Although $D_{2}O$ resembles $H_{2}O$ chemically, yet it is a toxic substance. Explain

Sure, here are the step-by-step solutions: 1. The toxicity of $D_{2}O$ is due to the slower rate of reaction of D+ ions. 2. Enzyme catalysed reactions involve the use of enzymes, which are proteins that help speed up chemical reactions in the body. 3. Enzymes work by binding to a specific substrate (the molecule that the enzyme acts on) and lowering the activation energy needed for the reaction to occur. 4. The lower the activation energy, the faster the reaction can occur. 5. However, when $D_{2}O$ is present, the D+ ions can interfere with the enzyme-substrate binding process and slow down the reaction. 6. This can lead to a decrease in enzyme activity and a slower overall rate of reaction. 7. Therefore, it is important to be aware of the potential toxicity of $D_{2}O$ in enzyme catalysed reactions and take appropriate precautions to minimize its effects.