HL Paper 1
The graph shows an example of an enzyme-catalysed reaction.
What does the curve labelled X represent?
A. No inhibition
B. Competitive inhibition
C. Non-competitive inhibition
D. Reversible inhibition
Which is a reduction reaction?
A. ATP changing to ADP
B. Maltose changing to glucose
C. FAD changing to FADH2
D. NADPH changing to NADP
Where in the mitochondrion does the formation of acetyl CoA occur?
Which reaction does not cause a net release of energy?
A. ADP combines with inorganic phosphate to form ATP
B. ATP releases inorganic phosphate to form ADP
C. Loss of hydrogen from reduced NAD
D. Oxidation of reduced FAD
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?
The graph shows the effect of increasing substrate concentration on the rate of an enzyme-catalysed reaction.
Which type of inhibition corresponds to the labelled curves?
Which process does not take place in the stroma of chloroplasts?
A. Synthesis of carbohydrates
B. Fixation of carbon
C. Reduction of NADP
D. Synthesis of ribulose bisphosphate
The diagram shows a section through a thylakoid. Electrons move from X to Y.
[Source: Courtesy Alyse Da Quynh.]
What do the letters X, Y and Z represent?
Which technological advance enabled Calvin to perform his lollipop experiment on the light-independent reactions of photosynthesis in 1949?
A. Methods for tracing radioactive carbon incorporated in molecules produced by the alga Chlorella
B. Development of electron microscopes enabling the molecules produced by the alga Scenedesmus to be viewed
C. Methods for changing the wavelength of light shining on the alga Scenedesmus contained in the lollipop
D. Development of X-ray diffraction techniques enabling the molecules produced by the alga Chlorella to be identified
What term is used for ATP synthesis coupled to electron transport and proton movement?
A. Chemiosmosis
B. Oxidation
C. Glycolysis
D. Cell respiration
Metabolic pathways are dependent on enzyme-catalysed reactions. Which term corresponds with the description?
Two reactions of the Krebs cycle are shown.
What type of reactions are isocitrate and oxalosuccinate undergoing?
Sulfanilamide inhibits an enzyme that catalyses a reaction involving PABA, an intermediate in the synthesis of folate in bacteria. The structures of sulfanilamide and PABA are shown.
The graph shows the rate of reaction with increasing substrate concentration and with fixed low concentration of different types of inhibitors. Which line on the graph represents the effect of sulfanilamide?
The diagram shows a mitochondrion. Which letter indicates the structure where ATP synthase is located?
Which process requires oxygen in aerobic cell respiration?
A. Oxidation of triose phosphate
B. Reduction of hydrogen carriers
C. Maintaining an oxygen concentration gradient in mitochondria
D. Accepting electrons at the end of the electron transport chain
Which products of the light-dependent reactions are used in the Calvin cycle?
A. O2 and hydrogen ions
B. ATP and CO2
C. Electrons and reduced NADP
D. ATP and reduced NADP
The electron micrograph shows part of a plant cell. Where do the light-independent reactions of photosynthesis take place?
What is used to reduce NADP in the light-dependent reactions of photosynthesis?
A. Conversion of ATP into ADP+Pi
B. Electrons from Photosystem I
C. Protons from the thylakoid space
D. Oxygen released by photolysis of water
Where are protons pumped, to allow chemiosmosis in aerobic respiration to occur?
A. From outside the mitochondrion through the double membranes
B. From carrier to carrier in the inner mitochondrial membrane
C. From the matrix of the mitochondrion to the space between the membranes
D. From the space between the membranes to the cytoplasm outside the mitochondrion
The graph shows the effect of substrate concentration on the rate of an enzyme-catalysed reaction with and without an inhibitor.
What do the curves J, K and L on the graph indicate?
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
What does electron tomography allow mitochondria researchers to do?
A. To produce images of cristae.
B. To produce images of ATP synthase molecules.
C. To trace the movement of electrons through the electron transport chain.
D. To visualize oxidation/reduction reactions.
A plant is allowed to photosynthesize in an atmosphere containing radioactive 14C. Where in the plant stem would radioactive sugars be found?
