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AA biology a level - pippa > Section 5: Energy transfers in and between organisms > Flashcards

Section 5: Energy transfers in and between organisms Flashcards

1
Q

Which wavelengths of light are best absorbed by chlorophyll

A

Orange and blue

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2
Q

How does the structure of the chloroplast enable effieciently photosynthesis.

A

The structure of the chloroplast enables efficient photosynthesis by:
1. Thylakoid membranes: Provide a large surface area for the attachment of chlorophyll, enzymes, and electron carriers involved in the light-dependent reactions.
2. Stroma: Contains enzymes for the light-independent reactions (Calvin cycle) and surrounds the thylakoids to allow easy diffusion of products from the light-dependent reactions.

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3
Q

What stage of photosynthesis occurs in the grana

A

Light dependent reaction

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4
Q

Name 2 products of the LDR that are needed in the LIR and what is the other waste product

A

ATP and NADPH used
O2 waste ish

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5
Q

What happens when chlorophyll pigments absorb light and what is this process called

A

Excited electrons and they move out of PS2 along electron transfer chain called photoionisation

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6
Q

How does light effect water in the LDR

A

Photolysis energy used to split water into protons oxygen and electrons. electrons goes to PS2

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7
Q

Where do the sub products of photolysis go and what stage of photosynthesis is it

A

Light dependent reaction
Proton/hydrogen is picked up by NADP to from NADPH used in the LIR
The electron goes to PS2 and is passed along electron transfer chain
The oxygen either used for respiration or diffuses out of the leaf through stomata

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8
Q

What happens to NADP in the LDR

A

Reduced
attaches to H to from NADPH

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9
Q

What is the process that involves the movement of hydrogen ions across a membrane to generate ATP and what stage of photosynthesis is it

A

Light dependent reaction
Chemiosmosis

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10
Q

Describe chemiosmosis

A

Chemiosmosis during the light-dependent reaction (AQA A-Level, 4 marks):
1. Energy from excited electrons, transferred along the electron transport chain in the thylakoid membrane, is used to pump protons (H⁺) into the thylakoid space from the stroma.
2. This creates a high concentration of protons in the thylakoid space, establishing a proton gradient across the thylakoid membrane.
3. ATP synthase: Protons diffuse back into the stroma (as-well as protons from photolysis) through ATP synthase, down the concentration gradient.
4. ATP formation: The movement of protons through ATP synthase provides energy for the synthesis of ATP from ADP and inorganic phosphate (Pi).

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11
Q

Who discovered the reactions of the light-independent reaction stage

A

Melvin Calvin

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12
Q

What is the role of ribulose bisphosphate?

A

Carbon fixation: combines to CO2 catalysed by enzyme rubisco to eventually release organic molecules

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13
Q

Give three reasons why ATP is required in the light-independent reactions

A

ATP is required in the light-independent reactions for:
1. Reduction of GP: Provides energy to reduce glycerate-3-phosphate (GP) into triose phosphate (TP).
2. Regeneration of RuBP: Supplies energy for the regeneration of ribulose bisphosphate (RuBP) from TP.
3. Synthesis of organic molecules: Provides energy for the formation of glucose and other carbohydrates.

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14
Q

What is the role of NADPH in the light independent reactions

A
  1. Reduction of GP: NADPH reduces GP into TP
    1. Provides hydrogen: Supplies the hydrogen needed for the reduction process.
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15
Q

What would happen to the level of GP if the lights were turned off?

A
  1. GP levels would increase: As RuBP continues to combine with CO₂, forming more GP.
    1. No reduction of GP: Without light, no NADPH or ATP is produced in the light-dependent reactions, so GP cannot be reduced to TP.
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16
Q

Name three possible products that might be synthesised as a result of the light-independent reactions?

