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Left RSFC Year 13 2022-24 > Year 13 5.Energy transfers > Flashcards

Year 13 5.Energy transfers Flashcards

1
Q

Describe the light dependent reaction (6)

A
  • Chlorophyll absorbs light energy & Excites electrons
  • electrons removed (Oxidation of chlorophyll) via photoionisation;
  • Electrons move along carriers/electron transport chain releasing energy (Series of REDOX reactions)
  • Energy released (by electrons) used to form proton gradient;
  • H+ ions move through ATP synthase;
  • providing energy to join ADP and Pi to form ATP;
  • Photolysis of water produces 2 protons, 2 electrons and ½ oxygen;
  • NADP reduced by electrons / electrons and protons / hydrogen;
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2
Q

Name the two products of the light-dependent reaction that are required for the light-independent reaction.

A
  1. ATP;
  2. Reduced NADP;
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3
Q

Proton pumping to form a proton gradient is an example of active transport.

True or False (explain your answer).

A

False:

Active transport requires ATP!

Energy for proton pumping is from high energy electrons.

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4
Q

Describe the light independent reaction (6)

A
  1. Carbon dioxide combines/reacts with ribulose bisphosphate/RuBP;
  2. Produces two glycerate (3- )phosphate/GP using (enzyme) Rubisco;
  3. GP reduced to triose phosphate;
  4. Using reduced NADP;
  5. Using energy from ATP;
  6. Triose phosphate converted to glucose/hexose/RuBP/ribulose bisphosphate/named organic substance;
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5
Q

Where precisely is rubisco found in a cell?

A
  • Stroma
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6
Q

Explain why scientists measure the rate of production of oxygen in this investigation. (Rate of photosynthesis)

A
  1. Oxygen produced in light-dependent reaction;
  2. The faster (oxygen) is produced, the faster the light-dependent reaction.
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7
Q

Explain why plants that have more chlorophyll will grow faster than plants with less chlorophyll.

A
  1. Have faster production of ATP and reduced NADP;
  2. (So) have faster / more light-independent reaction;
  3. (So) produce more sugars that can be used in respiration;
  4. (So) have more energy for growth;
  5. Have faster / more synthesis of new organic materials.
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8
Q

ATP is produced in the light dependant reaction, suggest why this is not their (plants) only source of ATP.

A
  • Plants don’t photosynthesis in the dark;
  • Not all the parts of the plants photosynthesise;
  • Plants require more ATP than is produced in the light dependant reaction;
  • ATP used in Active Transport (accept other named processes)
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9
Q

Describe the effect of introducing a herbicide/inhibitor on the electron transport chain (4)

A
  • Reduced transfer of protons across thylakoid membrane
    OR
  • Reduced chemiosmotic gradient/proton gradient across thylakoid membrane;
  • (So) less ATP produced;
  • (So) less reduced NADP produced;
  • (So) light-independent reaction slows/stops
    OR
  • Less reduction of GP to triose phosphate;
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10
Q

Describe what happens during photoionisation in the light dependent reaction.

A
  • Chlorophyll absorbs light
    OR
    Light excites/moves electrons in chlorophyll;
  • Electron/s are lost / chlorophyll is oxidised;
    OR
    (Chlorophyll) becomes positively charged;
    Accept electrons go to electron transport/carrier chain for ‘electrons lost’.
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11
Q

When producing a chromatogram explain why the origin is marked using a pencil rather than ink.

A
  • Ink and (leaf) pigments would mix
    OR
  • (With ink) origin/line in different position
    OR
  • (With pencil) origin/line in same position
    OR
  • (With pencil) origin/line still visible;
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12
Q

While making a chromatogram, describe the method used to separate the pigments after the solution of pigment had been applied to the origin.

A
  • Level of solvent below origin/line;
  • Remove/stop before (solvent) reaches top/end;
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13
Q

Suggest and explain the advantage to plants of having different colour pigments in leaves.

A
  • Absorb different/more wavelengths of light for photosynthesis
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14
Q

Explain the relationship between stomatal opening and photosynthesis.

