-reversible

Question 40

Non competitive inhibitorsb

Answer 40

non-competitive inhibitors bind to an allosteric site
of an enzyme causing a conformational change to the active site meaning the substrate can
no longer bind.—-irreversible

Question 41

why does the rate of reacton decrease alot more for non competiive inhibitors than competiive inhibitosr

Answer 41

Non-competitive inhibitors decrease the reaction rate more because they reduce the overall number of active enzymes, making less product no matter the substrate concentration.

Question 42

why is competiive inhibition reversible

Answer 42

The active site remains the same, therefore increasing the substrate concentration can outcompete the competiive inhibitors to bind to the active site of the enzyme

Question 43

two things can cause the plateau on the CO2 graph:

Answer 43

-The maximum rate of photosynthesis occurs when there is an increase in carbon dioxide (CO2), given that light, water, and temperature conditions are optimal. This is because the
enzyme-catalysed systems within the chloroplast are fully saturated and operating as fast as possible. Because enzymes are working at max capacity, further increase in photosynthesise cannot occur so plateau

-Limiitng factors like light, temp, water–if there’s not enough, plateau occurs

Question 44

The use of CRISPR-cas9 to improve crop yields and to increase the effiency of RuBisCo

Question 45

What are the 7 factors that affect photosynthesis

Answer 45

Light intensity
2.Wavelength of light
3.Temperature
4.PH
5.CO2 concentration
6.Water avabiltiy
7.Enzyme inhibition

Question 46

What happens after the point of saturation-point X and why does this happen

Answer 46

The rate of photosythensis plateausbecause the enzymes in the chloroplast become saturated but rate of photosyhtensis is still occuring at a high rate but the rate is not no longer increasing OR dueto limiting factors

Question 47

Allosteric site

Answer 47

An allosteric site is a specific region on an enzyme where molecules other than the substrate can bind and regulate the enzyme’s activity.

Question 48

what is the problem when alloestirc site changes

Answer 48

whenthe alloesoitrc site changes, the active site hcanges so now the substrate cannot bind because no longer complementary.’’

changing of alloestric site is irreversile

Question 49

why are C4 and CAM plants left affected by thelimitng factor of water than C3 plants

Answer 49

In general, the presence of inhibitors lowers the rate of photosynthesis. However, the
effect of competitive reversible inhibitors can be gradually overcome if the substrate
concentration is continually increased

Adding more substrate doesn’t counteract the effects of irreversible or reversible noncompetitive inhibitors or irrveirbsle comptieivt inhibitorson enzymes, as these inhibitors either permanently deactivate enzymes or change their shape, hindering their function. Consequently, the enzyme activity remains limited even with increased substrate concentration

3

36
q
why are C4 and CAM plants left affected by thelimitng factor of water than C3 plants

a
C4 and CAM plants are less
impacted by changes than C3 plants because c4 plants have adapted to decrease photopreisraiotn by photoysthensis in both the mesophyll cells and the bundle sheath cells, whereas CAM plants will photosythensis during both the day and night

Question 50

why is Pep carboxylase not going to bind with oxygen

Answer 50

pep carboxylase is complementary to and therefore will bind to PEP to produce oxaloacetate, therefore lacks a complementary active site to oxygen and will not bind. However RuBisCO can bind to either 02 and C02 depending on availability of these resources.

Question 51

a decrease in temperature from a plants optimal range decreases the rate of photosythensis, why

Answer 51

decreasing temperature means that there is less kinetic energy and therefore, the enzyme and the substrate molecules within the chloroplasts collide less frequently