Topic 5 Photosynthesis Flashcards
Give the structure of a chloroplast
(3)
Thylakoid - stacks of folded membrane
Stroma - fluid centre
Inner & outer membranes - controls what leaves
What stage of photosynthesis are the thylakoid membranes involved in
Light dependant reaction
What part of photosynthesis is the stoma involved in
Light independent reaction
What are the reactants and products used in the LDR
Requires light and water used to create ATP and REDUCED NADP
What are the 4 stages of the LDR
- Photolysis
- Photoionisation of chlorophyll
- Chemiosmosis
- Production of ATP & REDUCED NADP
What is photolysis of water and what are the products used for
When light energy is absorbed by chlorophyll and splits water into oxygen and hydrogen
H+ picked up by NADP forming NADPH used in LIR
e- passed along electron carrier proteins
What is photoionisation of chlorophyll
Light energy absorbed by chlorophyll results in electrons becoming excited and raising energy level so they leave the chlorophyll
Chlorophyll’s then ionised by light
Some energy released electrons used to make ATP
Explain chemiosmosis (5)
- Electrons gained energy left chlorophyll move along series of proteins embedded in thylakoid membrane
- As they move along they release energy which is used to pump protons across the chloroplast membrane
- An electrochemical gradient is created as protons pass through enzyme ATP synthase which results in ATP production
- This electrochemical gradient allows the protons to move via facilitated diffusion back across the membrane
- Protons combine with co-enzyme NADP becoming REDUCED NADP
What is chemiosmosis
Protons move from a high to low concentration gradient
What is the light independent reaction also known as
Calvin cycle
Where does the Calvin cycle occur and what enzymes are present
Occurs in stroma with enzyme rubisco
What reactants does the Calvin cycle need and what are the products
Reactants
Carbon dioxide
Reduced NADP
ATP
Product
Hexose sugar
Explain the Calvin cycle (5)
- Carbon dioxide reacted with ribulose biphosphate (RUBP) 5 carbon molecule to form 2 molecules of 3 Carbon glycerate phosphate (GP)
- Reaction is catalysed by enzyme rubisco
- GP is reduced to triode phosphate (TP) using energy from ATP by accepting a H from reduced NADP
- Some carbon from TP leaves cycle each turn be converted into useful organic substances
- ATP is needed to regenerate RUBP from the 5 carbons left
How many times must the Calvin cycle occur before a hexose sugar is made?
6
What are the 3 limiting factors for photosynthesis
Light intensity
, carbon dioxide concentration and temperature
What are the 4 key stages of aerobic and where do they occur
Glycolysis (cytoplasm)
Link reaction (mitochondrial matrix)
Kerbs cycle (mitochondrial matrix)
Oxidative phosphorylation (mitochondrial inner membrane)
What are the 3 key steps In glycolysis
- Phosphorylation glucose to glucose phosphate using ATP
- Production of triose phosphate
- Oxidation of triose phosphate to produce pyruvate and a net gain of ATP and reduced NAD
Explain the process of glycolysis
- Glucose (6C) is phosphorylated (addition of 2 P) using 2 ATP
- This glucose phosphate then is split into 2 lots of triose phosphate (3C)
- Using ATP and NADH this forms 2 pyruvate (3C)
Give the products of glycolysis
2 x pyruvate
Net gain of 2 ATP (make 4 but use 2)
2 x NADH
Explain the link reaction (2)
- Pyruvate made in glycolysis is oxidised to acetate (2C) with use of NAD which picks up hydrogen becoming Reduced NAD this produces a carbon dioxide
- Acetate then combined with coenzyme A to produce acetyl coenzyme A (2C)
How many times does the link reaction occur for every glucose molecule
2
What are the products of the link reaction
2 x acetyl CoA
2 x CO2 released
2 reduced NAD
Explain the kerbs cycle (3)
- Acetyl coA reacts with 4 carbon molecule releasing CoA and producing a 6C molecule that enters kerbs cycle
- Redox reactions result in kerbs cycle generating reduced co enzymes and ATP and losing 2 C
- 1 molecule if ATP produced
Create 3 reduced NAD
1 reduced FAD
What are the products of Krebs cycle per cycle
3 x decided NAD
1 x reduced FAD
1 x ATP
2 x CO2
What are the products produced by the Krebs cycle per glucose molecule
6 x reduced NAD
2 x reduced FAD
2 x ATP
4 x CO2
Explain oxidative phosphorylation (4)
- In mitochondrial matrix all of the co enzymes produced by Krebs cycle will split into protons and electrons
- Electrons will then be transported along electron transport chain this released energy which provided the energy for the protons to be actively transported across the membrane
- Electrochemical gradient created so protons can move back by facilitated diffusion across their conc gradient via ATP synthase
- ATP synthase then phosphorylated ADP to create ATP
How is water produced in oxidative phosphorylation
Once electrons have exited the electron transfer chain these electrons are picked up by oxygen this oxygen also picks up protons once passers back though facilitated diffusion creating water
Explain the process of glycolysis for anaerobic respiration
Same as aerobic except the pyruvate is reduced to form either lactate in animals or ethanol in plants
How is the majority of energy lost between each tropic level
Respiration and excretion
What is biomass
Mass of carbon within the organism
What is GPP
Gross primary production is the chemical energy store in plant biomass
The total energy resulting from photosynthesis
What is NPP
Net primary production - chemical energy store in plant biomass taking into account energy lost to respiration
What is the equation for NPP
NPP = GPP - R
What is the equation to work out the net production of consumers
N = I - F + R
N= consumer
I = chemical energy ingested
F = chemical energy lost to excretion
R = respiratory loss
What are the units for the rates of productivity and why?
