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George Biology > Energy for biological processes chp 17 > Flashcards

Energy for biological processes chp 17 Flashcards

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1
Q

what are some examples of metabolic activities

A
  • active transport
  • anabolic reactions (polymerisation of biological monomers)
  • movement brought about by cilia, flagella and contractile filaments in muscles cells
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2
Q

define respiration

A

process where organic molecules are broken down into smaller inorganic molecules in order to produce energy

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3
Q

write out the balanced symbol equation for photosynthesis and respiration

A
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4
Q

bond formation and bond breaking, which one takes in energy which one releases energy

A
  • energy is used to break bonds
  • energy is released when bonds are formed
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5
Q

what determines wether a reaction is overall exo or endo thermic

A

depends on the total number and strength of bonds that are broken or formed during the reaction

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6
Q

why are large organic molecules used in respiration

A
  • less energy is needed to break bonds than form bonds in products
  • excess energy is used to synthesis ATP
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7
Q

what is chemiosmosis

A
  • diffusion of protons from a region of high conc to a region of low conc through a partially permeable membrane
    ^releases energy used to make ATP
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8
Q

what does chemiosmosis depend on and how is this requirement met

A
  • on creation of a proton conc gradient
  • protons actively pumped using energy coming from electron transport chains
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9
Q

in which ways are excited electrons generated

A
  • electrons present in the pigment molecules are excited by absorbing light from the sun
  • high energy electrons released from NADH
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10
Q

what is an electron transport chain

A
  • made up of a series of electron carriers
  • ^each with progressively lower energy levels
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11
Q

How is energy generated from the electron carrier chain and how is it used

A
  • high energy electrons move from one carrier in the chain to another, energy is released
  • used to pump protons across a membrane, creating a conc gradient and therefore a proton gradient.
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12
Q

What is the only way the protons can move back through the membrane after the proton gradient has been generated during the process of ATP synthesis

dont just say chemiosmosis

A
  • diffusion through hydrophilic membrane channels linked to the enzyme ATP synthase
  • flow of protons through these provides energy to synthesis ATP
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13
Q

what is meant by autotrophic and heterotrophic

A
  • autotrophic - they make their own nutrients via photosynthesis
  • heterotrophic - obtain complex organic molecules by eating others
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14
Q

what is stacked to form grana (plural granum)

A

thylakoids are stacked to form grana

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15
Q

what links grana

A

joined by membranous channels called lamellae

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16
Q

where can chlorophyll be found within chloroplast

A

embedded within thylakoids membrane

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17
Q

what occurs within the storm of a chloroplast

A

chemical reactions occur within it

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18
Q

Why do plants appear green

A
  • the pigment chlorophyll absorbs specific wavelengths of light
  • ^mostly blue and red light , while it reflect green giving plants their green colour
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19
Q

where are most of the chloroplast and chlorophyll located in a plant

A

located in the upper mesophyll layer

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20
Q

what are examples of some other light harvesting pigments

A
  • chlorophyll b, xanthopylls and carotenoids
  • responsible for different shades of leaves
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21
Q

what is the antennae complex

A

it is the light harvesting system within plants formed from light sensitive pigments such as chlorophyll a and b and

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22
Q

what are the light harvesting system and reaction centre collectively known as

A

a photosystem

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23
Q

what light sensitive pigment gives plants there yellow and orange colours for example during the autum

A
  • carotenoids are responsible for the yellow/orange colour
  • orange carotene and yellow xanthophyll and 2 examples
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24
Q

what are the 2 stages of photosynthesis

A
  • light-dependent stage
  • light-independent stage
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25
Q

what occurs during the light dependent stage

A
  • energy from the sunlight is absorbed and used to form ATP.
  • Hydrogen from water is used 5to reduce coenzyme NADP to reduced NADP
26
Q

what occurs during the light-independent stage

A
  • hydrogen from reduced NADP and carbon dioxide is used to build organic molecules, such as glucose.
  • ATP supplies the required energy
27
Q

what reaction is involved within the light dependent stage of photosynthesis

A
  • non-cyclic photophosphorylation
28
Q

How many photosystems are involved in non-cyclic photophosphorylation

A
  • 2
  • photosystem 1 & 2
29
Q

what happens to the electrons that have been excited at photosystem 2

A
  • they are released from reaction centre in PS 2 and are passed to an electron transport chain (ATP produced by chemiosmosis)
  • electrons lost are replaced from water molecules broken down by the sun
30
Q

during the process of photosynthesis what photosystem is first in the process

A

photosystem 2

31
Q

what happens to the electrons in photosystem 1 during photosynthesis

A
  • excited electrons are released from reaction centre at PS 1, passed to another electron chain (ATP produced by chemiosmosis)
  • electrons lost from reaction centre are replaced by electrons from the electrons released from PS 2
32
Q

what happens to the electrons after they have left the electron transport chain during the process of photosynthesis

A

they are accepted along with a H+ ion, by the coenzyme NADP, forming reduced NADP

33
Q

what is the function of reduced NADP

A

provides the hydrogen/reducing power of organic molecules, such as glucose in the light-independent stage

34
Q

does the light dependent or independent stage come first

A

the light dependent stage comes first

35
Q

what is photolysis

A
  • water molecules are split into hydrogen ions, electrons and oxygen molecules using energy from the sun
  • this is why water is a raw material of photosynthesis
36
Q

