A yeast suspension is boiled for 5 minutes, then cooled under running tap water. Hydrogen peroxide is added and a glowing splint is inserted, exactly as was done with an unboiled sample. What is observed?
ABubbles form in the mixture but the splint does not relight.
BNo bubbles form in the mixture but the splint still relights.
CThe mixture bubbles vigorously, exactly as it did before boiling, and the splint relights when it is inserted.
DNo bubbles form in the mixture and the splint does not relight.
Explanation
Boiling denatures the catalase enzyme in the yeast, so it can no longer break down hydrogen peroxide. With no oxygen produced, there is no bubbling and the glowing splint is not relit.
Derived from ZIMSEC Biology Paper 4 (Practical Test), Jun 2004, Q2