AHL Topic 8 IB Biology Miss Werba

Transcription

1 CELL RESPIRATION & PHOTOSYNTHESIS AHL Topic 8 IB Biology Miss Werba

2 TOPIC 8 CELL RESPIRATION & PHOTOSYNTHESIS 8.1 CELL RESPIRATION 1. STATE that oxidation involves the loss of electrons from an element, whereas reduction involves a gain of electrons; and that oxidation frequently involves gaining oxygen or losing hydrogen, whereas reduction frequently involves losing oxygen or gaining hydrogen. 2. OUTLINE the process of glycolysis, including phosphorylation, lysis, oxidation and ATP formation. 3. DRAW and LABEL a diagram showing the structure of a mitochondrion as seen in electron micrographs. 4. EXPLAIN aerobic respiration, including the link reaction, the Krebs cycle, the role of NADH + H+, the electron transport chain and the role of oxygen 5. EXPLAIN oxidative phosphorylation in terms of chemiosmosis. 6. EXPLAIN the relationship between the structure of the mitochondrion and its function. 8.2 PHOTOSYNTHESIS 1. DRAW and LABEL a diagram showing the structure of a chloroplast as seen in electron micrographs. 2. STATE that photosynthesis consists of light-dependent and light independent reactions. 3. EXPLAIN the light-dependent reactions. 4. EXPLAIN photophosphorylation in terms of chemiosmosis. 5. EXPLAIN the light-independent reactions. 6. EXPLAIN the relationship between the structure of the chloroplast and its function. 7. EXPLAIN the relationship between the action spectrum and the absorption spectrum of photosynthetic pigments in green plants. 8. EXPLAIN the concept of limiting factors in photosynthesis, with reference to light intensity, temperature and concentration of carbon dioxide.

3 Cell respiration

4 8.1 Involves Involves (chains and cycles) Involves Involves Adds the third phosphate to ADP to Respiration includes:

5 8.1.3

6 8.1.6 : form a have needed for the electron transport chain in their membrane : to allow to and create a : containing needed for the Krebs cycle Cell respiration involves different reactions that involve the of These reactions are known as (ie. and reactions) Oxidation & reduction occur together;. Remember: OIL RIG. Reduction reactions may include: Gain of Removal of Gain of Oxidation reactions may include: of electrons of oxygen of hydrogen

7 8.1.1 (nicotinamide adenine dinucleotide) is the used electron carrier. NAD + is as another substrate is oxidised ie. when a substrate is loses 2 hydrogen atoms, NAD + the from both atoms (2e ) and the from one: Other electron carriers involved in cell respiration include: OXIDISED STATE REDUCED STATE Both and mean that the molecule has attached to it Di- means the two phosphates are attached to Bis- means that the two phosphates are attached to of the molecule

8 FINAL PRODUCT GOES HERE

9 8.1 Can be or 4 stages: The The The The first step in cellular respiration Glycolysis can occur anaerobically meaning...? Thus glycolysis is occurs in the or molecule is converted into molecules. molecules are used but are produced, so there is. are converted into There are 4 main stages to Glycolysis: 4. are added to a molecule of to form molecules provide the phosphate groups 5. Glucose bisphosphate is split into molecules called

10 3. atoms are removed from each triose phosphate molecule ( accepts them). The energy released is used to add group to each triose phosphate molecule is formed by removing the groups and by passing them to. This results in ATP formation and is called

11 8.1.4 The second step in cellular respiration After glycolysis, moves to the. in the mitochondrial matrix remove and. accepts the hydrogen the is released The removal of CO 2 is called. The whole conversion is called. The product of this is an group, which is accepted by an enzyme,. This forms

12 Also known as the The third step in cellular respiration Happens in the Yields (total now ) but process is C and O from C 6 H 12 O 6 are released as is left over The Krebs Cycle occurs in a number of stages: 1) The enters the cycle and is joined to This forms. The is released and within the mitochondrion. 2) is converted to a compound (C5) is released (decarboxylation) accepts atoms (oxidation) 3) the C5 compound is converted to a compound is released (decarboxylation) accepts atoms (oxidation) 4) ATP is synthesised from (substrate level phosphorylation) and reactions:

13 One turn of the Krebs Cycle yields: (by substrate level phosphorylation) Remember that there are of the Krebs cycle for each glucose molecule!!!