What happens to the electrons generated during photolysis

A

they replace the electrons lost from the reaction centre of PS 2

37
Q

what happens to the protons generated by photolysis during the process of photosynthesis

A
  • they are released into the lumen of the thylakoids, increasing the concentration across the membrane
  • as they move back across the membrane they drive the synthesis of ATP
  • Once H+ ions are back in the stroma they combine with NADP and an electron to form reduced NADP
38
Q

why is it important that during the light dependent stage H+ ions are used to form reduced NADP

A

it removes hydrogen ions from the stroma so it helps to maintain proton gradient across thylakoid membrane

39
Q

There is a light dependent and independent stages during photosynthesis, which one has cyclic and non-cyclic photophosphorylation

A
  • the light dependent reaction involves non-cyclic photophosphorylation
  • the light independent reaction involves cyclic photophosphorylation
40
Q

How can cyclic photophosphorylation occur

A
  • electrons leaving the electron transport chain after PS 1 can be returned to PS 1, instead of being used to form reduced NADP,
    ^this leads to cyclic photophosphorylation
41
Q

where does the light-independent stage of photosynthesis occur within the plant

A
  • occurs in the stroma
42
Q

what reactants are required for the light-independent stage

A
  • CO2
  • products from light dependent stage ATP and reduced NADP
43
Q

what is the Calvin cycle

A

a series of reactions that produce organic molecules such as glucose in the light-independent stage of photosynthesis

44
Q

what physically happens to carbon dioxide during the Calvin cycle

A
  • enters spongy mesophyll layer of leaves by diffusion through stomata.
  • diffuses into cells then further into stroma of chloroplasts where it combines with RuBP
45
Q

How can the carbon within carbon dioxide be described as fixed during the calvin cycle

A
  • it is incorporated into an organic molecule
46
Q

what is the function of RuBisCO in the Calvin cycle

A
  • it catalyses the reaction of carbon of CO2 being incorporated into RuBP
  • ^producing an unstable intermediate
47
Q

why is so much RuBisCO the most abundant enzyme in the world

A

it is very inefficient as it is competitively inhibited by oxygen so a lot it needed to carry out photosynthesis

48
Q

what happens to the unstable intermediate formed from RuBisCO during the Calvin cycle

A

it immediately breaks down forming 2 GP molecules

49
Q

During the calvin cycle what does a single GP molecule breakdown into and how is it done

A

each GP molecule is converted into TP (triose phosphate), using a hydrogen atom from reduced NADP and energy supplied from ATP

50
Q

what is the majority of triose phosphate molecules converted into and why

A

it is recycled to regenerate RuBP so that the Calvin cycle can continue

51
Q

what 3 steps can summarise the Calvin cycle

A
  • fixation - carbon dioxide is incorporated into an organic molecule in the first step
  • reduction - GP is reduced to TP by addition of hydrogen from reduced NADP using energy supplied by ATP
  • regeneration - RuBP is regenerated from the recycled TP
52
Q

how many full turns of the Calvin cycle are required to produce 1 glucose molecule

A

6 CO2 molecules have to enter the Calvin cycle, resulting in 6 full turns of the cycle

53
Q

What would be the products of 6 full turns of the Calvin cycle

A
  • 12 TP molecules, 2 of which will be removed to make a glucose molecule
    ^the other 10 will be recycled to regenerate 6 RuBP molecules
54
Q

what are the factors that affect the rate of photosynthesis

A
  • light intensity
  • CO2 concentration
  • Temperature
55
Q

How does light intensity affect the rate of photosynthesis

A
  • As light intensity increases, ATP and reduced NADP are produced at a higher rate
56
Q

How does CO2 concentration affect the rate of photosynthesis

A
  • CO2 Is needed as a source of carbon, so cetris paribus, increasing the CO2 conc increases the rate of carbon fixation in the Calvin cycle and therefore the rate of TP production
57
Q

how could temperature increase the rate of photosynthesis

A
  • at temp rises the rate of enzyme activity increases until they denature
  • the rate of enzyme controlled reactions such as carbon fixation would increase
58
Q

How could temperature decrease the rate of photosynthesis

A
  • the rate of photorespiration increases above 25°C meaning photosynthetic rates may not be seen at higher temps even if enzymes aren’t denatured
  • stomata on leaves will close to avoid water loss during dry spells which can limit CO2 diffusion into the leaf reducing the rate of the light-independent reaction, eventually halting photosynthesis
59
Q

What is the effect of reduced light intensity on the Calvin cycle

A
  • it will reduce the rate of the light-dependent stage.
    ^this will reduce the quantity of ATP and reduced NADP produced, both of these are needed in the light-independent stage
  • ^the conc of GP will increase and the conc of TP will decrease (as there is less TP there will be less regeneration of RuBP

vice versa

60
Q

How would temperature effect the Calvin cycle

A

the Calvin cycle involves many different enzymes so temperature can increase or decrease enzyme activity

61
Q

How could CO2 concentration effect the calvin cycle

A
  • CO2 is an essential substrate for the Calvin cycle
  • low cons will lead to reduced concs of GP (as there will be less carbon fixation) and TP
  • Conc of RuBP will increase as it is still being formed from TP but not being used to fix CO2

George Biology (71 decks)

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