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alevel biology ocr > chapter 17- energy for biological processes > Flashcards

chapter 17- energy for biological processes Flashcards

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1
Q

what do cells require energy for (4)

MRS NERG

A

synthesis of molecules (eg protein)
transport of molecules or ions
cellular movement
synthesis of sugar by photosynthesis

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2
Q

what is the cycle of energy

A

radiation from the sun fuels all metabolic reactions and processes neccessary to keep organisms alive, and then it is transferred back to the atmosphere as heat.

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3
Q

respiration is the process by which….. (add egs)

A

organic molecules like glucose are broken down into smaller inorganic molecules like co2 and water

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4
Q

breaking the bonds of the organic molecules in respiration is used to….

A

sythesise atp (energy is stored in the bonds of eg glucose)

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5
Q

respiration involves organisms breaking down …. to provide…… to drive the ……

A

biomass to provide the atp needed to drive the metabolic reactions that take place in cells

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6
Q

what is the overall reaction/chemical equation for photosynthesis

A

6CO2 + 6H2O <> C6H12O6 + 6O2

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7
Q

what is the overall reaction for respiration

A

C6H12O6 + 6O2 > 6CO2 + 6H2O

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8
Q

energy is released when bonds are

A

formed

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9
Q

what is the bond energy

A

the energy that is needed to break or released when a bond is made (it is equal)

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10
Q

whether an overall reaction is exothermic or endothermic depends on the total number…..

A

and strength of bonds that are broken or formed during the reaction

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11
Q

are the atoms in small inorganic molecules joined by strong or weak bonds? wmt

A

strong bonds that are covalent (they have high bond energies) wmt they release a lot of energy when they form but require a lot of energy to break

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12
Q

example of small inorganic molecules

A

carbon dioxide and water

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13
Q

example of large(r) organic molecules

A

glucose and amino acids

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14
Q

do organic molecules contain more or less bonds than small inorganic molecules

A

more

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15
Q

are the bonds in organic molecules stronger or weaker than the bonds in small inorganic molecules? wmt

A

weaker bonds wmt they release less energy when they form and require less energy to be broken

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16
Q

apply bond energy to respiration

A

the total energy required to break all the bonds in a complex organic molecule is less than the total energy released in the formation of all the bonds in the smaller inorganic products.

the excess energy released by the bond formation is used to synthesis atp

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17
Q

do organic molecules contain many or few carbon-hydrogen bonds

A

many/large numbers of

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18
Q

which organic molecule has particularly many large numbers of carbon-hydrogen bonds

A

lipids/triglycerides

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19
Q

explain the importance of atp to living organisms (4)

(why is atp good)

A

universal energy currency, quick energy transfer, energy is in a usable quantity, atp can be resynthesised

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20
Q

describe the properties of cell membranes neccessary for the formation of a proton gradient
(3/4)

A

impermeable to ions/protons, there can be different conc of protons on each side of membrane, contains integral proteins, eg atp synthase responsible for atp synthesis

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21
Q

describe a carbon-hydrogen bond

A

a covalent bond/share the electrons almost equally in the bonds that form between them.

the bond is nonpolar therefore it does not require a lot of energy to break (bond energy is low)

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22
Q

in respiration what happens when carbon-hydrogen bonds break

A

the carbon and hydrogen released form strong bonds with oxygen atoms forming carbon dioxide and water (small inorganic molecules) resulting in the release of large quantities of energy

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23
Q

photosynthesis is the process by which small inorganic molecules make

A

organic molecules and the energy required to build these comes from the sun

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24
Q

explain why it is incorrect to say that energy is produced (2)

A

energy cannot be created or destroyed only transferred (1) atp is produced however (1)

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25
Q

explain why atp is not a good energy storage molecule but why organic molecules like lipids and carbs are (4)

A

atp is not very stable (1) as it is easy to remove the phosphate group (1) organic molecules are more stable (1) organic molecules are more energy dense (1)

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26
Q

explain the interrelationship between respiration and photosynthesis of organisms (5)

what happens in each:
-…..molecules converted into …. molecules
-reactants and products
-transfers of energy

A

in P light energy is converted into chemical energy (1) inorganic molecules are converted into organic molecules (1) water and co2 are converted into glucose (and oxygen) (1)

R uses oxygen produced in photosynthesis (1) organic molecules are broken down into inorganic molecules (1) energy released is used to synthesise atp (1) carbon dioxide produced is used in photosynthesis(1)

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27
Q

light energy is transferred to ……….. energy stored in ………… molecules such as .

