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Bio PPQs > Energy transfers > Flashcards

Energy transfers Flashcards

1
Q

Describe the light dependent reaction

(6 marks)

A
  • Chlorophyll absorbs light energy & electrons become photoexcited
  • Electrons removed (Oxidation of chlorophyll) via photoionisation;
  • Electrons move along 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 and protons -> NADPH;
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2
Q

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

(2 marks)

A
  • ATP
  • Reduced NADP/ NAHPH
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3
Q

Where does the energy for proton pumping come from?

A

High energy electrons moving across ETC

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4
Q

Describe the light independent reaction

(6 marks)

A
  • Carbon dioxide reacts with RuBP - Carbon fixation;
  • Produces two GP using (enzyme) Rubisco;
  • GP reduced to triose phosphate;
  • Using reduced NADP;
  • Using energy from ATP;
  • Triose phosphate converted to glucose and RuBP
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5
Q

Where exactly is rubisco found in a cell?

A

Stroma

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6
Q

Explain how scientists measure the rate of Photosynthesis and why

(3 marks)

A
  • Volume of oxygen released
  • Oxygen released in LDR
  • The faster oxygen in produced, the faster the LDR
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7
Q

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

(5 marks)

A
  • Have faster production of ATP and reduced NADP;
  • So have faster / more light-independent reaction;
  • Produce more sugars that can be used in respiration;
  • More energy for growth;
  • 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 only source of ATP

(4 marks)

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
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9
Q

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

(4 marks)

A
  • Reduced transfer of protons across thylakoid membrane
    OR
  • Reduced chemiosmotic gradient/proton gradient across thylakoid membrane;
  • Less ATP produced;
  • Less reduced NADP produced;
  • LDR slows so less reduction of GP to Triose Phsophate
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10
Q

Describe what happens during photoionisation in the light dependent reaction

(2 marks)

A
  • Chlorophyll absorbs light energy and electrons become photoexcited
  • Electrons lost from chlorophyll and it is oxidised and become postively charged
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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 pigments would mix
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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

(2 marks)

A
  • Level of solvent below origin/ line
  • Remove before solvent reaches top
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13
Q

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

A
  • Absorb more wavelengths of light for photosynthesis
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14
Q

Explain the relationship between stomatal opening and photosynthesis

A
  • Stomata allow uptake of CO2
  • CO2 used in photosynthesis
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15
Q

In which part of a chloroplast does the LDR occur?

(1 mark)

A

Thylakoid Membrane

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16
Q

Explain how the energy of light is converted into chemical energy

(3 marks)

A
  • Electrons excited to higher energy level
  • Use of electron carriers
  • For production of ATP
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17
Q

Describe how NADP is reduced in the LDR of photosynthesis

(2 marks)

A
  • Electrons
  • From chlorophyll/ photolysis
18
Q

Fresh water marsh soils are normally water-logged. This creates anaerobic conditions.

Use your knowledge of the Nitrogen cycle to suggest why these soils contain relatively high concentrations of ammonium compounds and low concentrations of nitrate and nitrite ions.

(2 marks)

A
  • Less nitrification/ less active nitrifying bacteria
  • Less conversion of ammonium ions to nitrate and nitrite ions
  • More denitrification/ more active denitrifying bacteria
  • So more nitrate ions converted to nitrogen gas.
19
Q

A scientist heated a plant to 80 degrees for two hours in order to determine its dry mass.

Suggest what the scientist should do in order to ensure he removed all the water from the plant.

(2 marks)

A
  • Weigh and heat
  • Until mass is constant
20
Q

Suggest one way in which the uptake of phosphate ions can help increase plant growth

(2 marks)

A
  • Used to produce named phosphate compounds: eg. ATP, phospholipids, DNA, RNA, RuBP
21
Q

Suggest one way ion which AMF (fungi which grow on the roots of plants) may benefit from their association with plants

(1 mark)

A
  • Example of carbon containing compound: eg. amino acids, glucose etc
22
Q

Describe the role of saprobionts in the nitrogen cycle

(2 marks)

A
  • Use enzymes to decompose proteins/ DNA/ RNA/ urea(nitrogen containing compounds)
  • Producing ammonium compounds
23
Q

Eutrophication causes water to become cloudy.

Describe how to obtain a quantative measure of the cloudiness of 3 samples of river water.

