Video Transcript
Mycoplasma genitalium is a
single-celled bacterium thought to be one of the smallest living organisms. The biggest living animal, the blue
whale, pictured, is thought to have around three times 10 to the 16th cells. Which principle of cell theory does
this evidence support? (A) Cells are the basic functional
unit of living organisms. (B) All living organisms are made
up of one or more cells. Or (C) all cells come from
preexisting cells.
Cell theory is one of the unifying
theories in biology that was developed over hundreds of years by many different
scientists. It has three principles or
postulates. Let’s go through each one to see
which best describes this comparison of the smallest and largest living
organisms.
The first principle states that all
living things are made of at least one cell, from the smallest organisms that are
just a single cell to the largest organisms like this whale with around three times
10 to the 16th cells. All living things are made of at
least one cell. So answer choice (B) seems to be
correct, but let’s look at the other two principles to be certain.
The second principle states that
cells are the basic unit of life. We’re all made up of cells that
work together to give us life. This doesn’t really describe the
comparison in cell numbers, so answer choice (A) is incorrect.
The third principle states that all
cells come from preexisting cells. This principle describes more about
how cells divide to form copies of themselves, which doesn’t describe the comparison
of the smallest organism to the largest. So answer choice (C) is
incorrect.
Therefore, the comparison between
the smallest and largest organisms in terms of their cell number is evidence that
supports the principle of cell theory, which states that all living organisms are
made up of one or more cells.