A

chemical (potenial)
organic
glucose

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28
Q

does photosynthesis trap or release energy

A

trap energy

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29
Q

is photosynthesis an endo or exothermic reaction exp why

A

endothermic because energy is absorbed in the form of light

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30
Q

does respiration trap or release energy

A

release energy

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31
Q

is respiration an endo or exothermic reaction exp why

A

exothermic because it released energy from glucose this energy is transferred to adp and pi when atp is made

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32
Q

is photosynthesis a catabolic or anabolic reaction

A

anabolic

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33
Q

is respiration a catabolic or anabolic reaction

A

catabolic

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34
Q

what are the components of oxidation

A

loss of electrons, gain of oxygen, loss of hydrogen ions

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35
Q

what are the components of reduction

A

gain of electrons, loss of oxygen, gain of hydrogen ions

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36
Q

what is a redox reaction

A

a reaction where oxidation and reduction takes place

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37
Q

photosynthesis and respiration are both ….. reactions

A

redox reactions

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38
Q

where does oxidation occur in respiration

A

glucose loses electrons (and hydrogen) to become carbon dioxide

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39
Q

where does reduction occur in respiration

A

oxygen gains electrons (and hydrogen) to become water

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40
Q

where does oxidation occur in photosynthesis

A

water is oxidised to produce oxygen

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41
Q

where does reduction occur in photosynthesis

A

carbon dioxide is reduced into glucose

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42
Q

a palisade mesophyll cell may contain up to .. chloroplasts

A

50

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43
Q

chloroplasts transduce light into

A

chemical energy as either atp (light dependent) or organic compounds (light independent)

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44
Q

in which cells are chloroplasts found (3)

A

in the mesophyll cells of leaves, in the guard cells of stomata, cells of the outer part of green plant stems (cortex)

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45
Q

what is the shape of a chloroplast

A

biconvex disc

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46
Q

the chloroplast is surrounded by a…..

A

double membrane (envelope) with an inner bilayer membrane and an outer bilayer membrane

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47
Q

instead of a cytoplasm the chloroplast contains the …….. which is… and what does it do

A

the stroma a jelly like matrix, enclosing the liquid of the chloroplast, it is the site of many chemical reactions resulting in the formation of complex organic molecules

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48
Q

in a chloroplast the space between the outer and inner membrane is called the

A

intermembrane space

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49
Q

what does the stroma contain

A

contains the appropriate enzymes and suitable pH for calvin

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50
Q

the outer and inner membrane on a chloroplast is evidence for

A

endosymbiosis

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51
Q

what do the stroma lamellae do

A

connect and separate thylakoid stacks/granum

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52
Q

what are granum and what do they do

A

flat membrane stacks that increase sa:v ratio

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53
Q

what do thylakoids have

A

has an etc and atpsynthase for photophosphorylation

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54
Q

the thylakoid membrane is the site of

A

light dependent reactions of photosynthesis with the photosynthetic pigments embedded directly in the membrane

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55
Q

what are the adaptations, for photosynthesis, of a dicotyledonous leaf

A

broad, thin, flat, large sa

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56
Q

why are the apical surfaces of the upper and lower mesophyll moist

A

for gas exchange the gases dissolve, enzymes cant work in gas

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57
Q

why do the lower or spongy mesophyll have air spaces

A

large sa to let gases circulate

co2 has dissolved so creates low conc in the air sac so conc gradient is created and the co2 needed for photosynthesis diffuses in

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58
Q

why is the cuticle on a leaf waxy

A

to let the light (max amount)

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59
Q

why is the upper epidermis on a leaf thin and have no chloroplasts

A

short diffusion pathway
not block any light

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60
Q

how many plasma membranes does a chloroplast have

A

2 (outer and inner)

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61
Q

what is the lamellae for in chloroplasts

A

holds the grana together (intergranal)

62
Q

how is a large sa of thylakoid membranes achieved in a chloroplast

A

they are flattened sacs and then stacked into grana

63
Q

what other things to chloroplasts contain

A

circular dna
ribosomes
lipid droplets

64
Q

what do the ribosomes in chloroplasts make

A

enzymes, pigments and pigments binding protein

65
Q

what is the enzyme in chloroplasts

A

rubisco (the most abundant enzyme in the world)

66
Q

where is the chlorophyll located in a chloroplast and how is it arranged

A

in the grana, sanwiched between the lipids and proteins of the thylakoid membranes

67
Q

with the pigments are what else…

A

enzymes and electron carrier molecules/proteins

68
Q

why are there so many pigment molecules

A

becasue they absorb and reflect different wave lengths = different colours
absorption is low in the green spectrum

