Enzymes — IGCSE Sciences - Co-Ordinated (0654) questions by topic
Identifying which of five labelled enzymes are active at a given pH from a table, and reading an amylase activity-against-temperature graph to find an optimum, are the core tasks across the 6 enzyme questions set in 2023 and 2024, each worth 10 or 11 marks.
State, identify and describe are the top command words, with complete and circle used where a diagram or table must be marked directly rather than a value calculated. Because matching an enzyme's pH range to a description depends on reading a table accurately under time pressure, submit your enzyme-identification answers for instant marking to catch any misread row before it costs marks on a linked question.
What examiners look for
- A recurring criticism is that few candidates suggested nitrogen is a chemical element found in all enzymes.
- Examiners note the only smaller molecule correctly identified by candidates was amino acids, from which proteins are made.
- Reports flag that some candidates ticked more than two statements where exactly two were required, losing the mark.
May–June 2024, Paper 31
Fig. 10.1 shows the activity of some bacterial enzymes (A, B, C, D, E) at different temperatures (enzyme activity against temperature / C from -10 to 110). Complete the sentences…
Answer this question and get it marked →October–November 2024, Paper 32
Table 7.1 shows some information about five different enzymes: A (pH range 4.5-8.5, pH value most active 6.5); B (7.0-8.0, 7.5); C (7.0-11.0, 9.0); D (1.0-3.0, 1.5); E (6.0-8.5,…
Answer this question and get it marked →October–November 2024, Paper 33
Table 7.1 shows some information about five different enzymes: A (pH range 4.5-8.5, pH value most active 6.5); B (7.0-8.0, 7.5); C (7.0-11.0, 9.0); D (1.0-3.0, 1.5); E (6.0-8.5,…
Answer this question and get it marked →May–June 2023, Paper 42
Photosynthesis is an enzyme-controlled reaction. Fig. 4.1 is a graph showing the effect of temperature on the rate of photosynthesis (rate against temperature 0–50 °C, peak then…
Answer this question and get it marked →October–November 2023, Paper 33
Enzymes are only active within a specific pH range. Table 7.1 shows the specific pH range for five different enzymes: A 1-5, B 5-9, C 7-12, D 2-3, E 10-12. Identify the enzyme(s)…
Answer this question and get it marked →October–November 2023, Paper 41
A scientist measures the activity of the enzyme amylase at different temperatures. Fig. 7.1 shows a graph of the results (enzyme activity / arbitrary units on the y-axis 0-120,…
Answer this question and get it marked →Other IGCSE Sciences - Co-Ordinated topics
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- Metals (11)
- Atoms, elements and compounds (10)
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