Unit 5 Flashcards
1
Q
Light Dependent Reaction – Describe the process (6)
A
- Excites electrons / electrons removed (from chlorophyll);
- Electrons move along carriers/electron transfer chain releasing energy;
Accept: movement of H+/protons across membrane releases energy.
Reject: ‘produces energy’ for either mark but not for both. - Energy used to join ADP and Pi to form ATP;.
- Photolysis of water produces protons, electrons and oxygen;
- NADP reduced by electrons / electrons and protons / hydrogen;
2
Q
Light Dependent Reaction. Describe the electron transport chain (5)
A
- Excites electrons (from chlorophyll);
- Electrons move along carriers/electron transfer chain releasing energy; 3. Energy used to join ADP and Pi to form ATP;
- Photolysis of water produces protons, electrons and oxygen;
- NADP reduced by electrons;
3
Q
Light Independent Reaction. Describe the Calvin Cycle (6)
A
- Carbon dioxide combines with RuBP; 2. Produces two GP;
- GP reduced to TP;
- Using reduced NADP;
- Using energy from ATP;
- TP converted to glucose / hexose / RuBP / ribulose bisphosphate / named organic substance;
4
Q
Why weedkillers cause plants to give off heat? (2)
A
- Energy is released from high energy/excited electron/s (that were lost from chlorophyll
- This energy which should be used to form ATP, cannot do this as the weedkiller blocks the ETC, (so the energy
is lost as heat)
5
Q
Why does increased light intensity stimulate plant growth? (5)
A
- Have faster production of ATP and reduced NADP;
- (So) have faster/more light-independent reaction;
- (So) produce more sugars that can be used in respiration; 4. (So) have more energy for growth;
- Have faster/more synthesis of new organic materials;
6
Q
How is ATP produced? (11)
A
- ATP produced in glycolysis;
- Involving the oxidation of glucose/TP to pyruvate;
- ATP production/ Substrate level phosphorylation directly from Krebs cycle; 4. Glycolysis/Krebs cycle produce reduced NAD/FAD;
- Reduced NAD/FAD transfer electrons to electron transport chain;
- Electrons transferred down a chain of carriers;
- (Carriers) at decreasing energy levels;
- Energy (lost by electrons) used to produce ATP;
- From ADP and (inorganic) phosphate;
- Protons move into intermembrane space;
- ATP synthase;
7
Q
Describe chemiosmosis. (4)
A
- Electrons transferred down electron transfer chain;
- Provide energy to transport protons into space between membranes;
- Protons diffuse/pass back, through membrane/into matrix/through ATP synthase; 4. Energy (from H+ movement) used to combine ADP and phosphate to form ATP
8
Q
Why is there less
ATP produced in anaerobic respiration? (4)
A
- ATP formed as electrons pass along transport chain;
- Oxygen is terminal electron acceptor
- Forms H2O;
- Electrons cannot be passed along electron transport chain if no O2 to accept them;
9
Q
Why is energy transfer along food chain not 100% efficient? (9)
A
- Some light energy fails to strike/is reflected/not of appropriate wavelength; 2. Efficiency of photosynthesis in plants is low
- Respiratory loss / excretion / faeces / not eaten;
- Loss as heat;
- In excreta / excretion / urine / carbon dioxide;
- Inedible parts / indigestible parts / egestion / to decomposers
- Efficiency of transfer to consumers greater than transfer to producers;
- Efficiency lower in older animals/herbivores/ primary consumers/warm blooded animals/homoiotherms; 9. Carnivores use more of their food than herbivores
10
Q
Describe anaerobic respiration in animals. (5)
A
- Forms lactate;
- Use of NADH;
- Regenerates NAD;
- NAD allows glycolysis to continue;
- Can still release energy from ATP when no oxygen;
11
Q
How do we improve productivity during farming of animals? (5)
A
- Slaughtered while young so more energy transferred to biomass;
- Fed on controlled diet so higher proportion of food absorbed/lower proportion lost in faeces; 3. Movement restricted so less respiratory loss;
- Heating/Kept inside so less heat/respiratory loss;
- Genetically selected / selective breeding (for high productivity)
12
Q
How are nitrogen compounds in animals made available for plants? (8)
A
- Proteins/amino acids broken down;
- by saprophytes/decomposers;
- deamination/ammonium compounds/ammonia formed; 4. Ammonia converted to nitrite;
- by nitrifying bacteria;
- Nitrite converted to nitrate;
- Nitrate can be absorbed by roots;
- Nitrogen fixation forms ammonium compounds;
13
Q
Describe how the action of
microorganisms in the soil produces
a source of nitrates for crop plants.
(5)
A
- Protein / amino acids / DNA into ammonium compounds / ammonia;
- By saprobionts;
- Ammonium / ammonia into nitrite;
- Nitrite into nitrate;
- By nitrifying bacteria / microorganisms;
- Nitrogen to ammonia / ammonium;
(5)
14
Q
Describe the phosphorus cycle. (10)
A
- Phosphate ions in rocks released to soil by erosion/weathering;
- Phosphate ions taken into plants by roots/root hair cells;
- Phosphate ions assimilated into DNA/RNA/phospholipids/NADP/RuBP;
- Rate of absorption increased by mycorrhizae;
- Phosphate ions transferred through food chain;
- Some phosphate ions lost by excretion/when plants and animals die;
- Phosphorus containing compounds are decomposed by saprobionts/fungi;
- Weathering of rocks releases phosphate ions into seas and taken up by aquatic producers/algae; 9. Phosphate ions passed along food chain to birds;
- Guano returns phosphate ions to soils
15
Q
Describe the importance of phosphorylation
(2)
A
- Makes substrates more reactive;
- Lowers activation energy for the reaction