69
Q

what is the reason for the different shades and colours of leaves

A

different combinations of pigments

70
Q

which colours are absorbed by chlorophyll a

A

red and blue

71
Q

which colours are reflected by chlorophyll a

A

blue and green

72
Q

what does chlorophyll b reflect

A

yellow and green

73
Q

when there is a peak in the graph of absorption what does it indicate

A

that that is the wavelength that is most strongly absorbed

74
Q

what is indicated on a dip on an absorption graph

A

that that is the wavelength that is reflected

75
Q

nm is what is standard form

A

x10-9m

76
Q

where is chlorophyll a located

A

in the reaction centre (bound to chlorophyll a/b binding protein), where reactions involved in photosynthesis take place

77
Q

what is the reaction centre surrounded by

A

the anetnnae complex

78
Q

where are the secondary photosynthetic pigments located, what do they combine with and do (antennae complex)

A

embedded in the thylakoid membrane, bound to proteins, they form a light harvesting system (antennae complex). the system absorbs/harvest light energy of different wavelengths and transfers the energy to the reaction centre

79
Q

which colours are reflected by chlorophyll a

A

green

80
Q

what is the role of the anntenae complex

A

to channel light energy to the reaction centre

81
Q

as light hits the accessory pigments what happens in terms of electrons

A

electrons become excited to a higher energy level

82
Q

the absorption spectrum indicates…

A

the wavelengths of light absorbed by each pigment

83
Q

the action spectrum indicated

A

the overall rate of photosynthesis at each wavelength of light

84
Q

does chlorophyll a lose or gain electrons

A

lose

85
Q

at the start of photosynthesis, plant cells need to make …….. from ….. and …..

A

atp from adp and pi

86
Q

what is atp synthase and what does it do

A

it is an enzyme that catalyses the formation of atp using adp and an inorganic phosphate

also lowers activation energy

87
Q

what is a photosystem

A

pigment-protein complexes are arranged into arrays of hundreds of pigment molecules called photosystems
the light harvesting system (antennae complex) and reaction centre make up the photosystem

pigments with chlorophyll A at the centre

88
Q

photosystems can also be called

A

pigment systems

89
Q

in a photosystem what does the spatial and geometric organisation cause

A

most of the pigments to function as light harvesters and transfer the excitation energy to other pigments before unwanted photochemistry occurs

90
Q

in photosystems what role do accessory/antenna pigments play

A

form a light harvesting system which absorbs light energy and transfers it to the reaction centre

91
Q

in photosystems what do electron acceptors do

A

synthesise atp via chemiosmosis

92
Q

where are photosystems located

A

in thylakoid membranes

93
Q

in photosynthesis light excites……

A

chlorophyll electrons (in photosystems) and they become energised/excitied

94
Q

in photosynthesis the electrons are released when ….. and where do they go

A

chemical bonds are broken and they pass into an etc and are used to generate a proton gradient

95
Q

in photosynthesis excited electrons pass through

A

electron transport chain making atp via chemiosmosis

96
Q

atp synthase also requires ….. to ensure that the reaction occurs in the forward direction

A

energy

the reaction would normally proceed in the reverse direction

97
Q

where are electron transport chain located

A

between the intermembrane space and the matrix of mitochondria

98
Q

electron transport chains establish …. gradient

A

the proton gradient across the inner mitochondrial membrane

99
Q

how is the energy supplied for adp + pi making atp (in respiration and photosynthesis)

A

the protons diffuse back into the matrix by diffusing through atp synthase -chemiosmosis

the flow of protons through the channels provides the energy for synthesis of atp

100
Q

atp synthase is linked with….

A

hydrophilic membrane channel proteins

facilitated diffusion

101
Q

what is the difference in protons across the inner mitochondrial membrane called

A

electrochemical gradient

102
Q

in lose terms chemiosmosis is the

A

diffusion of protons/movement of ions across a partially permeable membrane down their electrochemical gradient/from a region of high conc to a region of low conc

103
Q

energy is needed for chemiosmosis, where does it come from

A

high energy electrons/excited electrons

104
Q

eg of respiratory substrate molecule

A

glucose

105
Q

what are the 2 ways electrons can become excited

A

electrons in pigment molecules (eg chlorophyll) are excited by absorbing light from the sun

high energy electrons are released when chemical bonds are broken in rsm (eg glucose)

106
Q

an etc is made up of a series of … each with progressively

A

electron carriers each with progressively lower energy levels

107
Q

what enters an etc

A

a high energy electron/excited electron

108
Q

as high energy electrons move from …… to ……. , …… is released

A

one carrier to another carrier energy is releasedw

109
Q

what is the energy released in an etc used for

A

pumping protons across the membrane creating a proton gradient (electrochemical)

110
Q

when the protons are pumped across the membrane because of the etc, where do they go

A

into the inter-membrane space of the mitochondrion

111
Q

how is the proton gradient maintained

A

as a result of the impermeability of the membrane to hydrogen ions

112
Q

in an etc how do the protons move back across the membrane down the gradient (chemiosmosis)

