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Biology Paper 2 > Energy Transfers In and Between Organisms > Flashcards

Energy Transfers In and Between Organisms Flashcards

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1
Q

What two reactions can photosynthesis be separated into?

A
  1. light dependant reactions
  2. light independent reactions
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2
Q

what features are in a thylakoid membrane

A
  • phospholipid bilayer
  • electron transport chain (proteins)
  • PS1
  • PS2
  • ATP synthase
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3
Q

Non-cyclic phosphorylation
first stage of the light dependant reaction
photolysis of water

A

photon of light enters the thylakoid disc where it uses energy to split (lyse) water molecule into hydrogen ions, electrons, and oxygen gas

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4
Q

second stage of the light dependant reaction
photoionization of PS2

A
  1. PS2 is a complex of photosynthetic pigments i.e. chlorophyll A & B, carotene. each respond to a different wavelength of light
  2. energy from a photon of light is transferred to an electron, that becomes energised.
  3. this leaves the photosystem (ionising it) and join the electron transport chain.
  4. electrons are replaced by the photolysis of water
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5
Q

third stage of the light dependant reaction
energised electron

A

energy from energized electron pumps H+ across the membranes into the thylakoid through the proton pumps, of the electron transport chain. once all of the energy is used, the electron joins PS1

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6
Q

fourth stage of the light dependant reaction

A

electron is struck by another photon of light, it becomes energized again and leaves PS1 and enters the stroma

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7
Q

fifth stage of the light dependant reaction
chemiosmosis

A

increase in H+ inside thylakoid disc gives an electrochemical gradient. H+ move into the stroma down their electrochemical gradient, by facilitated diffusion through ATP synthase. this provides the energy for phosphorylation of ADP into ATP

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8
Q

sixth stage of the light dependant reaction
Reduction of NADP

A

NADP is a coenzyme. it collects the energised electrons from PS1 and the excess H+ from chemiosmosis. it becomes reduced

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9
Q

what is a coenzyme

A

it is not an enzyme.
it carriers molecules e.g. H+ and e- from one reaction to another, without changing them

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10
Q

process of cyclic phosphorylation

A

involves PS1, e- become energized through photons of light they leave PS1 and join the electron transport chain, using the energy to pump H+ into the thylakoid. the e- returns to PS1. H+ moves with others in chemiosmosis providing energy for the phosphorylation of ADP to ATP

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11
Q

light-independent reaction/Calvin cycle

A

Calvin Cycle takes place in stroma of the chloroplast and uses the products of the LDR (ATP & reduced NADP) to form glucose. The reactions can be divided into three main stages: carbon fixation, reduction, and regeneration.

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12
Q

Carbon fixation

A

CO2 is added to a 5 C-molecule called ribulose bisphosphate (RuBP), forming a 6-carbon molecule. This is catalysed by an enzyme called Rubisco.
The unstable molecule breaks down to form two 3-carbon compounds called glycerate-3-phosphate (GP).

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13
Q

Reduction

A
  • isomerization reaction converts GP into a 3-carbon compound called triose phosphate. ATP (LDR) is hydrolyzed into ADP.
  • reaction requires electrons from electron carrier to reduce NADP (LDR). Reduced NADP transfers electrons to GP, reducing it to GALP.
  • TP is converted into organic molecules, e.g. glucose, regenerate RuBP. For every 6 molecules of GALP, 1 produces organic molecules whereas 5 will be used for RuBP regeneration.
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14
Q

Regeneration

A
  • GALP is converted back into RuBP - this process requires energy which is generated by ATP hydrolysis.
  • cycle is completed and another round of carbon fixation takes place.
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15
Q

what is a limiting factor

A

a limiting factor is that which prevents the rate of reaction increasing

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16
Q

limiting factor
increasing light intensity

A

if we increase light intensity, we increase the rate of photosynthesis, due to more photolysis of water and more photoionization of photosynthetic pigment that is due to increased light intensity

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17
Q

limiting factor
decreasing light intensity

A

decrease light intensity, we will get an increase in the glycerate-3-phosphate concentration and a decrease in both this triphosphate and RUBP

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18
Q

limiting factor
CO2 concentration

A

if we decrease CO2 conc, we will see an increase in RUBP and a decrease in glycerate-3-phosphate and triose phosphate

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19
Q

limiting factor
temperature

A

increase in temperature, increases the kinetic energy of particles therefore increasing the rate of enzyme reactions. this has a much bigger impact on the light-independent reaction than the right dependent reaction

