Final answer:
The claim that the body can remove any quantity of an unwanted substance is false. While the immune system is robust, it can be overwhelmed or evaded by pathogens, and there are limits to how quickly the body can excrete toxins.
Step-by-step explanation:
The statement that the body has very efficient internal defenses which can remove any quantity of an unwanted substance is false. The immunological system is indeed sophisticated and capable of defending against many pathogens and foreign substances through mechanisms such as phagocytosis and the production of antibodies. However, this system has its limits. Certain pathogens can evade or overwhelm the body's defenses, especially in large quantities or when the body is compromised due to other factors like illness or stress. Furthermore, toxins and substances can also accumulate faster than the body can excrete them, leading to toxicity or disease. The body strives to maintain homeostasis and uses its defenses to combat foreign invaders, but it is not infallible.