[Source: sinhyu/123rf.com.]
The diagram shows the structure of a chloroplast. Where is chlorophyll located?
Which process occurs during the light-dependent reaction of photosynthesis?
A. ATP, CO2 and H2O are produced.
B. CO2 is used to produce carbohydrates.
C. ATP and O2 are produced.
D. RuBP is phosphorylated.
The first enzyme in the metabolic pathway that produces isoleucine is threonine deaminase. Which graph illustrates the relationship between threonine deaminase activity and threonine concentration?
[Source: © International Baccalaureate Organization 2019]
The graph shows the rate of an enzymatic reaction versus the substrate concentration, in the absence or presence of an enzyme inhibitor.
Which condition is indicated by lines Y and Z?
Which equation is an example of decarboxylation?
A. Pyruvate Acetyl CoA + CO2
B. CO2 + H2O H2CO3
C. CH4 + 2O2 CO2 + 2H2O
D.
Which process is common to photosynthesis and cell respiration?
A. Photolysis
B. The Calvin cycle
C. The Krebs cycle
D. Chemiosmosis
The grey line in each of the graphs below represents the rate of reaction catalysed by an uninhibited enzyme as substrate concentration is increased.
Which graph shows expected results if a competitive inhibitor was added to the reaction?
[Source: © International Baccalaureate Organization 2019]
This reaction occurs in mitochondria.
What explains that this reaction enables energy to be converted into a usable form?
A. The oxidized NAD+ will transfer the energy from the C6 compound to ATP.
B. The chemical energy stored in the C6 compound is used to reduce NAD+ allowing ATP production.
C. Energy stored in the CO2 molecule will generate an electron gradient.
D. The C6 compound is reduced and the energy resulting from the removal of one carbon is used to oxidize NAD+.
What is reduced by Photosystem I ?
A. ADP
B. NADP
C. NAD
D. FAD
ATP is needed to change products of the carboxylation of ribulose bisphosphate into triose phosphate. What other substance is also needed?
A. Rubisco
B. NADP
C. NAD
D. Reduced NADP
The following processes occur in aerobic cell respiration.
I. Decarboxylation of pyruvate
II. Diffusion of protons through ATP synthase
III. Phosphorylation of glucose
Which is the correct sequence for these processes?
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.
The diagram shows some of the intermediate compounds produced during the Calvin cycle. At what stage does carboxylation take place?
Photolysis and carboxylation of RuBP occur during photosynthesis. Where in the chloroplast do these reactions occur?
A summary diagram of photosynthesis is shown. Which molecule represents ATP?
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?
What happens when pyruvate is converted to acetyl CoA in the link reaction?
A. Decarboxylation
B. Phosphorylation
C. Hydrolysis
D. Reduction of pyruvate
Some bacteria can synthesize the amino acid isoleucine from threonine, a process involving five enzymes (E1 to E5) and four intermediary products (P, Q, R and S). The production of isoleucine is controlled by end-product inhibition.
Which statement describes this end-product inhibition?
A. If isoleucine accumulates, it inhibits the production of P.
B. End-product inhibition causes a build-up of intermediary products.
C. Isoleucine inhibits E5, so no more isoleucine is produced.
D. Isoleucine affects the structure of threonine.
The Hill reaction occurs when isolated chloroplasts are exposed to sunlight in the presence of DCPIP. DCPIP replaces NADP as the final electron acceptor for the light-dependent reactions of photosynthesis. What are products of the Hill reaction?
A. H2O and ATP
B. ATP and CO2
C. O2 and ATP
D. C6H12O6 and O2
What molecule functions as the final electron acceptor in the mitochondrial electron transport chain?
A. Oxygen
B. ATP
C. Reduced NAD
D. Reduced FAD
What are final products of photosynthesis and of aerobic respiration?
Which structure in the chloroplast diagram is adapted to carry out chemiosmosis?
[Source: © International Baccalaureate Organization 2019]
The mitochondrion in the electron micrograph shows some features that make it efficient for its function. Which labelled feature allows a rapid build-up of proton concentration for chemiosmosis?