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20
Q

1t stage of an/aerobic respiration
glycolysis

A
  • addition of phosphate (and energy) destabilizes the glucose so it splits into 2 identical molecules of triose phosphate
  • triose phosphate is oxidised. these reactions occur twice. the second phosphate to phosphorylate the ADP is gained through substrate-level phosphorylation
  • in presence of oxygen, pyruvate is actively transported into the mitochondrial matrix
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21
Q

glycolysis
what do you get from 1lgucose molecule

A
  • 2x pyruvate
  • 2x reduced NAD
  • 2x ATP (net)
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22
Q

2nd stage of aerobic respiration
the link reaction

A
  • NAD become reduced NAD, decarboxylation happens so CO2 is formed, acetate is formed from this
  • acetate combines with the molecule called coenzyme A to form acetyl coenzyme A
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23
Q

the link reaction
from 1 molecule of glucose

A
  • 2x Acetyl CoA
  • 2x CO2
  • 2x reduced NAD
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24
Q

the krebs cycle

A
  • (2C) Acetyl CoA enters the circular pathway
    -(4C) oxaloacetate accepts the 2C acetyl CoA to form the 6 carbon (6C) citrate
  • Coenzyme A is released in this reaction
  • CO2 is released, NAD becomes reduced NAD
  • this forms a 5C intermediation, decarboxylation occurs releasing CO2, FAD is reduced to rescued FAD, 2 NAD is reduced to 2 reduced NAD, ADP + Pi forms ATP (substrate-level phosphorylation)
  • 4C oxalo acetate is formed
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25
Q

from 1 molecule of glucose

A
  • 6x Reduced NAD
  • 4x CO2
  • 2x ATP
  • 2x reduced FAD
26
Q

oxidative phosphorylation - cristae membrane
part 1

A
  • reduced NAD & FAD are oxidised to NAD & FAD, releasing e- & H+
  • energy from the energised electrons is used to pump H+ across the membrane through the electron transport chain
  • when the election has no energy, it comes out the electron transport chain into the matrix
27
Q

oxidative phosphorylation - cristae membrane
part 2

A
  • increase in H+ inside the intermembrane creates an electrochemical gradient
  • H+ moves by facilitated diffusion through ATP synthase, aka chemiosmosis, this provides energy for the phosphorylation of ADP to ATP
  • H+ & e- react with O2 to produce water
28
Q

theoretically how many ATP’s should we get from glucose

A

32

29
Q

Chloroplasts are the site of photosynthesis and are adapted to photosynthesis in the following
ways:

A
  • stacks of thylakoid membranes called grana provide a large surface area for the attachment of chlorophyll, e- and enzymes.
  • a network of proteins in the grana hold the chlorophyll to absorb the maximum amount of light.
  • granal membrane has ATP synthase channels embedded allowing ATP to be synthesized
  • Chloroplasts contain DNA and ribosomes allowing them to synthesize proteins
30
Q

how many rounds of the Calvin cycle need to take place to reproduce one glucose molecules

A

6

31
Q

Features of anaerobic respiration

A
  • no oxygen
  • only occurs in the cytoplasm
  • releases less ATP/ energy
32
Q

Anaerobic respiration in plants and yeast

A
  1. pyruvate(3c) converts into ethanal(2c), as CO2 is released (decarboxylation)
  2. Ethanal is reduced to ethanol(2c) as reduced NAD is oxidised to NAD
33
Q

Anaerobic respiration in animals

A

Pyruvate is reduced to lactic acid, as reduced NAD is oxidized to NAD

34
Q

in anaerobic respiration what happens to the NAD that’s formed

A

its recycled back to glycolysis

35
Q

energy flow

A

energy flows through an ecosystem. most ecosystems get their energy from sunlight. photosynthesis fixes this energy into glucose

36
Q

Only 1% of light energy is used, what happens to the rest of it:

A
  • some is blocked by the atmosphere
  • some is transferred to heat energy (transpiration)
  • some doesn’t hit a leaf
  • is reflected by photosynthetic pigments (green wavelengths)
37
Q

What is the glucose made in photosynthesis used in

A
  • release energy in respiration
  • make cellulose, starch, fructose
  • make oil/lipids from seeds
  • to make amino acids when added to nitrates from the soil
    THIS ALL FORMS BIOMASS
38
Q

