REVISION 1 (44 Marks)



REVISION 1 (44 Marks)

IB Standard and Higher level Biology Dulwich College Shanghai

Topic 3 (SL): Chemistry of Life

Topic 8 (HL): Respiration and Photosynthesis

7. Respiration (SL)

1. Define cell respiration ( cell respiration is the controlled release of energy from organic compounds in cells to form ATP.

2. State that, in cell respiration, glucose in the cytoplasm is broken down by glycolysis into pyruvate, with a small yield of ATP.

3. Explain that, during anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and carbon dioxide, with no further yield of ATP.

4. Explain that, during aerobic cell respiration, pyruvate can be broken down in the mitochondrion into carbon dioxide and water with a large yield of ATP.

1. Cell Respiration (HL)

1. State that oxidation involves the loss of electrons from an element, whereas reduction involves a gain 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 (in the cytoplasm, one hexose sugar is converted into three-carbon atom compounds – pyruvate, with a net gain of two ATP and two NADH + H+.

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.

In aerobic respiration (in mitochondria in eukaryotes), each pyruvate is decarboxylated (CO2 removed). The remaining two-carbon molecule (acetyl group) reacts with reduced coenzyme A, and, at the same time, one NADH + H+ is formed. This is known as the link reaction.

In the Krebs cycle, each acetyl group (CH3CO) formed in the link reaction yields two CO2. The names of the intermediate compounds in the cycle are not required. Thus it would be acceptable to note:

C2 + C4 = C6 ( C5 ( and so on.

5. Explain oxidative phosphorylation in terms of chemiosmosis.

6. Explain the relationship between the structure of the mitochondrion and its function.

Paper 1

Multiple Choice (8 Marks)

1. Of the following products, which is produced by both anaerobic respiration and aerobic respiration in humans?

I. Pyruvate

II. ATP

III. Lactate

A. I only

B. I and II only

C. I, II and III

D. II and III only

2. Which is not a product of the Krebs cycle?

A. CO2

B. NADH + H+

C. Pyruvate

D. ATP

3. How many ATP molecules (net yield) are produced per molecule of glucose as a direct result of glycolysis?

A. 2

B. 4

C. 10

D. 38

4. What happens during muscle contraction?

A. Both actin and myosin filaments shorten.

B. Na+ ions are taken up by the sarcoplasmic reticulum.

C. The actin and myosin filaments slide over each other.

D. Cross bridges remain attached to the filaments.

5. What is the “link reaction” in eukaryotic respiration?

A. Pyruvate joining with coenzyme A to produce CO2 and NADH + H+

B. Oxidation of NADH to yield electrons and protons

C. Acetyl coenzyme A combining or joining with a C4 compound to give C6 + coenzyme A

D. Passage of acetyl coenzyme A through the mitochondrial membrane

6. How are photosynthesis and aerobic respiration similar?

| |ATP synthetase enzyme |Electron transport chain |NADH + H+ |

|A. |[pic] |[pic] |[pic] |

|B. |[pic] |[pic] |[pic] |

|C. |[pic] |[pic] |[pic] |

|D. |[pic] |[pic] |[pic] |

Key: [pic] = both have or use this [pic] = both do not have or use this

7. Which row in the table describes the first stage of cellular respiration?

| |Substrate |Location |Product |Product |

|A. |pyruvate |mitochondria |oxygen |water |

|B. |pyruvate |cytoplasm |carbon dioxide |ATP |

|C. |glucose |mitochondria |pyruvate |water |

|D. |glucose |cytoplasm |pyruvate |ATP |

8. The diagram below shows the three stages of glycolysis. Which processes are indicated by I, II and III?

[pic]

-

| |I |II |III |

|A. |Lysis |Phosphorylation |Oxidation and ATP formation |

|B. |Oxidation and ATP formation |Phosphorylation |Lysis |

|C. |Phosphorylation |Lysis |Oxidation and ATP formation |

|D. |Phosphorylation |Oxidation and ATP formation |Lysis |

Paper 2

Section A

Data Analysis (6 marks)

1. The rate of carbon dioxide uptake by the green succulent shrub Aeonium goochiae can indicate the amount of photosynthesis taking place in the plant. This rate was measured at 15°C and 30°C over a 24-hour period. The units of carbon dioxide absorption are mg CO2 h–1.

The results are shown below. The centre of the graph corresponds to –2 mg CO2 h–1 and the outer ring is +2.5 mg CO2 h–1.

[pic]

[Source: adapted from biologie.uni-hamburg.de/b-online/e24/9.htm]

(a) Identify a time that carbon dioxide uptake was the same at both temperatures. (1)

06:00 / 19:30 to 19:45 1

Accept 6 am / 7:30 pm to 7:45 pm.

