photosynthesis - HS Biology IB

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Topic 8 : Cell respiration and Photosynthesis
AND
OPTION C: Cells and Energy
C1: Proteins
C.1.1:Primary Structure
C.1.1: Secondary Structures
Alpha Helix
Beta Pleated Sheet
protein ribbonprotein ribbon
7.5.1: Quaternary Structure
C.1.1: Conjugated Protein
C.1.2
C.1.2: Globular Protein
C.1.2:Fibrous Protein
C.1.3 Polar Amino Acid
C.1.3: Non-polar amino acids
C.1.3
C.1.3
C.1.3
C.1.4: Functions of proteins (other than
membrane proteins)
C2: Enzymes
C.2.1
C.2.2
C.2.3
C.2.4
C.2.4
Prontosil is a competitive inhibitor that
is used as an antibiotic because it
inhibits folic acid synthesis in bacteria.
Nerve gases like Sarin function by
inactivating the enzyme ethanoyl
(acetyl) cholinesterase.
C.2.5
7.6.5
C3, 8.1: Cellular Respiration
C.3.1, 8.1.1:Oxidation/Reduction
STATE: oxidation involves the gain of oxygen
reduction involves the loss of oxygen
C.3.1, 8.1.1: Oxidation/Reduction
STATE: oxidation involves loss of electrons
reduction involves gain of electrons
C.3.1, 8.1.1:Oxidation/Reduction
STATE: oxidation involves loosing hydrogen
reduction involves gaining hydrogen
C.3.1, OiL RiG ???????
( OiL RiG only applies to electrons and hydrogen)
(Aerobic)Cellular Respiration Formula
GLUCOSE + OXYGEN + ADP +Pi CARBON DIOXIDE + WATER + ATP
C6H12O6 + 6O2
 6CO2
+ 6H2O
C.3.2, 8.1.2: Outline the process of glycolysis, including phosphorylation, lysis, oxidation and ATP formation
8.1.2: Glycolysis
Adenosine triphosphate
NAD: Electron Carrier
NAD+ = oxidised form
NADH + H + = reduced form
NAD+ + 2H → NADH + H+
2
2
2
2
Pyruvate
Pyruvate
Oxidation of triose phosphate
Reduction of NAD + to NADH + H +
From one glucose molecule in
glycolysis:
2 x ATP (net)
2 X (NADH + H+)
2 X pyruvate
NAD: Nicotinamide adenine dinucleotide, abbreviated NAD
A co-enzyme is a non-protein chemical compound that is loosely bound to a protein
and is required for the protein's biological activity.
C.3.3, 8.1.3: Draw and label a diagram showing the structure of a mitochondria as seen
in electron micrographs
Mitochondrion
inter
IB Question: Draw and label a mitochondrion as seen in electron micrographs. [4]
M08/4/BIOLO/HP2/ENG/TZ2/XX
Award [1] for each of the following clearly drawn and correctly labelled.
outer membrane;
inner membrane – folded into thin cristae;
cristae – shown as thin;
matrix;
intermembrane space – shown as thin;
(70S) ribosomes;
ATP synthase – shown on the inner membrane surface;
(naked) loop of DNA; [4 max]
C.3.4, 8.1.4: Explain aerobic respiration, including the link reaction, the Kreb’s cycle, the role of
NADH + H+, the electron transport chain and the role of oxygen
Pyruvate
decarboxylation
(Oxidative decarboxylaytion)
Oxidation of
pyruvate
From one pyruvate molecule in the link
reaction the products are:
1 x (NADH + H+)
1 x CO2
1 x acetyl CoA
The Kreb’s Cycle occurs in the
matrix of the mitochondria
C.3.5, 8.1.4: Chemiosmosis
ADP joins with inorganic phosphate
IB QuestionExplain the process of aerobic cell respiration after glycolysis has occurred. [8]
pyruvate produced by glycolysis;
pyruvate enters mitochondrion/mitochondria;
pyruvate loses CO2 in link reaction;
and NADH + H+;
with formation of acetyl CoA;
to take part in Krebs cycle;
where two CO2 are produced (per molecule of pyruvate);
one ATP from ADP + Pi;
along with (three) NADH + H+ (and one FADH2);
NADH + H+ provide electrons circulating in the electron transport chain on the
inner mitochondrial membrane;
allowing H+ to accumulate in the intermembrane space;
and come back to the matrix through ATP synthase/synthetase to produce ATP
(by chemiosmosis);
presence of O2 required as the final electron acceptor for the electron transport chain;
producing water with H + ; [8 max]
8.1.5: Explain oxidative phosphorylation in terms of chemiosmosis.
