Cell Size Free Response Question

Object                                     Approximate size
ribosomes                                    0.01μm
viruses                                         0.05μm to 0.1μm
smallest bacteria (mycoplasms)     0.1μm to 1.0μm
mitochondria                                1.0μm to 10μm
most bacteria cells                        1.0μm to 10μm
most animal cells                          10μm to 100μm
 

Consider the chart above and the information you have read regarding cell biology.

a) Why is it very unlikely that something smaller than 0.1μm would be considered a living thing? (Use your definition of life to support your argument.)
b) Why is it impossible for a one-celled animal to reach a size larger than 1000μm?