(b) State the maximum rate of carbon dioxide uptake at 15°C. (1)

2.3 mg CO2 h–l (±0.1) (units required)

(c) Compare the rate of carbon dioxide uptake at each temperature in daylight and darkness. (3)

more uptake at 15°C than 30°C during the hours of daylight;

both are high during the hours of daylight / reverse argument;

greater uptake at 30°C than 15°C during the hours of darkness;

at only 15°C uptake become negative;

(d) Suggest why the carbon dioxide uptake may at times be negative. (1)

respiration rate greater than photosynthesis (during the hours of darkness)

Paper 2

Section A

Short Structured (17 Marks)

1. The diagram below shows possible pathways for the breakdown of glucose in various cells.

[pic]

(a) State the names of processes Q and R. (2)

Q: anaerobic respiration / fermentation;

R: aerobic respiration / Kreb’s (citric acid) cycle;

(b) Deduce the names of substances A and D. (2)

A: pyruvate / 3-oxopropanoate;

D: carbon dioxide;

(c) State the organelle in which process R takes place. (1)

mitochondrion;

2. The electron micrographs below show mitochondria in longitudinal section. The mitochondrion in A is from a bat pancreas cell and that in B is from a mouse liver cell.

[pic]

[Source: Tribe and Whittaker, Chloroplasts and Mitochondria, (1972), 31, pp 28–29]

(a) Annotate the micrographs to show two similarities in the structure of the mitochondria. (2)

both have two (outer) membranes;

both have cristae;

both have a matrix (with a grainy appearance) / ribosomes;

(b) The mitochondria differ in size. State two other differences that are visible in the mitochondria. (2)

shape;

arrangement of cristae;

density of cristae;

amount of matrix granules / any reference to dark dots;

(do not accept ribosomes)

(c) Predict, with two reasons, which of the mitochondria would have been able to produce ATP at a greater rate. (3)

A / bat’s;

larger size / volume;

greater surface area of cristae / more cristae;

closeness of mitochondria in B mouse reduces rate;

3. (a) State the net gain of ATP molecules during glycolysis of one glucose molecule. (1)

2

(b) State where in the mitochondrion the enzymes of the Krebs cycle are found. (1)

Matrix (fluid)

(c) Compare the process of chemiosmosis in both respiration and photosynthesis. (3)

Award [1] for each row, up to [3 max].

|Respiration |Photosynthesis |

|both make ATP; |

|both involve electron transport; |

|protons move against a concentration gradient in both; |

|both require ATP synthetase; |

|occurs in mitochondrion |occurs in chloroplasts / thylakoids; |

|uses energy from oxidation |uses energy from light; |

|has NADH for electron production |has water for electron production; |

Section B

Extended Response (13 Marks)

1. Explain the process of aerobic respiration including oxidative phosphorylation. (8)

glucose converted to pyruvate (two molecules);

by glycolysis;

pyruvate enters the mitochondria;

pyruvate converted to acetyl CoA / ethyl CoA;

by oxidative decarboxylation / NADH and CO2 formed;

fatty acids / lipids converted to acetyl CoA;

acetyl groups enter the Krebs cycle (accept acetyl CoA);

FAD / NAD+ accepts hydrogen (from respiratory substrates) to form NADH / FADH2;

FADH2 / NADH donates electrons / hydrogen to electron transport chain (reject

donates H+);

electrons release energy as they pass along the chain;

oxygen final electron acceptor;

production of water;

builds up proton gradient / protons pumped across inner membrane;

protons flow into matrix of mitochondria through ATPase;

ATP produced;

produces 36 / 38 ATP (per glucose); 8 max

Accept any appropriate terminology for NAD and FAD.

(Plus up to [2] for quality)

2. Using a table, compare aerobic and anaerobic respiration in a eukaryotic cell. (5)

Award [1] for each correct row, up to [5 max].

|Aerobic respiration |Anaerobic respiration |

|occurs in mitochondria |occurs in cytoplasm; |

|requires O2 |occurs without O2; |

|both produce pyruvate from glucose (glycolysis); |

|uses fatty acids / lipids / amino acids |doesn’t use fatty acids; |

|(Krebs cycle) produces CO2 and H2O |(fermentation) produces ethanol / CO2 |

| |(in yeast); |

|(Krebs cycle) produces CO2 and H2O |(fermentation) produces lactate in |

| |animals (humans); |

|NADH produced in both; |

|large amount of ATP (36 per glucose |small amount of ATP (2 per glucose |

|molecule) produced |molecule) produced; |

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