14 8.1.4 The Electron Transport Chain (ETC) passes from or from one electron carrier to another by a of reactions These electron carriers are found in the The are across the membrane to the by the energy released from the electrons. is the final acceptor of the electrons, which uses them to with to form. This occurs in the of the mitochondrion. catalyses this last reaction. Some metabolic poisons, such as, inhibit the action of this enzyme, with potentially fatal results

15 & The Electron Transport Chain (ETC) passes from or from one electron carrier to another by a of reactions These electron carriers are found in the The are across the membrane to the by the energy released from the electrons. is the final acceptor of the electrons, which uses them to with to form. This occurs in the of the mitochondrion. catalyses this last reaction.

16 Thus the net production of energy from aerobic respiration from ONE glucose molecule is:

17 Photosynthesis

18 8.2 Involves Involves (chains and cycles) Consists of both and stages for use in cellular respiration or storage Respiration includes: Light reactions Light reactions

19 8.2.1

20 8.2.1, Chloroplasts are bordered by a : site of light-dependent reactions made from of membrane-bound sacs called provide a for light absorption are linked to each other by other membranes called space: small to allow to and create a : site of light-independent reactions contains needed for the cycle also contains and Also contains and as chemical energy stores

21 8.2.2 Photosynthesis consists of light-dependent and light-independent reactions. Light dependent reactions Occur in membranes Involves of water Involves Light independent reactions Occur in the Involves Involves Involves

22 Short n sweet: splitting of water releases enough energy to make molecules requires molecules split into 24 H + and 6 O 2 for light-independent reactions as O 2 gas Chlorophyll absorbs light light energy transfers to in the molecule results in an electron this is known as Chloroplasts are bordered by a Chlorophyll is located in the membrane It is arranged in groups of hundreds of molecules called. There are two types of photosystem: Photosystem I Photosystem II 1) absorbs light energy this energy excites electrons in the chlorophyll the excited electron is passed along a of in the 2) replaces the lost electrons from molecules break apart is released the protons (H + ) can either: combine with at the end of the pathway or be into the

23 ) Electrons are passed through carrier acts as a protons are pumped into the 4) the protons back through through this (From ) 5) absorbs light energy the electrons are passed to is also absorbed here the excited electrons pass through a of to, in the, forming 6), rather than heading to directly can flow back through the to Photosystem I. this causes to be pumped across the forms a allows by

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25 8.2.4 The synthesis of ATP using the from. The same principle as for in the. 1. Electrons flow through the 2. As the pass through the, are pumped into the 3. builds up 4. Protons diffuse through, down a 5. from ADP + P i There is a difference between cyclic and non-cyclic phosphorylation non-cyclic on to end in cyclic are to

26 Short n sweet: requires from light-dependent reactions H combines with C and O to molecules are as a by-product process molecules overall = 18 ATP 18 ATP = 1) ( ) enters the chloroplast by at the start of the Calvin cycle, CO 2 combines with, a five carbon compound the enzyme involved is called the compound product to form of 2) Glycerate 3-phosphate is converted into (C3) by a reaction hydrogen is supplied by energy is required in the form of Both the were synthesised in the 3) molecules are together to form join the glucose phosphate molecules together to form

27 -

28 & A spectrum is a of of. The spectrum is the range of wavelengths from nm. Each wavelength is colour of light: The of photosynthesis is not the same in all wavelengths. Action Spectrum = the efficiency of the different wavelengths of light that are Absorption Spectrum = how much of a particular wavelength of light is by the The two most common pigments are: and The action spectrum and absorption show strong similarities: greatest absorption in a high level of absorption in lowest absorption in There is a between the action spectrum and the absorption spectrum

29 8.2.8 There are 3 main factors that can affect the rate of photosynthesis: Changes to one of these factors can affect the of photosynthesis. Limiting Factor =

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31 FINAL PRODUCT GOES HERE

32 Sample questions

33 Topic 8.1: 1. During glycolysis, a hexose sugar is broken down to two pyruvate molecules. What is the correct sequence of stages? A. Phosphorylation oxidation lysis B. Oxidation phosphorylation lysis C. Phosphorylation lysis oxidation D. Lysis oxidation phosphorylation 2. What is the role of NADH + H + in aerobic cell respiration? A. To transfer hydrogen to the electron transport chain B. B. To reduce intermediates in the Krebs cycle C. C. To accept electrons from the electron transport chain D. D. To combine with oxygen to produce water 3. Explain the link reaction that occurs between glycolysis and the Krebs cycle. (Total 4 marks)

34 Topic 8.2: 1. Where are the light-dependent and light-independent reactions taking place in the diagram below? 2. Where are complex carbohydrates made in the chloroplast? A. In the intermembrane space B. In the stroma C. On the inner membrane D. In the thylakoid space

35 3. Outline the light-dependent reactions of photosynthesis. (Total 6 marks)