Chapter 11 - Photosynthesis Flashcards
The factor with a value furthest away from the optimum is described as what?
The limiting factor
If you change a different factor which is not limiting the rate what will happen to the reaction rate?
It will remain the same
List 5 factors that are limiting factors for photosynthesis
Carbon dioxide, water, light intensity, chlorophyll levels, temperature
What are atmospheric levels of carbon dioxide?
0.04%
What are optimum levels of CO2 for plant growth?
0.1%
What stage of photosynthesis does temperature effect?
the calvin cycle
As distance increases, what happens to light intensity? Why?
it decreases, because light photons spread out in all directions.
List 4 solutions to prevent limiting factors in real life
Use a generator to heat
Use the waste CO2 from generators to supply it
Using probes to supply water directly to the roots
Leave lights on all night to limit darkness.
State the inverse square law
If the distance doubles, the light intensity becomes 1/4 of the original value
What is the inverse square law equation?
Intensity is directly proportional to 1/ distance squared
What is the light compensation point
When the levels of CO2 released during respiration equals that taken up during photosynthesis
What are photosynthetic pigments?
Are coloured compounds found in chloroplasts
What colour is chlorophyll?
Green
What colour are carotenoids?
red, orange, or yellow
Where is chlorophyll a found in?
all photosynthetic organisms
Where is chlorophyll b found?
plants and green algae
Where is chlorophyll c found?
algae and bacteria
Is chlorophyll water soluble?
No
are carotenoids water soluble?
no
is phycobilin water soluble?
yes
How do photosynthetic pigments display colour?
They absorb different wavelenghts of light and the colour that they reflect is their colour
What are the 8 adaptations of plants to aid photosynthesis?
Large surface are Thin Transport cuticle and upper epidermis Numerous stomata that open and close many air spaces a xylem a phloem an arrangement of leaves that minimises overlaps
Where does the light dependent reaction occur?
In the thylakoid membranes
Where does the light independent reaction occur
in the stroma
What are the 2 products of the light-dependent reaction?
NADPH and ATP
What are the 2 products of the light-independent reaction?
CO2 and glucose
What are the 3 main processes involved in the light dependent reaction?
Water is split into hydrogen ions and oxygen by photolysis
Electrons are excited via light energy
NADPH and ATP are produced
Where are photosynthetic pigments held?
embedded in proteins in the thylakoid membranes
How are electrons excited in the light dependent reaction?
by the photosystem absorbing light energy
What happens to the electrons in the photosystem when they are excited? LDR
They leave the chlorophyll molecule
What happens to the chlorophyll molecule when an electron has left?
It is also oxidised
they are ionised via photoionisation (because an electron is lost leaving the chlorophyll ion positively charged
Where do electrons go when they leave the photosystem when they are excited?
Electrons are taken up by an electron carrier in the thylakoid membrane
What is the electron carrier said to be when it accepts an electron in LDR?
Reduced
Electrons are passed along a series of electron carriers via a collection of
oxidation reduction reactions.
What happens to the electrons when they pass from one electron carrier to another?
it loses energy
What is the process of photophosphorylation?
The process by which ATP is made
What is photolysis?
The break down of water to produce 2H ions, 2 electrons and 1/2 O2
Name 3 parts of a chloroplast
Plasma membrane, grana, stroma
What is the optimum pH of enzymes working in the light independent reaction and why?
8 because the stroma has a lack of hydrogen ions because they are pumped into the thylakoid membrane
what are the 3 stages of the LIR?
- Fixation of carbon dioxide to RuBs via the enzyme RuBisCO to produce 2 glycerate 3 phosphate molecules
- Formation of organic molecules via reduction of G3P to TP
- regeneration of ribuse disphosphate.