A
  1. Stomata allow uptake of carbon dioxide;
  2. Carbon dioxide used in / required for photosynthesis;
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15
Q

Describe the process of glycolysis. [4]

A
  • Phosphorylation of glucose using ATP;
  • Oxidation of triose phosphate to pyruvate;
  • Net gain of ATP;
  • NAD reduced;
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16
Q

Describe the link reaction [4]

A
  • Occurs in the matix (mitochondrion)
  • Pyruvate oxidised and decarboxylated into Acetate.
  • Produces reduced NAD and CO2
  • Acetate combines with coenzyme A to produce Acetyl co A
  • Reject ATP is formed.
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17
Q

Describe how oxidation takes place in glycolysis and in the Krebs cycle. [4]

A
  • removal of hydrogen/dehydrogenation;
  • by enzymes/dehydrogenases;
  • H accepted by NAD/reduced NAD formed;
  • in Krebs cycle, FAD (used as well);
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18
Q

Water is a waste product of aerobic respiration. Describe how water is formed at the end of aerobic respiration. [2]

A
  • oxygen is terminal/final electron acceptor;
  • combines with electrons and protons (to form water);
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19
Q

Explain how the amount of ATP is increased by reactions occurring inside a mitochondrion. [6]

A
  • oxidation of/removal of electrons and H+
  • from pyruvate
  • acetyl CoA / 6 carbon compound; (credit oxidative decarboxylation)
  • substrate level production of ATP / ATP produced in Krebs cycle;
  • production of reduced NAD / FAD (allow they take up hydrogen);
  • in matrix of mitochondria;
  • electrons fed into electron transport chain / used in oxidative
  • (Electrons) pass along carriers/through electron transport chain/through series of redox reactions;
  • Energy released;
  • Protons move into intermembrane space;
  • ADP/ADP + Pi;
  • ATP synthase;
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20
Q

Describe the roles of the coenzymes and carrier proteins in the synthesis of ATP.

OR

Describe the events of oxidative phosphorylation

[5]

A
  • NAD/FAD reduced / hydrogen attached to NAD/FAD;
  • H+ ions/electrons transferred from coenzyme to coenzyme/carrier to carrier (ETC on cristae of inner membrane)
  • Energy released (from electrons) through series of redox reactions;
  • Energy released used to pump H+/ protons into intermembrane space forming an electro-chemical gradient (of protons);
  • H+/ protons flow back through ATP synthase to produce ATP from ADP and phosphate.
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21
Q

In many mammals, ‘uncoupling proteins’ help to maintain a constant body temperature during hibernation.

Suggest and explain how.

A
  1. Allow passage of protons/H+;
  2. (Energy) released as heat;
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22
Q

The mitochondria in muscles contain many cristae. Explain the advantage of this. [2]

A
  • larger surface area for electron carrier system / MORE oxidative phosphorylation;
  • provide MORE ATP / energy for contraction
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23
Q

Give two reasons why the respirometer was left for 10 minutes when it was first placed in the water bath. [2]

A
  • Equilibrium reached;
  • Allow for expansion (gases/liquids) /pressure change in apparatus;
  • Allow respiration rate of seeds to stabilise;
24
Q

Explain why a log scale is used to record the number of cells/bacteria.

A
  • Large range/difference/increase in numbers;
  • Accept reference to exponential (increase)
25
Q

Explain why converting pyruvate to lactate allows the continued production of ATP by anaerobic respiration. [2]

A
  • Regenerates NAD / Oxidises reduced NAD;
  • (So) glycolysis continues;
26
Q

Explain why converting pyruvate to lactate allows the continued production of ATP by anaerobic respiration. [2]

A
  • Regenerates NAD / Oxidises reduced NAD;
  • (So) glycolysis continues;
27
Q

Explain why converting pyruvate to lactate allows the continued production of ATP by anaerobic respiration. [2]

A
  • Regenerates NAD / Oxidises reduced NAD;
  • (So) glycolysis continues;
28
Q

Malonate inhibits a reaction in the Krebs cycle.

Explain why malonate would decrease the uptake of oxygen in a respiring cell.
[2]

A
  • Less/no reduced NAD/coenzymes OR Fewer/no hydrogens/electrons removed (and passed to electron transfer chain);
  • Oxygen is the final/terminal (electron) acceptor;
29
Q

Define Biomass

A
  • Mass of carbon (organic compounds)
  • Dry mass of tissue per given area
30
Q

Suggest what you should do to ensure all water is removed from a tissue / sample. [2]

A
  • Regularly weigh and Heat (less than 100 °C)
  • Until mass is constant
31
Q

What is GPP?

