• What is the overall equation for photosynthesis?

  6CO2 + 6H2O ------> C6H12O6 + 6O2
• What is photosynthesis an example of?

  A metabolic pathway (reactions controlled by enzymes)
• What is respiration?

  What are the two types of respiration?

  Releasing energy from glucose

  
  

  Aerobic

  Anaerobic
• What is the overall equation for cellular respiration?

  C6H12O6 + 6O2 ------> 6CO2 + 6H2O + Energy
• In humans what does anaerobic respiration produce?

  Lactate ( Lactic acid ) and energy
• What catalyses the process of phosphorylation?

  ATP synthase
• What does ATP hydrolase do?

  Catalyses the hydrolysis reaction of ATP into ADP and Pi, the chemical energy released from the phosphate bond is used by the cell.
• ATPs properties

  Small, soluble so can easily be transported around the body

  Easily broken down so releases instantaneous energy

  Can make other molecules more reactive through phosphorylation

  Small amount of energy is released so no energy is wasted as heat
• What is a compensation point for light intensity

  Where a particular level of light intensity causes rate of photosynthesis to exactly match rate of respiration
• How can you work out compensation point for a plant?

  Measure rate of oxygen produced by the plant at different light intensities. Photosynthesis produces oxygen and respiration uses it so the compensation point is where oxygen is being used as quickly as it is being produced.
• What are Thylakoids?


  Fluid-filled sacs that are stacked up in the chloroplast into structures called grana

  
• What are grana linked by?

  Lamellae

  
• Name two photosynthetic pigments

  Any two from:

  Chlorophyll a

  Chlorophyll b

  Carotene
• What are photosynthetic pigments?

  Coloured substances that absorb the light energy needed for photosynthesis
• Where are photosynthetic pigments found?

  In thylakoid membranes attached to proteins
• What is a photosystem?

  Pigments and proteins that capture light energy

  There are two photosystems, photosystem I (which absorbs wavelength of 700nm) and Photosystem II (which absorbs wavelength of 680 nm)
• Tell me about the Stroma


  Contains enzymes, sugars and organic acids. Carbohydrates produced by photosynthesis that aren't used are stored as starch grains in the stroma
• What is a redox reaction

  They involve oxidation and reduction.

  When something is reduced it gains electrons or hydrogen but looses oxygen

  When something is oxidised it loses electrons or hydrogen but gains oxygen.

  Oxidation of one molecule always involves the reduction of another molecule
• What is a coenzyme?

  An enzyme that transfers a chemical group between molecules

  E.g NADP is a coenzyme that transfers hydrogen.
• What is the Light-dependant reaction?

  Takes place in the thylakoid membranes of the chloroplast, here light energy is absorbed by photosynthetic pigments in the photosystem. Light energy excites electrons in the chlorophyll increasing their energy, releasing them from the chlorophyll. This is called photoionisation. The chlorophyll is a positively charged ion where some of the energy released by electrons is used to add a phosphate to ADP to form ATP, some is used to form reduced NADP (NADPH) from NADP.

  Atp transfers energy and reduced NADP transfers hydrogen to the light-independent reaction, during this process h20 is oxidised to form 02

  
• What is the light-Independent reaction (Calvin cycle)?

  It relies on products from the light dependant reaction

  Takes place in the stroma of the chloroplast where ATP and reduced NADP from the light-dependant reaction supply the energy and hydrogen to make glucose from CO2

  
• In the light-dependant reaction what is energy from photoionisation used for?

  Photophosphorylation - making ATP from ADP and an inorganic phosphate

  Making reduced NADP (NADPH) from NADP

  Photolysis - Splitting water molecules into H+ and O- using light energy
• What are the two types of photophosphorylation included in light-dependant reactions?

  Non-Cyclic

  Cyclic
• Explain the process of Non-cyclic Photophosphorylation.

  Light energy is absorbed by PSII which excites electrons in the chlorophyll and moveto a higher energy level. The higher energy electrons are released from chlorophyll and move down the electron transport chain to PSI

  
  

  As the excited electrons from the chlorophyll move down the electron transport chain they must be replaced so photolysis is used to split water into protons and electrons using light energy.

  
  

  Excited electrons lose energy as they move down the electron transport chain, the energy is used to transport protons (H+) into the thylakoid so it has a higher concentration of protons than the stroma. This form a proton gradient into the stroma from the thylakoid via the enzyme ATP synthase. The movement of protons drive ATP synthesis from ADP and Pi to form ATP.

  
  

  Light energy is absorbed by PSI which excites the electrons again to an even higher energy level where they are transferred to NADP along with a proton (H+) from the stroma to form NADP.

  
• What is chemiosmotic theory?

  The process of electrons flowing down the electron transport chains and creating a proton gradient across the membrane to drive ATP synthase

  
• Explain the process of cyclic photophosphorylation

  It produces ATP only using PSI, electrons from the chlorophyll molecule are aren't passed onto NADP bu back into PSI via electron transport carriers. Electrons are recycled, producing small amounts of ATP and no NADPH or oxygen.

