CIE A Level Biology 9700 Topic 13: Photosynthesis Summary Notes
21 views 0 purchase
Course
Unit 13 - M Photosynthesis (9700)
Institution
CIE
Book
Cambridge International AS and A Level Biology
Clear, concise, effective summary notes covering all points in Topic 13: Photosynthesis of the new 2022-24 CIE A Level Biology syllabus. A must-have revision tool that helped me achieve an A* in A-Level Biology.
CIE A Level Biology 9700 Topic 15: Control and Coordination Summary Notes
All for this textbook (9)
Written for
A/AS Level
CIE
Biology
Unit 13 - M Photosynthesis (9700)
All documents for this subject (10)
Seller
Follow
nathanzhang
Reviews received
Content preview
Topic 13: Photosynthesis
Chloroplast structure & function
● how chloroplast structure is suitable for its functions
Stroma contains 70S ribosomes & loops of Enable prod. of chloroplast proteins & enzymes for
chloroplast DNA light-independent reactions
Stroma contains large starch grains Stores sugars formed by photosynthesis as starch
→ insoluble
Thylakoids stacked into grana & connected by Create ↑ SA for ↑ photosynthetic pigments → ↑ no.
lamellae of light-dependent reactions occurring at same
time → as much light absorbed as possible
Pigment molecules in photosystem arranged in Pass E. down to reaction centre
funnel-like structures
Photosynthesis
● overview of stages
○ light-dependent reactions – light drives transfer of e-s and H+s to carrier NADP+ & reduce
it to NADPH + prod. ATP by photophosphorylation
■ occurs in thylakoid membrane
○ light-independent reactions – CO2 incorporated into organic molecules by carbon fixation
& then reduced to carbs. by NADPH using E. in ATP
■ occurs in stroma
● photosynthetic pigments
○ substance that absorbs visible light
○ we see the colour most transmitted/reflected by pigment
■ chlorophyll absorbs violet-blue & red light, reflects/transmits green light ∴ why
leaves are green
Pigment group Name Colour reflected Functions
Chlorophylls chlorophyll a yellow-green ● participates directly in light-dependent
reactions
xanthophyll yellow ● widen action spectrum of wavelengths
that can drive photosynthesis
● photoprotection – absorbs & dissipates
excessive & harmful light E.
, ● wavelength spectra
○ absorption spectrum
■ shows absorbance of different wavelengths of light by a particular photosynthetic
pigment
■ eg. chlorophyll a peaks at ~470nm & ~680nm → absorbs lights from blue-violet &
red regions
○ action spectrum
■ shows rate of photosynthesis at different wavelengths of light
■ ie. cumulation of absorption spectra of all pigments
■ ∴ peaks in blue-violet, red regions, trough in green-yellow region
● light-dependent reactions
○ makes ATP & NADPH for light-independent reaction
■ can be cyclic/non-cyclic depending on e- flow (non-linear/linear)
○ photosystems
■ reaction-centre complex surrounded by several light-harvesting complexes
● reaction-centre complex – an organised association of proteins holding a
special pair of chlorophyll a molecules and a primary electron acceptor
● light-harvesting complex – various pigment molecules bound to proteins
○ wide variety & large number of pigment molecules → broader
spectrum of wavelengths of light can be harvested at high SA
○ act as antennae molecules for reaction-centre complex
■ found in thylakoid membrane of chloroplasts
■ photosystem II (PS II) & photosystem I (PS I) cooperate in light reactions
● each has particular kind of primary pigment = pair of chlorophyll a
molecules
● PS II pair = P680 ∵ best absorption at 680 nm
● PS I pair = P700 ∵ best absorption at 700 nm
○ photoactivation
■ ie. excitation of chlorophyll by light
■ upon absorption of light photons, pigment molecule changes from ground state →
excited state
● ∵ an e- elevated to higher energy orbital
■ e- instantaneously drops back to ground state orbital → releasing E. doing so as
heat → excites e- of nearby pigment molecule
■ photons are also released → release of light = fluorescence
● difficult to see unless w/ UV light
○ photolysis
■ enzyme = oxygen-evolving complex/water-splitting complex splits H2O → 2e- +
2H+ + ½O2
■ e-s fill gap in P680 left by photoexcited e-s
■ O2 exits as by-product
■ H+ forms NADPH from NADP+
○ photophosphorylation
■ photoexcited e-s pass down ETC → generates E. w/ each step → pumps H+ from
stroma into thylakoid space by chemiosmosis→ proton grad. established → H+
diffuse back into stroma via ATP synthase → ATP created
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller nathanzhang. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $2.99. You're not tied to anything after your purchase.