A

Gross Primary Productivity
* Chemical energy store in plant biomass, in a given area or volume. (Rate of photosynthesis)

32
Q

What is NPP?

A

Net Primary Production

  • Chemical energy store in plant biomass after respiratory losses to the environment have been taken into account. NPP= GPP -R
  • NPP is available for new plant growth and reproduction OR available for other trophic levels in the ecosystem, such as herbivores and saprobionts.
33
Q

Suggest suitable units to measure productivity (e.g. NPP)

A
  • kJ ha–1 year–1
    OR
    kJ km–2 year–1
    OR
    kJ km–3 year–1
34
Q

The percentage of the light energy trapped by the producers is very low. Give two reasons why. [2]

A
  • Reflected / absorbed by water vapour;
  • Reflected from producers / wrong wavelength;
  • Transmitted / passes between chloroplasts/ between plants / too few chloroplasts;
35
Q

In natural ecosystems, most of the light falling on producers is not used in photosynthesis.
Suggest two reasons why. [2]

A
  1. (Light is) reflected;
  2. (Light is) wrong wavelength;
  3. (Light) misses chlorophyll/ chloroplasts/photosynthetic tissue;
  4. CO2 concentration or temperature is a limiting factor.
36
Q

The biomass of primary consumers is less than the biomass of producers. Explain why. [4]

A
  • Loss of energy/heat / use of energy / less energy to be passed on;
  • In respiration;
  • In excreta / excretion / urine / carbon dioxide;
  • Inedible parts / indigestible parts / egesta / egestion / to decomposers;
37
Q

Describe how and explain why the efficiency of energy transfer is different at different stages in the transfer. [6]

A
  • Some light energy fails to strike/is reflected/not of appropriate wavelength;
  • Efficiency of photosynthesis in plants is low / approximately;
  • 2% efficient;
  • Respiratory loss / excretion / faeces / not eaten;
  • Loss as heat;
  • Efficiency of transfer to consumers greater than transfer to producers/approximately 10%;
  • Efficiency lower in older animals/herbivores/ primary consumers/warm blooded animals;
  • Carnivores use more of their food than herbivores;
38
Q

Explain how the intensive rearing of domestic livestock increases net productivity [5]

A
  • Slaughtered when still growing/before maturity/while young so more energy transferred to biomass/tissue/production;
  • Fed on concentrate /controlled diet /controlled conditions/so higher proportion of (digested) food absorbed/lower proportion lost in faeces / valid reason for addition;
  • **Movement restricted **so less respiratory loss / less energy used;
    * Kept inside/heating/shelter / confined so less heat loss / no predators;
  • Genetically selected for high productivity;
39
Q

Describe the need for plants to both photosynthesise AND respire [5]

A
  • In the dark no ATP production in photosynthesis;
  • Some tissues unable to photosynthesise/produce ATP;
  • ATP cannot be moved from cell to cell/stored;
  • Plant uses more ATP than produced in photosynthesis;
  • ATP for active transport;
  • ATP for synthesis (of named substance);
40
Q

The concentrations of carbon dioxide in the air at different heights above ground in a forest changes over a period of 24 hours. Use your knowledge of photosynthesis to describe these changes and explain why they occur. [5]

A
  • High concentration of carbon dioxide linked with night/darkness;
  • No photosynthesis in dark/night / light required for photosynthesis/light-dependent reaction;
  • (In dark) plants (and other organisms) respire;
  • In light net uptake of carbon dioxide by plants/plants use more carbon dioxide than they produce/ rate of photosynthesis greater than rate of respiration;
  • Decrease in carbon dioxide concentration with height;
  • At ground level fewer leaves/less photosynthesising tissue/more animals/less light;
41
Q

Explain what is meant by the term carbon sink.

Not on spec (GCSE)

A
  • Takes up / locks up / stores carbon / carbon dioxide (for a long time) / eq ;
  • Named example e.g. peat / coal / limestone / trees / fossil fuel / chalk / shells ;
42
Q

Describe the role of saprobionts in the nitrogen cycle. [2]

A
  • (use enzymes to) decompose proteins / DNA / RNA / urea;
  • Producing / releasing ammonia / ammonium ions;
43
Q

Explain how carbon-containing compounds present in the pine leaves that fall from the trees are absorbed and used for growth by saprobionts/fungi that live in the soil. [5]

A
  • extracellular digestion;
  • by secretion of enzymes;
  • absorption of digested/soluble products;
  • synthesis of structural compounds/named compound;.
  • respiration provide energy for growth
44
Q

Nitrogen compounds in the plants are made available for the main crop after ploughing in spring.

