What is a common characteristic of toxins like rattlesnake venom and ricin?

Rattlesnake venom and ricin are both known for their toxic properties, which can lead to severe health effects or death in humans. Rattlesnake venom contains a complex mixture of enzymes and proteins that can disrupt blood clotting, damage tissue, and cause paralysis, potentially leading to fatal outcomes if not treated promptly. Ricin, a highly potent protein toxin derived from castor beans, can interfere with protein synthesis within cells, causing cell death and systemic failure if ingested or inhaled. The common characteristic of these substances is their potential lethality, demonstrating how certain biological toxins can pose significant dangers to human health.

In contrast, options suggesting that these toxins are safe for consumption do not accurately reflect their harmful nature. Promoting plant growth would also be misleading, as these substances primarily focus on harming biological systems rather than benefitting them. Although certain toxins may have medical applications after significant modification and testing, rattlesnake venom and ricin are not typically used in therapeutics directly, as their natural forms are extremely dangerous. Thus, the defining trait shared between rattlesnake venom and ricin is their capacity to cause fatal harm to humans.