There is no natural death in single called organisms like Amoeba and bacteria because:

Question

Accepted Answer

The correct option is 3:
In single-celled organisms such as Amoeba and bacteria, there is no natural death in the conventional sense because their entire parental body is distributed among the daughter cells during reproduction. When these organisms reproduce, typically through asexual methods like binary fission, the parent cell simply divides into two or more daughter cells. There is no residual "old" or "dead" body left behind. Essentially, the parent organism continues to live on in its offspring, making them biologically "immortal" under ideal conditions. This contrasts sharply with multicellular organisms, where specialized cells form tissues and organs, and the death of the organism is a distinct event from the reproduction of its cells.

The incorrect option is 1: They cannot reproduce sexually.
While many single-celled organisms, like bacteria, primarily reproduce asexually, some can engage in forms of genetic exchange that are analogous to sexual reproduction, such as conjugation (as mentioned in the Google search results). However, whether they reproduce sexually or asexually does not directly explain the absence of natural death. The key factor is how the parental biomass is handled during reproduction.

The incorrect option is 2: They reproduce by binary fission.
Reproducing by binary fission is indeed a common method of asexual reproduction for organisms like Amoeba and bacteria. While binary fission is the process by which the parental body is distributed, stating that they "reproduce by binary fission" alone does not fully explain *why* there is no natural death. The distribution of the parental material is the critical consequence of binary fission that leads to their biological immortality.

The incorrect option is 4: They are microscopic.
Being microscopic describes the size of these organisms and has no direct bearing on the concept of natural death. Many multicellular organisms are also microscopic (e.g., rotifers), but they still undergo natural death. The size of an organism does not dictate its mortality.