Photosynthesis and Respiration Flashcards
What are the two types of respiration?
- Aerobic: requires oxygen, produces water and ATP
- Anaerobic: Absence of oxygen, produces lactate (in animals) and ethanol + CO2 (in plants), small amount of ATP produced
What are the four stages of aerobic respiration and where do they take place?
- Glycolysis - cytoplasm
- Link reaction - matrix (mitochondria)
- Krebs Cycle - matrix (mitochondria)
- Oxidative Phosphorylation/ETC - cristae (mitochondria)
Explain briefly the process of glycolysis
- Phosphorylation of glucose (6C)
- So 1 molecule of Glucose Phosphate is produced (6C)
- This splits into two Triose Phosphate molecules (3C each)
- For formation of pyruvate (3C) and formation of reduced NAD (by NAD collecting H+ ions)
- Total production 4 ATP / net production 2 ATP
What is the net production of ATP in glycolysis?
2 ATP molecules released
Explain the Link Reaction
- Pyruvate molecules produced in glycolysis are actively transported from cytoplasm to matrix
- The pyruvate (3C) is oxidised by removing hydrogen
- This hydrogen is accepted by NAD to from reduced NAD
- Acetyl group (2C) formed from pyruvate combines with co enzyme A to produce acetylcoenzyme A
- A CO2 molecule is formed
What is the equation for the Link Reaction?
Pyruvate + NAD + CoA > acetyl CoA + reduced NAD + CO2
Summarise the Krebs Cycle
- Acetylcoenzyme A combines with a 4-carbon molecule to form a 6 carbon-molecule
- NAD is reduced to NAD and CO2 is released causes a %-carbon molecule to form
- x2 NAD & x1 FAD is reduced again to form reduced x2 NAD & x1 FAD and a single molecule of ATP is produced
Apart from respiration, give three uses of ATP in a liver cell
- Active Transport
- Phagocytosis
- Mitosis
- Synthesis
Explain what happens to pyruvate in anaerobic conditions
In animals: forms lactate
In plants; forms ethanol and CO2
Both: use reduced NAD regenerated to produce NAD so glycolysis can be continued and small amounts of ATP can be produced
Name the four products of the Krebs Cycle
- ATP
- CO2
- Reduced NAD
- Reduced FAD
Describe the part played by the inner membrane of the mitochondrion in producing ATP
- Electrons are transferred down ETC which provides energy top take protons into space between membranes.
- Protons then pass back through membrane (through ATP Synthase)into matrix and energy is used to combine ADP and phosphate (Pi) to produce ATP
Give two advantages of ATP as an energy-storage molecule in a cell
- Cannot pass out of cell
- Quick, single reaction to release energy
- Releases small, manageable amounts of energy at any one time
Name the two stages in Aerobic Respiration where CO2 is produced
- Links Reaction
2. Krebs Cycle
What is the equation for Photosynthesis?
6CO2 + 6H20 + Energy > C6H12O6 +6o2
What is the process of photosynthesis an example of?
A metabolic pathway- a series of small reactions controlled by enzymes
How do animals obtain glucose?
By eating plants or eating other animals, then respire the glucose to release energy
Why do plants and animal cells need energy?
For biological processes to occur
What is any organism that carries out photosynthesis known as?
As a ‘photoautotroph’ (can make its own food using light energy)
What is the equation for Respiration?
C6H12O6 + 602 > 6CO2 + 6H2O + Energy
What does ATP stand for?
Adenosine triphosphate
How is ATP synthesised?
Ina condensation reaction between ADP and inorganic phosphate (Pi) using energy from an energy-releasing reaction (e.g the breakdown of glucose)
Which enzyme catalyses the synthesis of ATP?
ATP synthase
Give three properties of ATP?
- It’s a small, soluble molecule so it can be easily transported around the cell
- Releases small, manageable amount of energy at a time
- It’s easily broken down, takes a single reaction
What is the ‘Condensation point’ for light intensity?
There’s a particular level of light intensity at which the rate of photosynthesis exactly matches the rate of respiration
What is the unit that can be used when measuring light intensity?
m-2 s-1 (u moles)
ATP isn’t energy it is a …
store of energy
Which structure in chloroplast absorbs the light energy needed for photosynthesis?
Photosynthetic pigments
OILRIG =
Oxidation is Loss (of electrons)
Reduction is Gain (of electrons)
Where does the light-dependent reaction take place?
Thylakoid Membrane
What is a co-enzyme?
A molecule that aids the function of an enzyme
What co-enzyme is used in photosynthesis?
NADP
What does the co-enzyme NADP do?
Transfers hydrogen from one molecule to another - reduce or oxidise
What is photoionisation?
