Video Transcript
Which of the following is a
difference between eubacteria and archaebacteria? (A) The number of cells per
organism is larger for eubacteria than for archaebacteria. (B) They contain different
arrangements of membranous organelles. (C) Their cell walls have different
compositions. (D) The structures of their nuclear
membranes differ significantly.
This question is asking us about
the difference between eubacteria and archaebacteria. These are both organisms that fall
within the kingdom Monera, which are made up of prokaryotes. A defining feature of prokaryotes
is that they do not contain a nucleus to contain their DNA. Instead, it floats freely in the
cytoplasm, often as a single, circular chromosome.
Because prokaryotes like eubacteria
and archaebacteria don’t contain a nucleus, they won’t contain a nuclear membrane,
so we can eliminate answer choice (D).
Prokaryotes also don’t contain
membrane-bound organelles, which are generally only found in eukaryotes. So we can eliminate answer choice
(B).
Prokaryotic organisms are typically
unicellular. This means that for most of the
organisms in the domains archaebacteria and eubacteria, there’s only one cell per
organism. So we can eliminate answer choice
(A).
Another feature of prokaryotes is
that many contain three layers to separate their inner contents from the outside
environment. These are the capsule, the cell
wall, and the cell membrane. In eubacteria, the cell wall
contains peptidoglycan, whereas archaebacteria have cell walls with a different
composition. Therefore, the option that best
identifies the difference between eubacteria and archaebacteria is given by answer
choice (C). Their cell walls have different
compositions.