  
• Explain each stage of the Calvin cycle

  Stage 1 ) CO2 enters the leaf via the stomata, diffusing into the stroma ( of the chloroplast ), here it combines with ribulose bisphosphate (RuBP) which is catalysed by the enzyme rubisco. #this forms a 6 carbon compound (6C) which breaks down into two molecules of glycerate 3-phosphate (GP) which is a 3 carbon compound

  
  

  Rubisco

  Equation: RuBP (5C) + CO2 -----------> unstable 6C compound ----> 2 x GP (3C)

  
  

  Stage 2) Hydrolysis of ATP (from the light-dependant reaction) provides energy to reduce GP (3C) to another type of 3C called Triose phosphate (TP). This reaction requires H+ which come from NADPH ( from the light dependant reaction ). NADPH is recycled into NADP, some triose phosphate is converted into organic compounds i.e glucose, some continues to be used in the calvin cycle to regenerate RuBP.

  
  

  Equation:

  2 x ATP 2 x ADP + Pi 2 x NADPH 2 x NADP

  \ / \ /

  2 x GP (3C) -------------------------------------> 2x TP (3C)

  
  

  
  

  Stage 3) 5 out of every 6 molecules of ATP produced in the cycle aren't used to make useful organic compounds but to regenerate RuB which uses the rest of the ATP produced by the light-dependant reaction.

  
  

  Equations:

  
  

  ATP ADP + Pi

  \ /

  2 x TP (3C) -------------------------------------> RuBP (5C)

  \

  Useful organic compounds (1C)

  
• Why does the calvin cycle need to turn six times to make one hexose sugar?

  5 out of 6 TP molecules are used to regenerate RuBP so only one C is produced to make an organic compound, the Cycle needs to turn 6 times to produce 6 C to be able to form a hexose sugar e.g. glucose
• What are Triose Phosphate (TP) and glycerate-3-Phosphate (GP) used for?

  To make:

  Carbohydrates - Hexose sugars are made from two triose phosphate molecules

  Lipids - Made using glycerol, which is synthesised from TP and fatty acids, which are synthesised from GP

  Amino acids - Some amino acids are made from GP
• What are the optimum conditions for photosynthesis?

  High light intensity of a certain Wavelength

  Temperature generally around 25C

  Carbon dioxide at 0.4% concentration

  Water
• Describe and explain each of the four optimum conditions needed for photosynthesis

  High light intensity of a certain Wavelength

  - Light is needed to provide the energy for the light-dependant reaction, higher intensity, the more the energy provided.

  - Certain wavelengths of light are used for photosynthesis, photosynthetic pigments ( chlorophyll a, chlorophyll b, carotene ) only absorb the red and blue light in sunlight.

  
  

  Temperature generally around 25C

  - Photosynthesis involves enzymes, if temperature falls under 10C they become inactive, Above 45C they denature.

  -Stomata also close at high temperature to avoid losing to much water, causing photosynthesis to slow down as less CO2 enters the leaf when the stomata are closed.

  
  

  Carbon dioxide at 0.4% concentration

  - 0.04% of CO2 makes up the atmosphere, increasing concentration to 0.4% increases rate of photosynthesis, but any higher will cause stomata to close.

  
  

  Water

  - To little water and photosynthesis will stop but too much will cause the solid to become waterlogged, reducing uptake of minerals needed to make e.g. chlorophyll a
• What are the limiting factors of photosynthesis?

  Light intensity, temperature, carbon dioxide concentration
• How do farmers increase plants grown in glasshouses/greenhouses?

  CO2 is added to the air by burning small amounts of propane in a carbon dioxide generator

  Light can get in through glass and lamps are used in the night

  Temperature is controlled using heaters and cooling systems for optimum temperature and glasshouses trap heat energy from sunlight.
• How does chromatography work?

  The mobile phase moves through the stationary phase

  The components in the mixture spend different amount of time in the mobile phase and the stationary phase

  The components that spend longer in the mobile phase travel faster / further, the time spent in the different phases is what separates out the components of the mixture.
• How to you work out Rf value?

  Distance travelled by spot/ distance travelled by solvent
• What are coenzymes?

  A molecule that aids the function of an enzyme by transferring a chemical group from one molecule to another. e.g. NAD, coenzyme A, FAD
• What are the 4 stages of aerobic respiration?

  Glycolysis

  Link reaction

  Krebs cycle

  Oxidative phosphorylation
• What is glycolysis?

  Splitting of a molecule of glucose (6C) into two 3c pyruvate molecules in the cytoplasm of cells. It is the first stage of both anaerobic and aerobic as oxygen isn't needed for this reaction to take place
• What are the Stages of Glycolysis?

  Explain each stage

  Phosphorylation

  - Glucose is phosphorylated using a phosphate from a molecule of ATP creating one molecule of glucose phosphate and one molecule of ATP.

  - ATP is used to add another phosphate, forming hexose biphosphate

  -Hexose biphosphate is then split into two molecules of triose phosphate.

  
  

  Oxidation

  -Triose phosphate is oxidised (by losing hydrogen), forming 2 molecules of pyruvate. NAD collects the hydrogen forming 2 reduced NAD and 4 ATP. However 2 ATP have been used so net gain of ATP is 2

  
• What happens to all the products of glycolysis in aerobic respiration?

  2 reduced NAD (NADH) - goes to oxidative phosphorylation

  2 pyruvate - Actively transported into the mitochondrial matrix for use in the link reaction

  2 ATP (net gain) - Used for energy