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Biology · Enzymes · Substrate concentration
Effect of [H₂O₂] on catalase activity
A filter-paper disc soaked in yeast suspension (catalase) is dropped into hydrogen peroxide. Oxygen bubbles form on the disc until it floats up. The time it takes to rise is a measure of how fast the reaction is going.
t = 0.0 s
Results table
| [H₂O₂] | t (s) | rate (1/t) |
|---|---|---|
| 1.0 % | — | — |
| 2.0 % | — | — |
| 4.0 % | — | — |
| 6.0 % | — | — |
| 8.0 % | — | — |
| 10.0 % | — | — |
Exam-style questions
1. At low substrate concentration, doubling [H₂O₂] approximately doubles the rate. Why?
2. At high substrate concentration, rate plateaus. Limiting factor?
3. Why use the SAME yeast volume in every tube?
4. Why does the disc RISE faster in higher [H₂O₂]?