Photosynthesis

Question 1

what are the factors that the rate of photosynthesis is limited by?

Answer 1

light intensity
CO2 concentration
Température

Question 2

where does photosynthesis take place?

Answer 2

chloroplasts

Question 3

what are the 2 stages of photosynthesis called?

Answer 3

light- dependent reaction
light-independent reaction

Question 4

where does the light dependent reaction take place?

Answer 4

thylakoid membrane
- site between the thylakoid space and the stroma

Question 5

what does the light dependent reaction require?

Answer 5

an enzyme in the membrane which catalysed the reaction of ATP

Question 6

what’s the first molecule produced in the light dependent reaction?

Answer 6

ATP

Question 7

where is ATP produced?

Answer 7

an enzyme in the thylakoid membrane is needed
catalysing the reaction between ADP and a free inorganic phosphate group

Question 8

what is the enzyme which synthesises (produces) ATP called?

Answer 8

ATP synthase

Question 9

what does ATP synthase require to combine ADP and a phosphate group?

Answer 9

energy
provided by H+ ions- protons

Question 10

How do H+ ions transfer energy to ATP synthase?

Answer 10

higher concentration of protons in thylakoid space compared to the stroma

a concentration gradient between the thylakoid space and the stroma
- a proton gradient

protons move down the proton gradient

chemiosmosis

Question 11

what is the method in the light dependent stage of the creation of ATP called?

Answer 11

photophosphorylation

Question 12

what is an electrochemical gradient?

Answer 12

a gradient involving a charged particle
such as a proton

Question 13

how is the proton gradient maintained?

Answer 13

protons are actively transported from the stroma to the thylakoid space
ensuring a higher concentration of protons in the thylakoid space compared to the stroma

Question 14

what is oxidation and reduction in terms of hydrogen?

Answer 14

when a substance loses hydrogen- oxidation

when a substance gains hydrogen-
reduction

Question 15

where is the energy for the active transport of protons back into the thylakoid space, from?

Answer 15

supplied by electrons from chlorophyll

Question 16

what is photoionisation?

Answer 16

light hits leaf
chlorophyll absorbs the light and light energy is transferred to electrons within chlorophyll
(electrons in ‘excited’ state)
after this gain of energy they leave chlorophyll

Question 17

what are the electrons moving through a collection of protein complexes through the electron transfer chain moving by?

Answer 17

oxidation- reduction reaction
this releases energy enabling the specific protein complex enabling it to actively transport protons necessary in the light dependent stage

Question 18

what happens when the electrons reach the end of the electron transfer chain?

Answer 18

molecule within chloroplasts-
nicotinamide adenine dinucleotide phosphate
NADP
a coenzyme- molecule which helps enzymes carry out its function

NADP reacts with the electrons and a proton in the stroma that has not yet been actively transported
NADP is gaining an electron hence it is reduced

this reaction forms NADPH
(reduced NADP)

Question 19

what are the two molecules produced in the light dependent reaction needed for the light independent reaction called?

Answer 19

ATP
NADPH (reduced NADP)

Question 20

what else happens when light hits the leaf? -photolysis

Answer 20

it’s splits water up into
protons- maintain high concentration
electrons- replace those lost in chlorophyll
oxygen- diffuses out of plant or respiration
—

Question 21

how are chloroplasts adapted to make sure the light- dependent reaction is as efficient as possible?

Answer 21

adaptation 1-
the thylakoid membrane has a large surface area for molecules involved in the light dependent reaction
maximising the amount of ADP and NADPH that can be made at one time

adaptation 2-
proteins in the grana hold the chlorophyll in such a way that the maximum of light can be absorbed at one time

adaptation 3-
the thylakoid membranes contain ATP synthase for efficient ATP production
the membranes are also selectively permeable which allows them to establish and maintain a proton gradient

adaptation 4-
chloroplasts contain both DNA and ribosomes
this means that proteins involved in the light- dependent reaction can be easily and quickly produced

Question 22

which three molecules does the light independent reaction require?

Answer 22

carbon dioxide
ATP
NADPH

Question 23

what is the light independent reaction also known as?

Answer 23

calvin cycle

Question 24

where does the light independent reaction within the chloroplast take place?

Answer 24

stroma

Question 25

what happens when carbon dioxide enters the stroma?

Answer 25

it reacts with a molecule called ribulose bisphosphate RuBP contains 5 carbons two phosphates carbon dioxide and RuBP react to form two identical molecules Glycerate 3-phosphate GP 3carbons 1 phosphate group this reaction catalysed by enzyme called rubisco

Question 26

what needs to happen to glycerate 3-phosphate for it to become useful?

Answer 26

it needs to be converted to triose phosphate TP contains 3 carbons 1 phosphate group glycerate 3-phosphate needs to lose oxygen and gain hydrogen -reduction Hydrogen needed for this reaction is supplied by NADPH donates hydrogen becomes NADP

Question 27

what else is required for the reduction of glycerate-3 phosphate?

Answer 27

energy ATP by breaking down into ADP and inorganic phosphate group

Question 28

what are about 80% of triose phosphate molecules converted into?

Answer 28

back to ribulose bisphosphate allowing cycle to continue uses ATP

Question 29

what are three main organic substances made from triose phosphate?

Answer 29

glucose- for respiration amino acids- proteins glycerol- triglycerides

Question 30

what happens as light intensity increases?

Answer 30

rate of photosynthesis increases at a certain point it stops increasing

Question 31

how does carbon dioxide limit the rate of photosynthesis?

Answer 31

as co2 increase rate of photosynthesis increase needed in light independent in reaction used in conversation of ribulose bisphosphate to glycerate 3- phosphate

Question 32

how does temperature affect rate of photosynthesis?

Answer 32

as temperature increases rate of photosynthesis increases y decreases rate at which enzymes in light independent reaction affects molecules in thylakoid membrane too if temp too high enzymes denature

Question 33

How many times does a Calvin cycle have to run to make -glucose molecule -triose phosphate

Answer 33

-6 -3

Question 34

What is the light compensation point?

Answer 34

When we measure the gas exchange of the whole plant we find a balance point between carbon dioxide produced by respiration and taken up for photosynthesis