Topic Test : Properties of Life          [answers given below]

1.   Self-replicating RNA molecules exhibit all the characteristics of living organisms.
2.  Most of the metabolic reactions that occur in cells are at equilibrium.
3.  Both Prokaryotes and Eukaryotes compartmentalize cellular functions in specific organelles.

Multiple Choice
4.  Mitochondria from plant cells and animal cells
   a)  have the same molecular structure but different functions
   b)  have a different molecular structure but the same function
   c)  are similar in both structure and function
   d)  vary widely in molecular structure and function

5.  Cell metabolism is best described as
 a)  random reactions which release of energy stored carbon compounds
b)  a closed equilibrium system with no exchange of material or energy with the environment
c)  only endergonic reactions which expend energy driving reactions
d)  reactions that use energy and material from the environment to synthesize cell components
                    and do metabolic work

6.  The observation that cell structure and function are similar from organism to organism, despite
 differences in cell specialization and organism complexity provides evidence that
 a)  all cells have evolved from a common ancestor
 b)  cell function is independent of cell function
 c)  all cells have the same blueprint for reproduction
 d)  cells do not evolve

Short Answer/Essay

7.  How might the differences in cellular organization of Prokaryotes and Eukaryotes affect their metabolic efficiency?

8.  Why is the ability of a living system to maintain its metabolic reactions far from chemical equilibrium essential for life as we know it?

9.  What essential characteristic(s) of life separate(s) viruses from cells?













Topic Test  : Properties of Life       Answers

1.      False.

2.      False. Energy and material fluxes in cells are far from chemical equilibrium.

3.      False. Compartmentalization of cellular functions in Eukaryotes separates them from

4.      c. With only minor differences, mitochondria from plants and animals have the same
             structure and function.

5.      d. Cells exchange energy and material with the environment to counteract the tendency
             toward disorder.

6.      a.

7.      Compartmentalization of metabolic processes reduces the dependence of metabolism on
    molecular diffusion, a relatively slow process. Maintaining the flux of metabolites in a
    particular pathway in close proximity with the molecular machinery (enzymes) increases
    the efficiency of metabolic reactions, enabling cells to grow larger and specialize.

8.      The organization and complexity of cell structure and function is maintained only through a
    continual flux of energy and materials to reverse the natural tendency towards disorder
    (increase in entropy) where all chemical reactions are at thermodynamic equilibrium.

9.      While some biologists consider viruses to be living organisms, the most would agree that viruses,
    while capable of carrying out most all of the characteristics essential for life, are incapable of
    reproducing outside of a host cell. Since the ability of cells to reproduce independently of other
    cells is a defining characteristic of life, viruses are generally not considered to be living