Studied by 2 people
What is photosynthesis?
Occurs ONLY in plants. The plant makes glucose from light, carbon dioxide and water
What is the equation for photosynthesis?
6CO2 + 6H2O -> C6H12O6 + 6O2
How is energy stored in plants?
In the glucose until plants release it by respiration
What is a metabolic pathway?
A series of reactions that are catalyzed by different enzymes and result in one or more products - photosynthesis
What is aerobic respiration?
Respiration with oxygen
What is anaerobic respiration?
Respiration without oxygen
What is respiration?
The release of energy from glucose
What is the chemical equation for aerobic respiration?
C6H12 + 6O2 > 6CO2 + 6H2O + energy
What does anaerobic respiration produce in plants and yeast?
Ethanol, carbon dioxide and releases energy
What does anaerobic respiration produce in humans?
Lactate and releases energy
What is ATP?
Adenosine Triphosphate - immediate source of energy in a cell
In respiration, the energy released from glucose is used to make.....
ATP
Describe the structure of ATP
Adenine base, combined with ribose sugar and three phosphate groups
how is ATP synthesized?
Via a condensation reaction between ADP (adenosine diohosphate) + P ( inorganic phosphate) using energy from an energy releasing reaction eg the breakdown of glucose in respiration
Where is energy stored in ATP?
In the phosphate bond
What enzyme catalyses the synthesis of atp?
ATP synthase
What is phosphorylation?
Addition of a phosphate group
How does ATP release energy in a cell?
Diffuses to part of cell that needs energy, here it is broken down back into ADP+P by hydrolysis- chemical energy is then released from the phosphate bond that was broken
What enzyme catalyses the breakdown of ATP
ATP hydrolase
6 ATP properties that make it so useful
Stores or releases only small manageable amount
Small soluble so easily transported
Easily broken down
Quickly remade
Can make other molecules more reactive by transferring phosphate group
Can't pass out of cell
What is the compensation point for light intensity?
When there is a particular level of light intensity at which the rate of photosynthesis exactly matches the rate of respiration
How do you work out the compensation point in plants?
Measure the rate at which oxygen is used at different light intensities - photosynthesis produces oxygen and respiration uses it so the compensation point is the light intensity at which oxygen is being used as quickly as it's produced
Where does photosynthesis take place?
Chloroplast
Chloroplasts are small flattened organelles surrounded by a double membrane. ..........1........... are stacked into structures called ................. which are linked tighter by bits of .........1...... membrane called .................
Thylakoids
Grana
Lamellae
What are photosynthetic pigments?
Coloured substances that absorb light energy needed for photosynthesis
Photosynthetic pigments are found in the ................. ..................... and they're attached to ................... . This is called a .........................
Thylakoid membrane
Proteins
Photosystem
What are the two photoSystems?
Photosystem 1 - absorbs light best at wavelength of 700nm
Photosystem 2 - absorbs light best at 680nm
Describe stroma
Gel like substance contained within the inner membrane of a chloroplast and surrounding the thylakoids , contains enzymes, sugars and organic acids
Carbohydrates produced by photosynthesis and not used straight away are stored as............
Starch grains in the stroma
What are redox reactions?
Oxidation-reduction reactions. Electrons are transferred from one molecule to another
If something is reduced It has .................. electrons and may have gained hydrogen or lost ................
Gained
Oxygen
If something is oxidised it has .............. electrons and may have lost hydrogen or .............. oxygen
Lost
Gained
Oxidation on one molecule always involves ................. of another molecule
Reduction
What is a coenzyme?
AIDS the function of an enzyme- work by transferring a chemical group from one molecule to another
What is NADP and what does it do?
A coenzyme used in photosynthesis - transfers hydrogen from one molecule to another ( it can reduce or oxidise a molecule)
What are the 2 stages that make up photosynthesis?
The light dependent reaction
The light independent reaction ( the Calvin cycle)
the light dependent reaction needs ............... it takes place in the ................ .............. of the chloroplasts. Light energy is absorbed by ..................... in the photoSystems. The light energy excites the ................... in the chlorophyll giving them more energy which eventually causes them to be ............... from the chlorophyll molecule. This process is called ............................
Light
Thylakoid membrane
Chlorophyll
Electrons
Released
Photo ionisation
After photoionisation in the light dependent reaction, the chlorophyll molecule is now a ........................ charged ion. Some of the energy released from electrons is used to add a ........................... to adp to form atp and some is used to .............. NADP to form ............ NADP. ATP transfers .............. and NADP transfers ................. to the light independent reaction.
Positively
Phosphate group
Reduce
Reduced
Energy
Hydrogen
Briefly describe the light independent reaction ( Calvin cycle)
Doesn't use light energy directly but uses the products of the light dependent reaction, takes place in the stroma of the chloroplast . The atp and reduced NADP supply the energy and hydrogen to make glucose from co2
What are electron carriers?
Proteins that transfer electrons
What is chemiosmosis?
The process of electrons flowing down the electron transport chain and creating a proton gradient across the membrane to drive atp synthesis.
A proton is the same thing as
A hydrogen ion
What are the two types of photophosphorylation?
Non cyclic
Cyclic
The Calvin cycle makes a molecule called ............ ..................... from .................. and ................ ............................. ( 5 carbon compound)
Triose phosphate
Co2
Ribulose bisphosphate
Draw a diagram of the Calvin cycle
What happens in the 1st stage of the Calvin cycle?
Co2 is combined with ribulose bisohosphate - catalysed by enzyme rubisco
This gives an unstable 6 carbon compound which breaks down into two molecules of a 3 carbon compound called glycerate 3-phosphate
What happens in the 2nd stage of the Calvin cycle?
Formation of triose phosphate- glycerate 3 phosphate is reduced to a compound called triose phosphate , some is converted into useful organic compounds such as glucose and some continues in the Calvin cycle
What is the final stage of the Calvin cycle
Regeneration of ribulose bisphosphate five of the six triose phosphates are used to regenerate ribulose bisphosphate not male glucose
What is a hexose sugar?
Simple 6 carbon sugar like glucose
How is a hexose sugar made?
By joining two molecules of triose phosphate together
How many times does the Calvin cycle need to turn to produce 1 hexose sugar?
6 times
How many ATP and reduced NADP is needed from the light dependent reaction for 6 turns of the Calvin cycle?
18 ATP
12 reduces NADP
Why is it important that ribulose bisphosphate is regenerated in the Calvin cycle?
If it wasn't then glycerate 3 phosphate wouldn't be formed, Calvin cycle would stop and photosynthesis would stop
The Calvin cycle is also called ...........
Carbon fixation because carbon from co2 is fixed into an organic molecule
What are the inputs and outputs of Calvin cycle?
Inputs- co2, atp, reduced NADP
Outputs- organic substances, ribulose bisphosphate
What 3 things are made from triosphosphate and glycerate 3phosphate molecules?
Carbohydrates, lipids and amino acids
What are the 4 ideal conditions for photosynthesis?
High light intensity of a certain wavelength
Temperature around 25 degrees
C02 at 0.04%
Right amount of water
What are the coenzymes used in respiration?
NAD and FAD - transfer hydrogen from one molecule to another
Coenzyme A - transfers acetate between molecules
What are the 4 stages of aerobic respiration?
Glycolysis
Link reaction
Kerbs cycle
Oxidative phosphorylation
What are the 2 stages of glycolysis?
Phosphorylation
Oxidation
What are the products of glycolysis is aerobic respiration?
2 reduced NAD
2 ATP
2 pyruvate
Note 
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