8.2.4: Explain photophosphorylation in terms of chemiosmosis.
Oxidative phosphorylation
Chemiosmosis
Non-cyclical photophosporylation
Photophosporylation
Cyclical photophosporylation
C.3.5, 8.1.5: Explain oxidative phosphorylation in terms of chemiosmosis
Chemiosmosis: The generation of ATP produced by the coupling of the movement of
electrons down the electron transport chain with the movement of hydrogen ions
across a membrane during cellular respiration and photosynthesis.
Oxidative phosphorylation and photophosphorylation are but specialised examples
of chemiosmosis.
Oxidative phosphorylation: is a metabolic pathway that uses energy released by the
oxidation of nutrients to produce adenosine triphosphate (ATP).
Oxidative phosphorylation
photophosphorylation
IB Question: Describe the function of oxygen in oxidative phosphorylation
[2]
oxygen is the final acceptor of electrons/protons/; water is formed / oxygen is reduced; in the
(mitochondrial) electron transport chain; (aerobic respiration) increases yield of ATP; [2 max] H
IB Question: Explain how chemiosmosis assists in ATP production during oxidative
phosphorylation. [9]
occurs during aerobic respiration;
oxidative phosphorylation occurs during the electron transport chain;
hydrogen/electrons are passed between carriers;
releasing energy;
finally join with oxygen (to produce water);
occurs in cristae of mitochondria;
chemiosmosis is the movement of protons/hydrogen ions;
protons move/are moved against their concentration gradient;
into the space between the two membranes;
protons flow back to the matrix;
through the ATP synthase/synthetase (enzyme);
energy is released which produces more ATP/combines ADP and Pi; [9 max]
8.1.6: Explain the relationship between the structure of the mitochondrion and its function
Mitochondrion
Structure
Matrix
Inter-membrane
space
Cristae
Function of structure
The matrix is the mitochondrion’s cytoplasm. It is
the fluid contained inside the inner membrane.
The matrix contains enzymes for the Krebs cycle.
The small intermembrane space is in-between
the inner and outer membrane of a
mitochondrion. It functions to store protons,
which are then used to make ATP as they flow
down a concentration gradient.
Cristae are infoldings of the inner membrane,
which is the location of the electron transport
chain of cell respiration. The cristae increase
surface area of the inner membrane; thus
increasing the rate of ATP formation.
Cellular Respiration: Overview
PHOTOSYNTHESIS
CARBON DIOXIDE +WATER  GLUCOSE + OXYGEN
6CO2
+ 6H2O
 C6H12O6
+ 6O2
Photosynthesis
Photosynthesis
• Chloroplast - Electron micrograph
8.2.1: Draw and label a diagram showing the structure of a chloroplast as seen in electron
micrographs
IB Question: Draw a labelled diagram of the structure of a chloroplast as seen with an electron
microscope. [4]
M09/4/BIOLO/HP2/ENG/TZ1/XX
Award [1] for each of the following clearly drawn and correctly labelled. Label lines must be
unambiguous in terms of what they are indicating.
double/inner and outer membrane/envelope – shown as two concentric continuous lines close
together;
granum/grana – shown as a stack of several disc-shaped subunits;
(intergranal) lamella – shown continuous with thylakoid membrane;
thylakoid – one of the flattened sacs;
stroma;
(70S) ribosomes/(circular) DNA / lipid globules / starch granules / thylakoid space; [4 max]
8.2.2: STATE: Photosynthesis consists of the Light Dependent Reaction and the
Light Independent Reaction
8.2.3: Explain the light-dependent
reaction and
8.2.4: Explain oxidative
photophosphosphorylation in terms
of chemiosmosis
1
2
3
4
5
6
7
8
9
ADP joins with inorganic phosphate
10
Non Cyclical andCyclical
Photophosphorylation
IB Question: Outline the light-dependent reactions of photosynthesis. [6]
M09/4/BIOLO/HP2/ENG/TZ2/XX
(chlorophyll/antenna) in photosystem II absorbs light;
absorbing light/photoactivation produces an excited/high energy/free electron;
electron passed along a series of carriers;
reduction of / generates ; NADP NADPH H
absorption of light in photosystem II provides electron for photosystem I;
photolysis of water produces ; 2 H /O
called non-cyclic photophosphorylation;
in cyclic photophosphorylation electron returns to chlorophyll;
generates ATP by pumped across thylakoid membrane / by chemiosmosis / through ATP
synthetase/synthase; [6 max] H
8.2.5: Explain the Light independent
reaction
(calvin cycle)
CARBON
FIXATION
RuBP
carboxylase
CARBON
FIXATION
Glycerate -3phosphate
REDUCTION of
gylcerate 3phosphate
Triose phosphate
(TP)
Regeneration
of
RuBP
IB QuestionExplain the light-independent reactions.
