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biology paper 2 > topic 5- energy transfers > Flashcards

topic 5- energy transfers Flashcards

1
Q

photosynthesis definition

A

process by which light energy is used to make organic molecules for growth of the plant eg glucose

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2
Q

where do you find photosynthetic pigments

A

thylakoid membrane

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3
Q

structure of chlorophyll

A

hydrocarbon tail that is hydrophobic which impregnates the pigment into membrane

needs magnesium ion in order to function and absorb light

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4
Q

what different chlorophyll pigments are there

A

chlorophyll a
chlorophyll b
phaeophytin
(all green)

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5
Q

what different carotenoid pigments are there

A

alpha and beta carotene (found in carrots) are orange

lycopene (found in tomatoes) is bright red

xanthophylls eg lutein are yellow

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6
Q

where does the LIR happen

A

stroma of chloroplast

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7
Q

where does the LDR happen

A

thylakoid membrane

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8
Q

what does the LDR create and what does it require

A

ATP and reduced NADP using light energy and water

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9
Q

what are the 4 key steps of LDR

A

1) photolysis
2) photoionization of chlorophyll
3) chemiosmosis
4) production of ATP and reduced NADP

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10
Q

what is photolysis

A

light energy is absorbed by chlorophyll and splits water apart into

1/2 O2+ 2e- + 2H+

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11
Q

what happens to the products created in photolysis

A

H+ reduces NADP to be used in LIR
e- passed along a chain of electron carrier proteins
O2 used in respiration or waste product

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12
Q

what is photoionisation

A

light energy is absorbed by chlorophyll, exciting the electrons meaning they are raised up an energy level and leave chlorophyll

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13
Q

what is chemiosmosis

A

the electrons that gained energy move along a series of proteins embedded in the thylakoid membrane (electron transfer chain) in a series of redox reactions. they release energy whilst doing this fueling the proton pumps to pump H+ into the thylakoid. this creates an electrochemical gradient, H+ facilitatedly diffuses through ATP synthase phosphorylating ADP into ATP

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14
Q

what do leftover protons and electrons combine with

A

NADP to make NADPH

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15
Q

what does the Calvin cycle make and use

A

uses ATP, NADPH and carbon dioxide to make hexose sugar

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16
Q

what is ATP used for in the Calvin cycle

A

provides energy for reaction

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17
Q

what is NADPH used for in the Calvin cycle

A

donates hydrogen to reduce GP

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18
Q

steps of Calvin cycle

A

1) ribulose bisphosphate (5) reacts with CO2 catalysed by enzyme rubisco to form unstable 6 carbon compound -> hydrolysed to 2GP
2) GP picks up hydrogen from NADPH and is reduced to form TP (triose phosphate)
3) one carbon from TP used to form hexose sugar
4) the rest of the molecule is used to regenerate RuBP using energy provided from ATP

