Download Name: Date: Symbiotic Relationship Practice PROCEDURE, Part 1

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Date:
Symbiotic Relationship Practice
PROCEDURE, Part 1: Look at each relationship that is described. Determine if the relationship is one of mutualism,
commensalism or parasitism. Explain your reasons for picking each answer.
1. The remora is a bony fish that has a modified dorsal fin. The fin has been modified into a sucker with which it
forms a temporary attachment to the shark. When the shark feeds, the remora picks up scraps of food. The
shark makes no attempt to prey on the remora.
2. During the day the bobtailed squid, Euprymna scolopes, remains buried in the sand of shallow reef flats. As the
sun sets, the nocturnal animal emerges from its safe hiding place and searches for food. In the moonlit night,
the squid would appear as a dark silhouette when it swims through the water and would be easily detected by
predatory fish from below. The squid camouflages itself by projecting light downward from its light organ.
Inside the light organ are luminescent bacteria, Vibrio fischeri, that produce light. The squid provides an
environment for the bacteria to live that is very rich in amino acids.
3. Mycobacterium leprae is a bacterium that takes up residence in the Schwann cells (part of nerve cells in
humans). The bacterium receives nourishment. This bacterium eventually triggers the host to produce an
autoimmune attack on the cells that leads to the cell’s destruction. The resulting loss of sensation makes it
difficult to avoid injury to the extremities.
4. Legumes, a type of plant, can survive independently of a symbiotic relationship if they live in soil that is rich in
nitrates. Rhizobia, a type of bacteria, can live freely in soil. However, Rhizobia do not fix nitrogen if they live
alone. If the soil is nitrate poor, then the legume will form a relationship with Rhizobia. The bacteria live within
the tissue of the legume and receives nutrition. The bacteria will then fix nitrogen so the legumes will receive
nitrogen in order to make proteins and DNA.
PROCEDURE, Part 2: Below are three sets of graphs used to show mutualism, commensalisms or parasitism. Identify
each set of graphs by its type of symbiotic relationship. Then explain why that set of graphs is either mutualism,
commensalisms or parasitism.
Set A
Average
number of
Organism
When
Living
Average
number of
Organism
When
Living
Separately
Together
3
6
9
12
3
6
Time (months)
9
12
Time (months)
Type of symbiotic relationship demonstrated by graphs (Set A):
Explanation:
Set B
Average
Number of
Organism
When
Living
Average
Number of
Organism
When
Living
Separately
Together
3
6
9
12
Time (months)
3
6
9
12
Time (months)
Type of symbiotic relationship demonstrated by graphs (Set B):
Explanation:
Set C
Average
Number of
Organism
When
Living
Average
Number of
Organism
When
Living
Separately
Together
3
6
9
12
Time (months)
Type of symbiotic relationship demonstrated by graphs (Set C):
Explanation:
3
6
9
12
Time (months)