KJ ha-1 year -1
KJ - energy
Also requires per unit area and per year
Give 3 biological molecules that contain nitrogen
Proteins, ATP and nucleic acids
What is the importance of nitrogen and it’s structure
Air is 78% nitrogen
Nitrogen contains triple bond
Microorganisms are need to cover T nitrogen gas into nitrogen containing substances that plants and animals can absorb
What are the 5 key processes of the nitrogen cycle
- Salrobiotic nutrition And microbes
2 ammonification
- Nitrification
- Nitrogen fixation
- Denitrification
What is an abiotic factor
Non living environmental factors
What is saprobiotic nutrition
When microbes are feeding on dead plant matter or waste
What is he first step in nitrogen cycle
Nitrogen in atmosphere absorbed by soil and nitrogen fixing bacteria which can convert the nitrogen into ammonium this is either done directly by nitrogen fixing bacteria from root nodules of legumes types of plants which have nodules that contain the bacteria
OR
Plants that don’t have root nodules there is free living nitrogen fixing bacteria in the soil
Explain nitrification
Nitrifying bacteria oxidises ammonium into NITRITES (NO2-)
And then Is further oxidised into NITRATES (NO3-)
This is then absorbed by active transport into the plant roots
Name the waste produced by animals that are decomposers
Urea
What are the dead plant material that are decomposers
Proteins or DNA
What is the process of saprobiotic nutrition
The decomposers will break down the proteins to release nitrogen converting it back into ammonium so cycle can repeat
What happens if there is a lack of oxygen in soil?
Anaerobic denitrifying Bactria that can turn the nitrates back into nitrogen gas using denitrifying bacteria
What is phosphorus used for in organisms
DNA/RNA
ARO
Phospholipid bilayer
What is the main source of phosphate
Phosphate ions in mineral form found in sedimentary rocks
What are mycorrhizae
Fungal associations between plant and root and beneficial fungi
Why are mycorrhizae beneficial for plant growth?
- Fungi increase SA of water and mineral absorption
- The mycorrhizae acts like a sponge so holds water and minerals around roots
- Makes plants more drought resistant
Mutualistic relationship
Explain the phosphorous cycle
- Plants absorb water which contains phosphate ions these plants are then consumed by animals which excrete which will release phosphorus back into the oceans
- Phosphate ions from waste and remains are broken down these remains are eroded to release phosphate ions back into the oceans
- Deposition is when phosphate ions build up to create rocks through sedimentation
- rocks erode to release phosphate ions back into ocean
What are fertilisers used for
Added to soil to replace nitrate and phosphate ions lost when crops harvested
Give an advantage and a disadvantage of natural fertilisers
Cheaper
Exact mineral proportion can’t be controlled
Give an advantage and disadvantage of artificial fertilisers
Can create exact proportions of minerals
Very soluble and so can leach and wash away
What is leaching
When water soluble compounds are washed away in river or ponds
What is eutrophication
Nitrates leached stimulate growth of algae in a pond creating blanket of algae on water so plants underneath can’t respire
What is the equation to work out the rf value
RF= distance traveled by pigment /distance travelled by solvent
