AP BIOLOGY

Detailed explanation-1: -Cancers is the result of loss of multicellular traits; thus, it is a disease of multicellularity. Caveat: Many of the so-called multicellular traits are also expressed by unicellular organisms and their loss can result in cancer-like mutants.

Detailed explanation-2: -Non-malignant infectious neoplasms occur pervasively in multicellular life, but oncogenic progression to malignancy is often uncertain. Evidence from humans and domestic animals shows that non-malignant infectious neoplasms can develop into cancer, although generally with low frequency.

Detailed explanation-3: -This is consistent with the observation that neoplasms are not exclusive to high-order organisms but appear across the entire range of multicellular organisms, including metazoans, fungi, plants and algae (Aktipis et al, 2015).

Detailed explanation-4: -The simple answer is no-single-celled organisms cannot become cancerous. Since a complete organism consists only of one cell, it does not have multicellular tissues from which a tumor could arise.

Detailed explanation-5: -Cancer represents a breakdown of molecular mechanisms evolved by multicellular life to impose constraints on cell growth, resulting in more “primitive” proliferative cellular phenotypes.