- Light energy is absorbed by chlorophyll
2. The light energy excites the electrons in the chlorophyll, giving them more energy, causing them to be released
What is phosphorylation?
Making ATP from ADP and inorganic phosphate (Pi) - adding phosphate to a molecule using light
What is the energy from photoionisation used for?
- Phosphorylation
- Making reduced NADP from NADP
- Photolysis = splitting water into protons, electrons and oxygen
After photoionisation, what happens to the released, excited electrons?
NON-CYCLIC PHOTOPHOSPHORYLATION
- These high-energy electrons move down the ETC through a series of REDOX reactions.
- They lose energy as they move down the ETC and this energy is sued to transport protons (H+ ions) into the thylakoid membrane.
- Protons then move down a concentraionn gradient into the Stroma via the enzyme ATP synthase, which is embedded in the thylakoid membrane.
- The energy from this movement combines ADP and inorganic phosphate to form ATP
The process of electron flowing down the ETC and creating a proton gradient across the membrane to drive ATP synthesis is called..,
Chemiosmosis
What is the light-independent reaction also known as?
The Calvin Cycle
Give the order of events in the Calvin Cycle
- Rubulose biphosphate (RuBP) combines with CO2 to form 2 x Glycerate 3-phosphate (3C) using the enzyme rubisco
- 2x Glycerate 3-phosphate is then reduced to form 2x triose phosphate (3C). Some of this triose phosphate is converted into useful organic compounds
- ATP is converted into ADP + Pi
- Reduced NADP is recycled to NADP
- Triose phosphate, not used to make organic compounds, is regenerated to RuBP
How many turns of the Calvin cycle would produce 2 GP?
One turn
How many turns of the Calvin cycle would produce 12 GP?
6 x 2 GP = 12 GP
…so six turns
What are the inputs of the Calvin cycle?
CO2
ATP
Reduced NADP
What are the outputs of the Calvin cycle?
Organic substances (TP) RuBP (ribulose bisphosphate)
Can the light-independent reaction take place in the dark?
YES, however it needs products from the LDR (ATP and reduced NADP) in order for it to continue
What is different about cyclic photophosphorylation compared to non-cyclic (the normal way)?
Electrons from the chlorophyll molecule aren’t passed onto NADP, but are passed back to photo-systems via electron carriers. The produce does not produce any reduced NADP or oxygen - only small amounts of ATP
Where does the oxygen in photosynthesis come from?
From water and is made in the LDR. It diffuses out of the chloroplast and eventually into the atmosphere
Why do plants look green?
As green light is reflected
What happens when an enzyme becomes denatured which may affect photoysnthesis?
- The tertiary structure changes shape
- so hydrogen, disulphide and ionic bonds form in different places
- meaning the active site will change shape and therefore substrates will no longer fit into it
- which stops ES complexes from occurring
What factors provide optimum conditions for photosynthesis?
- Temperature around 25 degrees
- Carbon dioxide at 0.4% (any higher stomata closes)
- High light intensity
- Water
What are stomata?
Pores in the epidermis of a plant that allow gas exchange
There is less oxygen in waterlogged soil, how does this affect transport of minerals into roots?
- Less oxygen so roots are unable to respire aerobically
* This means less ATP available for the active transport of minerals into the roots
What is the ‘saturation point’?
The point where a factor is no longer limiting the reaction - something else is now the limiting factor
How does management of glasshouses provide ideal conditions for plant growth?
- Carbon dioxide is added to the air
- Light can get through glasshouse and lamps are provided at night
- Glasshouses trap heat energy from sunlight and hearers/cooling systems can be used to keep a constant optimum tempertaure
Why would a control such as growing plants in a greenhouse where CO2 wasn’t added be needed?
To make sure that no other factors, apart from CO2, were affecting the results
What is a popular photosynthesis experiment to do?
Chromatography
What is a centrifuge?
A machine that spins samples really quickly and results in the separation of the components. The same weight is required for all components
How can you measure the rate of dehydrogenase activity?
By measuring the rate at which DCPIP loses its blue colour and turns colourless. A colorimeter is needed to do this.
Overall how many molecules of ATP are produced using aerobic respiration?
32 ATP molecules
Give one way ATP production can be affected
By Mitochondrial Diseases - they can affect proteins and may cause anaerobic respiration to increase so lactate is produced, causing muscle fatigue and weakness.
What is Oxygen’s role in respiration?
it is the FINAL ELECTRON ACCEPTOR
For each molecule of glucose, how many ATP molecules are produced?
28
How many molecules of CO2 are released during the Krebs Cycle?
Two CO2 molecules
What is the purpose of a buffer solution?
It is able to resist changes in pH when small amounts of acid or alkali are added - maintains pH value
How do you calculate the rate of CO2 production?
the number of minutes the apparatus was left for
