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Biology Year 2 > 5.2.1- Photosynthesis > Flashcards

5.2.1- Photosynthesis Flashcards

1
Q

what are autotrophs?

A

organisms that use light energy/chemical energy to synthesise organic molecules from inorganic molecules

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2
Q

what are the two types of autotrophs?

A

-chemoaytotrophs
-photoautotrophs

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3
Q

what are chemoautotrophs?

A

autotrophs which use energy derived from chemical reactions.

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4
Q

what are photoautotrophs?

A

autotrophs which use energy derived from sunlight to convert carbon dioxide and water to complex organic molecules such as glucose during the process called photosynthesis

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5
Q

what are the examples of autotrophs?

A

-plants (photo)
-cyanobacteria (photo)
-protoctists (photo)
-bacteria (chemo)

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6
Q

What are heterotrophs?

A

organisms that ingest and digest complex organic molecules releasing in the chemical potential energy stored in them

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7
Q

what are examples of heterotrophs?

A

-animals
-fungi
-some bacteria

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8
Q

how are photosynthesis and respiration linked?

A

-the equations are the opposite of each other
-photosynthesis is endothermic while respiration is exothermic
-photosynthesis supplies oxygen needed for respiration, and also supplies the complex organic molecules needed for respiration

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9
Q

what is an endothermic reaction?

A

when more energy is used to make bonds compared to breaking bonds

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10
Q

What is an exothermic reaction?

A

When energy is released because more energy is used to break bonds compared to making bonds

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11
Q

what is the equation of photosynthesis?

A

water + Co2 ——> (sunlight) glucose + O2

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12
Q

how do plants gain water and CO2 for photosynthesis?

A

-water= absorbed by the roots
-CO2= enters through the stomata of the leaf

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13
Q

where does photosynthesis take place in the plants?

A

in chloroplasts

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14
Q

what are the two stages of photosynthesis?

A

-light dependent stage
-light independent stage

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15
Q

where in the chloroplast does the light dependent stage take place?

A

in the grana

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16
Q

where in the chloroplast does the light independent stage take place?

A

in the stroma

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17
Q

what are the 7 adaptations of chloroplasts?

A

-large SA to absorb light
-thylakoids/lamellae contain photo systems for LDS
-photosynthetic pigments for LIS
-stroma contains enzymes for LIS
-stroma contain lipid droplets and starch grains to store products of photosynthesis
-loops of DNA to code for some of the proteins needed for photosynthesis
-ribosomes to make these proteins

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18
Q

what are photosynthetic pigments?

A

molecules that absorb light energy

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19
Q

why are photosynthetic pigments different colours?

A

because they are different wavelengths and so they absorb and reflect different parts of the visible spectrum as possible, allowing maximum energy

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20
Q

how many different photosynthetic pigments are there and what are they called?

A

1- chlorophyll a
2- chlorophyll b
3- carotene
4- xanothophyll

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21
Q

what stage are photosynthetic pigments used in?

A

the light dependent stage

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22
Q

what colour and type of pigment are chlorophyll a and b?

A

a= blue-green, primary
b= yellow-green, accessory

23
Q

what colour and type of pigment are carotene and xanthophyll?

A

carotene= orange, accessory
xanthophyll= yellow, accessory

24
Q

where is chlorophyll found?

