5.2.1 Flashcards
What is the equation for photsynthesis?
Carbon dioxide and water
->
glucose and oxygen
What is the compensation point?
rate of photosynthesis and rate of respiration are the same / equal
because the volume of carbon dioxide entering the plant is the same as the volume of carbon dioxide leaving the plant
What is the compensation period?
The time it takes a plant to reach it’s compensation point
What does photosynthesis rely on?
light
What s the relationship between light intensity and photosynthesis?
as light intensity increases
we get a higher rate of photosynthesis
compared to respiration
How can you tell from the compensation point graph that light intensity increases the rate of photosynthesis compared to respiration?
more CO2 is being taken in than being taken out
What is the liquid inside the chloroplast known as?
stroma
What size are the ribosomes in a chloroplast?
70S
What is embedded in the thylakoid membrane?
ATP synthase
What is the role of the loop of DNA in the chloroplast?
contains genetic information on enzymes involved in photosynthesis
What is the role of the starch granule in a chloroplast?
glucose is stored as starch
What is advantageous about the many grana in chloroplasts?
provides a large surface area for photosynthetic pigments
Describe 2 ways in which the grana is adapted to it’s function?
large SA for light absorption
contain photosystems
contain ATP synthase / electron carriers
What is a photosystem?
photosynthetic pigments arranged in special structures.
held in place by proteins embedded in the grana
Where is the primary pigment kept?
at the reaction centre of each photosystem
What is the primary pigment?
chlorophyll
What are the names of other pigments?
chlorophyll B
xanthophylls
cartenoids
What do pigments that are not chlorophyll a do with light that is different?
chlorophyll B, xanthophylls, cartenoids
absorb different wavelengths of light
Where are chlorophyll B, xanthophylls and cartenoids found?
in the thylakoid membrane of the chloroplast#in the antenna complex
What pigments are known as acsessory pigments?
chlorophyll B and cartenoids
What 2 groups can cartenoids be?
xanthophyll or beta carotene
What do carotenoids do with light?
absorb blue light and reflect yellow and orange
Why is there different pigments?
to absorb different wavelengths of light
What do the acsessory pigments do?
pass energy to the primary pigment
Explain why the rate of photosynthesis varies during a 24 hour period but the rate of respiration does not?
Photosynthesis depends on light
so the rate of photosynthesis is 0 in the dark and the rate increases as light intensity increases
the rate of photosynthesis is highest at around midday when the env is warmer
for respiration and this could increase the rate of enzyme catalysed reactions
respiration doesnt depend on light
for photosynthesis a higher temperature may speed up enzyme catalysed
Why is a pestle and mortar used in the TLC?
To break down the cell wall and release photosynthetic pigments
What is the first stage of the light dependent stage?
Photolysis of water
What happens in photolysis?
Water is broken into hydrogen ions and oxygen and an electron
How is oxygen released after photolysis?
Released from the plant through diffusion through the stomata
What happens to the electrons after photolysis?
Used in the photosystem
What happens in the light dependent stage?
Pigments absorb light
Electrons are excited to higher energy levels
Acsessory pigments pass energy yo reaction centre and primary pigments
Primary pigments become oxidised losing electrons
Electrons are passed to the etc FOR lc=d
What do pigments absorb?
light
What is beneficial about having many grana?
provides a large surface area for photosynthetic pigments
How are pigments arranged?
photosystems
What holds the photosystems in place?
proteins embedded in grana
What is the primary pigment?
chlorophyll A
Where is chlorophyll A found?
the reaction centre of each photosystem
Why is there different pigments?
to absorb different wavelengths of light
Where are chlorophyll a, carotenoids and xanthophylls found?
embedded in thylakoid membrane
What are some examples of accessory pigments ?
Carotenoids
Chlorophyll B
How do these pigments work?
- different pigments absorb different wavelengths of light
- acsessory pigments either xanthophyll or beta carotene pass energy to primary pigment
- range of acsessory pigment has allows a range of wavelengths to be absorbed
- primary pigment becomes excited and loses electrons to the ETC
- These excite electrons to a higher energy level
- to be used in the light dependent reaction
What do different pigments absorb?
different wavelengths of light
What do acsessory pigments do with energy?
pass it to the primary pigment
What happens after the primary pigment recieves energy?
becomes excited and loses electrons
What reaction are the electrons used in?
light-dependent reaction
Why do we crush the plant using a pestle and mortar?
to break down cell wall and cell membrane
to release photosynthetic pigments
Why should we handle the TLC with gloves?
to avoid amino acids on hands to contaminate results
Why is the pigment allowed to dry between reapplications?
makes it more concentrated
Why is the line drawn in pencil?
pen would dissolve in solvent
What is RuBP
5 carbon
compound
How does the CO2 even enter the light independent reaction?
diffuses into the stomata
What does RuBP do when it comes into contact with CO2?
2 X GP
What enzyme converts RuBP into 2 GP’s?
rubisco
What is carbon fixation?
where the carbon from carbon dioxide is fixed to the RuBP to make 2 lots of GP
What is GP?
A 3 carbon compound
What is GP converted into?
2 X TP
What is used to convert GP into TP?
NADPH + H+
from light dependent reaction
What does the GP gain from ATP?
an inorganic phosphate
What forms and goes back to the light dependent stage when TP is formed?
NADP
What phosphorylates ADP into ATP
ATP synthase from the light dependent stage
What is product regeneration?
1 carbon is removed from TP’s
RuBP regenerated
What is non-cyclic phosphorylation?
1) e- passes through PSII
2) e- passes along electron carriers
3) e- passes into PSI
4) e- binds to NADP to form NADPH
What is cyclic phosphorylation?
1) e- passes down e- carriers
2) using energy from a series of redox reactions, H+ actively transported into IMS
3) e- excited to higher energy level in PSI
4) e- re-enters ETC
Why would a plant undergo cyclic phosphorylation?
lack of water
Why do plants undergo cyclic phosphorylation when they have a lack of water?
e- is being recycled and the e- is from photolysis
so ATP still produced
How is ATP produced in photosynthesis?
chemiosmosis
