| Date | November 2020 | Marks available | 1 | Reference code | 20N.1.HL.TZ0.31 |
| Level | Higher level | Paper | Paper 1 | Time zone | TZ0 / no time zone |
| Command term | Question number | 31 | Adapted from | N/A |
Question
Two reactions of the Krebs cycle are shown.
What type of reactions are isocitrate and oxalosuccinate undergoing?
Markscheme
D
Examiners report
Nearly all candidates knew that one type of reaction was decarboxylation and, from the answers offered, the other had to be either oxidation or reduction. More candidates than expected got this wrong and thought that removal of hydrogen from a Krebs cycle intermediate is reduction.
Syllabus sections
- 21M.1.HL.TZ2.30: What molecule functions as the final electron acceptor in the mitochondrial electron...
- 22M.1.HL.TZ2.30: The mitochondrion in the electron micrograph shows some features that make it efficient for...
- 17M.2.HL.TZ2.2b.i: Describe its location.
- 16N.3.SL.TZ0.9a: Outline how a gene gun inserts genes into plants.
- 17M.1.HL.TZ2.14: This reaction occurs in mitochondria. What explains that this reaction enables energy to...
- 16N.1.HL.TZ0.30: Which process requires oxygen in aerobic cell respiration? A. Oxidation of triose...
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19N.1.HL.TZ0.30:
The diagram shows the link reaction between glycolysis and the Krebs cycle.
[Source: © International Baccalaureate Organization 2019]
Which type of reaction is occurring?
A. Pyruvate is carboxylated.
B. CO2 is oxidized.
C. NAD+ is reduced.
D. Pyruvate is phosphorylated.
- 21M.1.SL.TZ2.30: What is a similarity between the testes of males and the ovaries of females in humans? A....
- 18M.1.HL.TZ1.30: What happens when pyruvate is converted to acetyl CoA in the link reaction? A....
- 18N.1.HL.TZ0.29: What term is used for ATP synthesis coupled to electron transport and proton movement? A. ...
- 18N.1.HL.TZ0.10: What are final products of photosynthesis and of aerobic respiration?
-
19N.1.HL.TZ0.31:
Which structure in the chloroplast diagram is adapted to carry out chemiosmosis?
[Source: © International Baccalaureate Organization 2019]
- 17M.1.HL.TZ1.29: The diagram shows a mitochondrion. Which letter indicates the structure where ATP synthase is...
- 21N.1.HL.TZ1.30: Where are protons pumped, to allow chemiosmosis in aerobic respiration to occur? A. From...
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17N.1.HL.TZ0.31:
The image shows a portion of a cell containing a mitochondrion.
[Source: ‘TEM of a mitochondrion’ by Prof. R. Bellairs. Credit: Prof. R. Bellairs. CC BY 4.0.]
Where do glycolysis and electron transport occur?
- 19M.1.HL.TZ1.31: Which process is common to photosynthesis and cell respiration? A. Photolysis B. The Calvin...
- 17M.1.SL.TZ1.1: Which structure found in eukaryotes has a single membrane? A. Nucleus B. Lysosome C....
- 18M.1.HL.TZ2.14: The following processes occur in aerobic cell respiration. I. Decarboxylation of...
- 21M.1.SL.TZ2.29: What is the function of the hormone leptin? A. Increase the uptake of glucose from the...
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21M.1.HL.TZ1.29:
Which equation is an example of decarboxylation?
A. Pyruvate Acetyl CoA + CO2
B. CO2 + H2O H2CO3
C. CH4 + 2O2 CO2 + 2H2O
D.
- 22M.1.HL.TZ1.30: Where in the mitochondrion does the formation of acetyl CoA occur?
- 18N.1.HL.TZ0.31: Which is a reduction reaction? A. ATP changing to ADP B. Maltose changing to glucose C. ...
- 22M.1.HL.TZ2.31: Photolysis and carboxylation of RuBP occur during photosynthesis. Where in the chloroplast do...
- 17M.2.HL.TZ2.2b.ii: Describe its function.
-
22M.2.HL.TZ1.7c:
Explain the role of the electron transport chain in the generation of ATP by cell respiration.
- 17N.1.HL.TZ0.29: Which reaction does not cause a net release of energy? A. ADP combines with inorganic...
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21M.2.HL.TZ1.2b:
Compare and contrast mitochondria and chloroplasts in terms of the substrates they use and the products they produce.
-
18M.2.HL.TZ1.5b:
Compare and contrast the location of ATP synthase and the movement of protons during aerobic cell respiration and photosynthesis.
- 21M.1.HL.TZ1.31: What does electron tomography allow mitochondria researchers to do? A. To produce images of...
- 17M.2.HL.TZ1.5a: Explain how chemical energy for use in the cell is generated by electron transport and...
- 18M.2.HL.TZ2.6a: Explain the stages of aerobic respiration that occur in the mitochondria of eukaryotes.
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19M.1.HL.TZ2.15:
The diagram shows compounds in the Krebs cycle labelled as X, Y and Z.
[Source: © International Baccalaureate Organization 2019]
How many carbon atoms are there in Y and in the acetyl group of acetyl CoA?
- 19M.2.HL.TZ1.7a: Outline the roles of helicase and ligase in DNA replication.
- 20N.2.HL.TZ0.3b: Explain how ATP is generated in mitochondria by chemiosmosis.
-
18N.2.HL.TZ0.6b:
Describe the role of oxygen in aerobic cell respiration.
- 18M.2.HL.TZ1.5c: Using the table, distinguish between the production of ATP, use of oxygen and release of CO2...
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19M.1.HL.TZ1.30:
The electron micrograph shows a section through part of an animal cell.
[Source: https://en.wikipedia.org/wiki/Mitochondrion#/media/File:Mitochondria,mammalian_lung_-TEM.jpg,
by Louisa Howard.]Which process is occurring on the structures labelled X?
A. The Krebs cycle
B. The link reaction
C. Glycolysis
D. Phosphorylation of ADP
