Malonate inhibits a reaction in the Krebs cycle - AQA - A-Level Biology - Question 2 - 2021 - Paper 1

Malonate acts as a competitive inhibitor for an enzyme involved in the Krebs cycle, specifically succinate dehydrogenase. By inhibiting this enzyme, malonate prevents the conversion of succinate to fumarate in the Krebs cycle.

As the cycle slows down, less ATP is produced, leading to reduced availability of energy needed for cellular processes, including those required for optimal oxygen utilization. Consequently, less oxygen is used for cellular respiration, which leads to a decrease in overall oxygen uptake.