Which of the following statements is false?

Question

Accepted Answer

1.  **Blood Clotting:** Calcium ions ($Ca^{2+}$) play a very important role in the coagulation (clotting) of blood . Thus, the first statement is true.
2.  **Heart Beat:** Calcium ions are essential for muscle contraction . The heart is a muscular organ, and its rhythmic contraction (beating) relies on the regulation of $Ca^{2+}$ levels. Low levels of $Ca^{2+}$ can lead to tetany (wild contractions) . Therefore, the statement that $Ca^{2+}$ ions are *not* important for the regular beating of the heart is **false**.
3.  **Photosynthesis:** Chlorophyll, the green pigment responsible for photosynthesis in plants, is a coordination compound of magnesium ($Mg^{2+}$) . Thus, the third statement is true.
4.  **ATP Complex:** In biological systems, Magnesium ions ($Mg^{2+}$) are required as cofactors for enzymes that utilise ATP in phosphate transfer. $Mg^{2+}$ forms a complex with ATP (Adenosine Triphosphate), making it biologically active . Thus, the fourth statement is true.

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