A

through the hydrophilic membrane channels which atp synthase is linked with

113
Q

what is the name of organisms that photosynthesise

A

autotrophic organisms

114
Q

in respiration the high energy electrons that go into the etc come from reduced

A

nad and fad

115
Q

what is the enzyme called that hydrolyses atp producing adp and pi

A

atpase

116
Q

atpase and atpsynthase is the same enzyme how is this possible

A

the reaction is reversible and happens depending on the conc of substrates and products of either side of the reaction

it is possible because the active site is complementary to both substrates and products

117
Q

how many photosystems are there

A

2

118
Q

light hits which photosystem first

A

photosystem 2

119
Q

what happens at photosystem 2 and what is the process called

A

photolysis
water is broken down into oxygen, H+ and electrons

120
Q

what happens to the electrons that come from photolysis

A

they go through electron carrier molecules

121
Q

what happens to the H+ from photolysis

A

they go to resynthesise ATP

122
Q

what does thin layer chromatography use as the solvent

A

silica gel or

123
Q

what would happen if the gel layer in thin layer chromatography was thick

A

the spot wouldnt travel as far/fast so it would take longer to achieve the desired result

124
Q

what can you do if you only get 1 spot in tlc and yk theres more than 1 solute

A

rotate the chromatagram 90degrees and use a different solvent

125
Q

describe 2 ways in which the grana are adapted to their function (2)

A

contains pigments for the absorption of light (dependent reactions)

contains etc, contains atp synthase

has a large sa for light absorption

126
Q

are the phospholipid bilayers within the chloroplast permeable or impermeable to protons

A

impermeable

127
Q

do thylakoid membranes contains etc proteins

A

yes

128
Q

is there atp synthase embedded in thylakoid membranes to maintain chemiosmotic gradients

A

no

129
Q

outline the role of membranes WITHIN a cell (2)

A

separates cell into compartments/compartmentalisation
for example mitochondria and resp eznymes

130
Q

why is it important that the leaf extract is dried before mixing with the organic solvent in tlc

A

the water may have affected the Rf value, solvent became too dilute

131
Q
A
132
Q

in tlc which spot has the least polar (pigment)

A

the one that is most soluble in the mobile phase and least attracted to the stationary phase

133
Q

in tlc why is it important that the plate is carefully held by the edges to avoid damaging the surface of the plate

A

so movement of spots not affected by damage

so that plates are not contaminated by fingerprints/oils from skin

134
Q

in tlc why is it important that the plate doesnt touch the sides of the jar or anywhere else

A

condensation on sides of jar may affects movement of spots

to avoid spots travelling in the wrong direction

135
Q

suggest an advantage of working as quickly as possible when extracting pigments for tlc

A

to reduce damage, contamination of pigments

to avoid evaporation of solvent

136
Q

What is the primary pigment which is used to absorb light in chloroplasts?

A

chlorophylla.

137
Q

What name is given to the arrangement of accessory pigments used to absorb light energy from a wide range of wavelengths?

A

light harvesting system

138
Q

What name is given to the arrangement of proteins containing the primary pigment which carries out the reactions of the light-dependent stage?

A

reaction centre

139
Q

What name is given to the arrangement of accessory and primary pigments grouped together to gather and use light energy?

A

photosystem

140
Q

What are the three products of photolysis?

A

Protons, electrons and oxygen

141
Q

What are the two useful products of the light-dependent reaction?

A

ATP, NADH

142
Q

In the light-dependent reaction, excited electrons lost from photosystem I are replaced from where?

A

From the electron transport chain starting from photosystem 2

143
Q

Which photosystems are involved in non-cyclic photophosphorylation?

A

photosystem 2
photosystem 1

144
Q

Which photosystem is involved in cyclic photophosphorylation?

A

photosystem 1

145
Q

What is the name of the five-carbon compound combined with carbon dioxide in the first stage of the Calvin Cycle?

A

rubp

146
Q

Which enzyme catalyses the production of an unstable six-carbon compound in the first stage of the Calvin Cycle?

A

rubisco

147
Q

What substance is produced by the breakdown of the unstable six-carbon compound in the first stage of the Calvin Cycle?

A

gp

148
Q

What substance is produced by the reduction of glycerate 3-phosphate in the Calvin cycle?

A

tp

149
Q

What happens to the majority of the triose phosphate produced by the Calvin cycle

A

rubp

150
Q

What is meant by the term fixation of carbon dioxide?

A

Incorporating carbon dioxide into an organic compound.

151
Q

Triose phosphate can be used to synthesise which organic molecules

A

Carbohydrates, amino acids and lipids.

152
Q
A

alevel biology ocr (22 decks)

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