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Biology Year 2 > 5.2.1- Photosynthesis > Flashcards

5.2.1- Photosynthesis Flashcards

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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
Q

where are the accessory pigments found?

A

light harvesting system

26
Q

where are the pigments arranged?

A

in funnel shaped structures called photo systems which are embedded in thylakoid membranes and lamellae membranes

27
Q

what are the two types of photo system?

A

PS1 and PS11

28
Q

give detail on photo system 1?

A

type of chlorophyll a= P700
peak absorption= 700nm
main location= intergranal lamallae

29
Q

give detail on photo system 2?

A

type of chlorophyll a= P680
peak absorption= 680nm
main location= grana (thylakoids)

30
Q

what are the two pathways of LDS?

A

-cyclic photo phosphorylation
-non-cyclic photo phosphorylation

31
Q

what occurs during cyclic photophosphorylation?

A

-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
Q

what is the only product of cyclic photophosphorylation?

A

ATP

33
Q

what occurs in noncyclic photophosphorylation?

A

-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
Q

how are the electrons lost from P680 replaced?

A

replaced by electrons released by photolysis of water, which releases H+ ions and oxygen

35
Q

what is the equation of photolysis of water?

A

H2O ——> 2H+ + 1/2 O2

36
Q

what are the three products of non-cyclic photo phosphorylation?

A

-ATP
-Reduced NADP
-Oxygen

37
Q

what is the light independent stage?

A

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
Q

where does the LIS occur?

A

in the stroma of the chloroplasts

39
Q

what happens during the Calvin Cycle/LIS?

A

-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
Q

what is the fate of TP during the Calvin Cycle?

A

-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
Q

what does the Calvin Cycle look like?

A

RuBP
+ RuBisCo
+ CO2
= 2 x GP
-ATP—-> ADP + Pi
- reduced NADP—-> NADP
= 2 x TP
-glucose
-ATP—-> ADP + Pi
= RuBP (regeneration)

42
Q

how many cycles of the Calvin Cycle does it take to form glucose?

A

6

43
Q

what is the role of the enzyme rubisco during LIS?

A

it combines with CO2, helping form GP

44
Q

what are the 3 main factors that effect the rate of photosynthesis?

A

-light intensity
-CO2 concentration
- temperature

45
Q

what are the factors that effect photosynthesis known as ?

A

limiting factors

46
Q

how does CO2 conc effect the rate?

A

-more CO2 = faster carboxylation of RuBP= more GP, more TP = faster rate of photosynthesis

47
Q

what happens if CO2 conc is too high?

A

-RuBP conc is too low as it is used up quickly
-GP and TP conc are high and they accumulate

48
Q

how does light intensity effect the rate?

A

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
Q

what happens at high light intensity?

A

-GP conc is low (used up quickly)
-TP and RuBP conc is high (accumulate)

50
Q

how does temperature effect the rate?

A

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
Q

what happens when temperature is too high?

A

-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
Q

what is used to measure the rate if photosynthesis?

A

a photosynthometer, which is an apparatus that measures the rage of oxygen production and so measures the rate of photosynthesis

53
Q

what other method can investigate the factors effecting the rate of photosynthesis?

A

the leaf disc method

54
Q

how does the leaf disc method help explain rate of photosynthesis?

A

the quicker the discs float. the quicker the rate of photosynthesis

Biology Year 2 (13 decks)

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