Read the following passage. Notice that there are numbers at the end of some of the sentences
Refer to these numbers when answering the question(s) below.
Melanoma cells metastasize by leaving the primary tumor and entering the bloodstream,
which carries them to distant parts of the body. The cancer cells leave the bloodstream by
crossing the capillary basal lamina to enter another tissue (1). As a cancer researcher you
think that somehow preventing the cancer cells from crossing the basal lamina of the blood
vessels will inhibit metastasis (2). You believe that if you block the integrin receptors on the
melanoma cells from binding to the extracellular matrix proteins of the basal lamina, then the
cells will not be able to adhere to the basal lamina and therefore will not be able to migrate
across it (3).
You and your colleagues set about to make antibodies that will bind specifically to the
integrins on the surface of the melanoma cells, preventing them from adhering to the proteins
in the basal lamina. Once you have these integrin-specific antibodies, you test them on
cancer cells in culture to see if they prevent the cells from crossing an artificial basal lamina.
To do this, you and you colleagues set up nine cultures of cancer cells. You treat three
cultures with the integrin-specific antibody. You treat three more cultures with a non-specific
antibody that does not bind to integrins. Three cultures of cells are not treated with
antibodies. (4).
In the passage above, sentence number 2 is:
A. support for their idea that blocking integrin
function inhibits some tumor cells from
binding the basal lamina.
B. proof that their idea about blocking
integrins will prevent metastasis.
C. an observation.
D. a prediction.
E. a hypothesis.
E
You might also like to view...
In the reactions of glycolysis, acetyl-CoA formation and the citric acid cycle, chemical energy is transferred to the bonds in:
A. ATP. B. electron carriers. C. fats. D. a and b are correct. E. a, b, and c are all correct.
Huntington disease is caused by expansion of the trinucleotide repeat region of the HD gene that results in the production of a Huntingtin protein with an expanded number of glutamines. An animal model with most features of this syndrome could be created by
A) adding a transgene containing a disease-causing mutant allele of the HD gene to a mouse or primate genome. B) adding a transgene containing a wild-type copy of the HD gene to a mouse or primate genome. C) knocking out both copies of the HD gene from a mouse or primate genome. D) knocking out one copy of the HD gene from a mouse or primate genome.
A general trend in the structure of many biomolecules is
A) that the order and bonding of monomers form the basis for the secondary and tertiary structure of the polymer. B) that they are all soluble in water independent of the size of the polymer. C) that each class of biomolecule forms one type of secondary structure independent of the order of the monomers in the polymer. D) that each class of biomolecule can form either fibrous or globular conformations depending on the chemical conditions inside the cell. E) that four different monomers form the basis for the functional and structural properties of each polymer.
Which of the following explains why females are more likely to be "choosy" about mating partners than males?
a. Females are more limited in the number of offspring they can produce than males are b. Eggs require more energy to produce than sperm c. Males can fertilize the eggs of multiple females, while a female's egg can only be fertilized by a single male d. All of these