ESSENTIAL CELL BIOLOGY, 5th EDITION CHAPTER 1:
CELLS: THE FUNDAMENTAL UNITS OF LIFE
Unity and Diversity of Cells
1-1 Living systems are incredibly diverse in size, shape, environment, and behavior. It is
estimated that there are between 10 million and 100 million different species. Despite this
wide variety of organisms, it remains difficult to define what it means to say something is
alive. Which of the following can be described as the smallest living unit?
(a) DNA
(b) cell
(c) organelle
(d) protein
1-2 Indicate whether the following statements are true or false. If the statement is false,
explain why it is false.
A. The Paramecium is a multicellular microorganism covered with hairlike cilia.
B. Cells of different types can have different chemical requirements.
C. The branchlike extensions that sprout from a single nerve cell in a mammalian
brain can extend over several hundred micrometers.
1-3 For each of the following sentences, fill in the blanks with the best word or phrase
selected from the list below. Not all words or phrases will be used; each word or phrase
should be used only once.
Cells can be very diverse: superficially, they come in various sizes, ranging from
bacterial cells such as Lactobacillus, which is a few _ in
length, to larger cells such as a frog’s egg, which has a diameter of about one
. Despite the diversity, cells resemble each other to an
astonishing degree in their chemistry. For example, the same 20
are used to make proteins. Similarly, the genetic
information of all cells is stored in their . Although
contain the same types of molecules as cells, their inability
to reproduce themselves by their own efforts means that they are not considered
living matter.
amino acids micrometer(s) viruses
DNA millimeter(s) yeast
fatty acids plants
meter plasma membranes