A
  1. Glucose (or other carbohydrates).
    1. Amino acids.
    2. Lipids.
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17
Q

Explain why the rate of photosynthesis will not increase indefinitely if the light intensity continues to be increased

A
  1. Limiting factors: Other factors, such as CO₂ concentration or temperature, become limiting.
    1. Saturation point: Light-dependent reactions reach a maximum rate as all photosystems are saturated.
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18
Q

How many carbon molecules does these molecules have:
RuBP
GP
TP
CO2

A

RuBP = 5C
GP = 3C
TP = 3C
CO2 = 1C

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19
Q

Describe how NADP os reduced in the light-dependent reaction

A
  1. Electrons: NADP is reduced by electrons from the electron transport chain.
    1. Protons: NADP also combines with protons (H⁺) from the photolysis of water (after it has gone through ATP synthase) to form reduced NADP (NADPH).
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20
Q

Describe the part played by reduced NADP in the light-independent reaction

A
  1. Reduction of GP: Reduced NADP (NADPH) donates electrons and hydrogen ions to reduce GP to TP
  2. provides energy from hydrolysis reaction of NADPH splitting
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21
Q

Describe 2 features of an ATP molecule which make it a useful source of energy

A
  1. Small and soluble: ATP is small and soluble, so it can easily move within cells to where energy is needed.
  2. Instant release of energy: ATP releases energy quickly when one phosphate group is removed, making it efficient for cellular processes.
  3. Quickly regenerated: ATP can be easily converted back from ADP and Pi, providing a constant supply of energy.
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22
Q

Write a simple equation summarising reaction involving CO2 GP and RuBP

A

RuBP + CO2 ——-> 2 GP
Catalysed by Rubisco enzyme

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23
Q

What are the three stages in the light dependent reaction?

A

Photoionisation: light energy excited electrons they move out of chlorophyll. Chlorophyll has been ionised by light
Photolysis: Light energy absorbed in photo system 2 splits water into protons hydrogen and electron
Chemiosmosis: Electron transfer chain provide energy for Protons to move into thylakoid space which are then pumped back into stroma along with protons from photolysis through ATP synthase release ATP and reduce NADP

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24
Q

Where in a cell is the enzyme rubisco found

A

Stroma of a chloroplasts

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25
Q

What substance combines with CO2 in a chloroplast

A

RuBP

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26
Q

Name the four stages of Aerobic respiration

A
  1. Glycolysis
  2. Link reaction
  3. Krebs cycle
  4. Oxidative phosphorylation
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27
Q

What is glycolysis?

A

Glucose (6C) phosphorylated to hexose bisphophate
hexose bisphosphate split into 2TP
Oxidation of TP to produce 2 pyruvates
the production of ATP

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28
Q

What is the link reaction summarised equation

A

pyruvate + NAD +coA ——> acetyl CoA + reduced NAD + CO2

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29
Q

What is the overall yeild from glycolysis

A

2 ATP
2 reduced NADP
2 molecules of pyruvate

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30
Q

Describe the Krebs cycle

A
  1. Acetyl-CoA combines with 4 carbon molecule to form a 6 carbon molecule
    1. Series of decarboxylation and dehydrogenation reactions occur.
    2. CO₂ is released (two molecules per cycle).
    3. Reduced NAD (three molecules) and reduced FAD (one molecule) are produced.
    4. ATP is produced via substrate-level phosphorylation.
    5. 4 carbon molecule is regenerated.
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31
Q

Explain the significance of the Krebs cycle in respiration (6 marks)

A
  1. Makes reduced NAD and FAD, which carry electrons to make energy.
    1. These are used in the electron transport chain to produce ATP.
    2. Produces a small amount of ATP directly.
    3. Releases carbon dioxide as a waste product.
    4. Restarts the cycle by regenerating oxaloacetate.
    5. Provides molecules needed for making other substances like amino acids.
32
Q

State an equation for anaerobic respiration in plants after glycolysis

A

pyruvate + NADH —> ethanol + carbon dioxide + NAD

33
Q

What is the product of glycolysis

A

2 Pyruvate
2 NADH
2 ATP

34
Q

Describe the equation for anaerobic respiration in animal cells following glycolysis

A

2 pyruvate + 2NADH —-> 2 Lactate + 2 NAD

35
Q

Where does anaerobic respiration take place

A

Cytoplasm

36
Q

Describe a light-dependent reaction

A

1 - Chlorophyll absorbs light energy
2 - Excites electrons
3 - Electron transport chain releases energy
4 - Energy used to join ADP + Pi —> ATP
5 - Photolysis of water produces protons, oxygen and electrons
6 - H+ ions pumped/ actively transported out and back in (ATP Synthase)
7 - NADPH hydrogen carrier reduced

37
Q

What is an accessory pigments

A

absorb wavelengths of light that are not easily absorbed by chlorophyll

38
Q

What is a producer

A

photosynthetic organisms that manufacture organic substances using light energy, water, carbon dioxide, and mineral ions.

