B an increase in the number of autotrophs available

B. an increase in the number of autotrophs
available for food
C. a decrease in the incidence of disease
D. an increase in competition between the deer
A. parasitism B. mutualism
C. saprophytism D. commensalism
page 9 Biodiversity and Population Size
45. Nitrogen-°xing bacteria live on the roots of
leguminous plants in swellings called nodules.
The bacteria synthesize nitrogen compounds that
are used by the plants, and the plants provide
moisture and nutrients for the bacteria. The
interaction between the nitrogen-°xing bacteria and
the leguminous plants is known as

46. The role of an organism within a community is
known as its
49. Select the term that is most closely associated
with the following relationship:
Protozoans digest cellulose within the
digestive tract of termites. The termites
receive nutrients, and the protozoans are
provided with a niche.
47. A ²ea in the fur of a mouse bene°ts at the
mouse’s expense. This type of relationship is
known as
48. In a forest in northern New York State, the most
intense competition would most likely occur
between white-tailed deer and
50. Select the term that is most closely associated
with the following relationship:
Orchids grow on large tropical trees. The
orchids depend on the support o±ered by the
trees but do not harm the trees.
A. Predation B. Saprophytism
C. Commensalism D. Mutualism

51. A group of 100 female water ²eas was placed
in each of three culture jars of di±erent sizes.
The graph shows the average number of o±spring
produced per female each day in each jar. The
information in the graph suggests that
52. The graph shows the changes in two populations
of herbivores in a grassy °eld. A possible reason
for these changes is that