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aqa biology > 3.5 Energy transfers in and between organisms > Flashcards

3.5 Energy transfers in and between organisms Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

3.5.1
describe the light-dependent reaction

A

chlorophyll absorbs light, leading to photoionisation of chlorophyll

some of the energy from electrons released during photoionisation is conserved in the production of ATP and NADPH

the production of ATP involves electron transfer associated with the transfer of electrons down the electron transfer chain

passage of protons across chloroplast membranes and is catalysed by ATP synthase embedded in these membranes

(chemiosmotic theory)

photolysis of water produces protons, electrons and oxygen

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2
Q

3.5.1
where do the products of the light-independent reaction come from?

A

uses NADPH from the light-dependent reaction (to form a simple sugar)

the hydrolysis of ATP, also from the light-dependent reaction, provides the additional energy for this reaction

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3
Q

3.5.1
describe the light-independent reaction

A

carbon dioxide reacts with ribulose bisphosphate (RuBP) to
form two molecules of glycerate 3-phosphate (GP).

this reaction is catalysed by the enzyme rubisco

ATP and NADPH from the light-dependent reaction are used to reduce GP to triose phosphate

some of the triose phosphate is used to regenerate RuBP in the Calvin cycle

some of the triose phosphate is converted to useful organic substances

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4
Q

3.5.1
what is the name of the light-dependent reaction?

A

photophosphorylation

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5
Q

3.5.1
what is the name of the light-independent reaction?

A

calvin cycle

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6
Q

3.5.2
what is the first stage of respiration?

A

glycolysis

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7
Q

3.5.2
where does glycolysis occur?

A

cytoplasm

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8
Q

3.5.2
what happens during phosphorylation?

A

phosphate molecules binds to glucose

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9
Q

3.5.2
what happens during oxidation?

A

hydrogen molecule is lost from glucose

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10
Q

3.5.2
how many ATP molecules are used during this first stage of respiration?

A

2

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11
Q

3.5.2
how many ATP molecules are produced during this first stage of respiration?

A

4

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12
Q

3.5.2
what is the NET gain of ATP produced during this first stage of respiration?

A

2

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13
Q

3.5.2
what is the only stage of respiration common to aerobic and anaerobic respiration?

A

glycolysis

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14
Q

3.5.2
what are the products of glycolysis?

A

2 pyruvate
2 NADH
4 ATP

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15
Q

3.5.2
What are the key steps that occur in glycolysis?

A

glucose is phosphorylated and splits
this produces two triosephosphate and two NAD -> NADH
triose phosphate is oxidised with two ATP
produces four ATP and two pyruvate

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16
Q

3.5.2
what is meant by the term oxidation reaction?

A

loss of an electron or a hydrogen molecule

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17
Q

3.5.2
what is meant by the term reduction reaction?

A

gain of an electron or a hydrogen molecule

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18
Q

3.5.2
what is a co-enzyme?

A

a molecule needed for an enzyme to do its function but is NOT an enzyme

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19
Q

3.5.2
what is an example of a co-enzyme in glycolysis?

A

NAD -or- NADH

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20
Q

3.5.2
TRUE OR FALSE
the link reaction uses oxygen molecules

A

FALSE
the link reaction requires the presence of oxygen but it is not used in the reaction

21
Q

3.5.2
what is the second stage of respiration called?

A

the link reaction

22
Q

3.5.2
where does the link reaction occur?

A

mitochondria

23
Q

3.5.2
what happens in the link reaction?

A

two pyruvate are oxidised and decarboxylated into two acetate, two NADH and two carbon dioxide molecules

acetate binds with co-enzyme-A to form two acetatlycoenzymeA

produces two acetatlycoenzymeA, two NADH and two carbon dioxide molecules

24
Q

3.5.2
how many times does the link reaction occur for every glucose molecule?

A

twice

25
Q

3.5.2
what happens to the products produced in the link reaction?

A

NADH -> electron chain
CO2 -> released from mitochondria
AcetatlycoenzymeA -> kerbs cycle

26
Q

3.5.2
how many ATP molecules does the link reaction produce?

A

zero

27
Q

3.5.2
name all components of a mitochondria?
(eight)

A

inner membrane
outer membrane
cristae
matrix
intermembrane space
ribosomes
DNA
stalked particles (ATP synthase)

28
Q

3.5.2
what products are produced from the kreb’s cycle?
(per glucose molecule)

A

ATP - 2
C02 - 4
NADH - 6
FADH2 - 2

29
Q

3.5.2
what goes into the kreb’s cycle?