39
Q

What is a consumer

A

Consumers are organisms that obtain their energy by feeding on other organisms rather than using energy of sunlight directly.

40
Q

What is a primary consumer

A

Organisms that directly eat producers (green plants)

41
Q

What is a saprobionts

A

a group of organisms that break down the complex materials materials in dead organisms into simple ones

42
Q

Define a food chain

A

a feeding relationship in which the produces are eaten by primary consumers then secondary consumers and so fourth… referring

43
Q

Describe a food web

A

different food chains within a habitat interact with each other gm-2

44
Q

What is bio mass

A

Total mass of living material in a given time in a specific area

45
Q

What do food webs show

A

The relationship between organisms and energy transfers
Multiple food chains

46
Q

How can the chemical energy store in an organism be estimated

A

calorimetry

47
Q

Name three reasons why not all light energy. reaching a leaf is converted to biomass

A

Misses chlorophyll
Wrong wavelength
Respiration

48
Q

What is GPP?

A

gross primary production
total quantity of the chemical energy store in plant biomass in a given area or volume in a given time

49
Q

What is NPP

A

net primary production
NPP = GPP - respiration

50
Q

What is a stage in a food chain called

A

tropic levels

51
Q

What is the main source of energy for all ecosystems

A

The Sun

52
Q

How does factory farming increase productivity

A

Movement restricted so less energy used in muscle contraction kept warm to reduce heat loss
feeding controlled
protects them from predators

53
Q

Describe the nutrient cycle

A
  1. nutrient is taken up by producers as simple inorganic molecules
  2. the producer incorporates the nutrient into complex organic molecules
  3. when the producer is eaten, the nutrient passes into consumers
  4. It then passes along the food chain when these animals are eaten by other consumers
  5. when the producers and consumers die their complex molecules are broke down by saprobiontic microorganisms that release the nutrient in its original simple form
54
Q

Describe the nitrogen cycle

A
  1. Nitrogen Fixation: Nitrogen-fixing bacteria, such as Rhizobium in root nodules of legumes, convert atmospheric nitrogen (N₂) into ammonia (NH₃), which then forms ammonium ions (NH₄⁺).
    1. Ammonification: Decomposers, including saprobionts, break down organic nitrogen compounds from dead organisms and waste products into ammonia, which is subsequently converted into ammonium ions.
    2. Nitrification: Nitrifying bacteria in the soil convert ammonium ions into nitrite ions (NO₂⁻) and then into nitrate ions (NO₃⁻), which plants can absorb and utilize.
    3. Denitrification: In anaerobic conditions, denitrifying bacteria convert nitrate ions back into nitrogen gas (N₂), releasing it into the atmosphere and completing the cycle.
55
Q

What happens during denitrification

A

converts nitrates to nitrogen in absence of oxygen

56
Q

What is nitrification

A

Ammonia —-> nitrite ——> nitrate

57
Q

Where does the ammonia come from in nitrification

A

Nitrogen fixation
Ammonification

58
Q

What stage of the nitrogen cycle converts nitrogen to ammonia

A

Nitrogen fixation

59
Q

What are the 2 stages of ammonification

A
  1. Proteins to amino acid using extracellular protease enzyme
  2. Removal of the amino group from the aqa using delaminate enzyme (deamination)
60
Q

What are phosphorus used in

A

ATP: for respiration, active transport, energy release, growth
DNA: nucleotides, backbone, cell division, growth, proteins
Phospholipid bilayer: cell membrane

61
Q

Describe the phosphorus cycle

A
  1. Weathering of Rocks: Phosphate ions are released from sedimentary rocks through weathering and erosion, entering soils, lakes, rivers, and oceans.
    1. Absorption by Plants: Plants absorb these phosphate ions from the soil through their roots, often with the assistance of mycorrhizal fungi, which enhance phosphate uptake.
    2. Consumption by Animals: Herbivores obtain phosphorus by eating plants, and carnivores obtain it by eating herbivores. Phosphorus is essential for forming biological molecules like DNA, RNA, and ATP.
    3. Return to the Environment: When plants and animals die, decomposers like bacteria and fungi break down their organic matter, releasing phosphate ions back into the soil or water, making them available for reuse by plants.
62
Q