A

the reaction centre

25
where are the accessory pigments found?
light harvesting system
26
where are the pigments arranged?
in funnel shaped structures called photo systems which are embedded in thylakoid membranes and lamellae membranes
27
what are the two types of photo system?
PS1 and PS11
28
give detail on photo system 1?
type of chlorophyll a= P700 peak absorption= 700nm main location= intergranal lamallae
29
give detail on photo system 2?
type of chlorophyll a= P680 peak absorption= 680nm main location= grana (thylakoids)
30
what are the two pathways of LDS?
-cyclic photo phosphorylation -non-cyclic photo phosphorylation
31
what occurs during cyclic photophosphorylation?
-photon of light is absorbed by PS1 -electrons in primary pigment become excited to a higher level energy -electrons are emitted from P 700 and then captured by an electron acceptor -The electrons return to P 700 via a chain of electron carriers -Energy is released as electrons are passed down the chain of electron carriers -this energy is used to synthesise ATP from ADP and Pi
32
what is the only product of cyclic photophosphorylation?
ATP
33
what occurs in noncyclic photophosphorylation?
-photons of light are absorbed by both photosystems and electrons of both primary pigments become excited to higher energy levels -electrons emitted from P 700 in P6 80 are captured by electron acceptors, but they do not return to either -electrons from P 700 passed down a chain of electron carriers and I used to reduce NADP -The electrons from P6 80 are passed from down a chain of electron carriers releasing energy to make ATP -The electrons from P680 in PS11 combine with P700 in PS1 -photolysis -H+ ions from photo lysis accumulate in thylakoids, ATP is used to pump these from stroma across thylakoid membrane and into thylakoid -H+ ions generate energy by chemiosmosis, and they diffuse down conc gradient via ATP synthase -more ATP is formed at ATP synthase -H+ ions combine with electrons from P700 and coenzyme NADP to make reduced NADP
34
how are the electrons lost from P680 replaced?
replaced by electrons released by photolysis of water, which releases H+ ions and oxygen
35
what is the equation of photolysis of water?
H2O ——> 2H+ + 1/2 O2
36
what are the three products of non-cyclic photo phosphorylation?
-ATP -Reduced NADP -Oxygen
37
what is the light independent stage?
the stage of photosynthesis where light is not directly needed, but stops if light is not available as it used products of the LDS
38
where does the LIS occur?
in the stroma of the chloroplasts
39
what happens during the Calvin Cycle/LIS?
-CO2 from the air diffuses into the leaf through open stomata into palisade mesophyll cells and into chloroplasts -In the stroma CO2 combines with ribulose bisphosphate to form an unstable 6C compound (carboxylation) and is catalysed by enzyme rubisco -unstable compound splits into 2 glycerate-3-phosphate -ATP and reduced NADP from the LDS are used to convert GP into triose phosphate
40
what is the fate of TP during the Calvin Cycle?
-5/6 are recycled by phosphorylation, to make RuBP -rest of TP (1/6) is used to make glucose/starch, lipids and amino acids/proteins
41
what does the Calvin Cycle look like?
RuBP + RuBisCo + CO2 = 2 x GP -ATP—-> ADP + Pi - reduced NADP—-> NADP = 2 x TP -glucose -ATP—-> ADP + Pi = RuBP (regeneration)
42
how many cycles of the Calvin Cycle does it take to form glucose?
6
43
what is the role of the enzyme rubisco during LIS?
it combines with CO2, helping form GP
44
what are the 3 main factors that effect the rate of photosynthesis?
-light intensity -CO2 concentration - temperature
45
what are the factors that effect photosynthesis known as ?
limiting factors
46
how does CO2 conc effect the rate?
-more CO2 = faster carboxylation of RuBP= more GP, more TP = faster rate of photosynthesis
47
what happens if CO2 conc is too high?
-RuBP conc is too low as it is used up quickly -GP and TP conc are high and they accumulate
48
how does light intensity effect the rate?
more light= more excited electrons in the LDS= more photo phosphorylation = more reduced NADP and ATP= faster reduction of GP= more TP, more RuBP= faster rate
49
what happens at high light intensity?
-GP conc is low (used up quickly) -TP and RuBP conc is high (accumulate)
50
how does temperature effect the rate?
each reaction in LIS is catalysed by enzymes -increased temp= increased ke of enzyme and substrate molecules= more successful collisions between them = faster rate
51
what happens when temperature is too high?
-denatures enzymes used in LIS and needed for photolysis in LDS -reduced levels of ATP and reduced NADP -plant will wilt, stomata will close and so CO2 uptake is reduced
52
what is used to measure the rate if photosynthesis?
a photosynthometer, which is an apparatus that measures the rage of oxygen production and so measures the rate of photosynthesis
53
what other method can investigate the factors effecting the rate of photosynthesis?
the leaf disc method
54
how does the leaf disc method help explain rate of photosynthesis?
the quicker the discs float. the quicker the rate of photosynthesis

Biology Year 2 (13 decks)

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