Describe the role of microorganisms in this process.
[5]

A
  • proteins/amino acids broken down;
  • deamination/ammonification/ release of ammonium compounds;
  • By saprophytes/saprobionts/decomposers;
  • conversion to nitrates via nitrites;
  • by nitrifying bacteria/named bacterium;
  • nitrates absorbed into roots via active transport
45
Q

The scientists used units of μg g−1 for the concentration of ammonia in soil.

Suggest why, in this investigation, the scientists used these units.

A
  • (μg because) very little ammonia (in soil);
  • (μg because) avoids use of (lots of) decimal places (in their results) / avoids the use of powers of 10 / avoids the use of standard form /makes numbers more manageable / Accept makes easier to plot graph
  • (g-1) to allow comparisons (between samples);
46
Q

Give two examples of biological molecules containing nitrogen that would be removed when a crop is harvested. [2]

A
  1. amino acid/protein/ polypeptide/peptide;
  2. nucleic acid/nucleotide/base;
  3. DNA;
  4. RNA / pre-mRNA / mRNA / rRNA / tRNA
  5. ATP/ADP;
  6. NAD/NADP (reduced or not);
  7. Cyclic AMP/cAMP; (More on this later in the year)
  8. Chlorophyll;
47
Q

Plants absorb a number of other nutrients from the soil including phosphates. Describe why phosphates are needed by a growing plant [4]

A
  • production of phospholipids;
  • in cell membranes;
  • synthesis of ATP;
  • production of DNA;
  • production of RNA;
  • production of NADP
48
Q

Describe how a lack of phosphates in the soil surrounding a plant can affect its growth [4]

A
  • (Required to) make ATP/glucose phosphate, so less respiration/less energy for growth;
  • (Required to) make nucleotides, so less DNA/mRNA/tRNA for cell division/production of protein (for growth);
  • (Required to) make RuBP/NADP, so less CO2 fixed/reduced into sugar;
  • (Required to) make phospholipids for membranes;
49
Q

Outline the advantages of having Mycorrhizae
growth near plants [2]

A
  • Mycorrhizae help plants to defend themselves (causing an increase in crop yield);
  • Mycorrhizae help plants to take up nitrates/phosphates (causing an increase in crop yield);
50
Q

You are given samples of water from three different rivers.
Describe how you would obtain a quantitative measurement of their cloudiness.
[3]

A
  • Use of colorimeter;
  • Measure the absorbance/transmission (of light);
  • Example of how method can be standardised eg same volume of water, zeroing colorimeter, same wavelength of light, shaking the sample;
51
Q

Describe the process of eutrophication. [5]

A
  • Nitrates / Phosphates / Ammonium ions flushed into waterway
  • Increased algal bloom
  • Light blocked out
  • Submerged aquatic plant unable to photosynthesise and die
  • Increase in **saprobionts so increases rate of aerobic respiration **
  • Saprobionts / aero.resp organismsn die as lack of oxygen (anoxic)
  • *Increase in anaerobic microorganisms
  • Production of toxins*
52
Q

Explain why an increase in plant biomass can be taken as a measurement of net primary productivity.

A
  1. Represents dry mass / mass of carbon;
  2. Represents gross production minus respiratory losses;
    or NPP =GPP - R
53
Q

a) Nitrogen gas to Ammonium ions
b) Ammonium ions to Nitrates
c) Nitrates to Nitrogen gas

Which stage of the Nitrogen cycle involves NITRIFICATION ?

A

b) Ammonium ions to Nitrates

54
Q

a) Nitrogen gas to Ammonium ions
b) Ammonium ions to Nitrates
c) Nitrates to Nitrogen gas

Which stage of the Nitrogen cycle involves DENITRIFICATION ?

A

c) Nitrates to Nitrogen gas

55
Q

a) Nitrogen gas to Ammonium ions
b) Ammonium ions to Nitrates
c) Nitrates to Nitrogen gas

Which stage of the Nitrogen cycle involves Rhizobium bacteria ?

A

a) Nitrogen gas to Ammonium ions
Nitrogen fixation

56
Q

Name the process by which some bacteria oxidise ammonia to nitrate.

A

Nitrification

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