What is the role of mycorrhizae in nitrogen cycle

A

The fungi acts like extensions of the plants root system and vastly increases the total surface area for the absorption of water and minerals. Enables them to better resist drought and take up inorganic ions more readily
mutualistic

63
Q

How does the phosphorus cycle work

A

Phosphorus uptake by plants: Phosphorus is taken up by plants through their roots and used to build molecules such as DNA, RNA, and ATP.
Decomposition of dead plants and animals: When plants and animals die, their remains are decomposed by decomposers such as bacteria and fungi, releasing phosphorus back into the soil.
Soil phosphorus: Some of the phosphorus released during decomposition is taken up by plants and reused, while some of it is lost from the soil through runoff and leaching.
Phosphorus in water: Phosphorus in water can be taken up by aquatic plants and animals, or it can be lost from the water through runoff, leaching, and precipitation.
Phosphorus in the atmosphere: Phosphorus in the atmosphere is primarily in the form of phosphates in aerosols, which can be transported long distances before being deposited on land or in water.

64
Q

What is eutrophication and why is it important to understand in relation to the phosphorus cycle?

A

Eutrophication is the process by which a body of water becomes enriched with nutrients, leading to excessive growth of algae and other aquatic plants. This can have negative impacts on aquatic ecosystems, including reduced oxygen levels, changes in species composition, and increased disease outbreaks. Understanding eutrophication is important in relation to the phosphorus cycle because it highlights the impacts of human activity on the availability of phosphorus in the environment and the need to manage this resource sustainably.

65
Q

How does human activity impact the phosphorus cycle?

A

Fertilizer use: The use of fertilizers can increase the amount of phosphorus in the soil, leading to over-fertilization and runoff into water bodies.
Land use changes: Changes in land use, such as deforestation and urbanization, can reduce the amount of phosphorus in the soil and increase the amount of phosphorus in runoff and leaching.
Sewage discharge: Sewage discharge can increase the amount of phosphorus in water bodies, leading to eutrophication and changes in aquatic ecosystems.

66
Q

Why is the phosphorus cycle important

A

The phosphorus cycle is important because it helps to regulate the availability of phosphorus in the environment. This is important because phosphorus is an essential nutrient for all living organisms, and without an adequate supply of phosphorus, growth and reproduction would be limited.

67
Q

What is leaching

A

Leaching is where fertilisers are washed into rivers and lakes. This occurs when too much fertiliser is applied, or during heavy rainfall, removing the water soluble compounds from the soil.

68
Q

What are the concequences of fertiliser use

A

reduced biodiversity
leaching
eutrophication

69
Q

Describe eutrophication

A

step 1 - mineral ions leached into rivers from fertilised fields stimulates the rapid growth of algae
step 2 - large amounts of algae blocks sunlight reaching the plants at the bottom of the water
step 3 - the plant at the bottom die
step 4 - Bacteria feed on the dead plant matter, reducing the oxygen concentration (aerobic respiration)
step 5 - Fish and other aquatic organisms die because there isnt enough oxygen

70
Q

What are factors effecting eutrophication

A

temperature
still water

71
Q

What is B.O.D

A

mass of oxygen consumed by microbial respiration

72
Q

How does temperature affect eutrophication

A

Higher rate of respiration and metabolic processes are sped up due to inc enzyme activity. Mineral concentration increases as water evaporates

73
Q

How does still water affect eutrophication

A

algae bloom stays stagnant and wont be disturbed in moving water water is constantly re-oxygenated

74
Q

Give an example of natural fertilisers and an example of artificial fertilisers

A

natural - dead and decaying plants or animal waste
artificial - NPK ( nitrogen, phosphorus, potassium)

75
Q

How do fertilisers increase productivity?

A

The application of either type of fertiliser can provide plants with the essential minerals they need for growth. For example, nitrogen in fertilisers is an essential component of amino acids and nucleotides in DNA, increases the rates of photosynthesis and growth, and improves crop productivity.

AA biology a level - pippa (7 decks)

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