A Level Biology Practice Exam

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What type of stem cell is described as totipotent?

a stem cell that can only form tissue-specific cells
a stem cell that can differentiate into any type of cell and form a whole organism
a stem cell that is limited to forming only blood cells
the initial precursor cells in embryonic development

The correct answer is: a stem cell that can differentiate into any type of cell and form a whole organism

Totipotent stem cells possess the remarkable ability to differentiate into any type of cell in the body, as well as to give rise to an entire organism. This capability arises from the fact that totipotent cells are the first cells formed after fertilization, specifically the zygote and the very early blastomeres. At this stage, the cells have not yet begun to specialize, meaning they can contribute to both embryonic and extra-embryonic tissues (such as the placenta). In contrast, other types of stem cells, such as pluripotent or multipotent cells, have more limited differentiation potential. Pluripotent stem cells can form nearly any cell type but cannot form a whole organism because they cannot develop into extra-embryonic tissues. Multipotent stem cells are even more restricted, as they can only differentiate into a specific cell lineage. Therefore, the ability of totipotent stem cells to give rise to both the complete organism and its supporting structures makes option B the accurate description of totipotent stem cells.