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19
Q

how many times does Calvin cycle happen to form hexose sugar

A

6

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20
Q

what are the limiting factors of photosynthesis

A

light, temperature and carbon dioxide conc

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21
Q

what is a limiting factor

A

something that reduces the rate of a reaction

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22
Q

why does carbon dioxide conc limit photosynthesis

A

a reactant in Calvin cycle - none present then sugars cannot form

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23
Q

why does light intensity limit photosynthesis

A

light energy needed for LDR

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24
Q

how are limiting factors of photosynthesis used in agriculture

A

artificial lighting
heating a greenhouse
burning fuel

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25
what are the 4 key stages of aerobic respiration
glycolysis link reaction Krebs cycle oxidative phosphorylation
26
3 steps to glycolysis and where it is located
1) phosphorylation of glucose to glucose phosphate using 2ATP 2) production of triose phosphate as it is unstable 3) oxidation of triose phosphate with 2ADP and NAD to produce pyruvate with a net gain of ATP and reduced NADH
27
how is pyruvate and NADH transported for Link reaction
actively transported from the cytoplasm to mitochondrial matrix
28
steps to Link reaction
1) pyruvate is oxidised to acetate and loses carbon to form carbon dioxide 2) NAD picks up hydrogen to become NADH 3) acetate combines with coenzyme A to form acetyl coenzyme A
29
steps to Krebs cycle
1) acetyl coenzyme A reacts with 4 carbon molecule making a 6 carbon molecule 2) from six carbon compound to four: 2 CO2s lost 1 ATP made 1 FADH made 3 NADH made
30
steps to oxidative phosphorylation
1) reduced coenzymes release protons and electrons 2) electrons transported across electron transfer chain by a series of redox reactions 3) releases energy used to power proton pumps to pump H+ from mitochondrial matrix into intermembrane space 4) electrochemical gradient created so H+ diffuse through ATP synthase, phosphorylating ADP 5) electrons and protons are picked up by oxygen as it is the final electron acceptor -> forms water
31
what does anaerobic respiration in animals produce
lactate
32
why does glycolysis not form pyruvate in the absence of oxygen
gains the hydrogen from reduced NAD which oxidises NAD
33
what does anaerobic respiration in plants produce
ethanol + carbon dioxide
34
what are producers
plants that can photosynthesis to make their own organic compounds
35
why is lots of energy lost between each trophic level
respiration and excretion
36
what is biomass
mass of carbon or dry mass of tissue per given area
37
what is GPP
gross primary production- is the chemical energy stored in plant biomass, in a given area/volume
38
what is NPP
net primary production- is the chemical energy store in plant biomass taken into account the energy lost in respiration
39
formula for the net production of consumers
n = i - (f+r) i- chemical energy in ingested food f- faeces and urine r- respiration
40
units for rates of productivity
kJ ha-1 year-1
41
why are units of rate of productivity x3
pre unit area to standardise the results to enable environments to be compared - takes into account that environments are different sizes per year - takes into account the impact seasons will have on rain, light and heat
42
why can plants and animals not gain N2 from the atmosphere
it has a triple bond which cannot be broken
43
key processes in nitrogen cycle
-saprobiotic nutrition and microbes -ammonification -nitrification -nitrogen fixation -denitrification
44
steps to nitrogen cycle
1) ammonification- N2 gas in atmosphere converted to NH4+ by nitrogen fixing bacteria 2) nitrification- nitrifying bacteria oxidise NH4+ into NO2 and further to NO3- 3) assimilation- NO3- absorbed by plants through active transport so animals can absorb through digestion 4) saprobiotic nutrition- decomposers break down nitrogen compounds in dead plant matter (proteins) / waste of animals (urea)
45
where is nitrogen fixing bacteria found
- legume root nodules -soil
46
what happens to nitrogen compounds if there is a lack of oxygen in the soil
anaerobic denitrifying bacteria convert nitrates back into N2 gas
47
what is phosphorous used for in biology
-phospholipid bilayer -DNA and RNA -ATP
48
where is the main source of phosphorous
phosphate ions (mineral form) in sedimentary rocks
49
what is mycorrhizae
fungal associations between plant roots and beneficial fungi
50
why are mycorrhizae beneficial for plant growth
- fungi increase the surface area for water and mineral absorption - acts as a sponge so holds water and minerals around the roots - makes plants more drought resistant and able to take up more inorganic ions
51
what do plants provide to mycorrhizae
carbohydrates from photosynthesis
52
steps of phosphorous cycle
1) phosphate ions in ocean/soil are absorbed by plants root hair cells by active transport 2) animals consume by digestion 3) when animals excrete it releases ions back to soil / are eroded (bones) to release ions 4) bird faeces provides deposition on rocks of ions 5) sedimentation - high pressure so phosphate ions within soil will compact to make rocks 6) sedimentary rocks can be eroded by weathering to release ions 7) fertilisers can leach and provide ions to oceans
53
why are fertilisers used
to replace the nitrate and phosphate ions lost when plants are harvested and removed from nutrient cycles
54
example of a natural/artificial fertiliser
natural - manure artificial - inorganic chemicals
55
why are natural fertilisers good and bad
-cheaper, animals on farm can provide however -cannot control the exact minerals and proportions
56
why are artificial fertilisers bad
inorganic substances are water soluble therefore they may leach with rainwater and therefore wash away
57
steps of eutrophication
1) ions leach into water sources eg pond 2) stimulates growth of algae 3) creates a blanket of algae on surface of pond which blocks light 4) plants below cannot photosynthesise so die 5) bacteria in water feed and respire on dead plant matter, using up oxygen 6) fish die
58
where is rubisco found in cell
stroma of chloroplast
59
advantage of plants having different colour pigments
able to absorb different wavelengths of light for photosynthesis
60
why will there be more oxygen in respiring cells if the Krebs cycle isn't occuring
1) no reduced FAD, NAD (coenzymes) 2) no electrons removed 3) oxygen is final electron acceptor
61
why does anaerobic respiration allow the continuous production of ATP
-regenerates NAD -so glycolysis continues
62
why should you leave respirometer tap open
so equillibrium is reached allow pressure change in apparatus allow respiration rate of seeds to stabilise

biology paper 2 (4 decks)

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