(3 marks)

A
  • Colorometer
  • Measure the absorbance/ transmission of light
  • Method of standardisation: eg. zeroing colorometer, same wavelength of light, same volume

Principle is:
- Named apparatus
- What is measured
- Standardisation of method

24
Q

Heat stress (a condition caused by plants being exposed to high temperatures for prolonged amounts of time), decreased the LDR of photosynthesis.

Explain why this leads to a decrease in the LIR.

A
  • Less ATP
  • Less NADPH
25
Q

A decrease in the activity of the enzyme rubisco would limit the rate of photosynthesis. Explain why.

(2 marks)

A
  • Less carbon dioxide reacts with rubisco
  • Less GP
26
Q

Explain why chemicals which inhibit the decolorisation of DCPIP would slow the growth of weeds.

(2 marks)

A
  • Less ATP produced
  • Less NADPH produced
  • Less GP converted to Triose phosphate
27
Q

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

(2 marks)

A
  • Light is reflected
  • Light is wrong wavelength
  • Light misses chlorophyll
  • CO2 concentration or temperature is limiting factor
28
Q

Name two products which are produced in the LDP which are used in the LIR

(2 marks)

A
  • ATP
  • NADPH
29
Q

Atrazine binds to protons in the electron transfer chain, in the chloroplasts of weeds, reducing the transfer of electrons down the chain.

Explain how this reduces the rate of photosynthesis in weeds.

(4 marks)

A
  • Reduced transfer of electrons across thylakoid membrane/ reduced chemiosmotic gradient
  • Less ATP produced
  • Less NAPDH produced
  • So LIR slows

Most questions about reduced rate of photosynthesis can be linked to reduced amounts of ATP and NADPH

30
Q

When weeds are treated with a chemical that stops the transfer of electrons across the ETC, it has been shown that they give off small amounts of heat. Suggest and expanation for this observation.

(1 mark)

A
  • Energy is released from high energy/ excited electrons
31
Q

Explain the process of glycolysis

(4 marks)

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

Make sure to write Triose Phosphate during exam and not TP

32
Q

Malonate inhibits a reaction in the Krebs Cycle.

Explain why malonate would decrease the rate of oxygen uptake in a respiring cell.

(2 marks)

A
  • Less NAD reduced/ fewer electrons removed and passed down ETC
  • Oxygen is the terminal electron acceptor
33
Q

Explain why converting pyruvate to lactate allows the continued production of ATP by anaerobic respiration

(2 marks)

A
  • Regerates/ produces NAD
  • So glycolysis continues
34
Q

When measuring the rate of respiration in yeast, explain why it is important to leave the apparatus for one hour after the yeast culture reached a constant temperature

(1 mark)

A
  • So the oxygen is used/ absorbed
35
Q

In an investigation where a tube containing colored liquid is connected to a conical flask containing yeast culture in glucose, the coloured liquid moved away from the flask. Explain why.

(2 marks)

A
  • Anaerobic respiration produces CO2
  • Increase in pressure
36
Q

In an investigation measuring the rate of oxygen absorbtion by aeobic respiration in seeds, the apparatus was left for 10 minutes. Suggest 3 reasons why.

(3 marks)

A
  • Equillibrium reached
  • Allow for expansion/ pressure change in apparatus
  • Allow respiration rate of seeds to stabilise
37
Q

Describe how crop plants use light energy during the light dependant reaction

(5 marks)

A
  • Excites electrons
  • Electrons move along carriers/ ETC releasing energy
  • Energy used to join ADP and Pi to form ATP
  • Photolysis of water produces protons, electrons and oxygen
  • NADP reduced by electrons
37
Q

Explain how microorganisms in the soil produce a source of nitrates from the remains of crop plants after harvesting

(5 marks)

A
  • Protein/ amino acids into ammonia
  • By saprobionts
  • Ammonia into nitrate
  • Nitrate into nitrite
  • By nitrifying bacteria
37
Q

Explain how nutrients that enter ponds or lakes may cause the death of fish.

(5 marks)

A
  • Algal bloom blocks light
  • Reduced photsynthesis so plants die
  • Saprobionts
  • aerobically respire
  • Less oxygen for fish to respire
37
Q

Describe and explain how succession occurs

(4 marks)

A
  • Colonisation by pioneer species
  • Pioneers change environmental conditions
  • Less hostile for new species
  • Increase in biodiversity
  • Climax community

Bio PPQs (7 decks)

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