A

acetylcoenzymeA [2C]

30
Q

3.5.2
what is the first stage of the kreb’s cycle?

A

AcetylcoenzymeA reacts with a 4 carbon molecule (Oxaloacetate) to form a 6 carbon molecule (Citrate) that enters the Krebs cycle

Coenzyme A is released and goes back to the link reaction to be used again

31
Q

3.5.2
what is the second stage of the kreb’s cycle?

A

The 6 carbon molecule is both decarboxylated and oxidised meaning a carbon dioxide molecule is lost and it becomes a 5 carbon molecule.

A hydrogen is also removed which is picked up by NAD to form 1 reduced NAD (NADH).

32
Q

3.5.2
what is the third stage of the kreb’s cycle?

A

The 5 carbon molecule is decarboxylated and converted back into the 4 carbon molecule (Oxaloacetate) and another carbon dioxide molecule is lost.

A series of oxidation-reduction reactions also occur generating reduced coenzymes (2 reduced NAD and 1 reduced FAD) which pick up the hydrogens removed from the 5 carbon molecule.

ATP is also produced by substrate level phosphorylation.

33
Q

3.5.2
where does the kreb’s cycle occur?

A

matrix of the mitrochondria

34
Q

3.5.2
TRUE OR FALSE
each step is enzyme controlled in the kreb’s cycle

A

TRUE

35
Q

3.5.2
TRUE OR FALSE
oxygen is USED in the kreb’s cycle

A

FALSE
Does not require oxygen but can not take place if oxygen is not present

(therefore it is an aerobic process)

36
Q

3.5.2
how many times does the kreb’s cycle occur per glucose molecule and why?

A

twice

because two molecules of acetylcoenzymeA are produced by the link reaction

37
Q

3.5.2
what is the last stage of respiration?

A

oxidative phosphorylation

38
Q

3.5.2
where does oxidative phosphorylation occur?

A

in the inner mitochondrial membrane

39
Q

3.5.2
what is the first step of oxidative phosphorylation?

A

NADH and FADH2 are oxidised which releases hydrogen

the hydrogen splits into a proton (H+) and an electron (e-)

40
Q

3.5.2
what is the second step of oxidative phosphorylation?

A

electrons are donated to electron transport chain and pass along electron carriers via a series of oxidation-reduction reactions releasing energy as they move

41
Q

3.5.2
what is the third step of oxidative phosphorylation?

A

energy is used by the electron carriers to actively transport the protons from the matrix into the inter-membrane space which creates an electro-chemical gradient

42
Q

3.5.2
what is the fourth step of oxidative phosphorylation?

A

the protons move back from the inter-membrane space to matrix down the electro-chemical gradient by facilitated diffusion via ATP Synthase

43
Q

3.5.2
what is the fifth step of oxidative phosphorylation?

A

the movement of protons release enough energy for ATP Synthase to catalyse the formation of ATP from ADP + Pi (phosphorylation)

44
Q

3.5.2
what is the sixth stage of oxidative phosphorylation?

A

oxygen is the final electron acceptor and picks up the electron at the end of the electron transport chain as well as a proton (H+) to form water

45
Q

3.5.2
what is the seventh/last stage of oxidative phosphorylation?

A

without oxygen electrons cannot be passed on along the electron transport chain as no oxygen is able to be the final electron acceptance

NADH and FADH2 can also not be oxidised and returned to the link reaction and kreb’s cycle so these processes stop as well

46
Q

3.5.2
what is the chemiosmostic theory?

A

The active transport of protons (H+) across the inner mitochondrial membrane into the intermembrane space creates an electrochemical gradient

47
Q

3.5.2
what is moved in the chemiosmotic theory?

A

The movement of the protons down an electrochemical gradient from the intermembrane space through ATP synthase back into the matrix of the mitochondria provides the energy needed to form ATP from ADP and Pi

48
Q

3.5.2
how efficient is respiration in creating ATP?

A

32%

49
Q

3.5.2
why is respiration not 100% efficient?
(three)

A

Some ATP is used up moving hydrogen from reduced NAD made during glycolysis into the mitochondria.

Some ATP is used up moving pyruvate into the mitochondria by active transport.

Some energy is used to generate heat. This helps to maintain a suitable body temperature for enzyme-controlled reactions.

aqa biology (9 decks)

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