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, 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 hair-like 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
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, 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
1-4 How does cellular specialization serve multicellular organisms and how might a high
degree of specialization be detrimental?
1-5 The flow of genetic information is controlled by a series of biochemical reactions that
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, result in the production of proteins, each with its own specific order of amino acids.
Choose the correct series of biochemical reactions from the options presented here.
(a) replication, transcription, translation
(b) replication, translation, transcription
(c) translation, transcription, replication
(d) translation, replication, transcription
1-6 Proteins are important architectural and catalytic components within the cell, helping to
determine its chemistry, its shape, and its ability to respond to changes in the
environment. Remarkably, all of the different proteins in a cell are made from the same
20 . By linking them in different sequences, the cell can make protein
molecules with different conformations and surface chemistries, and therefore different
functions.
(a) nucleotides.
(b) sugars.
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