[8]
CO is fixed to form a carbohydrate;
ATP and NADPH produced in light dependent reactions used in light independent
reactions;
glyceraldehydes / three-carbon sugar;
occurs in stroma of chloroplast;
ribulose bisphosphate carboxylase (Rubisco) catalyzes attachment of 2 CO to
(five-carbon sugar) ribulose bisphosphate (RuBP);
(unstable six-carbon intermediate) forms two molecules of glycerate-3-phosphate;
each (of two) glycerate-3-phosphate then receives one phosphate from ATP;
each (of two) phosphorylated glycerate-3-phosphate is reduced by NADPH H ;
result is (two molecules of) glyceraldehyde phosphate/triose phosphate (TP);
for every six molecules of glyceraldehyde phosphate one goes to form glucose/
glucose phosphate;
remaining molecules reorganized to RuBP;
reorganization requires ATP;
RuBP allows cycle to start again; [8 max]
IB Qustion: Outline the conversion of light energy to chemical energy in photosynthesis. [6]
light energy absorbed by chlorophyll (photo) activates photosystems;
electron in chlorophyll/photosystem activated/excited / raised to higher energy
level;
photolysis of water replaces excited electrons;
energy passed through electron carriers/ETS;
hydrogen/high energy electrons reduce NADP+ ;
photophosphorylation by chemiosmosis;
(some) H+/protons pumped into thylakoid spaces;
proton gradient is created;
energy released as protons pass through ATP synthetase;
ATP produced;
correct reference to (non cyclic or cyclic) photophosphorylation;
glucose/sugar/monosaccharide produced in Calvin cycle; [6 max]
Credit can be given for any of these points shown on a correctly drawn and
labelled diagram.
C.4.6
8.2.6: Explain the relationship between the structure of the chloroplast and its function
Structure
Stroma
Thylakoids
Thylakoid space
Function of structure
The viscous fluid of the stroma provides
enzymes for the Calvin cycle.
The thylakoids provide a large surface area for
light absorption and the reactions of
photosynthesis.
The small center of each thylakoid provides
space (the thylakoid space) for the accumulation
of protons (H+), used to make ATP.
C.4.7, 8.2.6: : Explain the relationship between the action spectrum and the absorption spectrum
photosynthetic pigments in green plants
C.4.8, 8.2.8: Explain the concept of limiting factors in photosynthesis, with reference to light intensity,
temperature and concentration of carbon dioxide
C.4.8, 8.2.8
IB Question: Outline the cellular locations of different named processes in both photosynthesis
and cell respiration. [6]
photosynthesis: [3 max]
chloroplasts/photosystems: for light absorption/photosynthesis;
stroma: light-independent reactions / Calvin cycle;
thylakoid membranes of chloroplast: chemiosmosis / photophosphorylation/light
dependent reactions;
thylakoid space: build up H+ concentration gradient;
inner membrane of thylakoid: electron transfer;
inner membrane: ATP synthesis;
cell respiration: [3 max]
mitochondria: for ATP production/aerobic respiration;
cytoplasm: glycolysis / matrix: Krebs cycle/oxidative phosphorylation/link reaction;
double / inner membranes of mitochondria: chemiosmosis / oxidative phosphorylation;
intermembrane space: build-up H+ concentration gradient;
inner membrane of mitochondria: electron transfer;
inner membrane: ATP synthesis; [6 max]
Answers must indicate location and process to receive a mark.
Do not award a mark if it is ambiguous whether the candidate is discussing
photosynthesis or respiration.

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