What is gross primary productivity (GPP)

A

total energy fixed into glucose
units: KJm-2yr-1

39
Q

Net primary productivity (NPP) equation

A

GPP - respiratory losses =NPP

NPP is biomass that is available to the next trophic level

40
Q

Why is the transfer of energy from the trophic level to the trophic level approximately 10% efficient:

A
  • respiratory losses
    -active transport
    -movement/muscle contraction
    -production of protein
    -heat/body temperature
  • undigested matter (feces)
41
Q

How do farmers keep high profits in terms of energy

A
  • small enclosure - no movement of animals
  • inside/ warm - don’t have to regulate their body temperature
42
Q

what does a calorimeter do?

A

measure the energy in dry biomass

43
Q

how does a calorimeter work

A

as
- water content varies
- water has no energy

44
Q

features of calorimetry

A
  • an outer box full of water
  • ignition source
  • an inner box full of oxygen
  • thermometer
45
Q

why is pure oxygen used in. calorimeter

A

to ensure complete combustion of a material

46
Q

what does the temperature change determine

A

temp change of the water determines the energy of the material

47
Q

percentage efficiency

A

energy available after the transfer/ energy available before the transfer x 100

48
Q

many yeast cells die during the death phase

A

enzymes become denatured

49
Q

why freshwater marsh have a high carbon uses efficiency and they advantage of this

A
  • less respiration
  • more biomass available at the net trophic level
50
Q

what is a saprobiotic organism

A

all ecological cycles rely on the actions of these. These are organisms that carry out extracellular digestion. they release enzymes into their surroundings and absorb the products of digestion

51
Q

what do animals and plants require nitrogen for

A

to produce proteins and nucleic acids (DNA and RNA)

52
Q

4 key processes in the nitrogen cycle

A
  • Nitrogen fixation
  • Ammonification
  • Nitrification
  • Denitrification
53
Q

nitrogen fixation

A
  • Atmospheric N2 gas is converted into nitrogen-containing compounds by nitrogen-fixing bacteria e.g. Rhizobium
  • The bacteria convert nitrogen into ammonia, which forms ammonium ions that plants use
  • nitrogen-fixing bacteria are found inside the root nodules of leguminous plants e.g. peas, beans and clover
  • bacteria has a symbiotic relationship with plants - bacteria provide plants with nitrogen-containing compounds and plants provide organic compounds e.g. carbohydrates
54
Q

Ammonification:

A
  • Nitrogen compounds in waste products (e.g. urine/faeces) and dead organisms are converted into ammonia by saprobionts
  • This ammonia forms ammonium ions in the soil
55
Q

Nitrification:

A
  • Ammonium ions in soil are converted by nitrifying bacteria into nitrogen compounds that nitrates use
  • nitrifying bacteria e.g. Nitrosomonas convert ammonium ions into nitrites
  • nitrifying bacteria e.g. Nitrobacter convert nitrites into nitrates
56
Q

Denitrification:

A
  • Denitrifying bacteria use nitrates in the soil during respiration
  • This produces N2 gas, which returns to the atmosphere
  • This occurs in anaerobic conditions ( no oxygen, e.g. waterlogged soil)
57
Q

what is eutrophication

A

excess nutrients become leached into rivers/lakes, causing algal bloom. this blocks the light from reaching aquatic plants, leading to their death and decay by aerobic bacteria that increase biological oxygen demand. this reduces the O2 available and kills fish. the water becomes anaerobic and stagnant

58
Q

mycorrhizae

A

fungus that grows around the roots of plants, it increases the surface area of the roots allowing more water and ion uptake

59
Q

what does the phosphorous cycle show

A
  • phosphorus is recycled in ecosystems
  • Plants and animals require phosphorus to produce biological molecules e.g. phospholipids, nucleic acids and ATP
60
Q

The phosphorus cycle includes the following processes:

A
  • Phosphorus in rocks is released into soil and water sources as phosphate ions (PO₄³⁻) by the process of weathering
  • PO₄³⁻ are taken up from the soil by plants through their roots or absorbed from water by algae
  • PO₄³⁻ are transferred to consumers during feeding
  • PO₄³⁻ in waste products and dead organisms are released into soil or water during decomposition by saprobionts
  • PO₄³⁻ are taken up and used by producers or may be trapped in sediments, over long periods, turning into phosphorus-containing rock once again

Biology Paper 2 (3 decks)

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